Gunilla Oberg | University of British Columbia (original) (raw)

Science for policy by Gunilla Oberg

Enviroment International, 2019

In the past few decades, there has been a dramatic increase in scientific publications dealing wi... more In the past few decades, there has been a dramatic increase in scientific publications dealing with contaminants of emerging concern (CECs) and the escalating publication rate makes it close to impossible for individual researchers to get an overview of the field. Assuring the relevance and quality of the research conducted in any research field is a crucially important task. The rapidly increasing publication rates imply that review papers will play a progressively more central role to that end. The aim of the present paper is to critically assess whether reviews dealing with contaminants of emerging concern (CECs) are effective vehicles for a healthy dialogue about methodological weaknesses, uncertainties, research gaps and the future direction of the field. We carried out a tiered content-analysis of CEC review papers. Relevant papers were identified through searches in Web of Science (Clarivate), leading to the identification of 6391 original research papers of which 193 are review papers. We find that the majority of CEC reviews are written as if they are comprehensive, even though this clearly is not the case. A minority (~20%) take a critical-analytical approach to the reviewing task and identify weaknesses and research gaps. The following widespread tendencies in CEC research papers are commonly noted as concerning: to equate removal of CECs to ‘decreased concentrations in the effluent’; to focus on parent substances and not concern oneself with degradation products; to focus on most commonly studied substances rather than those of most concern; to not deal with the corollary of our inability to detect or assess the risk for all substances, and to give insufficient attention to uncertainties and the unknown. Several critical-analytical reviews are among the highest cited, which suggests that they have the potential to function as effective vehicles for a healthy dialogue on these topics. On the other hand, it would appear that the concerns expressed in these reviews have a limited impact, as the same concerns are repeated over time. This might be due to a tendency among review authors to express their concerns implicitly, instead of clearly spelling them out. Our study suggests that CEC reviews presently fail to provide adequate and reliable guidance regarding the relevance and quality of research in the field. We argue that the overwhelming number of publications in combination with a lack of quality criteria for review papers are reasons to this failure: it is well documented that choices made during the reviewing process have a major impact on the outcome of a review. These choices include: search engine; the criteria used to include or exclude papers; the criteria used to assess the quality of the data generated in the research papers included; the criteria used for the choice of substances/ organisms/ technologies reported on. The lack of transparent procedures makes it very difficult, if not impossible, to assess the quality of the findings presented or to put those findings in context. In this light, it is noteworthy that criteria for a good review paper are rarely spelled out by peer-reviewed journals or included in instructions on scientific writing.

The dramatic increase in publications is a challenge for the entire research community, particularly for research fields that are expected to provide policy-relevant data. We argue that only when peer-reviewed journals start specifying quality criteria for review papers, can such papers be relied upon to provide adequate and strategic guidance on the development of CEC research. We anticipate that our findings and conclusions are valid for many other research fields.

Critical Reviews in Environmental Science and Technology, 2019

The need for better nutrient management has spurred efforts towards more comprehensive recycling ... more The need for better nutrient management has spurred efforts towards more comprehensive recycling of nutrients contained in human excreta to agriculture. Research in this direction has intensified throughout the past years, continuously unfolding new knowledge and technologies. The present review aspires to provide a systematic synthesis of the field by providing an accessible overview of terminology, recovery pathways and treatment options, and products rendered by treatment. Our synthesis suggests that, rather than focusing on a specific recovery pathway or product and on a limited set of nutrients, there is scope for exploring how to maximize nutrient recovery by combining individual pathways and products and including a broader range of nutrients. To this end, finding ways to more effectively share and consolidate knowledge and information on recovery pathways and products would be beneficial. The present review aims to provide a template that aims to facilitate designing human excreta management for maximum nutrient recovery, and that can serve as foundation for organizing and categorizing information for more effective sharing and consolidation.

Risk Analysis, 2018

It is well documented that more research can lead to hardened positions, particularly when dealin... more It is well documented that more research can lead to hardened positions, particularly when dealing with complex, controversial, and value‐laden issues. This study is an attempt to unveil underlying values in a contemporary debate, where both sides use scientific evidence to support their argument. We analyze the problem framing, vocabulary, interpretation of evidence, and policy recommendations, with particular attention to the framing of nature and technology. We find clear differences between the two arguments. One side stress that there is no evidence that the present approach is causing harm to humans or the environment, does not ruminate on uncertainties to that end, references nature's ability to handle the problem, and indicates distrust in technological solutions. In contrast, the other side focuses on uncertainties, particularly the lack of knowledge about potential environmental effects and signals trust in technological development and human intervention as the solution. Our study suggests that the two sides’ diverging interpretations are tied to their perception of nature: vulnerable to human activities versus robust and able to handle human impacts. The two sides also seem to hold diverging views of technology, but there are indications that this might be rooted in their perception of governance and economy rather than about technology per se. We conclude that there is a need to further investigate how scientific arguments are related to worldviews, to see how (if at all) worldview typologies can help us to understand how value‐based judgments are embedded in science advice, and the impact these have on policy preferences.

Sewage management exhibits all characteristics of a ‘wicked’ problem: it is framed as a technical... more Sewage management exhibits all characteristics of a ‘wicked’ problem: it is framed as a technical problem even though it is surrounded by scientific uncertainties, and the framing hides both value-frameworks and the unequal distribution of risks and benefits. In this study, we analyze how uncertainties and the limits of scientific knowledge are approached and communicated in two jurisdictions that presently are in the process of revising their regulatory frameworks pertaining to land application of the residuals remaining after sewage treatment: Sweden, which is governed by the EU Directive 86/278/EEG, and the Canadian province of British Columbia, which draws heavily on the US EPA503 Rule. We find that the two jurisdictions take very different approaches to uncertainty and ignorance: The BC framing rests on the presumption that no evidence of harm can be taken as evidence that the practice is safe and draws on a persuasive narrative to that end. In contrast, the Swedish narrative rests on the presumption that absence of evidence cannot be taken as evidence of absence and that it therefore is better to hark on the safe side, when it is technically possible. The BC framing is indicative of a classic risk assessment approach and public acceptance is addressed as a knowledge deficit problem. The pursuasive tone and lack of transparency appears to negatively impact residents' trust in regulatory agencies. The Swedish framework takes a more precautionary approach, combining risk assessment with hazard determination and uses a deliberative and transparent approach, seemingly producing more socially ‘robust’ knowledge. Even though Sweden pays considerable attention to the challenges involved in making assessments based on limited data, the limits of science-based knowledge is not touched upon. In fact, Sweden and BC signal a similar view on humanities' ability to create reliable knowldge: given sufficient time, it will eveutally be possible to close the knowledge gaps and develop reliable (technical) solutions. We argue that treating the problem as if it is a technical challenge at its heart hides social aspects and forward that the value-judgements that underlie hazard determinations and risk assessments must be transparently identified and communicated, including the assessment of uncertainty and the limits of science, to avoid increased polarization and thus hardened conflicts.

