Viv Jones | University College London (original) (raw)

Papers by Viv Jones

Polar Research, 1995

Holocene environment on Bjorneya (Svalbard) inferred from multidisciplinary lake sediment studies... more Holocene environment on Bjorneya (Svalbard) inferred from multidisciplinary lake sediment studies. Polar Research 14(2). 253-215. BjOrnOya, a small (178 km2) island situated between the mainland of Norway and southern Spitsbergen, provides the opportunity for the reconstruction of early Holocene terrestrial and limnic palaeoenvironments in the southwestern Barents Sea. The AMS ''C dating technique, geochemical, mineral magnetic, microand macrofossil analyses were applied lo sediments recovered from lake Stevatnet and the results are interpreted in terms of palaeoenvironmental conditions between 9800 and 8300 I4C BP. After the disappearance of local glaciers before ca 9800 14C BP, the lake productivity increased rapidly at the same time as pioneer plant communities developed on soils which gradually became more stable. Insect data indicates that strong seasonal contrasts with mean July temperatures around 9°C and mean January temperatures around-12°C prevailed between 9500 and 8300 I4C BP. These high summer temperatures, possibly as much as 4-5°C higher than the present, favoured the development of a flora including Dryas and Angelica cf. archangelica. The enhanced freeze/thaw processes led to an increased erosion of minerogenic and organic material. After 8000 ''C BP the temperatures may have gradually declined. The environmental reconstruction derived from our data set supports the conceptual insolation model which proposes maximum Holocene seasonality for the Northern Hemisphere at ca 9000 I4C BP.

&lt;p&gt;We have recorded consistent (but low) numbers and a diverse range of dia... more &lt;p&gt;We have recorded consistent (but low) numbers and a diverse range of diatom taxa (siliceous algae) over a 400-year period in the RECAP ice core, drilled from the Renland ice cap on the east coast of Greenland. This is an exciting initial step in attempting a diatom-based environmental reconstruction for an Arctic ice core for the first time, since Greenland&amp;#8217;s inland ice cores (e.g. NGRIP, GRIP) do not appear to contain diatoms in enough numbers. Our novel study investigated the period 1528 - 1940 AD (encompassing the Little Ice Age (LIA)) and we developed a method for extracting diatom taxa from the ice-core meltwater samples for identification. This was done by microscopy using standard taxonomic techniques. In summary, the RECAP LIA assemblage comprises 93 species, 36 genera and 11 families where &lt;em&gt;Thalassiosira/Coscinodiscus&lt;/em&gt;, &lt;em&gt;Aulocoseira,&lt;/em&gt; &lt;em&gt;Pinnularia, Nitzschia, Luticola, Diadesmis, Staurosira, Achnanthidium, Psammothidium spp&lt;/em&gt; are the dominant genera. In this interval we found that Renland received air blown diatoms from both planktonic/benthic freshwater (80%) and planktonic marine (20%) sources. The freshwater species included aerophilic species (from damp environments), key indicators of exposed, environments and found widely in the Arctic. We observe that both total diatom numbers and species composition changes rapidly over time (i.e. decadal timescales), similar to other ice-core proxies, and with higher total numbers/yr between about 1780 and 1850 AD. Further analysis is required to establish a link to specific environmental variables, which could include aridity, wind strength or sea ice cover. We hypothesise that similar lower altitude, coastal ice cores from Greenland and Canada could be useful diatom repositories in the Arctic region.&lt;/p&gt;

The Holocene

Palaeoclimatic reconstructions from lake sediment biological records can be challenging, due to v... more Palaeoclimatic reconstructions from lake sediment biological records can be challenging, due to variation in non-climatic factors, which alter ecosystem responses. To consider this, it is important to replicate a study regionally, so as to gain information on spatial variability of ecosystem response and the influence of site-specific conditions. Previous pollen-based palaeoclimatic records from three well-dated Arctic lake sites highlight the response of regional Scots Pine ( Pinus sylvestris) and Mountain Birch ( Betula pubescens ssp. czerepanovii) forest-tundra transition to Holocene climatic variability and suggest the northernmost Peninsulas of Finnmark to be climatically sensitive. This study analysed dated sediment sequences between c. 3970 and c. 6200 cal. yr BP from these three previously published shallow lakes: Liten Čap’pesjav’ri (LCJ), over Gunnarsfjorden (OGF) and over Kobbkrokvatnet (OKV), for freshwater diatoms. Diatom assemblages showed an increase in the planktonic...

