海南清澜港红树林湿地沉积物中重金属形态及生物有效性

Speciation and Bioavailability of Heavy Metals in Sediments of Mangrove Wetland in Qinglan Harbor, Hainan Island

【目的】分析了沉积物各形态和沉积物部分理化性质间的相关性,并讨论了沉积物中形态特征和生物有效性,旨在为合理预防和治理红树林湿地沉积物重金属污染提供依据。【方法】以海南清澜港红树林湿地沉积物为研究对象,采用改进的BCR连续提取法并测定沉积物中Cu、Zn、Cd、Pb 4种重金属元素形态和含量。【结果】各重金属之间具有不同程度的相关性,Cd和Pb之间呈显著相关,二者存在一定的伴生关系,具有同源污染物质的可能;沉积物重金属各形态中Cu和Cd形态中含量最高的是弱酸提取态,Pb在可还原态中含量较高,Zn的残渣态含量较高,说明研究区沉积物中Cu、Cd、Zn的潜在危害大;沉积物重金属Cd、Cu、Zn、Pb的各形态之间具有显著相关性;沉积物pH值与Cd弱酸提取态、Cd可还原态、Cu弱酸提取态、Cu可还原态之间呈显著正相关关系。【结论】沉积物中这4种重金属生物有效态含量较高,具有较强的生物活性,易于被植物吸收和利用,同时也表明研究区沉积物中Cd、Cu、Zn、Pb具有较高的释放风险,应该引起足够重视。

【Objective】Correlations between contents of heavy metals and sediments properties were analyzed.Speciation character and the bioavailability of heavy metals were discussed based on the rations secondary phase and primary phase(RSP)and potential ecological risk assessment.【Method】Taking the mangrove wetland sediments of Qinglan Harbor wetland in Hainan as the research object,speciation and contents of four heavy metals(Cu,Zn,Cd and Pb)in sediments of mangrove wetland were treated by BCR sequential extraction procedure.【Result】Between heavy metals it had different degrees of correlation and exhibited significantly positive correlation between Cd and Pb,suggesting that the pollution of Cd and Pb resulted from homologous pollutants.Cu and Cd were mainly in the acid soluble-extractable fraction;Pb was mainly in the reducible fraction;Zn was dominated by residual fraction;It showed that Cu,Cd and Zn in the sediments of the study area had serious potential hazards.There was significant correlation between the forms of Cd,Cu,Zn and PB of heavy metals in sediments.Contents of Cu and Cd existed as weak acid soluble fraction and oxide fraction exhibits significantly positive correlation with pH,indicating that sediments pH had a certain impact on chemical speciation of heavy metals.【Conclusion】These 4 kinds of heavy metals in the sediments have high bioactive state,and have strong biological activity,which are easy to be absorbed and used by plants.Cd,Cu,Zn and Pb have higher risk of release in the sediments of the research area,which should be paid enough attention.