Management of biosolids is primarily handled as a technical matter. Land application is a cost ef... more Management of biosolids is primarily handled as a technical matter. Land application is a cost effective and commonly used method of disposal that offers additional ecological and agricultural benefits. Implementation is, however, often met by public concerns regarding potential human and environmental health impacts. It is commonly agreed that the effectiveness of a policy hinges on its ability to describe clear, attainable goals. It also requires transparency in the process underlying trade-off decisions, in particular those related to the distribution of risks and benefits. Consequently it is critical to not only specify what the problem is but also offer an overarching hierarchy amongst stated objectives. This study examines biosolids land application policies in Sweden and the Province of British Columbia, Canada, focusing on the prioritization of objectives. The regulators’ intention is clearly spelled out in both jurisdictions: to mitigate the residual’s double nature as something hat has both the potential to cause harm and the potential to be a great resource. The study shows that sub-objectives are not explicitly spelled out and the objectives hierarchy is consequently concealed, as is the process underlying trade-off decisions. Not least important: predicted outcomes are also not explicitly spelled out, including how risks and benefits are distributed. Neither jurisdiction pays any attention to social implications of land-application, such as unequal distribution of risks and benefits. We propose that the conflicts so often seen in relation to the implementation of biosolids management policies in part result from approaching the problem as if it were a ‘tame’ one, even though it represents a classic ‘wicked problem’, requiring trade-offs among conflicting objectives. We forward that an objectives hierarchy must be transparently developed where ethical aspects of biosolids management are clearly identified to avoid increased polarization and thus hardened conflicts.

For many in the Global North, urban life means that your shit is not your problem. We postulate t... more For many in the Global North, urban life means that your shit is not your problem. We postulate that a possible reason for the global sanitation failure in urban areas is a disconnect between sanitation expectations-what we term the urban sanitation imaginary-and the practices required by proposed sanitation solutions. The case study presented here is based on interviews with residents of Villa Lamadrid, a marginalized neighborhood in Buenos Aires, Argentina, which faces significant public health impacts from an inadequate sewage management system. We solicited feedback regarding specific sanitation technologies frequently prescribed for poor urban communities-among them a urine diversion dry toilet with dehydration vaults. Even as this system is posited as 'sustainable' for the context of Villa Lamadrid in terms of ecological and economic factors, conversations with residents revealed why this option might not be sustainable in terms of social expectations. On the basis of interviews with community members we have defined four aspects of residents' urban sanitation imaginaries that we consider highly relevant for any consideration of sanitation solutions in this context: (1) an urban citizen does not engage physically or mentally with their shit or its management; (2) an appropriate urban sanitation system requires flushing; (3) systems that require user's engagement with their shit and its management signify rural, underdeveloped, and backward lifestyles; and (4) urban sanitation is a state responsibility, not a local one. Highlighting the urban sanitation imaginary methodologically and analytically goes beyond a discussion of culturally and contextually appropriate technologies. It examines linkages between user expectations and notions of urban citizenship and modernity. Ultimately it also draws attention to the sociopolitical dynamics and environmental justice issues embedded in discussions of sanitation and hygiene. While some of our results are specific to the Villa Lamadrid context, our research more generally suggests the need to consider sanitation imaginaries to reframe the discussion on sanitation interventions, particularly in underserved and impoverished urban areas.

UBC Program of Water Governance, Mar 2013

Ecology and Society, 2014

The need for a radical shift to more iterative and adaptive solutions in sewage management is inc... more The need for a radical shift to more iterative and adaptive solutions in sewage management is increasingly recognized, but our ability to achieve such a shift is constrained by inertia to change. Here, we describe planning in two metropolitan areas that are upgrading their sewage systems, based on interviews with central actors and official documents. Using new institutionalism and concentrating on changes in normative, regulative, and cognitive patterns, we analyze if obstacles to the uptake of innovations can be understood in light of how these patterns counteract institutional change. Our aim is to understand obstacles to reformers implementing a wider vision of sewage management. Our study suggests that even though both Buenos Aires and Vancouver emphasize the need for integrated water management, it does not seem likely that either will implement a solution that challenges the end-of-pipe paradigm. We conclude that the main obstacle to change is the deeply rooted cognitive notion that sewage is waste. Framed as waste, sewage becomes something a community needs to get rid of, the faster the better. The notion of sewage being a worthless burden means that it is expected to generate costs, not revenues. When sewage is foremost framed as waste, the conventional linear end-of-pipe solution becomes the most logical way to manage it. We argue that this notion permeates the entire institutional structure and that its power is not recognized. We speculate on whether a shift toward iterative and adaptive solutions might be facilitated if sewage were redefined outside the water management umbrella and instead understood as resource management (for example, energy and nutrients), and if organizations responsible for delivering sewage services were reorganized accordingly.

Enviromental Management, 2005

Management by objectives (MBO) is a technique for integrating ecological concerns into national ... more Management by objectives (MBO) is a technique
for integrating ecological concerns into national political
and administrative structures. Politicians determine
environmental objectives and interim targets to be implemented
and assessed by civil servants in national, regional,
and local contexts. Well-developed organizational communication
is a prerequisite for MBO. However, communicationrelated
obstacles can arise when using MBO in public
environmental management. We examine communicative
aspects of environmental MBO, looking specifically at the
implementation, administration, and assessment of Swedish
environmental quality objectives. Our argument is illustrated
by quotations from individual and focus group interviews.
We conclude that communicative problems may arise, because
different actors interpret messages from different
perspectives, depending on their agendas, prior knowledge
and experience, and positions in the administrative system.
It is crucial to recognize the dialogical aspects of communication,
by involving the receiver of a message in a process
of response. In addition, the different timeframes underlying
different arguments could contribute to misunderstandings
between actors involved in handling environmental issues. In
assessing the achievement of environmental objectives,
indicators are used as communicative tools. It is important to
investigate whether and how these indicators contribute to
the de- and recontextualization of environmental objectives.

