The Effect of Toxic Organic Chemicals on Mogan Lake (original) (raw)
Related papers
Water Research, 2002
The Lake Suwa version of the comprehensive aquatic systems model (CASM SUWA) was developed using field data from Lake Suwa and evaluated to examine the utility of CASM SUWA for assessing the ecological risk of chemicals for aquatic ecosystems. The calibration of the parameters for the model provided that the established reference model simulation could reproduce complex seasonal biomass behavior of populations that were not significantly different from the general seasonal pattern for the Lake Suwa ecosystem. The sensitivity analyses revealed the potential importance of indirect effects and demonstrated that the parameter values of all the trophic levels were important in determining the biomass of each trophic level in the model. The risk estimation of linear alkylbenzene sulfonates (LAS) demonstrated that the model estimated the risks of direct toxic effects on each population and the indirect ecological effects that propagate through the food-web in the model ecosystem. The CASM SUWA-derived benchmark levels were approximately one order of magnitude less than the field-derived NOECs in literature. The analyses of the comparison implied that the model could provide a good basis in determining an ecological protective level of a chemical of concern in aquatic ecosystem. This modeling study demonstrated that the model can be used to provide additional information for the decision-making process in the management of the aquatic ecological risk of chemicals. r
Comparison between Water Quality Models for Toxics
Water quality models have been applied increasingly to represent the interaction between pollutants and aquatic environment due to transport and transformation phenomena: These models can be used to better understand pollution phenomena and to choose between different, alternative management strategies. The paper compares the results of two different water quality models, which have been applied to a water column-sediments system of a lake with an inflow contaminant loading. In the former, the system is idealized as well-mixed surface-water underlain by a well-mixed active sediment layer, where the resulting concentrations are attained by direct analytical solutions at the steady-state and in time-variable conditions. The latter is TOXI5 model, which is part of WASP5 modeling framework developed by USEPA. The models were applied to an idealized case in order to predict steady-state and time-variable concentrations in the water-column and in the active sediment layer for 4 pesticides. Comparison between the results obtained through the two models shows a good agreement both for the steady-state concentrations and for the timevariable ones. The transients from no-concentrations to the steady-state and from steady-state to negligible concentrations were performed; the simulations have pointed out the very long time for attaining both steady-state conditions and the system recovery in the lake and in the active sediments layer especially.
Evaluation of an ecosystem model in ecological risk assessment of chemicals
Chemosphere, 2003
We used a Lake Suwa version of Comprehensive Aquatic Systems Model (CASM_SUWA) to demonstrate the risk estimation of 10 different chemicals and examined the applicability and reliability of the model in ecological risk assessment by qualitatively and quantitatively comparing with the results of studies on multiple species using mesocosm tests. The qualitative comparison of the model results with those of the reported mesocosm tests indicated that some evidence observed in mesocosm studies supported the indirect effects predicted from simulation using the model. The comparison of the concentration levels at which 20% biomass reduction (BR20) in the most sensitive population estimated from the model with the no-observed effect concentration values derived from multiple species mesocosm tests (MS-NOEC) suggested that both data were related to each other and the model can be used to help in the determination of an ecological acceptable level of chemicals in aquatic environments. The analysis of the potential of indirect effects of a chemical for fish population indicated that the magnitude of the potential of indirect effects was quantified based on the ratio of BR50 to LC50 for fish population.
A Mathematical Approach to Study the Effect of Pollutants/Toxicants in Aquatic Environment
International Journal of Research -GRANTHAALAYAH
Acid lowers the pH levels in water bodies below what is required for survival of aquatic life and increases the toxicity of metals. For this effect, a mathematical model has been proposed using a system of non-linear ordinary differential equations with four state variables. The dependent variables are amount of acid and metal in water, density of favorable resources (phytoplankton), density of fish population and nutrient concentration under the assumption that the amount of metal present in water is less than the amount of acid present in water. Conditions for local stability and feasible equilibrium points have been determined. Nonlinear stability analysis of the non-trivial equilibrium points has been discussed and it was found that system of the differential equations show more feasible results if the crowding effect is incorporated for fish population. Further it was also observed that, nutrients play important role for the growth and survival of the species. Conditions for th...
