| Anodonta woodiana(Chinese pond mussel or swan mussel)is global distribution freshwater mussel in Mollusca,Bivalvia,Palaeoheterodonta,Unionoida,Unionidae,Anodonta/Sinanodonta.Because of its high bioaccumulation capability and low metabolic capacity of heavy metals,this mussel has been used as an important indicator for monitoring and evaluation of aquatic heavy metal pollution.In order to avoid the problems of mussel size variation and/or unabling to sample wild A.woodiana samples through traditional sampling approaches,my supervisor's laboratory has innovatively developed a"standardized"(i.e.,the same biological factors,stable inherited quality,low contamination background,sufficient quantity,and translatable/recapturable individuals)A.woodiana population by artificial breeding techniques.It can provide a model indicator for standardized heavy metal pollution monitoring and related toxicological evaluation.In order to promote the construction of ecological civilization and improve the water ecological environment,the state is carrying out a comprehensive implementation of the National River Chief/Lake Chief Policy.The "standardized" A.woodiana was transplanted to the course of Maifengbang River as a "monitoring group",the unpolluted clam remain at the Nanquan Base of the Freshwater Fisheries Research Center of the China Academy of Aquatic Sciences as a "control group",develop active monitoring and application of heavy metal pollution in river environment,and compared the dynamic changes of heavy metal content in water samples collected in two waters at the same time.The results showed that the contents of heavy metals in the water samples of Maifenbang River and Nanquan base were generally lower than those of surface water in China,which indicated that there was no obvious pollution source of heavy metals in the vicinity of the two waters in the near future.The contents of Cr and Zn in mussel samples were significantly higher than those in Nanquan base at 2 months(P<0.05),and the Zn content in mussel samples at 3 months was significantly higher than that in Nanquan base(P<0.05).The difference of heavy metal concentration in the middle and long term between the two mussels was shown.It is worth noting that although the average pollution index of mussel samples in Maifenbang River and Nanquan base is less than 0.2,which can be evaluated as no obvious pollution,the Pb residue index of the former is more than 0.3,which belongs to the scope of light pollution.Therefore,based on the active monitoring of mussel bioconcentration in this study,the results show that there is no general situation in the Maifenbang River.It was obviously unpolluted by heavy metals,but the effect of Pb stress should be paid more attention in the early stage.The "standardized" A.woodiana were transplanted to Lishan Bay,Meiliang Bay of the Taihu Lake,as the "monitoring group".and the same batch of mussels still raised in Nanquan base as the "control group" to carry out the active monitoring and application of heavy metal pollution in the lake environment.The dynamic changes of heavy metal content in water samples collected in the two waters at the same time were compared with those in the same period.The results showed that:(1)the content of Al,Fe,Cu in mussels was significantly higher than that in 1 month(P<0.05)when they were immigrated to Lishan Bay of Taihu Lake for 2 months.The content of Al,As in mussels was significantly higher than that in Lishan Bay of Taihu Lake(P<0.05)at 3 months(P<0.05).The mean pollution indices(?)at 1 month,2 months and 3 months were 0.2363,0.2708,0.4175(all more than 0.2),respectively,which could be evaluated as mild pollution level.The As residue index of the same migratory clam at 1 month,2 months and 3 months was more than 0.8.In addition,the residual index of Pb was higher than 0.2 at one month after transplanting into Meiliang Bay of Taihu Lake(P<0.05).(2)the content of Fe in Meiliang Bay of Taihu Lake was significantly higher than that of one month after immigrating to Meiliang Bay of Taihu Lake(P<0.05).The content of Al,Cr,Ni,Pb at 3 months is higher than that at 2 months.The content of Ni at 3 months after migration was significantly higher than that at 1 month(P<0.05).The mean pollution index(?)at one month,two months and three months in Meiliang Bay of Taihu Lake was 0.4132,0.3208,0.3789(all>0.3),and it could also be evaluated as mild pollution level.The residual indexes of As in Miliang Bay of Taihu Lake were more than 0.6 at 1 month,2 months and 3 months,and the residual index of Pb at 1 month was more than 0.2.Based on the active monitoring of mussel bioconcentration,the results showed that Lishan Bay and Meiliang Bay of Taihu Lake area have been polluted by heavy metals,and the related biological toxicity needs to be paid more attention.In order to understand the characteristics of histologic toxicity of Cd,a key heavy metal in water pollution,the bioaccumulation and accumulation of Cd in "standardized" A.woodian were investigated and evaluated under laboratory exposure conditions.Compared with the control group,the tissues of different exposure groups had different bioaccumulation effects on Cd.The accumulation of Cd in gill,digestive gland and mantle was higher.There was a significant positive linear correlation between the concentration of Cd in Gill,outer membrane,axopod and other tissues and the concentration of Cd in water,but there was no phase between the concentration of Cd in digestive gland and the concentration of Cd in water.There was a significant positive linear correlation between the concentration of Cd in foot and the concentration of Cd in gill,outer membrane,digestive gland and other tissues.The concentration of Cd in gill was positively correlated with the concentration of Cd in the mantle and other tissues,and there was a significant positive correlation between the concentration of Cd in the gill,the mantle,the digestive gland and other tissues.There was a significant positive linear correlation between the concentration of Cd in the mantle and the concentration of Cd in other tissues.There was no significant correlation between the concentration of Cd in digestive gland and the concentration of Cd in gill,mantle and other tissues.The results of this study provide a theoretical basis for the evaluation of heavy metals in different tissues.For grasping the characteristics of cytological toxicity of Cd,a key heavy metal in water pollution,in mussel body,the responses to stress and toxicity of primary gill cells of A.woodian were investigated and evaluated under the condition of Cd exposure in laboratory.1.25,2.5 and 5.0 ?g·L-1 Cd solutions were exposed to gill cells respectively.After 6 h,Cell viability,SOD,CAT and AcP did not change significantly.However,0.062,0.125,0.25,0.5 and 1.0 mg·mL-1 Cd decreased gill cells viability and induced activity of enzyme(SOD,CAT)and the activity of immune factor(AcP)were increased.These results suggest that Cd ion can induce gill cell toxicity and provide theoretical support for the toxicological effect of Cd at cell level.It is very necessary to control Cd pollution strictly. |
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