WCA Environment Ltd.

Faringdon, United Kingdom

WCA Environment Ltd.

Faringdon, United Kingdom

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Weltje L.,BASF | Simpson P.,WCA Environment Ltd | Gross M.,WCA Environment Ltd | Crane M.,WCA Environment Ltd | Wheeler J.R.,Hill International
Environmental Toxicology and Chemistry | Year: 2013

The relative sensitivity of amphibians to chemicals in the environment, including plant protection product active substances, is the subject of ongoing scientific debate. The objective of this study was to compare systematically the relative sensitivity of amphibians and fish to chemicals. Acute and chronic toxicity data were obtained from the U.S. Environmental Protection Agency (U.S. EPA) ECOTOX database and were supplemented with data from the scientific and regulatory literature. The overall outcome is that fish and amphibian toxicity data are highly correlated and that fish are more sensitive (both acute and chronic) than amphibians. In terms of acute sensitivity, amphibians were between 10- and 100-fold more sensitive than fish for only four of 55 chemicals and more than 100-fold more sensitive for only two chemicals. However, a detailed inspection of these cases showed a similar acute sensitivity of fish and amphibians. Chronic toxicity data for fish were available for 52 chemicals. Amphibians were between 10- and 100-fold more sensitive than fish for only two substances (carbaryl and dexamethasone) and greater than 100-fold more sensitive for only a single chemical (sodium perchlorate). The comparison for carbaryl was subsequently determined to be unreliable and that for sodium perchlorate is a potential artifact of the exposure medium. Only a substance such as dexamethasone, which interferes with a specific aspect of amphibian metamorphosis, might not be detected using fish tests. However, several other compounds known to influence amphibian metamorphosis were included in the analysis, and these did not affect amphibians disproportionately. These analyses suggest that additional amphibian testing is not necessary during chemical risk assessment. © 2013 SETAC.


Worrall F.,Durham University | Davies H.,UK Center for Ecology and Hydrology | Bhogal A.,ADAS Ltd. | Lilly A.,Macaulay Institute | And 6 more authors.
Journal of Hydrology | Year: 2012

The estimation of flux of dissolved organic carbon (DOC) from the terrestrial biosphere has been of concern because of its importance for the status of carbon storage in soils and the potential impact on atmospheric CO 2 levels. However, these studies have tended to focus on the flux at the tidal limit and from organic soils, without considering the losses at the soil source or processing within the watershed. This study constructs a database of 194 catchments where DOC export was predicted as a function of soil, land-use and hydrological characteristics of each catchment. By comparing across catchments of differing sizes while accounting for the effects of differences in soil and land use this study can estimate the export of DOC at the soil source and the net removal across the watershed. The study can show that although the dominant source of DOC was organic soils, there was significant DOC export from urban and grazed land on mineral and organo-mineral soils, but not from arable land. The average export at source from peat soils was 40±4tonnesC/km 2/yr. The average estimated annual DOC flux between 2001 and 2007 from the UK was 909±354ktonnesC/yr which was within the error of previous estimates. The study was able to estimate the loss of DOC at the soil source as between 3100 and 4000ktonnesC/yr, with a net watershed loss of DOC between 2200 and 3100ktonnesC/yr, equivalent to between 9.0 and 12.7tonnes C/km 2 of UK land area/yr. © 2012 Elsevier B.V..


Bell M.J.,Science Laboratories | Bell M.J.,University of Aberdeen | Worrall F.,Science Laboratories | Smith P.,University of Aberdeen | And 5 more authors.
Global Biogeochemical Cycles | Year: 2011

The contribution of soil organic carbon (SOC) to atmospheric greenhouse gas (GHG) concentrations could increase due to rising temperatures, agricultural land-management, and land-use change. Here the results of a modeling study are presented, which reviews the changing patterns of UK land-use from 1925 to 2007, and estimates the contribution that these changes have had toward UK GHG emissions. The study uses a large database of SOC concentrations from which SOC stocks are estimated for land-uses typical of the UK, and combines this with literature values of transition times for SOC to adjust to a new concentration following land-use change. The model was designed to be used with limited input data, allowing the impacts of historical land-use change, lacking in site specific soil and vegetation change data to be assessed. This study suggests that from 1925 to 2007 the UK's soils have acted as a net carbon sink as a result of land-use change, sequestering a total of 102 Tg C. This represents a 5% net gain in total SOC stocks, and an average increase of 1.9 Tg C/year (inter-quartile range: 0.19-3.12 Tg C/yr). When the reported losses of SOC due to climate change are compared to the gains resulting from land-use change the UK's soils are a sink of carbon, with the gains from land-use change offsetting those due to climate change. This overall sink is the result of an increase in the area of woodland, and conversion of arable land to permanent grassland. The greatest sequestration in any one year occurred in 1993 and coincides with the introduction of set-aside. The largest SOC flux to the atmosphere occurred in 1942 following arable expansion, emitting 12.3 Tg C in one year. This flux is equivalent to almost 10% of the UK's current total GHG emissions, indicating that such land-use change should be avoided in the future if targets to reduce GHG emissions are to be met. Copyright 2011 by the American Geophysical Union.


