Simulating behavior of perfluorooctane sulfonate (PFOS) in the mainstream of a river system with sluice regulations.

Perfluorooctane sulfonate (PFOS) is a persistent, anionic and ubiquitous contaminant that undergoes long-range transport within the environment. Its behavior has attracted wide-range academic and regulatory attention. In this article, a mass balance model was employed to simulate PFOS concentrations in the mainstream of Haihe River water system, encompassing sluices and artificial rivers. The dynamic simulation of PFOS concentrations in both sediment and freshwater took into account fluctuations in PFOS emissions, water levels and water discharge. Furthermore, the study delved into exploring the impacts of sluices and artificial rivers on the behavior of PFOS. The simulated concentrations of PFOS in steady state agreed with the measured concentrations in surveys carried out in Nov. 2019, July 2020, Oct. 2020, and June 2021. Every year, approximately 24 kg PFOS was discharged into the Bohai Sea with Chaobai New River being the largest contributor for 44 %. Moreover, the transport of PFOS in the original rivers is likely to be restricted by sluices and replaced by artificial rivers. Monte Carlo analysis showed that model predictions of PFOS concentrations in sediment were subject to greater uncertainty than those in freshwater as the former is impacted by more parameters, such as density of sediment. This study provides a scientific basis for the local government to manage and control PFOS.

Occurrence of current-use fungicides and bifenthrin in Rainwater Basin wetlands.

Wetlands in the Rainwater Basin (RWB) of Nebraska are commonly in close proximity to or embedded within row-crop agriculture. Several fungicides and bifenthrin are applied aerially to corn throughout the RWB during tassel stage. Thus, aerial spray drift and runoff may result in pesticide contamination of wetlands. The primary objective of this study was to determine water concentrations of five fungicides and bifenthrin in wetlands located in and near fields during a heavy application period (July 16th-26th 2014) to evaluate the influence of distance from crop field on wetland contamination. In addition, the sampling sites were grouped based upon the type of water body sampled and environmental concentrations were compared to relevant "levels of concern" (LOCs) from invertebrates, fish, and amphibians selected from the literature based upon relevant toxicity data. Bifenthrin was the most frequently detected analyte, appearing in 83% of the samples. The 95th percentile concentrations across all wetlands were found to be 0.07 µg/L for bifenthrin, 0.28 µg/L for pyraclostrobin, 0.28 µg/L for azoxystrobin, and <0.14 µg/L for all other analytes. Analyte concentrations did not differ by wetland type and were not correlated with distance from closest crop. Environmental concentrations of fungicides were lower than LOCs, indicating limited acute toxicity risk. However, bifenthrin concentrations were frequently higher than LOCs for aquatic arthropods. Because the water samples included particulate bound pesticides, further work is needed to determine if this bifenthrin is bioavailable and contamination levels within the sediment.

Predicted and measured concentrations of pharmaceuticals in hospital effluents. Examination of the strengths and weaknesses of the two approaches through the analysis of a case study.

This study deals with the chemical characterization of hospital effluents in terms of the predicted and measured concentrations of 38 pharmaceuticals belonging to 11 different therapeutic classes. The paper outlines the strengths and weaknesses of the two approaches through an analysis of a case study referring to a large hospital. It highlights the observed (and expected) ranges of variability for the parameters of the adopted model, presents the results of an uncertainty analysis of direct measurements (due to sampling mode and frequency and chemical analysis) and a sensitivity analysis of predicted concentrations (based on the annual consumption of pharmaceuticals, their excretion rate and annual wastewater volume generated by the hospital). Measured concentrations refer to two sampling campaigns carried out in summer and winter in order to investigate seasonal variability of the selected compounds. Predicted concentrations are compared to measured ones in the three scenarios: summer, winter and the whole year. It was found that predicted and measured concentrations are in agreement for a limited number of compounds (namely atenolol, atorvastatin and hydrochlorothiazide), and for most compounds the adoption of the model leads to a large overestimation in all three periods. Uncertainties in predictions are mainly due to the wastewater volume and excretion factor, whereas for measured concentrations, uncertainties are mainly due to sampling mode.