Modeling the influence of climate change on the mass balance of polychlorinated biphenyls in the Adriatic Sea

Environmental fate and exposure models: advances and challenges in 21st century chemical risk assessment

Environmental fate and exposure models are a powerful means to integrate information on chemicals, their partitioning and degradation behaviour, the environmental scenario and the emissions in order to compile a picture of chemical distribution and fluxes in the multimedia environment. A 1995 pioneering book, resulting from a series of workshops among model developers and users, reported the main advantages and identified needs for research in the field of multimedia fate models. Considerable efforts were devoted to their improvement in the past 25 years and many aspects were refined; notably the inclusion of nanomaterials among the modelled substances, the development of models at different spatial and temporal scales, the estimation of chemical properties and emission data, the incorporation of additional environmental media and processes, the integration of sensitivity and uncertainty analysis in the simulations. However, some challenging issues remain and require research efforts and attention: the need of methods to estimate partition coefficients for polar and ionizable chemical in the environment, a better description of bioavailability in different environments as well as the requirement of injecting more ecological realism in exposure predictions to account for the diversity of ecosystem structures and functions in risk assessment. Finally, to transfer new scientific developments into the realm of regulatory risk assessment, we propose the formation of expert groups that compare, discuss and recommend model modifications and updates and help develop practical tools for risk assessment.

Understanding and Predicting the Fate of Semivolatile Organic Pesticides in a Glacier-Fed Lake Using a Multimedia Chemical Fate Model

Melting glaciers release previously ice-entrapped chemicals to the surrounding environment. As glacier melting accelerates under future climate warming, chemical release may also increase. This study investigated the behavior of semivolatile pesticides over the course of one year and predicted their behavior under two future climate change scenarios. Pesticides were quantified in air, lake water, glacial meltwater, and streamwater in the catchment of Lake Brewster, an alpine glacier-fed lake located in the Southern Alps of New Zealand. Two historic-use pesticides (endosulfan I and hexachlorobenzene) and three current-use pesticides (dacthal, triallate, and chlorpyrifos) were frequently found in both air and water samples from the catchment. Regression analysis indicated that the pesticide concentrations in glacial meltwater and lake water were strongly correlated. A multimedia environmental fate model was developed for these five chemicals in Brewster Lake. Modeling results indicated that seasonal lake ice cover melt, and varying contributions of input from glacial melt and streamwater, created pulses in pesticide concentrations in lake water. Under future climate scenarios, the concentration pulse was altered and glacial melt made a greater contribution (as mass flux) to pesticide input in the lake water.

Estimation of PCB content in agricultural soils associated with long-term fertilization with organic waste

Polychlorinated biphenyl (PCB) pollution related to the use of organic waste as fertilizers in agricultural soils is a cause of major concern. In the study presented herein, PCB concentration was studied through a field trial conducted in two agricultural soils in the province of Palencia (Spain) over a 4-year period, assessing the impact of irrigation and of different types of organic waste materials. The amounts of organic waste added to the soil were calculated according to the nitrogen needs of the crop, and the concentration of PCBs was determined before and after the application of the organic waste. The resulting persistence of the total PCB content in the agricultural soils, compared with the PCB concentration in the original soils, ranged from 27% to 90%, with the lowest value corresponding to irrigated soils treated with municipal solid waste compost (MSWC) and the highest value to non-irrigated soils treated with composted sewage sludge (CSS). An estimate of the PCB content in agricultural soils after the application of organic waste materials until year 2050 was obtained, resulting in a value below 5 ng·g(-1), considered a background value for soils in sites far away from potential pollution sources.

