电感耦合等离子体质谱法研究乌梁素海上覆水-沉积物-植物-鱼体系中重金属的分布和评价

重金属污染已经成为全球性问题，由于其毒性、持久性和在食物链中的生物富集特点，对水生环境构成严重威胁。本研究选取乌梁素海为研究区域，采用电感耦合等离子体质谱法(ICP-MS)测定、分析了该湖泊中上覆水、沉积物、龙须眼子菜、芦苇和四种鱼类样品中重金属的含量，以探究其空间分布、富集特征、风险评估和可能的来源。结果表明：(1) Cr，Ni，Cu，Mn，Pb和Zn的平均含量大小顺序为：沉积物>龙须眼子菜（沉水植物）>芦苇（挺水植物）>鱼类>上覆水；但是上覆水中As的浓度高于芦苇和鱼类。芦苇中Cd的含量几乎是普通植物的50倍，且鱼类中Cd的含量是中国允许标准阈值的3.3倍。因此，推测Cd可能通过食物链生物累积对鱼类和人类的健康造成潜在危害。(2) 在沉积物中，As和Cd属于中度严重的富集程度。龙须眼子菜具有较高的生物富集因子(BCF)和较低的生物-沉积物积累因子(BASF)，表明该物种更有可能从上覆水中积累重金属，并可以作为超积累植物去除乌梁素海的重金属。(3) 沉积物中的Er_i和R_I值表明，Cd具有相当高的生态风险，可能对周围环境产生高风险。由于湖泊的入口、出口处及西北部重金属污染程度较高，因此应被当作金属污染监测和管理的优先区域。(4) 重金属源解析结果表明，Zn和Cd是来自采矿和工业废水，而As与农业的面源污染有关。本研究结果可为改善水环境质量、减少重金属污染对乌梁素海和黄河水质管理带来的风险提供重要信息。

Distribution and Assessment of Heavy Metals in the Overlying Water-Sediment-Plant-Fish System in the Wuliangsuhai Lake by Using Inductively Coupled Plasma Mass Spectrometry

Heavy metal (HM) contamination has become a widespread global problem and posed threat to the aquatic environment due to their toxicity, persistence and bioenrichment in the food chain. In this study, overlying water, sediment, Potamogeton pectinatus L. (P. pectinatus), Phragmites australis (P. australis), and four types of fish in Wuliangsuhai Lake, China, were analyzed for HMs. The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to determine the contents of HMs in collected samples in order to investigate their spatial distribution, enrichment characteristic, risk assessment and the possible sources. The results showed that: (1) The mean levels of Cr, Ni, Cu, Mn, Pb and Zn mainly followed an order of sediment>P. pectinatus (submerged plants)>P. australis (emergent plants)>fishes>overlying water, but for As, the concentration in overlying water was higher than that in P. australis and fishes. The content of Cd, in P. australis was almost 50 times higher than that in normal plants and in fish was 3.3 times higher than the permissible threshold standards in China, leading to potential hazards to fish and human health via food chain bioaccumulation. (2) In sediment As and Cd experienced moderately severe enrichment. For P. pectinatus, the higher bioconcentration factor (BCF) and the lower biota-sediment accumulation factor (BASF) indicated that this species was more likely to accumulate HMs from overlying water and could remove HMs from Wuliangsuhai Lake as a hyperaccumulator. (3) In sediment, the Er_i and R_I values suggested that Cd posed a considerable high ecological risk and a very high risk to the surroundings. Because of the high HM contamination levels in the northwest part of the lake, the inlet and outlet of the lake were identified as priority regions for metal pollution monitoring and management. (4) The results of source identification indicated that Zn and Cd were derived from mining and industrial wastewater, while As was related to nonpoint source pollution from agriculture. These results will provide important information for improving the aquatic environment, minimizing the potential risks posed by the HMs pollution in Wuliangsuhai Lake and managing the water quality of the Yellow River.