Limnology and Oceanography Letters

Global and Planetary Change, 2015

ABSTRACT A sediment sequence was taken from a closed, high altitude lake (informal name Olive-bac... more ABSTRACT A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated by Betula and Alnus woodland with a mosaic of open, wet, aquatic and semi-aquatic habitats. Between 7800 and 6000 cal yr BP the diatom-inferred lake water was pH 4.4 -5.3 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency of Pinus pumila (Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates that P. pumila arrived in the catchment between 4200 and 3000 cal yr BP. Its range expansion was probably mediated by strengthening of the Aleutian Low pressure system and increased winter snowfall. The diatom-inferred pH reconstructions show that after an initial period of low pH, pH gradually increased from 5500 cal yr BP to pH 5.8 at 1500 cal yr BP. This trend of increasing pH through the Holocene is unusual in lake records, but the initially low pH may have resulted directly or indirectly from intense regional volcanic activity during the mid-Holocene. The chironomid-inferred July temperature reconstruction suggests cool periods between 3200 – 2800 cal yr BP and 1100 – 700 cal yr BP and a warmer period between 2800 and 1100 cal yr BP. Chironomid and diatom DCA scores decline from ca. 6000 cal yr BP, indicating compositional changes in these aquatic assemblages. In comparison declines in pollen PCA scores are delayed, starting ca. 5100 cal yr BP. The results suggest that while catchment vegetation was responding primarily to climate change, the biota within the lake and lake water chemistry were responding to localised environmental conditions.

Global and Planetary Change, 2015

Quaternary Science Reviews, 2011

Global and Planetary Change

A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake)... more A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated b...

Global and Planetary Change

A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast ... more A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history.

Global and Planetary Change, 2015

Kamchatka is a remote, isolated and understudied area and is presumed to be pristine. Here we pre... more Kamchatka is a remote, isolated and understudied area and is presumed to be pristine. Here we present the first high-resolution palaeolimnological investigation of the recent past. A short core representing the last 250 years was taken from Olive-backed Lake situated in central Kamchatka. Lead-210 dating revealed that sediment accumulation has increased at the site since the 1960s and may be related to greater rates of catchment erosion associated with wetter winters in the region. Mercury and spheroidal carbonaceous particles (an unambiguous indicator of fossil fuel combustion) concentrations are low but clearly detectable indicating that both regional and global pollution sources are observed at this site. The recent increase in the flux of mercury is more related to catchment sources and catchment erosion than increases from regional or global sources. The diatom and chironomid populations are stable and do not show any statistically significant changes related to either the low levels of pollution, or to temperature and precipitation changes. The lake is not pristine since anthropogenic contamination has occurred but since there have been no significant effects on the flora and fauna the lake can be considered to be unimpacted. Olive-backed Lake may be a suitable reference site to benchmark the natural variability of a lake ecosystem.

Quaternary Science Reviews, 2004

Holocene climate variability was studied in a lake sediment record covering the last c. 9000 year... more Holocene climate variability was studied in a lake sediment record covering the last c. 9000 years from Lake Chuna on the Kola Peninsula, northwest Russia, using the oxygen isotope composition of diatom silica (d 18 O diatom). The evaporation of the lake waters is likely to be minimal, and thus the isotopic composition of the lake waters recorded by the d 18 O diatom reflects the isotopic composition of summer precipitation. Overall the d 18 O diatom signal seems to record a predominance of the polar Arctic air mass bringing cold summer air temperatures immediately after the last glaciation and again after 4000 years to present time. The Atlantic maritime air mass is likely to have supplied warm summer rainfall especially in the mid Holocene. The pattern is broadly consistent with a quantitative pollen reconstruction from Chuna Lake which suggests higher mean July temperatures from deglaciation to 5500 years BP with a rather steep decline to lower temperatures after 4000 years BP. Our results support the general regional scenario of a mid Holocene warm period deduced from the higher tree line, vegetation changes and glacier fluctuations in Fennoscandia. However, the d 18 O diatom record from the Kola Peninsula suggests a relatively cold early-Holocene with a gradual shift to warmer conditions to a maximum at around 5000-4000 years BP assuming that the modern d precipitation-temperature relationship has been constant throughout the Holocene.

Journal of Paleolimnology, 1999

Forensic science international, 2014

Forensic geoscience is concerned with the analysis of geological materials in order to compare an... more Forensic geoscience is concerned with the analysis of geological materials in order to compare and exclude environmental samples from a common source, or to identify an unknown provenance in a criminal investigation. Diatom analysis is currently an underused technique within the forensic geoscience approach, which has the potential to provide an independent ecological assessment of trace evidence. This study presents empirical data to provide a preliminary evidence base in order to be able to understand the nature of diatom transfers to items of clothing, and the collection of transferred diatom trace evidence from a range of environments under experimental conditions. Three diatom extraction methods were tested on clothing that had been in contact with soil and water sites: rinsing in water (RW), rinsing in ethanol (RE), and submersion in H2O2 solution (H). Scanning electron microscopy (S.E.M.) analysis was undertaken in order to examine the degree of diatom retention on treated cl...