The drive toward sustainable wastewater management is challenging the conventional paradigm of li... more The drive toward sustainable wastewater management is challenging the conventional paradigm of linear end-ofpipe solutions. A shift toward more sustainable solutions requires that information about new ideas, systems and technologies be more readily accessible for addressing wastewater problems. It is commonly argued that decision-making needs to involve engineers and other community representatives to define values and brainstorm solutions. This paper describes a decision support system (DSS) prototype that is designed to help community planners identify solutions which balance environmental, economic and social goals. The system is designed to be scalable, adaptable and flexible to allow fair assessment of new ideas and technologies. It supports the exploration of consequences of various alternatives and visualizes the trade-offs between them. Our DSS takes in modular descriptions of components and a description of a community context, automates the design of alternative wastewater systems, and facilitates evaluating how well each design satisfies the given context. It provides an adaptable platform from which new solutions can be designed without having to predefine how a single component fits within a specific system. Our DSS facilitates the exploration of alternative solutions by visualizing the effect of various trade-offs and their consequences in relation to the community's sustainability goals.

Environmental Reviews, 1996

The aim of the present study was to describe and analyse the process of formulating the acidifica... more The aim of the present study was to describe and analyse the process of formulating the acidification theory in the Swedish research community. The empirical material was limited to articles written by Swedish researchers during the period 1950–1989 and published in international scientific journals utilizing a peer-review system. A model was developed to represent what Swedish researchers have regarded as the core of the acidification theory. Guided by the developed model, a qualitative content analysis of the scientific articles was conducted; i.e., we examined how central components and causal relationships of the theory have been explained and discussed. It should be emphasized that the present article describes an investigation of science itself (i.e., science in action) and is not an up-to-date review of acidification research. Our analysis revealed that some parts of the chain of evidence underlying the acidification theory were accepted before they were scrutinized by the scientific community and that the acidification complex was not conceptualized in accordance with the conceptualization of its various components. Actually, the acidification problem as a whole (i.e., the sum of all of its components) was not treated as a scientific theory that needed to be evaluated. This strongly indicates that the conceptualization was guided by factors that are generally, within the scientific community, considered to be external to the research process. There is no evidence that Swedish acidification research has adhered less stringently to scientific norms than environmental research in general has. Indeed, it is likely that such hidden patterns normally influence the conceptualization of science and we, therefore, conclude that the influence of factors that are not strictly a part of the research process must be further elucidated if the prerequisites and implications of research are to be clarified.Key words: scientific conceptualization, research process, acidification.

Enviroment International, 2019

Critical Reviews in Environmental Science and Technology, 2019

Risk Analysis, 2018

UBC Program of Water Governance, Mar 2013

Ecology and Society, 2014

Enviromental Management, 2005

Environmental Reviews, 1996

There is an urgent need to strengthen undergraduate science students’ epistemic knowledge, which ... more There is an urgent need to strengthen undergraduate science students’ epistemic knowledge, which requires having the scientists qua teachers on board. The divide between scientists’ perceptions of science and the perceptions held by those who study science is in this context problematic. Even so, this remains a sorely understudied area. The aim of the study was to identify pragmatic ways that hold the potential to facilitate integration of scholarly studies of scientific knowledge production with experientially based knowledge held by scientists to support the teaching of epistemic knowledge content to undergraduate science students. Earlier studies suggest that trust building is a central component. Our exploratory case study focuses on instructor perceptions and is based on informal interviews, participatory observation and surveys with instructors in a first-year undergraduate science course under revision. We identified the following central components as central to successful navigation of the divide between the scientific practice and science studies: Explicit formulation of learning objectives tied to epistemic knowledge acquisition; Conscious attention to vocabulary that triggers scientists’ aversion to science studies; Careful selection of historic and contemporary cases; and Systematic scaffolding of course activities. The conclusion regarding a common vocabulary stands out: by ridding our instructions from the vocabulary that caused concern among science instructors we succeeded in engaging them in conversations with students about the knowledge-producing process and challenge the view of science as characterised by facts and truths, rather than a form of scholarly inquiry that aims to produce knowledge about the natural world.

Environmental issues are inherently interdisciplinary, and environmental academic programs increa... more Environmental issues are inherently interdisciplinary, and environmental academic programs increasingly use an interdisciplinary approach.

This timely book presents a core framework for conducting high quality interdisciplinary research. It focuses on the opportunities rather than the challenges of interdisciplinary work and is written for those doing interdisciplinary work (rather than those studying it). It is designed to facilitate high quality interdisciplinary work and the author uses illustrative examples from student work and papers published in the environmental literature.

This book's lucid, problem-solving approach is framed in an accessible easy-to-read style and will be indispensable for anyone embarking on a research project involving interdisciplinary collaboration.

Readership: graduate students, advanced undergraduates, and researchers involved in the interface between human and natural environmental systems

Participant interaction is said to be the hallmark of the focus group method, but a number of stu... more Participant interaction is said to be the hallmark of the focus group method, but a number of studies suggest that the defining feature of the method is virtually absent in most focus group research. Our meta-analysis of this debate over participant interaction in the focus group literature suggests that absence of interaction data reflects a philosophical position, rather than neglect. Participant interaction is treated differently in different types of research, reflecting a tacit division between researchers who view the participants primarily as individuals sharing held truths and those who view them as social beings co-constructing meaning while in the focus group. We question the habit of making assumptions about the 'proper' use of participant interaction and call for further reflection on its role and usage in light of the aim of each study. We argue that the treatment of participant interaction needs to be a conscious and explicit design decision -one clearly rooted in a theoretical perspective and best suited to the research purpose. While exploring this issue, we discuss how a researcher's lens affects how they deal with the interaction of participants, what they view as strengths and limitations of the method, and what kinds of results they end up with. We provide an overview of alternative approaches to participant interaction, offer strategies from different disciplines for analysing interaction, and propose a continuum of use demonstrating a range of options for when to use interaction.

Higher Education, 2009

Newcomers often underestimate the challenges of interdisciplinary work and, as a rule, do not spe... more Newcomers often underestimate the challenges of interdisciplinary work and, as a rule, do not spend sufficient time to allow them to overcome differences and create common ground, which in turn leads to frustration, unresolved conflicts, and, in the worst case scenario, discontinued work. The key to successful collaboration is to facilitate the creation of a climate that will stimulate awareness of such challenges. Differing perceptions of quality and credibility among disciplines are major obstacles to successful collaboration. Some of these differences are incommensurably rooted in different epistemologies while other differences are more a question of culture. In the present paper, a
framework is proposed which is designed to initiate a process necessary for success. First, the framework is designed to stimulate discussions about quality and credibility, and second it is designed to help separate epistemological differences from differences in culture. The framework takes its point of departure in five questions that deliberately include terms, such as ‘sufficiently’, ‘coherently’, and ‘reliable’, which are unproblematic
in a group with shared norms but become increasingly ambiguous as diversity increases. Experience suggest that pondering these questions, alone or in a group, stimulates reflection, leads to increased awareness of one’s own perspective, and facilitates dialogue, collaboration, and creation of common ground.

