Evaluating the usefulness of dynamic pollutant fate models for implementing the EU Water Framework Directive

Passive sampling and ecohydrologic modeling to investigate pesticide surface water loading in the Zollner Creek watershed, Oregon, USA

In the U.S. Pacific Northwest and California contaminants entering surface water may harm Endangered Species Act (ESA) listed salmonid species and consequently there is ongoing concern regarding agricultural practices and resulting pesticide surface water loading may adversely impact salmonid species, their food web, and habitat. Characterizing pesticide exposure in surface water at the watershed scale and beyond is challenging due to uncertainty regarding pesticide use practices and sparse monitoring data. We report here a 2-year continuous deployment of passive sampling devices (PSDs) for monitoring of pesticides in surface water at the outflow of the Zollner Creek watershed located within the Willamette Basin, Oregon, USA. This watershed is predominately agricultural and within the geographic range of two ESA listed Pacific salmonid species. Grab and passive sampling monitoring data were used to evaluate the performance of a probabilistic application of the Soil and Water Assessment Tool (SWAT), a physically based process model which integrates institutional and local knowledge and expertise to investigate the relationship between land use practices and pesticide surface water loading at the watershed scale. SWAT estimated pesticide surface water concentrations for the pesticides chlorpyrifos and trifluralin followed temporal trend in PSD monitoring results and the 5th to 95th percentile range of estimated pesticide concentrations based on the probabilistic assessment encompassed 65-76% of the observed PSD concentrations. Evaluation of model estimates for metolachlor in surface water was challenged by insufficient publicly available grab sample monitoring data. A process to estimate pesticide surface water concentrations on biologically relevant time scales and comparison to screening level aquatic life benchmarks is presented. Additionally, model estimates were used to characterize the variance in surface water concentrations in this small hydrologically responsive watershed to determine grab sampling frequency adequate for model evaluation.

A fugacity model assessment of ibuprofen, diclofenac, carbamazepine, and their transformation product concentrations in an aquatic environment

An updated version of FATEMOD, a multimedia fugacity model for environmental fate of organic chemicals, was set up to assess environmental behaviour of three pharmaceuticals in northern Lake Päijänne, Finland. Concentrations of ibuprofen, diclofenac, and carbamazepine were estimated at various depths at two sites: near a wastewater treatment plant and 3.5 km downstream the plant. When compared with environmental sampling data from corresponding depths and sites, the predicted concentrations, ranging from nanograms to hundreds of nanograms per litre, were found to be in good agreement. Weather data were utilised with the model to rationalise the effects of various environmental parameters on the sampling results, and, e.g. the roles of various properties of lake dynamics and photodegradation were identified. The new model also enables simultaneous assessment of transformation products. Environmentally formed transformation product concentrations were estimated to be at highest an order of magnitude lower than those of the parent compounds, and unlikely to reach a detectable level. However, a possibility that conjugates of ibuprofen are present at higher levels than the parent compound was identified. Simulation results suggest that environmental degradation half-lives of the inspected contaminants under stratified lake conditions are in the range of some weeks to months.

A black-box model for generation of site-specific WWTP influent quality data based on plant routine data

This paper presents a simple method for the generation of continuous influent quality datasets for wastewater treatment plants (WWTPs) that is based on incomplete available routine data, only, without referring to any further measurement. In the approach, Weibull-distributed random data are fitted to the available routine data, such that the resulting distribution of influent quality data shows the identical statistical characteristics. Beside the description of the method, this paper contains a comprehensive analysis of robustness and universality of the approach. It is shown that incomplete datasets with only 10% remaining influent quality data can be filled with this method with nearly the same statistical parameters as the original data. In addition, the use with datasets of different WWTP plants sizes results always in a good agreement between original and filled datasets.

Assessment of riverine load of contaminants to European seas under policy implementation scenarios: an example with 3 pilot substances

An evaluation of conventional emission scenarios is carried out targeting a possible impact of European Union (EU) policies on riverine loads to the European seas for 3 pilot pollutants: lindane, trifluralin, and perfluorooctane sulfonate (PFOS). The policy scenarios are investigated to the time horizon of year 2020 starting from chemical-specific reference conditions and considering different types of regulatory measures including business as usual (BAU), current trend (CT), partial implementation (PI), or complete ban (PI ban) of emissions. The scenario analyses show that the model-estimated lindane load of 745 t to European seas in 1995, based on the official emission data, would be reduced by 98.3% to approximately 12.5 t in 2005 (BAU scenario), 10 years after the start of the EU regulation of this chemical. The CT and PI ban scenarios indicate a reduction of sea loads of lindane in 2020 by 74% and 95%, respectively, when compared to the BAU estimate. For trifluralin, an annual load of approximately 61.7 t is estimated for the baseline year 2003 (BAU scenario), although the applied conservative assumptions related to pesticide use data availability in Europe. Under the PI (ban) scenario, assuming only small residual emissions of trifluralin, we estimate a sea loading of approximately 0.07 t/y. For PFOS, the total sea load from all European countries is estimated at approximately 5.8 t/y referred to 2007 (BAU scenario). Reducing the total load of PFOS below 1 t/y requires emissions to be reduced by 84%. The analysis of conventional scenarios or scenario typologies for emissions of contaminants using simple spatially explicit GIS-based models is suggested as a viable, affordable exercise that may support the assessment of implementation of policies and the identification or negotiation of emission reduction targets.

