Bisphenol A in German watersheds: Part II. FlowEQ model-based characterization of sources and current and future conditions

Increasing scientific and regulatory concern regarding environmental concentrations of bisphenol A (BPA) increases the need to understand the sources and sinks of this chemical. We developed a coupled flow network/fugacity-based fate and transport model to assess the contribution of different emissions sources to the concentration of BPA in surface water in Germany. The model utilizes BPA loadings and sinks, BPA physicochemical properties, a water flow network, environmental characteristics, and fugacity equations. The model considers industrial emissions, leaching from BPA-containing articles, wastewater treatment and bypass events, and emissions from landfills. The model also considers different scenarios that account for changes in the usage profile of BPA. Model predictions compare favorably to measured surface water concentrations, with the modeled concentrations generally falling within the range of measured values. Model scenarios that consider reductions in BPA usage due to government-mandated restrictions and voluntary reductions in usage predict falling BPA concentrations that are consistent with the most recent monitoring data. Model predictions of the contributions from different usage scenarios and wastewater treatment methods can be used to assess the efficacy of different restrictions and waste handling strategies to support efforts to evaluate the costs and benefits associated with actions aimed at reducing BPA levels in the environment. This feature of the model is of particular importance, given current efforts to update the regulations regarding BPA usage in the EU. The model indicates that as the current restriction on BPA in thermal paper works through the paper recycling process, BPA concentrations will continue to decrease. Other actions, such as upgrades to the stormwater and wastewater infrastructure to minimize the frequency of storm-related bypasses, are predicted to provide more meaningful reductions than additional restrictions on usage. Integr Environ Assess Manag 2024;20:226-238. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Bisphenol A in surface waters in Germany: Part I. Reassessment of sources and emissions pathways for FlowEQ modeling

Bisphenol A (BPA) enters the environment through various industrial and consumer-related pathways. Industrial sources include BPA manufacturing and secondary industrial uses such as the manufacturing of polymers and other substances based on or containing BPA. However, secondary sources and emissions to the environment, such as those related to the consumer use of articles containing BPA, may be more important than industrial emissions. Although readily biodegradable, BPA is widely distributed in various environmental compartments and living organisms. It is still not well understood which specific sources and pathways are responsible for releasing BPA into the environment. Therefore, we developed FlowEQ, a coupled flow network and fugacity-based fate and transport model for the assessment of BPA in surface water. The work is divided into two parts. In Part I, inputs needed to support the modeling and model validation were collected. Bisphenol A was measured at 23 wastewater treatment plants (WWTPs) and 21 landfills in Germany. In addition, the BPA content of 132 consumer articles from 27 article classes was analyzed. Bisphenol A concentrations in WWTPs ranged from 0.33 to 910 µg L-1 in influents and from less than 0.01 to 0.65 µg L-1 in effluents, resulting in removal efficiencies of 13%-100%. Average BPA concentrations in landfill leachate ranged from less than 0.01 to approximately 1400 µg L-1 . Bisphenol A concentrations measured in consumer articles varied significantly by type, ranging from less than 0.5 µg kg-1 in printing inks up to 1 691 700 µg kg-1 in articles made from recycled polyvinyl chloride (PVC). These concentrations were combined with information on use, leaching, and contact with water to develop estimates of loadings. Together with the results of the FlowEQ modeling presented in Part II, this assessment improves our understanding of the sources and emission pathways of BPA in surface water. The model considers various sources of BPA and can estimate future surface water concentrations of BPA based on changes in use. Integr Environ Assess Manag 2024;20:211-225. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Impact of reduced flow on 137Cs behavior in Ismailia Canal and surrounding groundwater systems

This paper assesses the potential impact of reduced Nile water due to the construction of Grand Ethiopian Renaissance Dam (GERD) on flow and contaminant transport pattern in Ismailia Canal and its surrounding area. The groundwater/surface water system has been characterized, conceptualized, and modeled numerically and analytically, with assessing the response against this expected reduced discharge. The isotopic signature of seventeen samples helped in the identification of different recharge sources in the study area and demarcates the boundary conditions that might encounter the conceptualization of the study area. Based on the inflow/outflow components from MODFLOW under present-day conditions and reducing surface water discharge in the studied area, it was revealed that at the end of the year 2024, the contribution from the canal to the modeled groundwater system will be decreased by 6%, 8%, and 11%, by decreasing 20%, 30%, and 40% of the original canal flow according to three proposed scenarios. This reduced flow would increase the contaminate load of ¹³⁷Cs in the groundwater system by 2.5-fold than that expected in case of the non-reduced flow in Ismailia Canal at the end of the simulation (year 2038). Furthermore, the impact of surface water conditions (flow, velocity, dispersion) on ¹³⁷Cs dispersion and temporal/spatial distribution has been analyzed, revealing the side effect of GERD on Ismailia Canal, as a response to the decrement in the Nile flow.