| Research background:Microplastics have been widely studied for their ability to adsorb heavy metals.In the natural environment,arsenic exists in different forms and its toxicity depends mainly on its form and concentration.However,different forms of arsenic combined with microplastics have yet to be explored for their biological hazards.Research objectives:The purpose of this study was to reveal the adsorption mechanism of different forms of arsenic on polystyrene microplastics,and to study the effects of polystyrene microplastics on the tissue accumulation and developmental toxicity of different forms of arsenic in zebrafish larvae.At the same time,whether polystyrene microplastics combined with more toxic arsenic trivalent affect the reproductive function of zebrafish and whether it has trans-generational toxic effects was further explored.Results and discussion:1.adsorption mechanism of microplastics and different forms of ArsenicAs a result,the absorbing ability of PSMP for As(Ⅲ)was 35 times higher than that of DMAs,in which hydrogen bonding plays an important role in the adsorption process.In addition,the adsorption of As(Ⅲ)and DMAs on PSMP were in good agreement with the pseudo-second-order kinetic model and Freundlich model.2.Toxic effects of microplastics combined with different forms of arsenic on zebrafish embryos(1)Furthermore,PSMP reduced the accumulation of As(Ⅲ)early in zebrafish larvae development,thereby increasing hatching rates,whereas PSMP had no significant effect on DMAs accumulation in zebrafish larvae,but decreased hatching rates.In addition,except for the microplastic exposure group,the other treatment groups could lead to a decrease in the heart rate of zebrafish larvae.Both PSMP+As(Ⅲ)and PSMP+DMAs exhibited aggravated oxidative stress,but PSMP+As(Ⅲ)caused more severe oxidative stress at later stages of zebrafish larvae development.(2)Moreover,specific metabolic differences(e.g.,AMP,IMP,and guanosine)were produced in the PSMP+As(Ⅲ)exposure group,which would mainly affect purine metabolism and promoted specific metabolic disturbances.However,PSMP+DMAs exposure shared metabolic pathways altered by PSMP and DMAs,indicating an independent effect of these two chemicals.Taken together,our findings emphasized that the combined toxicity of PSMP and different forms of arsenic posed a health risk that cannot be ignored.3.Toxic effects of microplastics combined with arsenic triad exposure on reproductive system and progeny growth and development of Zebrafish(1)The results showed that,compared with the single exposure group,exposure to microplastics combined with arsenic triad significantly affected the ovarian development of female zebrafish,resulting in a decrease in gonad index.At the same time,it was observed histologically that the proportion of oocytes at primary growth stage was significantly decreased and the proportion of oocytes at maturity stage was significantly increased.Both combined exposure and single exposure affect the balance of sex hormone secretion,but combined exposure has greater effect on sex hormone secretion.(2)The combined exposure of microplastics and arsenic had a greater effect on ovarian metabolism,mainly affecting sphingolipid metabolism,linoleic acid metabolism,galactose metabolism,etc.,which were related to oxidative stress,sex hormone synthesis and lipid synthesis.(3)The single exposure of microplastics had no obvious cross-generation toxic effect on the offspring,while the single exposure of arsenic had obvious crossgeneration toxic effect.However,the combined exposure of microplastics and arsenic had a stronger inhibitory effect on the early development of the offspring,which was reflected in the increase of the early development death rate,the decrease of hatching rate and the attenuation of heart rate.Our results suggest that the toxicity of microplastics in combination with other toxins is more significant than the toxicity of microplastics alone. |
PDF Full Text Request