In a "mashup", a DJ plays songs over each other creating combinations that constitute a new piece... more In a "mashup", a DJ plays songs over each other creating combinations that constitute a new piece of music. At first blush this is an appealing metaphor for interdisciplinarity 1 . The major strength of the metaphor is that it brings to fore the image of the new as created out of the already existing. The new music emerges from existing music, just like the creation of interdisciplinary research emerges from the disciplines. The term "mashup" seems to be most widely used to indicate a transformative use. When a DJ fades one song out and fades the next song in, no one would say that's a mashup -it's just two songs next to each other. It is only when the two songs interact in some way that we start getting into mashup territory. The question of transformation suggests the metaphor of mashup works well in helping us to understand interdisciplinarity because the key factor is the transformative recontextualization: to say that something is a mashup is to say that it involves some creative undertaking which brings two or more familiar or pre-existing things together in a way that is surprising or not usually anticipated, and makes a point about the union of the two exceeding the sum of its parts. This paper is inspired by the discussions during the 6 th International Conference on Environmental Futures (ICEF 6) held in Newcastle upon Tyne in July 2011. When relevant, we quote speakers at the conference. The paper proceeds in four parts. In the first we explore the transformative capacity of interdisciplinary practice. In the second, we demonstrate that there is no capital I interdisciplinarity, but rather multiple interdisciplinarities. In the third, we investigate specific cases of interdisciplinary practice reported at ICEF 6 and how they result in transformation and the creation of interdisciplinarities. In the fourth, we explore institutional changes in various parts of the academy that would be necessary if interdisciplinarity is to flourish.

Qualitative Research, 2007

The focus group is a research methodology in which a small group of participants gathers to disc... more The focus group is a research methodology in which a small
group of participants gathers to discuss a specified issue under the
guidance of a moderator. The discussions are tape-recorded, transcribed and analysed. Notably, the interaction between focus group participants has seldom been evaluated, analysed or discussed in empirical research. We argue that considering the focus group in light of current research into interaction in problem-based learning (PBL) tutorial groups would facilitate the deliberate exploitation of group processes in designing focus
groups, staging data collection and analysing and interpreting data.
When the analytical focus shifts from mere content analysis to an analysis of what the participants themselves are trying to learn, one can explore not only what the participants are talking about, but also how they are trying to understand and conceptualise the issue under discussion.

In problem-based learning, scenarios relating to real life are used as a point of departure for t... more In problem-based learning, scenarios relating to real life are used as a point of departure for the learning process. Even though the importance of suitable cases or scenarios in bringing about a fruitful learning process is emphasised in the literature, few studies focus on how they actually function in the learning process. This study focuses on how the scenarios used in a ten-week introductory course of a new four-year undergraduate programme in environmental science functioned in terms of the structure and content of the questions they evoked. Data were gathered through diary notes from nine groups of students, comprising 5-8 students per group. The data were subjected to a qualitative analysis aimed at describing the structure and content of the questions generated by the groups. Five different kinds of questions were identified and labelled; encyclopaedic, meaning-oriented, relational, value-oriented and solution-oriented. All scenarios generated questions pertaining to all five categories in all groups, but the emphasis varied. The results are discussed in relation to the design of scenarios, and in relation to students' approaches to learning.

THE BERKSHIRE ENCYCLOPEDIA OF SUSTAINABILITY: MEASUREMENTS, INDICATORS, AND RESEARCH METHODS FOR SUSTAINABILITY, 2012

In general terms, quantitative research methods involve measurements while qualitative methods ad... more In general terms, quantitative research methods involve measurements while qualitative methods address questions of how and why. Both methods have strengths and weaknesses, and different disciplines prefer one to the other. As rigorous mixed-methods studies become increasingly valuable in sustainability research—where facts often are uncertain, values are in dispute, stakes are high, and decisions are urgent—scholars must be trained to develop an acute awareness of the possibilities and limitations of qualitative and quantitative methods.

THE BERKSHIRE ENCYCLOPEDIA OF SUSTAINABILITY: MEASUREMENTS, INDICATORS, AND RESEARCH METHODS FOR SUSTAINABILITY, 2012

British Journal of Visual Impairment, 1988

... can be found at: British Journal of Visual Impairment Additional services and information for... more ... can be found at: British Journal of Visual Impairment Additional services and information for ... talents of these students, that we will eventually be in a position to explore fully the limits and possibilities of non visual and low ... 'An Eye for Art' (Gunnersbury Park Museum, London, 19 ...

Environmental Science and Technology, 1991

Soil Biology and Biochemistry, 1993

Different pretreatments of soil samples were combined with incineration in oxygen atmosphere and ... more Different pretreatments of soil samples were combined with incineration in oxygen atmosphere and microcoulometric titration of formed hydrogen halides to determine the total and leachable amounts of organically bound halogens (TOX and LOX, respectively). The results showed that the investigated procedures can be standardised to provide reproducible results. In general, inorganic chloride present in soil particles and microorganisms did not have any significant impact on measured LOX concentrations. The possible impact of chloride on the determination of TOX in soil is more uncertain. However, even though analytical artifacts cannot be completely ruled out, there was strong evidence that the TOX measurements resulted in adequate estimates of the true organohalogen content of the analysed soil samples. A substantial part of the TOX was recovered as LOX by leaching with NaOH, and there was a good agreement between TOX-to-l.o.i. ratios of dried and ground soil samples and AOX-to-TOC ratios ofleachates of the same samples.

Water, Air and Soil Pollution, Jul 13, 1995

The total amount of organically bound halogens was determined in soil samples from the Palace Lea... more The total amount of organically bound halogens was determined in soil samples from the Palace Leas meadow hay plots, Northumberland, UK. These plots have been amended with different combinations of farmyard manure, potassium chloride, ammonium sulphate or nitrate since their establishment in 1897, resulting in, among other things, substantial pH differences between the plots. It was found that the amount of organically bound halogens increased significantly with decreasing pH. Net changes in amounts of organohalogens were also studied in soil obtained from a coniferous forest in southern Sweden. The collected soil was divided into four sets of samples, which were incubated in a climate chamber and subjected to different treatment regimes that influence soil pH. Significant changes in amounts of organically bound halogens were detected in three of the four sets of samples, resulting in significantly increasing amounts with decreasing pH. However, although the amount of organically bound halogens detected was related to soil pH in both the field and the experimental study, the net changes observed in the latter investigation were not directly related to soil pH. This shows that net changes in the amount of organically bound halogens in soil are caused by complex processes, and that further studies are needed to clarify the nature of the observed relation between soil pH and amounts of organically bound halogens.

