School of Environmental Science and Engineering, Sun Yat-Sen University, No. 135 Xingangxi Road, Haizhu District, Guangzhou, Guangdong 510275, China.
School of Environmental Science and Engineering, School of Geography and Planning, Sun Yat-Sen University, No. 135 Xingangxi Road, Haizhu District, Guangzhou, Guangdong 510275, China.
Sci Total Environ. 2019 Feb 1;649:448-460. doi: 10.1016/j.scitotenv.2018.08.283. Epub 2018 Aug 23.
Three sediment cores were collected from the Beijiang River to investigate the effects of human activities on the geochemical fractions of trace metals (Ni, Cr, Cu, Zn, Cd, Pb and Fe) and to reconstruct the ecological risks for the period 1951-2015. Cd had the highest concentration in exchangeable and carbonate fractions and was probably contributed by smelting wastewater. High Cu, Zn and Pb contents were observed in the iron oxide fraction (mean values of 32.2%, 38.2% and 43.9%, respectively), reflecting the influence of mining activities. Flood events led to coarser sediment grain sizes and higher trace metal residual fractions at upstream sites (S1 and S2). Similar to the mining history of the basin, the excess metal fluxes of Cu, Zn, Pb, and Fe in the Pb-dating core (S3) increased slowly from 1951 to 1987, increased rapidly from 1988 to 1998 and decreased gradually after 1999 because of government intervention. However, the excess Cd flux decreased continuously from 1951 to 1961, increased from 1961 to 2005, and declined by approximately 78.2% from 2005 to 2014. The excess Ni and Cr fluxes increased noticeably after 1996 because of the increasing sedimentation rate after the construction of the Feilai Gorge Dam. The enrichment factor (EF) and ratio of secondary and primary phases (RSP) indicated that sediments (S3) were moderately to strongly polluted by Cu, Zn and Pb from 1961 to 2007 and extremely polluted by Cd from 1951 to 2011. Human activities increased the bioavailable metal concentrations and resulted in a high risk of toxicity to benthic organisms, especially during intense mining activity (1990s) and Cd pollution incidents (2005). Cd and Pb were primarily responsible for the sediment toxicity in the Beijiang River. The integrated pollution and risk assessment methods provided a clearer understanding of the aquatic environmental quality.
从北江采集了三个沉积物岩芯，以研究人类活动对痕量金属（Ni、Cr、Cu、Zn、Cd、Pb 和 Fe）地球化学形态的影响，并重建 1951-2015 年期间的生态风险。Cd 在可交换态和碳酸盐态中的浓度最高，可能来自冶炼废水。高浓度的 Cu、Zn 和 Pb 存在于铁氧化物相中（平均值分别为 32.2%、38.2%和 43.9%），反映了采矿活动的影响。洪水事件导致上游站点（S1 和 S2）的沉积物粒径变粗，痕量金属残留态分数增加。与流域的采矿历史相似，Pb 年代测定岩芯（S3）中的 Cu、Zn、Pb 和 Fe 的过量金属通量从 1951 年到 1987 年缓慢增加，从 1988 年到 1998 年迅速增加，自 1999 年以来逐渐减少，这是由于政府干预。然而，Cd 的过量通量从 1951 年到 1961 年持续减少，从 1961 年到 2005 年增加，并在 2005 年至 2014 年期间下降了约 78.2%。由于飞来峡大坝建成后沉积速率增加，1996 年后 Ni 和 Cr 的过量通量明显增加。富集因子（EF）和次生相与原生相的比值（RSP）表明，1961 年至 2007 年期间，沉积物（S3）受到 Cu、Zn 和 Pb 的中度至重度污染，而 1951 年至 2011 年期间受到 Cd 的极度污染。人类活动增加了金属的生物可利用浓度，导致底栖生物面临高毒性风险，尤其是在采矿活动剧烈时期（20 世纪 90 年代）和 Cd 污染事件时期（2005 年）。Cd 和 Pb 是北江沉积物毒性的主要原因。综合污染和风险评估方法提供了对水生态环境质量更清晰的认识。
