调水调沙工程黄河口近岸沉积物重金属和砷含量的空间分布及其生态风险评估

为了明确调水调沙工程长期影响下黄河口近岸沉积物中重金属含量的分布特征及其生态风险,基于2012年黄河口近岸27个站位的表层沉积物样品,通过ICP-MS测定重金属(Zn、Cr、Ni、Pb、Cu、Cd)和砷(As)含量,并运用潜在生态风险指数法(RI)对其进行生态风险评估。结果表明:近岸沉积物中重金属和As的平均含量表现为AsZnCrNiPbCuCd。Cr、Ni、Cu和Pb四种元素的分布规律较为一致,整体呈现出近岸和近黄河口高而远离河口和岸线低的空间分异特征。Ni、Cu、Pb、Zn与粘土均呈极显著或显著正相关(P0.01或P0.05),而Cd、Cr和As与其相关性均未达到显著水平(P0.05)。近岸沉积物中6种重金属和As的平均单项潜在生态风险指数大小顺序整体表现为CdAsNiPbCuCrZn。就潜在生态风险(RI)而言,研究区域18.52%的站位属轻微生态危害,70.07%的站位属中等生态危害,7.41%的站位属强生态危害,Cd和As是造成危害的两种主要元素。近岸沉积物中重金属和As的来源复杂且多样,主要是由于农业化肥使用、海上石油开采和泄漏、化石燃料燃烧以及河口污染物输入所致。对比研究发现,随着调水调沙工程的长期实施,除Cd和As外沉积物中其他重金属含量均呈下降趋势,说明二者的生态风险将会随调水调沙的长期实施呈增加趋势,而其他重金属的生态风险将呈降低趋势,故未来应重点关注近岸沉积物中Cd和As的生态毒理风险。

Spatial distribution of heavy metals and As concentrations and assessment of their ecological risk in inshore sediments, affected by the Flow-sediment Regulation Scheme in the Yellow River estuary

To clarify the concentration distribution characteristics of heavy metal and arsenic (As) and their ecological risks in the sediments of the Yellow River estuary and the long-term effects of the Flow-sediment Regulation Scheme (FSRS), the concentrations of six heavy metals (Zn, Cr, Ni, Pb, Cu, Cd) and As in the surface sediments of 27 stations sampled in 2012 were determined by ICP-MS and their ecological risks were evaluated by determining the potential ecological risk index (RI). The results showed that the average levels of heavy metal and As in inshore sediments were in the order of As > Zn > Cr > Ni > Pb > Cu > Cd. The spatial distributions of Cr, Ni, Cu, and Pb concentrations were consistent, and higher values were generally detected in inshore and near the Yellow River estuary, whereas lower values were observed far from the estuary and coastline. Ni, Cu, Pb, and Zn concentrations showed significantly positive correlations with clay (P < 0.05), whereas no significant correlations were observed between clay and Cd (or Cr and As) (P > 0.05). The average potential ecological risk indices of six heavy metals and As in inshore sediments generally followed the order of Cd > As > Ni > Pb > Cu > Cr > Zn. According to the RI values in the study area, 18.52% of stations were slightly ecologically hazardous, 70.07% of stations were moderately ecologically hazardous, and 7.41% of stations were strongly ecologically hazardous, which was mainly caused by Cd and As. Because of the use of agricultural fertilizers, inshore oil extraction, fossil fuel combustion, and estuarine pollutant input, the sources of heavy metals and As in inshore sediments are complex and diverse. This study showed that only the concentrations of Cd and As showed an increasing trend following long-term implementation of the FSRS, indicating that their ecotoxicological risk in inshore sediments of the Yellow River estuary should be evaluated in the future.