Soil Biology & Biochemistry, 1999

The ability of Lepista nuda to produce organically bound halogens was tested both in a laboratory... more The ability of Lepista nuda to produce organically bound halogens was tested both in a laboratory study of a pure culture and in a ®eld study. It was found that L. nuda caused an increase in the total amount of organically bound halogens in the study of a pure culture, but possibly because of large variance between replicates, no such increase could be detected in the ®eld study. In addition, in both the laboratory and the ®eld studies, low-molecular-weight organohalogens such as chlorinated benzaldehydes were detected in all samples aected by the fungus and the amounts were 0.2±82 mg/g d.w. These low-molecular-weight compounds correspond to approximately 30% of the increase in organohalogens detected in the laboratory study. It is suggested that the low-molecular-weight organohalogens detected, most likely are produced de novo by L. nuda and that production of such compounds followed by an incorporation into high-molecular-weight compounds is an explanation for the increase in amounts in the laboratory study. # Soil Biology and Biochemistry 31 (1999) 1509±1515 0038-0717/99/$ -see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 0 3 8 -0 7 1 7 ( 9 9 ) 0 0 0 6 9 -3

Chemosphere, 2000

The aim of the present study is to investigate whether exo-enzymatically mediated chlorination of... more The aim of the present study is to investigate whether exo-enzymatically mediated chlorination of fulvic acid (FA) results in the formation of chlorinated groups within the macromolecules which correspond to those which were previously detected in soil and surface water samples. The chlorination was carried out by exposing FA to a commercial chloroperoxidase (CPO) in the presence of chloride and hydrogen peroxide. The exposed FA was then chemically degraded using an oxidative technique and ®nally analysed for four dierent aromatic groups and their chlorinated analogues. The particular aromatic groups included were the methyl esters of 4-ethoxybenzoic acid, 3-methoxy-4ethoxybenzoic acid, 3,4-diethoxybenzoic acid, and 3,5-dimethoxy-4-ethoxybenzoic acid, along with their mono-and dichlorinated analogues. Prior to the chemical degradation procedure, the FA was analysed for AOX (adsorbable organic halogens) and chlorinated acetic acids. The original FA contained 1.4 mg Cl org g À1 and detectable amounts of two chlorinated aromatic groups. After exposure to the enzyme, the concentration of AOX increased to 44.3 mg Cl org g À1 and detectable amounts of four chlorinated aromatic groups as well as di-and trichloroacetic acid were found. Ó

Soil Biology & Biochemistry, 2000

Recent research has shown that large amounts of high-molecular weight organic chlorine of unknown... more Recent research has shown that large amounts of high-molecular weight organic chlorine of unknown origin are present in the terrestrial environment. There are indications that an underlying process may be microorganisms which produce reactive chlorine that chemically degrades organic matter and facilitates degradation of recalcitrant organic matter on one hand, and on the other hand causes a formation of organic chlorine. Our aim was to test one part of this hypothesis by investigating whether reactive chlorine facilitates microbial degradation of lignin. Dierent concentrations of chlorine dioxide were added to the autoclaved lignin suspension. Mycelium of the white-rot fungus P. chrysosporium was used to inoculate¯asks with the lignin solutions. The evolution of CO 2 was followed during 8 d of continuous measurement. At the end of the experiment the solutions were analyzed for organic chlorine. The amount of CO 2 evolved was variable, but the results were repeatedable; addition of chlorine dioxide to the lignin solutions caused an increase in the mineralization by P. chrysosporium that increased with increasing additions of chlorine dioxide. This suggests that exposure of lignin to reactive chlorine enhance its biodegradability. The most likely cause of the observed eect is that the addition of chlorine dioxide initiated a fragmentation and oxidation of the lignin, thus rendering a more easily degraded substrate. However, the results may also be interpreted as if an additional cause to the observed eect is that the chlorination in itself somehow enhanced degradation. The amount of organically-bound chlorine decreased during the incubation, and the decrease was more pronounced with the chlorination of lignin, whereas no change at all was observable in the control batches. This makes it tempting to suggest that P. chrysosporium rather than having an enzyme system just capable of handling the chlorinated compounds, actually has a system that preferentially degrades such compounds. 7

Geoderma, 2001

Concentrations of organic and inorganic chlorine were estimated in samples collected in forest so... more Concentrations of organic and inorganic chlorine were estimated in samples collected in forest soils in the southern part of Sweden, and changes were observed after the addition of nitrogen in incubated samples. All of the investigated samples contained both inorganic and organic chlorine, and the concentration of organic chlorine was 2-4 times larger than that of inorganic chlorine. The results suggest that the amount of organic chlorine in mature spruce forest soils with a moderate chloride deposition in the temperate region is larger than the amount of inorganic chlorine. The results of the nitrogen incubation indicate that addition of ammonium nitrate causes a net decrease in the concentration of organic chlorine and a net increase in chloride concentration. The observed change appears to mainly be a result of a dechlorination of the organic matter present in the water leachable fraction. q E. Johansson .

Chemosphere, 2003

The concentration of organic carbon, organic chlorine and chloride was determined in Swedish fore... more The concentration of organic carbon, organic chlorine and chloride was determined in Swedish forest soil in the southern part of Sweden and the spatial distribution of the variables were studied. The concentration of organically bound chlorine was positively correlated to the organic carbon content, which is in line with previous studies. However, the spatial distribution patterns strongly indicate that some other variable adds structure to the spatial distribution of organic chlorine. The distribution patterns for chloride strongly resembled the distribution of organic chlorine. The spatial distribution of chloride in soil depends on the deposition pattern which in turn depends on prevailing winddirection, amount of precipitation and the distance from the sea. This suggests that the occurrence of organic chlorine in soil is influenced by the deposition of chloride or some variable that co-varies with chloride. Two clearly confined strata were found in the area: the concentrations of organic chlorine and chloride in the western area were significantly higher than in the eastern area. No such difference among the two areas was seen regarding the carbon content.

Chemosphere, 2003

The assumption that soil neither acts as a source or a sink of chloride is evaluated by incubatin... more The assumption that soil neither acts as a source or a sink of chloride is evaluated by incubating soil cores in lysimeters in a climate chamber under controlled conditions. Some of the lysimeters acted as a sink while others acted as a source of chloride. Considerable amounts of organic chlorine were lost by leaching. The loss by leaching of organic chlorine could only explain part of the discrepancy in the lysimeters where the soil acted as a sink and it could certainly not explain the cases where the soil acted as a source.

Environmental Science & Technology, 2004

Chemosphere, 2003

Surface water and aqueous solutions of isolated organic matter from a humic rich lake in southern... more Surface water and aqueous solutions of isolated organic matter from a humic rich lake in southern Sweden were exposed to artificial UV radiation to investigate the UV light induced influence on organic matter bound chlorine in natural systems. It was found that the photodegradation of organic matter bound chlorine was more pronounced than the photodegradation of organic carbon. After 120 h of irradiation of the isolated organic matter, only 35% of the initial organochlorine was still in the solution compared to about 70% of the dissolved organic carbon (DOC). A similar result was obtained for unfractionated surface water. Furthermore, our results indicate that the loss of organic chlorine was mainly due to a mineralization of organic chlorine into chloride ions. The total decrease of organic chlorine after 120 h was 32 lg Cl org l À1 , of which the major part disappeared in the initial irradiation phase. A similar increase was observed in the chloride concentration (34 lg Cl À l À1 ).