Ecotoxicity assessment of the aquatic environment around Lake Kojima, Japan
Environmental Toxicology and Water Quality, 1996
To reduce the impact of chemical substances on the aquatic ecosystem, it is essential to understand their ecotoxicological properties in the natural aquatic environment. Consequently, we conducted an ecotoxicological study on the aquatic environment around Lake Kojima, a man-made lake located in the southwest of Japan. Lake Kojima receives its chemical inputs mainly from two rivers that flow through various agricultural and industrial areas. For ecotoxicity screening, surface water and sediment samples were collected 4 times in 1993 from 16 preselected sites. Then, the solutes in the filtered surface water were concentrated by ODS resin, and the organic chemicals in the suspended solids (SS) and sediments were extracted by acetone. A battery of five ecotoxicity tests (agar plate test using bacteria and yeast, algal growth inhibition test, Daphnia rnagna immobilization test, and root elongation test using lettuce seeds) was used to assess these extracts. The results show that the surface water extracts had a lethal effect on D. rnagna, the SS extracts suppressed algal growth, and the sediment extracts were inhibitory to the growth of yeast. A significant inhibitory effect by the sediment extracts from 4 lake sites and 3 river sites was detected by these ecotoxicity tests. Attempts also were made to identify the putative ecotoxic chemicals in the collected samples. Elementary sulfur was identified as one of the major toxicants in the sediment extracts that were inhibitory to the yeast growth. Moreover, samples of surface water around Lake Kojima, collected weekly from June to September in 1994, were found to contain three pesticides and were toxic to D. rnagna. But the concentration of the pesticides detected was too low to cause daphnia immobilization. It is believed that the toxicity of the water extracts was mainly due to the combined toxic effect of natural and man-made components. 0 7996 by John Wiley & Sons, lnc.
Water
As water management is still a problem of international concern, scientists and practitioners are collaborating to develop new tools and methods to improve and help in the decision-making process. When addressing the priority pollutant monitoring and impact assessment, the ecotoxicity effects, carcinogenic and non-carcinogenic, should be considered together with the exposure factor and health hazards. The main goals of this study were to assess the ecological and health hazards and to apply integrated impact and risk assessment based on the ecotoxicity and exposure factors of each priority pollutant present in the aquatic ecosystem. This study used as a database the measured concentrations of 5 inorganic and 14 organic priority pollutants from the Siret river basin from NE Romania, from 18 river sections monitored in the period 2015–2020. The USEtox methodology and a new integrated index for environmental impact and risk assessment were developed and applied to evaluate the ecologic...
EFSA Journal
Following a request from EFSA, the Panel on Plant Protection Products and their Residues (PPR) developed an opinion on the state of the art of Toxicokinetic/Toxicodynamic (TKTD) models and their use in prospective environmental risk assessment (ERA) for pesticides and aquatic organisms. TKTD models are species-and compound-specific and can be used to predict (sub)lethal effects of pesticides under untested (time-variable) exposure conditions. Three different types of TKTD models are described, viz., (i) the 'General Unified Threshold models of Survival' (GUTS), (ii) those based on the Dynamic Energy Budget theory (DEBtox models), and (iii) models for primary producers. All these TKTD models follow the principle that the processes influencing internal exposure of an organism, (TK), are separated from the processes that lead to damage and effects/mortality (TD). GUTS models can be used to predict survival rate under untested exposure conditions. DEBtox models explore the effects on growth and reproduction of toxicants over time, even over the entire life cycle. TKTD model for primary producers and pesticides have been developed for algae, Lemna and Myriophyllum. For all TKTD model calibration, both toxicity data on standard test species and/or additional species can be used. For validation, substance and species-specific data sets from independent refined-exposure experiments are required. Based on the current state of the art (e.g. lack of documented and evaluated examples), the DEBtox modelling approach is currently limited to research applications. However, its great potential for future use in prospective ERA for pesticides is recognised. The GUTS model and the Lemna model are considered ready to be used in risk assessment. A, Reed M, Arena M, Ippolito A, Byers H and Teodorovic I, 2018. Scientific Opinion on the state of the art of Toxicokinetic/Toxicodynamic (TKTD) effect models for regulatory risk assessment of pesticides for aquatic organisms.