The distribution of Polychlorinated Biphenyls (PCBs) in the River Thames Catchment under the scenarios of climate change

Measurements have shown low levels of PCBs in water but relatively high concentrations in the resident fish of the River Thames (UK). To better understand the distribution and behaviour of PCBs in the Thames river basin and their potential risks, a level III fugacity model was applied to selected PCB congeners (PCB 52, PCB 118 and PCB 153). The modelling results indicated that fish and sediments represent environmental compartments with the highest PCB concentrations; but the greatest mass of PCBs (over 70%) is likely to remain in the soil. As emissions decline, soil could then act as a significant secondary source of PCBs with the river bed-sediment functioning as a long-term reservoir of PCBs. The predicted changes in temperature and rainfall forecast in the UK Climate Projections 2009 (UKCP09) over the next 80 years had only a modest influence on PCB fate in the model. The most significant result was a tendency for climate change to enhance the evaporation of PCBs from soil to air in the Thames catchment.

Climate change and environmental concentrations of POPs: A review

In recent years, the climate change impact on the concentrations of persistent organic pollutants (POPs) has become a topic of notable concern. Changes in environmental conditions such as the increase of the average temperature, or the UV-B radiation, are likely to influence the fate and behavior of POPs, ultimately affecting human exposure. The state of the art of the impact of climate change on environmental concentrations of POPs, as well as on human health risks, is here reviewed. Research gaps are also identified, while future studies are suggested. Climate change and POPs are a hot issue, for which wide attention should be paid not only by scientists, but also and mainly by policy makers. Most studies reported in the scientific literature are focused on legacy POPs, mainly polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and pesticides. However, the number of investigations aimed at estimating the impact of climate change on the environmental levels of polycyclic aromatic hydrocarbons (PAHs) is scarce, despite of the fact that exposure to PAHs and photodegradation byproducts may result in adverse health effects. Furthermore, no data on emerging POPs are currently available in the scientific literature. In consequence, an intensification of studies to identify and mitigate the indirect effects of the climate change on POP fate is needed to minimize the human health impact. Furthermore, being this a global problem, interactions between climate change and POPs must be addressed from an international perspective.

Statistical analysis of long-term monitoring data for persistent organic pollutants in the atmosphere at 20 monitoring stations broadly indicates declining concentrations

During recent decades concentrations of persistent organic pollutants (POPs) in the atmosphere have been monitored at multiple stations worldwide. We used three statistical methods to analyze a total of 748 time series of selected POPs in the atmosphere to determine if there are statistically significant reductions in levels of POPs that have had control actions enacted to restrict or eliminate manufacture, use and emissions. Significant decreasing trends were identified in 560 (75%) of the 748 time series collected from the Arctic, North America, and Europe, indicating that the atmospheric concentrations of these POPs are generally decreasing, consistent with the overall effectiveness of emission control actions. Statistically significant trends in synthetic time series could be reliably identified with the improved Mann-Kendall (iMK) test and the digital filtration (DF) technique in time series longer than 5 years. The temporal trends of new (or emerging) POPs in the atmosphere are often unclear because time series are too short. A statistical detrending method based on the iMK test was not able to identify abrupt changes in the rates of decline of atmospheric POP concentrations encoded into synthetic time series.

Modelling the influence of climate change on the chemical concentrations in the Baltic Sea region with the POPCYCLING-Baltic model

The effect of projected future changes in temperature, wind speed, precipitation and particulate organic carbon on concentrations of persistent organic chemicals in the Baltic Sea regional environment is evaluated using the POPCYCLING-Baltic multimedia chemical fate model. Steady-state concentrations of hypothetical perfectly persistent chemicals with property combinations that encompass the entire plausible range for non-ionizing organic substances are modelled under two alternative climate change scenarios (IPCC A2 and B2) and compared to a baseline climate scenario. The contributions of individual climate parameters are deduced in model experiments in which only one of the four parameters is changed from the baseline scenario. Of the four selected climate parameters, temperature is the most influential, and wind speed is least. Chemical concentrations in the Baltic region are projected to change by factors of up to 3.0 compared to the baseline climate scenario. For chemicals with property combinations similar to legacy persistent organic pollutants listed by the Stockholm Convention, modelled concentration ratios between two climate change scenarios and the baseline scenario range from factors of 0.5 to 2.0. This study is a first step toward quantitatively assessing climate change-induced changes in the environmental concentrations of persistent organic chemicals in the Baltic Sea region.