Peters A.,WCA Environment Ltd. | Merrington G.,WCA Environment Ltd. | de Schamphelaere K.,Ghent University | Delbeke K.,European Copper Institute
Integrated Environmental Assessment and Management | Year: 2011

The chronic Cu biotic ligand model (CuBLM) provides a means by which the bioavailability of Cu can be taken into account in assessing the potential chronic risks posed by Cu at specific freshwater locations. One of the barriers to the widespread regulatory application of the CuBLM is the perceived complexity of the approach when compared to the current systems that are in place in many regulatory organizations. The CuBLM requires 10 measured input parameters, although some of these have a relatively limited influence on the predicted no-effect concentration (PNEC) for Cu. Simplification of the input requirements of the CuBLM is proposed by estimating the concentrations of the major ions Mg 2+, Na +, K +, SO 2- 4, Cl -, and alkalinity from Ca concentrations. A series of relationships between log10 (Ca,mgl -1) and log10 (major ion,mgl -1) was established from surface water monitoring data for Europe, and applied in the prediction of Cu PNEC values for some UK freshwater monitoring data. The use of default values for major ion concentrations was also considered, and both approaches were compared to the use of measured major ion concentrations. Both the use of fixed default major ion concentrations, and major ion concentrations estimated from Ca concentrations, provided Cu PNEC predictions which were in good agreement with the results of calculations using measured data. There is a slight loss of accuracy when using estimates of major ion concentrations compared to using measured concentration data, although to a lesser extent than when fixed default values are applied. The simplifications proposed provide a practical evidence-based methodology to facilitate the regulatory implementation of the CuBLM. © 2011 SETAC.


Peters A.,WCA Environment Ltd. | Simpson P.,WCA Environment Ltd. | Merrington G.,WCA Environment Ltd. | Rothenbacher K.,Precious Metals and Rhenium Consortium | Sturdy L.,UK Environment Agency
Bulletin of Environmental Contamination and Toxicology | Year: 2011

There is a paucity of monitoring data for silver in freshwater environments in Europe. There are several reasons for this, including the relatively low levels of silver in the aquatic environment and the requirement for commensurately low levels of detection (<100 ng l -1), which are generally not routinely achieved in analytical laboratories. In this study 425 separate analytical determinations for dissolved (<0.45 μm) silver from 84 Environment Agency monitoring stations were carried out. Sampling was carried out on a monthly basis over a period of 6 months. Of the 425 samples, 346 were reported as having dissolved silver concentrations below the limit of quantification (6.6 ng l -1) and, of these, 280 samples were reported as below the reporting limit of detection (3 ng l -1). The mean of the maximum dissolved silver concentrations reported at each station was calculated as 6.1 ng l -1 using a statistical extrapolation technique to allow for the high level of censorship in the dataset. The maximum mean dissolved silver concentration recorded at a station was 19.8 ng l -1. A freshwater Predicted No Effect Concentration (PNEC) of 40 ng l -1 was used in this study. © 2011 Springer Science+Business Media, LLC.


Peters A.,WCA Environment Ltd. | Simpson P.,WCA Environment Ltd. | Moccia A.,University of Insubria
Environmental Science and Pollution Research | Year: 2014

Recent years have seen considerable improvement in water quality standards (QS) for metals by taking account of the effect of local water chemistry conditions on their bioavailability. We describe preliminary efforts to further refine water quality standards, by taking account of the composition of the local ecological community (the ultimate protection objective) in addition to bioavailability. Relevance of QS to the local ecological community is critical as it is important to minimise instances where quality classification using QS does not reconcile with a quality classification based on an assessment of the composition of the local ecology (e.g. using benthic macroinvertebrate quality assessment metrics such as River InVertebrate Prediction and Classification System (RIVPACS)), particularly where ecology is assessed to be at good or better status, whilst chemical quality is determined to be failing relevant standards. The alternative approach outlined here describes a method to derive a site-specific species sensitivity distribution (SSD) based on the ecological community which is expected to be present at the site in the absence of anthropogenic pressures (reference conditions). The method combines a conventional laboratory ecotoxicity dataset normalised for bioavailability with field measurements of the response of benthic macroinvertebrate abundance to chemical exposure. Site-specific QSref are then derived from the 5%ile of this SSD. Using this method, site QSref have been derived for zinc in an area impacted by historic mining activities. Application of QSref can result in greater agreement between chemical and ecological metrics of environmental quality compared with the use of either conventional (QScon) or bioavailability-based QS (QSbio). In addition to zinc, the approach is likely to be applicable to other metals and possibly other types of chemical stressors (e.g. pesticides). However, the methodology for deriving site-specific targets requires additional development and validation before they can be robustly applied during surface water classification. © 2013 Springer-Verlag Berlin Heidelberg.


