Characteristics And Health Risks Of Atmospheric Marine Biotoxins In Coastal Areas Of Northern China

Marine biotoxins(MBs)enriched through food chain,causing diseases in fishs,shellfishs,mammals,and human body,which is harmful to human health and leads to serious economic losses.In recent years,studies have found that MBs can also be aerosolized into the atmosphere,causing negative health effects through respiratory exposure,such as stress response of human upper respiratory tract,and even death in severe cases.However,the information about the species,concentration,and particle size distribution of airborne marine biotoxins(AMBs)is still unclear,while the information about AMBs of China is even less.To obtain the information of MBs in coastal China,in this study,atmospheric particulate matter samples were collected from coastal and inland areas of Aoshan Bay in Qingdao from 2019 to 2020,to analyze the species,concentration,and particle size distribution of MBs,discussing the regulating factors of MBs and the main sources of AMBs.Specifically,HighBioTrap and Anderson six stage samplers were used to collect coastal air,and sterile polyethylene bottles were used to collect seawater at the same time.Enzyme linked immunosorbent assay(ELISA)was used for toxins analysis.For atmospheric and seawater samples,eight common and significant MBs were detected,including Brevetoxin(BTX),Okadaic acid(OA),Domoic acid(DA),Tetrodotoxin(TTX),Ciguatoxin(CTX),Saxitoxin(STX),and Saxitoxin(STX),Pectenotoxin-2(PTX-2),andω-Conotoxin.In our paper,the interannual,seasonal and diurnal variation characteristics of AMBs were compared,and the action mechanism of marine environmental factors(toxigenic algae and bacteria,seawater temperature,MBs and chlorophyll a in seawater)and atmospheric environmental factors(toxigenic algae and bacteria in air,temperature,relative humidity,illumination intensity,conventional air pollutants,wind speed and direction)on AMBs was discussed respectively,revealing the source of AMBs.The results showed that the concentration of AMBs ranged from 0.22 pg/m3 to 205.24 ng/m3.The lowest was BTX and the highest is ω-Conotoxin.In addition,DA,TTX,STX,PTX-2,and ω-Conotoxin is the first detected in atmosphere around the world.By analyzing the characteristics of the interannual,seasonal and diurnal variation of AMBs,we found that the seasonal variation was the most significant.The highest levels of BTX,OA,TTX,PTX-2 and ω-Conotoxin appeared in summer,the highest level of DA appeared in early spring,and the highest level of CTX appeared in winter.In addition,the size distribution of AMBs at daytime and nighttime is roughly the same.The aerodynamic diameter of DA,TTX,PTX-2,and ω-Conotoxin ranged from 4.49 μm to 6.86 μm.To assess the risk of respiratory exposure to AMBs,the Respiratory Deposition Flux(RDF)calculated by the exposure respiratory assessment model showed that most of(up to 75%)the AMBs could be deposited in the Head Airway(HA).Moreover,53.4%of marine biotoxin fine particles were inhaled and deposited in the Alveolar Region(AL),which may lead to decreased lung function and threaten human respiratory health.We found that the ratio of marine biotoxins in coastal atmosphere to seawater was relatively stable in different seasons and time.Except ω-Conotoxin.the airborne/seaborne ratio of other MBs ranged from 1×10-6%to 4×10-6%.Through the laboratory simulation and environmental measurement data,we found that the concentration of most AMBs is positively correlated with temperature,and the wind direction can also promote the level of AMBs.In addition,this work also proved that toxic algae and bacteria suspended on the surface of seawater directly release toxins,which are the main sources of AMBsCompared with the previous research,this work is an early study of AMBs along the northern coast of China,systematically revealing the information of levels and analyzing the diurnal,seasonal and annual variation characteristics of AMBs,discussing the regulating factors and main sources.We also illustrated the particle size distribution of AMBs and their potential health effects on human respiratory system.This dissertation provides a new perspective for the toxicity assessment of atmospheric particulates in coastal areas,and provides an important theoretical reference for public health in coastal areas.