A Preliminary Evaluation Of The Amynthas Heterochaetus As An Indicator Of Cd Pollution In Northern China

Ecological toxicological analysis method is one of the important methods to research the reasonable limit value of soil pollutants,which also known as the soil quality benchmark.Biotoxicological effect research is the core content.Studying the response characteristics of indicator organisms under the pollutant stress is an effective supplement to conventional chemical detection methods.To a certain extent,it can reflect the comprehensive impact and potential risks of various toxic substances on soil ecosystem,that is,soil environmental safety assessment and ecological early warning.In this study,we investigated the populations of earthworm in Beijing,Tianjin and Hebei.We analyzed the changes and differences in the population and community structure of earthwormin different habitats(vegetable land,farmland and grass).And investigated the rule of earthworm population level change in the genus distalopsis.The results showed that the detection rate of the Amynthas heterochaetus was the highest(51.2%),and the largest body size(average 5.24 g)was the dominant species in northern China.We studied the LC50 of Amynthas heterochaetus(Michaelsen,1891)when they under the heavy metal stress of Cadmium(Cd).In the meantime,we also compared the results to the Eisenia fetida(Savigny,1826),which is the Organization for Economic Co-operation and Development(OECD)recommended standard species by reference to the standard method for chemical toxicity testing of earthworm.The results showed that:Amynthas heterochaetus s LC50(respectively 11.23 and 5.17 μg/cm2)of Cd at 24 h and 48 h was lower than Eisenia fetida’s(respectively 21.99 and 16.95 μg/cm2),Amynthas heterochaetuss LC50(respectively 36.98 and 20.37 mg/kg)of Cd at 7 d and 14 d was lower than Eisenia fetida’s(respectively 1819 and 1047 mg/kg),which reflecting that the Amyynthas heterochaetus with a lower tolerance than Eisenia fetida on Cd stress.In the six-chamber avoidance experiment,this study tested the behavioral responses of Eisenia fetida and Amynthas heterochaetus under heavy-metal cadmium-contaminated soils with the six-chamber experimental device recommended by ISO.The results showed that the limit value of the obvious avoidance effect of Amynthas heterochaetus on Cd was about 1.17-2.34 mg/kg,which is much lower than that of Eisenia striata(about 37.5-75 mg/kg).Therefore,the scorpion is more sensitive to Cd.For the screening experiments of the markers of the Awynthas heterochaetus,this study investigated the activity changes of five immune-related enzyme markers in this process.The experimental results show that under the low concentration of Cd stress,the activities of SOD,GSH-PX,CAT,AchE and T-AOC were significantly shifted,both in Amynthas heterochaetus and Eisenia fetida indicating that the selected enzymes were sensitive to Cd stress,and that could be used as biomarkers;in addition,compared to Eisenia fetida,the response of enzymatic biomarkers in Amynthas heterochaetus were quicker(3 days)and lasted longer(28 days).In summary,the Amynthas heterochaetus is an ecologically representative species of the Beijing-Tianjin-Hebei region.And the enzyme markers in it have a significant response to Cd.It has a certain tolerance and high sensitivity to Cd,and its enzyme markers in the body respond to Cd.It has the research potential as a indicator organism for soil Cd pollution in the Beijing-Tianjin-Hebei region.