水体沉积物中酸可挥发性硫化物 (AVS)是总硫含量中活性最高的部分 ,是沉积物中有毒重金属的重要结合形态 ,它的含量在很大程度上影响着沉积物重金属的生物有效性 ,从而作为沉积物中有毒重金属环境污染评价的一个重要指标 ;就十多年来水体沉积物中酸可挥发性硫化物 (AVS)的研究进行了综述。概述了 AVS的测定方法及其影响因素 ;探讨了水体沉积物中 AVS含量时空变化的规律 ;同时就目前“同时可提取重金属”(SEM)与 AVS摩尔浓度比值和水体沉积物重金属生物毒性关系的研究进行了概括和分析。In this article, the latest development on the study of acid-volatile sulfide in aquatic sediment is reviewed. Acid-volatile sulfide (AVS) is operationally defined as sulfide in sediment which is soluble in cold acid, and was reported as the most active part of the total sulfur in aquatic sediments and a key partitioning phase controlling the activities of divalent cationic heavy metals in sediment. It has been reported that the measurement procedures of AVS concentration are very important for AVS study, the weight of sample taken for analysis, nitrogen flow rate, acid strength and digestion time could all affected the accuracy of AVS concentration analysis. Some other more convenient measure methods have been proposed, however, owing to different study conditions, there is no standard procedure to determine the concentration of AVS in aquatic sediment. The concentration of AVS in aquatic sediment is related to E _h (the redox potential) of the sediment, and has spatial and seasonal variations in sediment, therefore, it is very important which stratum of sediment should be selected to measure the AVS concentration and to used to predict the heavy metal pollution of the sediment. AVS had been proposed as the primary normalization phase for the development of sediment quality criteria for certain cationic metals because it could complex some cationic metals and thereby influences the toxicity of these metals to benthic organisms and has the potential to be an indicator of toxicity in both marine and freshwater sediments. Some studies indicated that the ratio of molar concentration between simultaneously extracted metals(SEM) and AVS can provide important insight into the potential bio-availability of toxic divalent heavy metal. Sediments with [SEM]/[AVS] ratios1.0 were thought to be toxic to benthic organisms. However, some other studies reported that the ratios>1.0 were not enough to indicate the sediment with heavy metals pollution, the other partitioning phases could also play an important role in reducing heavy metal toxicity. Furthermore, different benthic organisms may have different reactions under the same [SEM]/[AVS] ratio. The difference between the molar concentrations of SEM and AVS ([SEM]-[AVS]) should be used instead of [SEM]/[AVS] ratio as a measure of metals availability for it can provide important insight into the extent of additional available binding capacity, the magnitude by which AVS binding has been exceeded. More studies are therefore needed to understand the relations between the ratio of [SEM]/[AVS], heavy metal concentration in interstitial water, heavy metals distribution among different partitioning phases as well as different heavy metal interactions.国家自然科学基金资助项目 (3 0 170 190 )~