Geoderma, 2004

Organochlorine compounds were dumped by chemical industries during the 1970s in many areas of the... more Organochlorine compounds were dumped by chemical industries during the 1970s in many areas of the coastal plain of São Paulo state in Brazil. These dumps, located on hillsides and in valleys, in both rural and urban environments, are responsible for soil and water pollution. The objective of this work was to determine how the pollutants have spread in an area occupied by a spodosol-type soil mantle. The study combines soil morphological observations with soil and water analysis of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil toposequences. The results indicate that the highest pollutant concentrations are observed near the dump site and that the compounds contamination is increasing.A map integrating topography and chemical concentrations was created to visualize the spatial distribution of HCB levels in the landscape. Physical and chemical analyses were performed to measure HCB and PCP levels in the soil. Soil water appears to act as a vector of HCB, probably through complexation with and dispersal of dissolved organic matter. The persistence of HCB at the studied site is most likely due to the low pH values in combination with a high content of organic matter. HCB was consistently found in higher concentrations than PCP. It is plausible that the cause of this difference is that PCP is degraded more easily under sunlight than HCB and that degradation of PCP under acid conditions leads to the formation of HCB.

Biogeochemistry, 2005

The objective of this study is to construct a balanced chlorine budget for a small forested catch... more The objective of this study is to construct a balanced chlorine budget for a small forested catchment, focusing on the interaction between chloride (Clinorg) and organic-matter-bound chlorine (Clorg). Data from the actual catchment are combined with secondary data from other sites to elucidate more clearly which parts of the cycle are fairly well known and which are more or less unknown. The budget calculations show that the principal input and output fluxes of Cl in the catchment are inorganic but that the main pool is Clorg in the soil. In addition, the budget calculations suggest that a considerable portion of Clinorg in soil is transformed to Clorg and subsequently leached to deeper soil layers, that net mineralization of Clorg takes place in soil, preferably in deeper soil layers, and that degrading organic matter is a major source of Clinorg in runoff. The loss of Clorg through runoff is small to negligible in relation to other fluxes. It appears as if dry deposition of Clinorg is at risk of being underestimated if Clinorg is assumed to be conservative in soil. The pool of organic-matter-bound chlorine in soil is considerably larger than the annual flux of chloride through the system. The estimates suggest that the amount of Clorg in the upper 40 cm of the soil at the investigated site is approximately twice as large as the Clinorg. Furthermore, the amount of Clorg biomass is small in relation to the occurrence of Clorg in soil. Finally, the estimates indicate that the transport of volatile Clorg from the soil to the atmosphere may influence the chlorine cycle.

Hydrological Processes, 2005

Chloride (Clinorg) is generally considered to be a hydrologically and chemically inert substance.... more Chloride (Clinorg) is generally considered to be a hydrologically and chemically inert substance. Past research suggests that Clinorg participates in a complex biogeochemical cycle involving the formation of organically bound chlorine (Clorg). The present study examines whether Clorg cycling is sufficiently extensive as to influence the geochemical cycling of Clinorg. Undisturbed soil cores were collected in a coniferous forest soil in SE Sweden. The cores were stored in climate chambers for three months, irrigated with artificial rain, and the leachate was collected and analysed. The water balance of the lysimeters could be well described, and we found that 20–50% of the chlorine leached from the lysimeters was organically bound and that the amounts lost did not decrease with time. This strongly suggests that a substantial amount of Clorg forms in topsoil, and that subsequent leaching to deeper layers causes a considerable withdrawal of Clinorg. The concentration of both organic carbon and Clorg in the leachate was considerably higher than concentrations observed in the runoff in the actual catchment, suggesting that organic matter precipitates or is mineralized on its way through the soil. Copyright © 2005 John Wiley & Sons, Ltd.

Environmental Science & Technology, 2006

The common assumption that chloride (Cl -) is conservative in soils and can be used as a groundwa... more The common assumption that chloride (Cl -) is conservative in soils and can be used as a groundwater tracer is currently being questioned, and an increasing number of studies indicate that Clcan be retained in soils. We performed lysimeter experiments with soil from a coniferous forest in southeast Sweden to determine whether pore water residence time and nitrogen and Clloads affected Clretention. Over the first 42 days there was a net retention of Clwith retention rates averaging 3.1 mg Clm -2 d -1 (68% of the added Clretained over 42 days). Thereafter, a net release of Clat similar rates was observed for the remaining experimental period (85 d). Longer soil water residence time and higher Clload gave higher initial retention and subsequent release rates than shorter residence time and lower Clload did. Nitrogen load did not affect Cl transformation rates. This study indicates that simultaneous retention and release of Clcan occur in soils, and that rates may be considerable relative to the load. The retention of Clobserved was probably due to chlorination of soil organic matter or ion exchange. The cause of the shift between net retention and net release is unclear, but we hypothesize that the presence of O 2 or the presence of microbially available organic matter regulates Clretention and release rates.

Biogeochemistry, 2007

Chloroform concentrations were observed and input and output fluxes estimated over a 2-yr period ... more Chloroform concentrations were observed and input and output fluxes estimated over a 2-yr period in a small coniferous catchment
(0.22 km2) in southeast Sweden. Water discharge was measured daily, and runoff water was sampled bi-weekly for chloroform analysis. An approximate chloroform budget was calculated, which
indicated that the annual output of 6 lg m–2 yr–1 was approximately six times higher than the input, inferring an internal source of chloroform in the catchment. To the best of our knowledge, neither flux estimates nor mass balances have previously been made for chloroform on a catchment scale,
nor have data regarding natural runoff variation with time been gathered. Concentrations of chloroform in runoff were found to be generally high during wet periods, such as spring, but also peaked during summer rain events. The observed pattern suggests that chloroform is formed in surface soil layers and transported to the outlet under high-flow conditions and during dry-period rain events; it is lost through degradation or evaporation during drier periods due to longer soil water residence times. The data suggest that the variation among replicates increases with concentration; this emphasizes the need to know what the degree of on-site variation is, so one can collect a sufficient number of replicates to permit detection of spatial or temporal changes.

