东莞石马河沿岸土壤重金属污染及生态毒性研究

HEAVY METAL POLLUTION OF SOILS ALONGSIDE SHIMA RIVER, DONGGUAN AND ITS ECOTOXICITY

为研究河水一地下水交互作用对河流沿岸土壤环境质量的影响，以东莞石马河沿岸土壤为研究对象，采集沿岸距离河道不等的6个土壤剖面共31个土样，测定土壤重金属（As、cd、cr、cu、Fe、Mn、Ni、Pb和zn）含量和土壤水提取液对发光菌的抑制率。结果表明，cd、cu、Ni和zn的含量分别为2．80～11．2rngkg～、9．70～298mgkg～、11．4～69．7mgkg。和40．4～465mgkg；Cd的地累积系数为6．06，达到极度污染水平；土壤重金属污染的地累积系数排序为Cd〉Zn〉Cu〉Ni〉Cr〉Mn〉As〉Pb〉Fe；重金属含量差异与土壤有机质（SOM）含量和土壤微粒组分（〈63um）有关，cr、Cu、Ni、Zn、Mn和cr、Ni与SOM含量和微粒组分分别呈显著正相关（P〈0．05或P〈0．01）；土壤剖面毒性单位（∑Tu）评价结果为剖面s3〉s2〉Sb〉S1〉s4〉Sa，其中剖面s3的值最大，为5．51，属于中毒；土壤水提取液对发光菌的抑制率为2．45％～16．5％，为无毒或低毒。

To investigate effects of the interactions between river water and groundwater on soil environment along river banks, thirty-one soil samples were collected from 6 soil profiles, different in distance from the river, located along the Shima River in Dongguan City in China of and analyzed for heavy metals （As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn） by ICP- AES,and luminescent bacterium （Vibrio fischeri, LUMIStox 300 ） inhibition rate of soil extracted with deionized wa- ter. Results show that the concentration ofCd,Cu,Ni,and Zn was 2.8-11.2mgkg ~9.7-298mgkg ~11.4-69.7mg kg - l and 40.4 ~ 465 mg kg - 1 , respectively. Cd reached 6.06 in geo-accumulation （ I oo ） , and the level of extremely severe pollution. In terms of Igoo. the heavy metals followed the sequence of Cd 〉 Zn 〉 Cu 〉 Ni 〉 Cr 〉 Mn 〉 As 〉 Pb 〉 Fe. Differences between the soils in concentrations of the heavy metals were related to their soil organic matter （SOM） content and fraction of micro particles （ 〈 63 μm,CSP）. Cr,Cu,Ni,Zn and Mn concentration was significantly and posi- tively related （p 〈 0.05 or p 〈 0.01 ） to SOM content and Cr and Ni concentration was to the fraction of micro particles. In terms of toxic unit （ ~TU ,mean of the whole profile） ,the six soil profiles followed an order of $3 〉 $2 〉 Sb 〉 S1 〉 S4 〉 Sa. Profile $3 was the highest in ~ TU （5.51） , belonging to the moderate toxic level. And the luminescent bacterium inhi- bition rates of their soil extracts varied in the range from 2.45% to 16.5% ,indicating that the heavy metal pollutions in these soils could be sorted into the category of low or non toxicity. Bio-toxicity test could be used to better represent and characterize the eco-toxicity of polluted soils as some speciation of heavy metals in soil may be not bio-available.