Bioaccumulation And Biotransformation Of Inorganic Arsenic In Freshwater Carnivorous Fish Ophiocenhalus Argus Cantor

Arsenic(As)is a widely distributed toxic metalloid.Due to the rapid development of industrialization and urbanization activities,arsenic pollution in rivers and lakes is becoming increasingly serious.As an important component of the natural environment,the arsenic concentration in water,the bioaccumulation ability and distribution of As species in different trophic organisms of the freshwater ecosystem,and the transfer effect of As in the organism through the food chain are all related to Human health.In this study,the freshwater zoobenthos(chironomid larvae)and the carnivorous fish(Ophiocephalus argus Cantor)were used as the research object to construct a two-stage food chain indoor simulation experiment.And HPLC-ICP-MS was used to determine the total arsenic concentration and the distribution of arsenic species in chironomid larvae and Ophiocephalus argus Cantor after different waterborne or dietborne arsenite[As(III)]or arsenate[As(V)]exposure.Therefore,the objective of this work was to reveal the bioaccumulation and biotransformation of inorganic arsenic in freshwater organisms,and characterize the bioaccumulation and biotransformation of arsenic in different tissues of Ophiocephalus argus Cantor through the food chain.We consequently analyzed As speciation to comprehend the mechanisms of As bioaccumulation,biotransformation and detoxification in Ophiocephalus argus Cantor.The main results are as follows:(1)The bioavailability of inorganic arsenic in chironomid larvae was low,while As(III)was more bioavailable than As(V).And the biotransformation efficiency of inorganic arsenic decreased with the increase of exposure concentration.Besides,inorganic arsenic was the main arsenic species in chironomid larvae.(2)The concentration and pathway of inorganic arsenic exposure had little effect on the growth of Ophiocephalus argus Cantor.The absorption and assimilation of As in Ophiocephalus argus Cantor was low,and it was not related to the exposed inorganic arsenic species.The arsenic concentrations in different tissues of fish followed the order of intestine>gill>muscle.In addition,dietary intake could be the primary route of As bioaccumulation in Ophiocephalus argus Cantor(3)As has no biomagnification effect during the process of transferring along the trophic level of organisms.The bioavailability of organic arsenic compounds(mainly AsB)was higher than inorganic arsenic,arsenobetaine(AsB)was more easily absorbed and assimilated by Ophiocephalus argus Cantor than inorganic arsenic.And it also contributed to arsenic bioaccumulation in muscle tissue of Ophiocephalus argus Cantor.(4)The synthesis of AsB in different tissues of Ophiocephalus argus Cantor may include two important processes:the reduction of As(V)(from As(V)to As(?))and the subsequent methylation(from inorganic arsenic to methylarsenate(MMA)and dimethylarsenate(DMA)).This study has shown that biotransformation was an important mechanism for detoxification of arsenic in Ophiocephalus argus Cantor.Moreover,the methylation ability of Ophiocephalus argus Cantor was different in different tissues.Compared with inorganic arsenic was dominant in gill and intestine tissues,AsB was the most important arsenic specie in muscle tissue of Ophiocephalus argus Cantor,indicating that the ability of gill and intestine to transform methylated arsenic into AsB is lower than that of muscle tissue.