Biogeochemistry, 2007

Previous studies have revealed that chlorine participates in a complex biogeochemical cycle in so... more Previous studies have revealed that chlorine participates in a complex biogeochemical cycle in soil, which suggests that the transport of chloride through catchments may also be influenced. The present study is based on field observations of organic carbon, chloride (Clin), and chlorinated organic carbon (Clorg) in precipitation, soil, and runoff over a 2-year period from a small, forested catchment in southeast Sweden. The study reveals that (1) the soil pool is dominated by Clorg, (2) the input via wet deposition and output of Clin via runoff is 30 times smaller than the total storage of chlorine (Clin + Clorg) in soil, and (3) the transport is dominated by Clin. The organic matter that entered the outlet of the catchment was more chlorinated in the autumn than during the rest of the year, and rain events taking place in low-flow periods had a greater influence on TOC, Clorg, and Clin than did rain events taking place in high-flow periods. The seasonal pattern in combination with the low-flow versus high-flow pattern and previous findings of increasing chlorine-to-carbon ratios with soil depth suggests that the chlorine-to-carbon ratio variation in the leached organic matter is due that water preferentially comes from deeper layers in low-flow conditions. This study provides well-founded estimates of Clorg and Clin storage and fluxes for the studied catchment; however, the processes underlying the observed seasonal Clorg variations and transportation processes need further study.

Geochimica et Cosmochimica Acta, 2007

Inorganic chlorine (i.e. chloride; Clin) is generally considered inert in soil and is often used ... more Inorganic chlorine (i.e. chloride; Clin) is generally considered inert in soil and is often used as a tracer of soil and ground water movements. However, recent studies indicate that substantial retention or release of Clin can occur in soil, but the rates and processes responsible under different environmental conditions are largely unknown. We performed 36Cl tracer experiments which indicated that short-term microbial uptake and release of Clin, in combination with more long-term natural formation of chlorinated organic matter (Clorg), caused Clin imbalances in coniferous forest soil. Extensive microbial uptake and release of Clin occurred over short time scales, and were probably associated with changes in environmental conditions. Up to 24% of the initially available Clin within pore water was retained by microbial uptake within a week in our experiments, but most of this Clin was released to the pore water again within a month, probably associated with decreasing microbial populations. The natural formation of Clorg resulted in a net immobilization of 4% of the initial pore water Clin over four months. If this rate is representative for the area where soil was collected, Clorg formation would correspond to a conversion of 25% of the yearly wet deposition of Clin. The study illustrates the potential of two Clin retaining processes in addition to those previously addressed elsewhere (e.g. uptake of chloride by vegetation). Hence, several processes operating at different time scales and with different regulation mechanisms can cause Clin imbalances in soil. Altogether, the results of the present study (1) provide evidence that Clin cannot be assumed to be inert in soil, (2) show that microbial exchange can regulate pore water Clin concentrations and (3) confirm the controversial idea of substantial natural chlorination of soil organic matter.

Ecology and Society

Environmental Science and Policy, 2005

Environmental Science & Policy, 2005

For many in the Global North, urban life means that your shit is not your problem. We postulate t... more For many in the Global North, urban life means that your shit is not your problem. We postulate that a possible reason for the global sanitation failure in urban areas is a disconnect between sanitation expectations—what we term the urban sanitation imaginary—and the practices required by proposed sanitation solutions. The case study presented here is based on interviews with residents of Villa Lamadrid, a marginalized neighborhood in Buenos Aires, Argentina, which faces significant public health impacts from an inadequate sewage management system. We solicited feedback regarding specific sanitation technologies frequently prescribed for poor urban communities—among them a urine diversion dry toilet with dehydration vaults. Even as this system is posited as ‘sustainable’ for the context of Villa Lamadrid in terms of ecological and economic factors, conversations with residents revealed why this option might not be sustainable in terms of social expectations. On the basis of interviews with community members we have defined four aspects of residents’ urban sanitation imaginaries that we consider highly relevant for any consideration of sanitation solutions in this context: (1) an urban citizen does not engage physically or mentally with their shit or its management; (2) an appropriate urban sanitation system requires flushing; (3) systems that require user’s engagement with their shit and its management signify rural, underdeveloped, and backward lifestyles; and (4) urban sanitation is a state responsibility, not a local one. Highlighting the urban sanitation imaginary methodologically and analytically goes beyond a discussion of culturally and contextually appropriate technologies. It examines linkages between user expectations and notions of urban citizenship and modernity. Ultimately it also draws attention to the sociopolitical dynamics and environmental justice issues embedded in discussions of sanitation and hygiene. While some of our results are specific to the Villa Lamadrid context, our research more generally suggests the need to consider sanitation imaginaries to reframe the discussion on sanitation interventions, particularly in underserved and impoverished urban areas.

Soil Science Society of America Journal, 2011

... Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosy... more ... Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: Past, present and future Global Change Biol.doi:10.1046/j.1365 ... [View Article] [Web of Science]. ↵ Christensen, S., P. Ambus, JRM Arah, H. Clayton, B. Galle and DWT Griffith. ...

Soil Science Society of America Journal, 2011

Focus on Chlorine Science, 2006

Sustainability

There is an urgent need for innovation in the sanitation sector because the conventional model (t... more There is an urgent need for innovation in the sanitation sector because the conventional model (toilet-to-sewer-to-treatment) is too time-consuming and costly, and alternatives are lacking. We estimate the challenge ahead by developing scenarios for 60 of the fastest-growing urban conglomerates in the World. We find that the majority would need to build out their sewer systems at a rate that is ten to 50 times higher than the highest rate for any project in the World Bank’s database, which is unrealistic. We also carry out a case study of Lagos, Nigeria, which suggests that, in any given year, 14–37% of Lagos State’s budget would need to be invested to provide sanitation to the presently underserviced population while keeping up with population growth, which also is unrealistic. Our study provides clear evidence that the conventional model for sanitation is unworkable for rapidly growing urban areas. We conclude there is an urgent need to encourage and fund projects that promote inn...

Integrated Environmental Assessment and Management

Water Research

Recognition of human excreta as a resource, rather than as waste, has led to the emergence of a r... more Recognition of human excreta as a resource, rather than as waste, has led to the emergence of a range of new and innovative nutrient recovery solutions. Nevertheless, the management of human excreta remains largely rooted in current sanitation and wastewater management approaches, which often makes nutrient recovery an add-on to existing infrastructures. In this paper, we argue that framing human excreta management as a resource recovery challenge within waste management obscures important trade-offs. We explore the factors that would be brought to the fore by reframing human excreta management as part of food and farming systems. We find that such a reframing would accentuate (at least) six aspects of critical importance that are currently largely overlooked. Recognizing that the proposed framing may also have its limitations, we argue that it has the potential to better guide human excreta management towards long-term global food, soil, and nutrient security while reducing the risk of compromising other priorities related to human and environmental health.