Forensic science international, 2015

We wish to thank the authors for their comments in response to Scott et al. [1]. The response hig... more We wish to thank the authors for their comments in response to Scott et al. [1]. The response highlights the existing methodological comparisons present within the literature in regards to the extraction of diatom particulates from clothing for forensic analysis. A study by Uitdehaag et al. [2] found that rinsing clothing with ethanol (RE) was an effective recovery technique for the collection of diatoms. The study by Scott et al. [1] sought to compare additional approaches in the extraction of diatoms from both aquatic and terrestrial transfer samples. A H2O2 treatment of clothing subsamples was observed as an efficient technique for the qualitative and quantitative assessment of transferred diatoms to clothing [1]. We wish to acknowledge the comments highlighted in the letter to the editor. The rinsing with ethanol method outlined in Scott et al., does not fully replicate that which was initially used by Uitdehaag et al. This was primarily due to the difference in the shaker used. The turbulence associated with the use of the StuartFL-1 flask shaker in the RE extraction of diatoms in Uitdehaag et al.; was not sufficiently reproduced through the use of a platform shaker in Scott et al. We thank the respondents for appropriately highlighting this difference. The potential variability in the recovery of a diatom sample for analysis based upon the type of shaker used in these two studies has important implications for forensic investigation. When considering use of the RE method, it is important to be aware of the type of equipment available in order to optimise the collection of a sample. In those instances where the flask shaker described by Uitdehaag et al. is unavailable to the investigation, the Scott et al. [1] study demonstrates that the H2O2 method may provide an efficient and reproducible technique for the recovery and collection of diatom particulate evidence from clothing. Whilst we acknowledge that the RE method used was not directly comparable, it is important to note that the study by Scott et al. [1] altered the sample size for analysis. Assessment considered a smaller (1 cm) subsample of clothing material, as opposed to the 1 dm previously tested [2]. The volume of ethanol was also modified accordingly. The reduction in the sample size used by Scott et al., was deemed important as forensic investigation considers multiple analyses, and as such only a small amount of fabric may be available for the potential extraction of diatoms. The use of a small subsample therefore requires a sensitive extraction technique for the optimal recovery of particulates. The H2O2 treatment was consistently efficient in the collection of a large number of diatom valves and a representative species composition, from a 1 cm subsample of clothing exposed to both aquatic and terrestrial sites [1].

The Holocene, 2003

A record of Holocene hydrological changes has been produced from variations in oxygen-isotope com... more A record of Holocene hydrological changes has been produced from variations in oxygen-isotope composition (δ18O) preserved in freshwater lake sediments from maritime Antarctica. Small amounts (<5%) of authigenic carbonate have been extracted from a non-marl sediment core from Sombre Lake, Signy Island (60°43'S, 45°38'W). Oxygen-isotope and particle-size analysis provide a sensitive record of hydrological events in the lake arising from local and regional climate phenomena. The climate affects δ18O through snowpack volume and glacier activity in the catchment, lakewater temperatures, the input versus evaporation balance and the duration of seasonal lake ice cover. The most depleted (negative) δ18O values are associated with influxes of meltwater at times of glacier advance or retreat. Enriched (positive) δ18O values occur during more arid, warmer conditions with longer periods of open water in summer. This isotope record can be used to determine century-scale to decadal va...

Palaeogeography, Palaeoclimatology, Palaeoecology, 2008

Changes in diatom assemblages and spheroidal carbonaceous particle (SCP) profiles during the last... more Changes in diatom assemblages and spheroidal carbonaceous particle (SCP) profiles during the last 200 years in 210 Pb-dated sediment cores from five remote arctic and sub-arctic lakes in the northern Urals were analysed. The study area covers a large territory from arctic tundra in the north to boreal forest on the western slopes of the Ural mountains in the south. pH was reconstructed using a diatom-based model. The degrees of compositional turnover and rates-of-change were estimated numerically. The 20th century diatom floristic shifts, the rise in diatom accumulation rates and the rates of diatom compositional change in the northern Ural lakes correlate well with June temperature in the region and with the overall circum-arctic temperature increase from the 1970s. The main driving force behind diatom compositional shifts in the study lakes are the changes in the duration of ice-free season, timing of water turnover and stratification periods and habitat availability. Changes in spheroidal carbonaceous particles show no pronounced effect on diatom assemblages. Pollution is restricted to regional sources originating mainly from the Vorkuta coal industry. Changes in diatom plankton are more pronounced than changes in diatom benthos. There is no clear north-south gradient in degree of compositional changes, with greatest changes occurring in Lake Vankavad situated in northern boreal forest. The degree of the 20th century diatom changes in Lake Vankavad is greater than in most circum-arctic and sub-arctic lakes from northern Europe and Canada.

Journal of Quaternary Science, 1999

Polar Research, 1995

The Holocene

Limnology and Oceanography Letters

Global and Planetary Change, 2015

Quaternary Science Reviews, 2011

Global and Planetary Change

Global and Planetary Change, 2015

Quaternary Science Reviews, 2004

Journal of Paleolimnology, 1999

Forensic science international, 2014

Forensic science international, 2015

The Holocene, 2003

Palaeogeography, Palaeoclimatology, Palaeoecology, 2008

Journal of Quaternary Science, 1999