A Study On Bioaccumulation And Maternal Transfer Of Short- And Medium-Chain Chlorinated Paraffins In Organisms From An E-waste Site

Chlorinated paraffins(CPs)are synthetic polychlorinated n-alkanes,which can be classified into short-chain chlorinated paraffins(SCCPs),medium-chain chlorinated paraffins(MCCPs)and long-chain chlorinated paraffins(LCCPs)according to their length of carbon chains.There were few studies on bioaccumulation of chlorinated paraffins in reptiles and amphibians,few in biomagnification of animals with higher trophic levels and in maternal transfer of ovoviviparaous animals.Aquatic and amphibian organism samples were collected from an e-waste contaminated pond and adjacent areas.We studied bioaccumulation of S/MCCPs in two aquatic food chains,including fish-watersnake and fish-waterbird egg food chain.And we studied maternal transfer of S/MCCPs in watersnakes(ovoviviparaous animals)and bioaccumulation and congeners profiles of SCCPs in black-spotted frogs.The concentrations of SCCPs and MCCPs in the aquatic organisms ranged from 1.2to 250?g/g lipid weight(lw)and from 2.3 to 200?g/g lw,respectively.The highest S/MCCP concentrations were found in the watersnake muscle,and the lowest were found in the waterbird egg.SCCPs were found in all tissues of black-spotted frog.The concentrations of SCCPs in different tissues,including muscle,liver,kidney,heart,stomach and intestine,varied from 28 to 163,from 15 to 81,form 47 to 261,from 32to 479,from 38 to 119 and from 39 to 341?g/g lw,respectively.The highest median level of SCCPs was found in intestine(142?g/g lw)and the lowest one was found in liver(26?g/g lw).Homologue group patterns of SCCPs were species-specific to some extent.Prawn,small fish and different tissues of black-spotted frog showed similar SCCP homologue group patterns,with high abundances of C₁₀and C₁₁.For the two predators,the relative abundance of C₁₂and C₁₃congeners increased,while either the abundance of C₁₀(watersnake)or C₁₁(waterbird)congeners decreased.Unlike SCCPs,homologue profiles of MCCPs appeared to be homogeneous and no significant difference was observed between different sites and species.Different tissues used to calculate BMFs will influence the outcome.Calculated based on the lipid weight of watersnake muscle,most of the BMFs of fish–watersnake values were higher than 1 for different S/MCCP homologues,which implied that S/MCCPs have biomagnification potential in the fish–watersnake food chain.In fact,when BMFs in the fish–watersnake food chain was calculated on the basis of watersnake egg,the BMFs were several times lower than those calculated based on muscle(SCCPs:1.0 vs.2.9,MCCPs:0.47 vs.2.95)and biomagnification was not apparent.However,all BMFs values in the food chain of fish–waterbird eggs were below 1 for different S/MCCP homologues,which indicated a dilution of S/MCCPs through the food chain.The wet weight of watersnake eggs accounts for 27%of the total snake weight(muscle+egg).The proportions of SCCPs and MCCPs in the watersnake eggs were all higher than 27%,ranging from 37%to 73%.This implicated that S/MCCPs were more inclined to accumulate in the eggs because of higher volume of lipid in the eggs.However,all EMR_Lvalues were lower than 1,implying that the affinity of CPs for lipid components were higher in muscle than that in eggs.Besides,maternal transfer potential was negatively correlated with log K_OWfor all CP homologues.Ratios of lipid-normalized concentrations in other tissue(i.e.muscle,kidney,heart,stomach and intestine)apart from the liver(C/(C+L))were calculated.All C/(C+L)values were higher than 0.5,which implicated that SCCPs showed distribution tendency between other tissues and liver.The C_muscle/(C_muscle+L)values were significantly negatively correlated with carbon atoms(p<0.05),while other tissues(kidney,heart,stomach and intestine)didn't show the similar trend.The ratios of other tissues were significantly negatively correlated with chlorine atoms number(p<0.05),but the ratio of muscle had no significant relation with chlorine atoms number.The result showed that SCCPs with longer carbon chain and more chlorine atoms were more inclined to accumulate in the liver or SCCP with less chlorine atoms were easily to metabolisze in liver.