A Toxicologically-Based Framework Can Enhance Urban Aquatic Ecosystem Risk Assessment
This study proposes a toxicologically based algorithm to relate arsenic (As) toxicity to the internal effect concentration (IEC) in tilapia Oreochromis mossambicus. The relationships among As exposure, uptake, accumulation, and toxicity to tilapia are investigated using toxicokinetic (TK) and toxicodynamic (TD) modeling. A 7-d exposure bioassay reveals that the bioconcentration factor (BCF) value of tilapia is 2.88, indicating that the tilapia is capable of accumulating waterborne As. As acute toxicity is analyzed by determining the median external effect concentration (LC 50) at different integration times, indicating that 96-h LC 50 and LC 50 (∞) for tilapia are 28.68 (95% CI: 24.92-32.44) and 12.04 µg mL-1 , respectively. To determine the mode of action (MOA) governing the As toxicity, this study employed the damage-assessment model (DAM) to describe LC 50 s. Result suggests that the DAM characterizes As toxicity well and the intrinsic MOA of As toxicity acts through the reversible reaction between As and specific receptors. This study kinetically links the DAM with IEC-based Hill equation model to derive dose-response relationships between equilibrium As residue and mortality. We suggests that considering MOA in ecotoxicological assessment is useful to improve the construction of environmental quality criteria for protecting rapidly degrading aquatic ecosystems in urban area.
Published in Environmental Science and Pollution Research, online first. (DOI: 10.1007/s11356-013-1504-5)., 2013
Abstract The impounding of the Three Gorges Reservoir (TGR) at the Yangtze River caused large flooding of urban, industrial, and agricultural areas, and profound land use changes took place. Consequently, substantial amounts of organic and inorganic pollutants were released into the reser- voir. Additionally, contaminants and nutrients are entering the reservoir by drift, drainage, and runoff from adjacent agricultural areas as well as from sewage of industry, aqua- cultures, and households. The main aim of the presented research project is a deeper understanding of the processes that determines the bioaccumulation and biomagnification of or- ganic pollutants, i.e., mainly pesticides, in aquatic food webs under the newly developing conditions of the TGR. The proj- ect is part of the Yangtze-Hydro environmental program, fi- nanced by the German Ministry of Education and Science. In order to test combinations of environmental factors like nutrients and pollution, we use an integrated modeling ap- proach to study the potential accumulation and biomagnifica- tion. We describe the integrative modeling approach and the consecutive adaption of the AQUATOX model, used as mod- eling framework for ecological risk assessment. As a starting point, pre-calibrated simulations were adapted to Yangtze- specific conditions (regionalization). Two exemplary food webs were developed by a thorough review of the pertinent literature. The first typical for the flowing conditions of the original Yangtze River and the Daning River near the city of Wushan, and the second for the stagnant reservoir character- istics of the aforementioned region that is marked by an inter- mediate between lake and large river communities of aquatic organisms. In close cooperation with German and Chinese partners of the Yangtze-Hydro Research Association, other site-specific parameters were estimated. The MINIBAT project contributed to the calibration of physicochemical and bathy- metric parameters, and the TRANSMIC project delivered hy- drodynamic models for water volume and flow velocity conditions. The research questions were firstly focused on the definition of scenarios that could depict representative situations regarding food webs, pollution, and flow conditions in the TGR. The food webs and the abiotic site conditions in the main study area near the city of Wushan that determine the environmental preconditions for the organisms were defined. In our conceptual approach, we used the pesticide propanil as a model substance.