Grist E.P.M.,WCA Environment Ltd | Jackson G.D.,University of Tasmania | Meekan M.G.,Australian Institute of Marine Science
Environmental Biology of Fishes | Year: 2011

Individual growth patterns in ecology are often determined from population field data through the use of regression and model selection inference analyses. However, such approaches are typically unable to provide insight into dynamic processes when based upon collections of 'snapshot' data that consist of only a single observation for each individual. We caution how model selection inference from size-at-age data may lead to growth models that are mis-specified in the case of species such as squid and fishes that display fast and variable growth and for which, field data of the early part of the lifespan are typically sparse and difficult to obtain. © 2010 Springer Science+Business Media B.V.


Peters A.,Wca environment Ltd | Simpson P.,Wca environment Ltd | Merrington G.,Wca environment Ltd | Schlekat C.,NiPERA | Rogevich-Garman E.,NiPERA
Environmental Science and Pollution Research | Year: 2014

A field-based evaluation of the biological effects of potential nickel (Ni) exposures was conducted using monitoring data for benthic macroinvertebrates and water chemistry parameters for streams in England and Wales. Observed benthic community metrics were compared to expected community metrics under reference conditions using RIVPACS III+ software. In order to evaluate relationships between Ni concentrations and benthic community metrics, bioavailable Ni concentrations were also calculated for each site. A limiting effect from Ni on the 90th percentile of the maximum achievable ecological quality was derived at "bioavailable Ni" exposures of 10.3 μg l-1. As snails have been identified as particularly sensitive to nickel exposure, snail abundance in the field in response to nickel exposure, relative to reference conditions, was also analysed. A "low effects" threshold for snail abundance based on an average of spring and autumn data was derived as 3.9 μg l-1 bioavailable Ni. There was no apparent effect of Ni exposure on the abundance of Ephemeroptera (mayflies), Plecoptera (stoneflies) or Tricoptera (caddisflies) when expressed relative to a reference condition within the range of "bioavailable Ni" exposures observed within the dataset. Nickel exposure concentrations co-vary with the concentrations of other stressors in the dataset, and high concentrations of Ni are also associated with elevated concentrations of other contaminants. © 2013 Springer-Verlag Berlin Heidelberg.


Peters A.,WCA Environment Ltd. | Crane M.,WCA Environment Ltd. | Adams W.,Rio Tinto Alcan
Bulletin of Environmental Contamination and Toxicology | Year: 2011

Matched chemical and ecological monitoring data were used to assess the effects of iron on benthic macroinvertebrate communities. Three measures of iron exposure: dissolved, total, and particulate iron were assessed. Ecological responses were normalised to an unimpacted reference condition to make site-specific predictions of the reference condition. Ecological data were expressed as an Ecological Quality Index (EQI), indicating quality relative to the reference condition. Quantile regression analysis was used to derive thresholds as an EQI value equivalent to the cut-off between good and moderate ecological status for water quality classification. Thresholds for Good Ecological Status ranged from 1.25 to 2.46 mg L -1 depending on the measure of exposure and ecological response. © 2011 Springer Science+Business Media, LLC.


Hing L.S.,Royal Holloway, University of London | Ford T.,Royal Holloway, University of London | Finch P.,Royal Holloway, University of London | Crane M.,Wca environment Ltd | Morritt D.,Royal Holloway, University of London
Aquatic Toxicology | Year: 2011

Continuous culture conditions designed to achieve a dynamic equilibrium between phytoplankton growth and nutrient input were established for Phaeodactylum tricornutum, Isochrysis galbana and Chlorella salina. The technique was used to determine the no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for algae after spiking with diesel oil. P. tricornutum (NOEC = 0.25. mg/l, LOEC = 0.3. mg/l) was more sensitive than I. galbana (NOEC = 2.5. mg/l, LOEC = 2.6. mg/l), while C. salina (NOEC = 16.0. mg/l, LOEC = 17.0. mg/l) was the most tolerant. Continuous renewal of medium ensured that experimental conditions remained stable throughout the test period and is a more environmentally relevant method for assessing the effects of many contaminants. © 2011 Elsevier B.V.

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