Characteristics And Health Risk Assessment Of Freshwater And Marine Biotoxins In Wet Deposition Of Typical Cities In China

Freshwater and marine biotoxins(FMBs)can accumulate through the food chain and cause harm to human health.It is known that relevant research mainly focuses on the detection of FMBs in natural water bodies and the atmosphere,but there is a relatively lack of research on the distribution of FMBs in wet deposition.At present,the types and concentration levels of FMBs in wet deposition,as well as its influencing factors,are still unclear.In addition,most previous studies aimed to explore the health risks of direct ingestion of contaminated water resources or food to human health,while neglecting the harm of direct skin contact with FMBs to human health.To reveal the regional and temporal distribution characteristics of FMBs in wet deposition in China,reveal the environmental factors affecting different FMBs,and evaluate the potential health risks of FMBs in wet deposition,this study selected 18 typical cities from seven major geographical regions in China and collected their wet deposition samples.City types include coastal cities,riverside cities,and inland cities.For different samples,this study used enzyme-linked immunosorbent assay to analyze the concentration levels of 12 common FMBs(four freshwater toxins and eight marine toxins):microcystin LR(MC-LR),microcystin RR(MC-RR),microcystin YR(MC-YR),anatoxin-a(ANTX-a),tetrodotoxin(TTX),and saxitoxin(STX),ω-Conotoxin,ciguatoxin(CTX),pectenotoxin-2(PTX-2),okadaic acid(OA),brevetoxin(BTX),domoic acid(DA).At the same time,this study further revealed the main factors affecting the types and concentrations of FMBs in wet deposition,and evaluated the potential health risks of these toxins exposed through skin.The research results indicate that 12 types of FMBs were detected in the wet deposition of the target city,with concentrations ranging from 0.023-160.492 μg/L.From a regional perspective,the levels of freshwater toxins in wet deposition in central China are significantly lower than those in other regions,while the total levels of FMBs in Northeast and North China are the highest.Geographical factors,seasonal changes,and meteorological conditions are all important factors that affect the concentration level of wet deposition FMBs.The settling flux range of Qingdao FMBs is 0.05-15908.29 μg·m-2.The deposition flux of FMBs is positively correlated with rainfall.By comparing the monthly and seasonal changes of FMBs,this study found that most FMBs showed their highest levels from June to August,which may be due to the summer seawater temperature being suitable for the growth and reproduction of various toxin producing organisms.In addition,this study also found that the levels of rainwater toxins were relatively high during the early stages of rainfall,and the concentration of rainwater toxins first decreased and then increased during the rainfall process,showing dynamic changes.This may be related to the source of FMBs in wet deposition.This study also found that acidic rainwater is beneficial for wet deposition to remove marine toxins from the atmosphere,while alkaline rainwater is beneficial for wet deposition to remove freshwater toxins from the atmosphere.Additionally,there is a strong correlation between ions Na+,NH4+,Ca2+,Cl-,SO42-,NO3-,and FMBs in wet deposition.Based on the skin exposure model,this study found that the skin intake and skin exposure risk coefficient of microcystin LR were the highest,and the skin intake of FMBs in males was higher than that in females,while the skin exposure risk coefficient was lower than that in females.Compared to current existing research,this study analyzed the concentration levels of FMBs in wet deposition in China earlier,revealing the spatial and temporal differences in FMBs in wet deposition in China,revealing the effects of different factors such as pH value,anions and cations,and heavy metals on the concentration levels of FMBs in wet deposition,and evaluating the potential health risks caused by skin exposure of different FMBs.This study provides a theoretical.reference for comprehensively revealing the levels of pollutants in wet deposition,and provides new ideas for evaluating the human health risks caused by FMBs.