Use of new scientific developments in regulatory risk assessments: challenges and opportunities

Since the 1990s, science based ecological risk assessments constitute an essential tool for supporting decision making in the regulatory context. Using the European REACH Regulation as example, this article presents the challenges and opportunities for new scientific developments within the area of chemical control and environmental protection. These challenges can be sorted out in 3 main related topics (sets). In the short term, the challenges are directly associated with the regulatory requirements, required for facilitating a scientifically sound implementation of the different obligations for industry and authorities. It is important to mention that although the actual tools are different due to the regulatory requirements, the basic needs are still the same as those addressed in the early 1990s: understanding the ecological relevance of the predicted effects, including the uncertainty, and facilitating the link with the socio-economic assessment. The second set of challenges covers the opportunities for getting an added value from the regulatory efforts. The information compiled through REACH registration and notification processes is analyzed as source for new integrative developments for assessing the combined chemical risk at the regional level. Finally, the article discusses the challenge of inverting the process and developing risk assessment methods focusing on the receptor, the individual or ecosystem, instead of on the stressor or source. These approaches were limited in the past due to the lack of information, but the identification and dissemination of standard information, including uses, manufacturing sites, physical-chemical, environmental, ecotoxicological, and toxicological properties as well as operational conditions and risk management measures for thousands of chemicals, combined by the knowledge gathered through large scale monitoring programs and spatial information systems is generating new opportunities. The challenge is liking predictions and measured data in an integral "-omic type" approach, considering collectively data from different sources and offering a complete assessment of the chemical risk of individuals and ecosystems, with new conceptual approaches that could be defined as "risk-omics based" paradigms and models.

Influence of sampling strategies on the estimated nitrous oxide emission from wastewater treatment plants

In the last few years, the emission of nitrous oxide from wastewater treatment plants has become a topic of increased interest, given its considerable impact on the overall climate footprint of wastewater treatment plants. Various sampling strategies to estimate nitrous oxide emission from wastewater treatment plants have been applied in different studies. The present study addresses the influence of sampling strategies on the estimated emission by analysing the variability of an extensive dataset of nitrous oxide emissions resulting from a long-term online monitoring campaign at a full-scale municipal wastewater treatment plant. It is shown that short-term sampling is inadequate to accurately estimate the average nitrous oxide emissions from a particular wastewater treatment plant, while online monitoring is indispensable to capture the short-term variability (diurnal dynamics).

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L(-1) (mean 39.8 ng L(-1)), 75.2-1520 ng L(-1) (mean 645 ng L(-1)), 410-2990 ng L(-1) (mean 1535 ng L(-1)), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g(-1), 145-349 ng g(-1) and 626-3584 ng g(-1) with the average concentrations of 21.4 ng g(-1), 257 ng g(-1) and 2291 ng g(-1), respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K(oc)') in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr(-1)) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 μg L(-1) under all normal, high water and low water season in 2007.

Defining established and emerging microbial risks in the aquatic environment: current knowledge, implications, and outlooks

This timely review primarily addresses important but presently undefined microbial risks to public health and to the natural environment. It specifically focuses on current knowledge, future outlooks and offers some potential alleviation strategies that may reduce or eliminate the risk of problematic microbes in their viable but nonculturable (VBNC) state and Cryptosporidium oocysts in the aquatic environment. As emphasis is placed on water quality, particularly surrounding efficacy of decontamination at the wastewater treatment plant level, this review also touches upon other related emerging issues, namely, the fate and potential ecotoxicological impact of untreated antibiotics and other pharmaceutically active compounds in water. Deciphering best published data has elucidated gaps between science and policy that will help stakeholders work towards the European Union's Water Framework Directive (2000/60/EC), which provides an ambitious legislative framework for water quality improvements within its region and seeks to restore all water bodies to "good ecological status" by 2015. Future effective risk-based assessment and management, post definition of the plethora of dynamic inter-related factors governing the occurrence, persistence and/or control of these presently undefined hazards in water will also demand exploiting and harnessing tangential advances in allied disciplines such as mathematical and computer modeling that will permit efficient data generation and transparent reporting to be undertaken by well-balanced consortia of stakeholders.