School of Environmental Science and Engineering, Tianjin University, 135 Yaguan Road, Tianjin 300350, China; College of Architecture Engineering, Northeast Electric Power University, 169 Changchun Road, Jilin 132012, China.
School of Environmental Science and Engineering, Tianjin University, 135 Yaguan Road, Tianjin 300350, China.
Sci Total Environ. 2019 Jan 15;648:861-870. doi: 10.1016/j.scitotenv.2018.08.201. Epub 2018 Aug 17.
In aquatic systems worldwide, heavy metal pollution has been increasing alongside rapidly growing anthropogenic activities, and most heavy metals are stored in sediments. Overlying water conditions may influence whether sediments act as heavy metal sinks or sources. In this study, we investigated the effects of the dissolved oxygen (DO) and nutrient levels of overlying water on the total contents and fractions of Pb, Zn, Ni, Cu, Mo, and Fe in river surface sediments. Sediments and overlying water were collected from a tributary of the Hai River in Tianjin, China, and then incubated for 61 days under laboratory conditions. The chemical speciation of heavy metals was determined following the modified Community Bureau of Reference (BCR) three-step sequential extraction procedure. The results showed that Pb, Zn, and Fe were released from the sediments in an anoxic environment and adsorbed from the overlying water in an aerobic environment. High nutrient levels facilitated the adsorption of Pb, Zn, Cu, and Fe in the sediments, while the total content of Mo was higher under low nutrient level conditions. The DO and nutrient levels appeared to have no influence on the total content of Ni. According to the risk assessment code classification (RAC), anoxic conditions decrease the potential bioavailability risks of Pb, Zn, Ni, Cu, Mo, and Fe. Anoxic conditions can also reduce the percentage of the potentially mobile fractions of Pb, Zn, Cu, and Fe. The low nutrient level contributed, to some extent, to reducing the potential bioavailability risk of Pb, but increasing the risk of Cu. The high nutrient level increased the potentially mobile fractions of Pb, Zn, Cu, and Fe. The information obtained in this study improves our scientific understanding of the effects of overlying water conditions on the total heavy metal contents and fractions.
在全球的水生系统中，随着人类活动的迅速增长，重金属污染也在不断增加，而大多数重金属都储存在沉积物中。上覆水的条件可能会影响沉积物是作为重金属的汇还是源。在这项研究中，我们调查了上覆水中溶解氧（DO）和营养水平对河流表层沉积物中 Pb、Zn、Ni、Cu、Mo 和 Fe 的总量和形态的影响。沉积物和上覆水是从中国天津海河的一条支流中采集的，然后在实验室条件下培养了 61 天。采用改进的欧共体参比局（BCR）三步连续提取程序测定重金属的化学形态。结果表明，在缺氧环境中，Pb、Zn 和 Fe 从沉积物中释放出来，而在好氧环境中则从上覆水中吸附。高营养水平有利于沉积物中 Pb、Zn、Cu 和 Fe 的吸附，而低营养水平下 Mo 的总量较高。DO 和营养水平似乎对 Ni 的总量没有影响。根据风险评估代码分类（RAC），缺氧条件降低了 Pb、Zn、Ni、Cu、Mo 和 Fe 的潜在生物利用风险。缺氧条件还可以降低 Pb、Zn、Cu 和 Fe 的潜在可移动分数的比例。低营养水平在一定程度上降低了 Pb 的潜在生物利用风险，但增加了 Cu 的风险。高营养水平增加了 Pb、Zn、Cu 和 Fe 的潜在可移动分数。本研究获得的信息提高了我们对上覆水条件对重金属总量和形态影响的科学认识。