Risk Analysis

Regional Environmental Change

Understanding how cities can transform organic waste into a valuable resource is critical to urba... more Understanding how cities can transform organic waste into a valuable resource is critical to urban sustainability. The capture and recycling of phosphorus (P), and other essential nutrients, from human excreta is particularly important as an alternative organic fertilizer source for agriculture. However, the complex set of socio-environmental factors influencing urban human excreta management is not yet sufficiently integrated into sustainable P research. Here, we synthesize information about the pathways P can take through urban sanitation systems along with barriers and facilitators to P recycling across cities. We examine five case study cities by using a sanitation chains approach: Accra, Ghana; Buenos Aires, Argentina; Beijing, China; Baltimore, USA; and London, England. Our cross-city comparison shows that London and Baltimore recycle a larger percentage of P from human excreta back to agricultural lands than other cities, and that there is a large diversity in socio-environmental factors that affect the patterns of recycling observed across cities. Our research highlights conditions that may be "necessary but not sufficient" for P recycling, including access to capital resources. Path dependencies of large sanitation infrastructure investments in the Global North contrast with rapidly urbanizing cities in the Global South, which present opportunities for alternative sanitation development pathways. Understanding such city-specific social and environmental barriers to P recycling options could help address multiple interacting societal objectives related to sanitation and provide options for satisfying global agricultural nutrient demand.

International Journal of Science Education

Soil Biology and Biochemistry

The objectives of the present study were: (i) to evaluate methods for detection of low rates of c... more The objectives of the present study were: (i) to evaluate methods for detection of low rates of chloroperoxidase activity in aqueous solutions; (ii) to investigate the ability of soil extracts to catalyze chlorination; (iii) to investigate if the catalyzing ability of soil extracts is due to enzymatic activity. Initially, solutions of a commercially-available chloroperoxidase (EC 1.11.1.10, CPO) were studied, and it was found that chlorination of monochlorodimedone (MCD) and anisole followed by gas chomatographic analysis of chlorinated reaction products represented sensitive assay methods for determination of chloroperoxidase activity. Using these methods, eight out of nine soil extracts, obtained by performing a modified peroxidase extraction procedure, were found to catalyze chlorination. Further experimentation provided the following information: (i) the reaction did not proceed in the absence of hydrogen peroxide; (ii) the catalyst had a molecular weight larger than 10,000, (iii) the incorporation of chlorine was strongly pH-dependent, with an optimum at pH 3.G3.5; (iv) the reaction was inhibited by orcinol, resorcinol and phloroglucinol. All these properties are similar to those of the commercial chloroperoxidase. It was therefore concluded that a chloroperoxidase-like catalyst was present in the investigated soils.

Proceedings of the Seventh International Learning Analytics & Knowledge Conference on - LAK '17, 2017

Geochimica Et Cosmochimica Acta, Jul 1, 2007

Inorganic chlorine (i.e. chloride; Cl in ) is generally considered inert in soil and is often use... more Inorganic chlorine (i.e. chloride; Cl in ) is generally considered inert in soil and is often used as a tracer of soil and ground water movements. However, recent studies indicate that substantial retention or release of Cl in can occur in soil, but the rates and processes responsible under different environmental conditions are largely unknown. We performed 36 Cl tracer experiments which indicated that short-term microbial uptake and release of Cl in , in combination with more long-term natural formation of chlorinated organic matter (Cl org ), caused Cl in imbalances in coniferous forest soil. Extensive microbial uptake and release of Cl in occurred over short time scales, and were probably associated with changes in environmental conditions. Up to 24% of the initially available Cl in within pore water was retained by microbial uptake within a week in our experiments, but most of this Cl in was released to the pore water again within a month, probably associated with decreasing microbial populations. The natural formation of Cl org resulted in a net immobilization of 4% of the initial pore water Cl in over four months. If this rate is representative for the area where soil was collected, Cl org formation would correspond to a conversion of 25% of the yearly wet deposition of Cl in . The study illustrates the potential of two Cl in retaining processes in addition to those previously addressed elsewhere (e.g. uptake of chloride by vegetation). Hence, several processes operating at different time scales and with different regulation mechanisms can cause Cl in imbalances in soil. Altogether, the results of the present study (1) provide evidence that Cl in cannot be assumed to be inert in soil, (2) show that microbial exchange can regulate pore water Cl in concentrations and (3) confirm the controversial idea of substantial natural chlorination of soil organic matter.

ABSTRACT The concentration of organic carbon, organic chlorine and chloride was determined in Swe... more ABSTRACT The concentration of organic carbon, organic chlorine and chloride was determined in Swedish forest soil in the southern part of Sweden and the spatial distribution of the variables were studied. The concentration of organically bound chlorine was positively correlated to the organic carbon content, which is in line with previous studies. However, the spatial distribution patterns strongly indicate that some other variable adds structure to the spatial distribution of organic chlorine. The distribution patterns for chloride strongly resembled the distribution of organic chlorine. The spatial distribution of chloride in soil depends on the deposition pattern which in turn depends on prevailing wind-direction, amount of precipitation and the distance from the sea. This suggests that the occurrence of organic chlorine in soil is influenced by the deposition of chloride or some variable that co-varies with chloride. Two clearly confined strata were found in the area: the concentrations of organic chlorine and chloride in the western area were significantly higher than in the eastern area. No such difference among the two areas was seen regarding the carbon content.

Chemosphere, Jul 31, 2003

Vest Tidskrift For Vetenskapsstudier, 1997

Environmental Science and Technology, Apr 23, 1998

It is known that large amounts of organic halogens are present in soil, but the relative contribu... more It is known that large amounts of organic halogens are present in soil, but the relative contribution from different sources is unclear. The aim of the present study was to determine the storage of organic halogens in a spruce forest soil and the deposition by needle litterfall and to elucidate the relative contribution from needle litterfall in relation to other sources and sinks. Sampling was conducted in a small spruce forest area in Denmark. Soil samples were collected at six locations to a depth of 60 cm. Litterfall was collected in 15 sample collectors every third month during 1 year. Soil leachate was collected below the B h horizon over two periods of 5 days at five locations distributed over the study site. Throughfall data was compiled from a previous study conducted at the same site and during the same period as the present study, and data concerning net formation in soil was estimated from previous studies at similar sites. The pool was 630 kg of Cl org ha -1 , contribution from litterfall was 0.35 kg ha -1 yr -1 , and loss by leaching was 0.63 kg of Cl org ha -1 yr -1 (mean values). The estimated contributions from throughfall and net formation within the soil were 0.38 and 0.36 kg of Cl org ha -1 yr -1 , respectively. The results suggest that the pool in the investigated soil originates mainly from sources within the forest and that it increases with time.

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