Rain Amplification of Persistent Organic Pollutants

Abstract

Scavenging of gas- and aerosol-phase organic pollutants by rain is an efficient wet deposition mechanism of organic pollutants. However, whereas snow has been identified as a key amplification mechanism of fugacities in cold environments, rain has received less attention in terms of amplification of organic pollutants. In this work, we provide new measurements of concentrations of perfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and polycyclic aromatic hydrocarbons (PAHs) in rain from Antarctica, showing high scavenging ratios. Furthermore, a meta-analysis of previously published concentrations in air and rain was performed, with 46 works covering different climatic regions and a wide range of chemical classes, including PFAS, OPEs, PAHs, polychlorinated biphenyls and organochlorine compounds, polybromodiphenyl ethers, and dioxins. The rain–aerosol (K RP) and rain–gas (K RG) partition constants averaged 105.5 and 104.1, respectively, but showed large variability. The high field-derived values of K RG are consistent with adsorption onto the raindrops as a scavenging mechanism, in addition to gas–water absorption. The amplification of fugacities by rain deposition was up to 3 orders of magnitude for all chemical classes and was comparable to that due to snow. The amplification of concentrations and fugacities by rain underscores its relevance, explaining the occurrence of organic pollutants in environments across different climatic regions.

Snow-Dependent Biogeochemical Cycling of Polycyclic Aromatic Hydrocarbons at Coastal Antarctica

“…These concentrations are within the range of those reported in the open oceans and the Arctic Ocean. ,,, However, these coastal concentrations are significantly lower than those reported in other coastal regions such as the coastal eastern Indian Ocean (West Australia coast), coastal Mediterranean, , or Eastern Asia (Eastern China coast). − This is consistent with the small population in the research stations at South Bay and Port Foster (Livingston and Deception Islands, respectively) and the remoteness to populated regions. The Antarctic circumpolar current acts as a barrier for the North–South transport of organic pollutants by oceanic currents; therefore, PAHs reaching coastal Antarctica are driven by long-range atmospheric transport followed by air–water diffusive exchange or wet deposition. ,,, …”

Concerted Evaluation of Pesticides in Soils of Extensive Grassland Sites and Organic and Conventional Vegetable Fields Facilitates the Identification of Major Input Processes

“… 53 Regarding wet deposition, considerable loads are deposited through rain. 54 We therefore calculated the potential input of pesticides previously found in rain in Switzerland, that is, atrazine and its transformation product 2-hydroxyatrazine, azoxystrobin, carbendazim, fenpropidin, linuron, metamitron, metylaxyl, pirimicarb, S-metolachlor, and terbuthylazine, to test whether this diffuse input pathway can explain their occurrence ( Figure 3 ). The actual measured pesticide concentrations in the soil were then normalized to the potential input through precipitation over an assumed time period of 20 years.…”

“…The latter mainly takes place through dry or wet deposition, whereby the respective proportion varies depending on the pesticide . Regarding wet deposition, considerable loads are deposited through rain . We therefore calculated the potential input of pesticides previously found in rain in Switzerland, that is, atrazine and its transformation product 2-hydroxyatrazine, azoxystrobin, carbendazim, fenpropidin, linuron, metamitron, metylaxyl, pirimicarb, S-metolachlor, and terbuthylazine, to test whether this diffuse input pathway can explain their occurrence (Figure ).…”

Response Model for Urban Area Source Pollution and Water Environmental Quality in a River Network Region

“…Water quality varies seasonally and is affected by different factors, albeit mainly by rainfall. Rainfall affects the hydrological cycle, the physical and chemical properties of pollutants [ 49 ], pollutant migration, and the ability of water bodies to dilute pollutants. To understand the underlying mechanism driving the variations in pollutant concentrations, this study simulated environmental water quality measurements in a river course under different rainfall scenarios.…”