Magar Victor S, Martello Linda, Southworth Barbara, Fuchsman Phyllis, Sorensen Mary, Wenning Richard J
ENVIRON International Corporation, 123 N. Wacker Drive, Suite 250, Chicago, IL 60606, USA.
Sci Total Environ. 2008 May 1;394(1):103-11. doi: 10.1016/j.scitotenv.2008.01.007. Epub 2008 Mar 4.
Elevated levels of chromium, partly attributable to historical disposal of chromite ore processing residue, are present in sediment along the eastern shore of the lower Hackensack River near the confluence with Newark Bay. Due to anaerobic conditions in the sediment, the chromium is in the form of Cr(III), which poses no unacceptable risks to human health or to the river ecology. However, as water quality conditions have improved since the 1970s, aerobic conditions have become increasingly prevalent in the overlying water column. If these conditions result in oxidation of Cr(III) to Cr(VI), either under quiescent conditions or during severe weather or anthropogenic scouring events, the potential for adverse ecological effects due to biological exposures to Cr(VI) is possible, though the reaction kinetics associated with oxidation of Cr(III) to Cr(VI) are unfavorable. To investigate the stability of Cr(III) in Hackensack River sediments exposed to oxic conditions, sediment suspension and oxidation experiments and intertidal sediment exposure experiments that exposed the sediments to oxic conditions were conducted. Results revealed no detectable concentrations of Cr(VI), and thus no measurable potential for total chromium oxidation to Cr(VI). Furthermore, total chromium released from sediment to elutriate water in the oxidation and suspension experiments ranged from below detection (<0.01 mg/L) to 0.18 mg/L, below the freshwater National Recommended Water Quality Criteria (NRWQC) of 0.57 mg/L for Cr(III). These results support conclusions of a stable, in situ geochemical environment in sediments in the lower Hackensack River with respect to chromium. Results showed that chemicals other than Cr(VI), including copper, lead, mercury, zinc, and PCBs, were released at levels that may pose a potential for adverse ecological effects.
哈肯萨克河下游靠近与纽瓦克湾交汇处的东岸沉积物中铬含量升高，部分原因是铬铁矿加工残渣的历史处置。由于沉积物中的厌氧条件，铬以Cr(III)的形式存在，对人类健康或河流生态没有不可接受的风险。然而，自20世纪70年代以来水质条件有所改善，上覆水柱中的好氧条件越来越普遍。如果这些条件导致Cr(III)氧化为Cr(VI)，无论是在静止条件下，还是在恶劣天气或人为冲刷事件期间，由于生物接触Cr(VI)而产生不利生态影响的可能性是存在的，尽管与Cr(III)氧化为Cr(VI)相关的反应动力学不利。为了研究哈肯萨克河沉积物中Cr(III)在有氧条件下的稳定性，进行了沉积物悬浮和氧化实验以及将沉积物暴露于有氧条件下的潮间带沉积物暴露实验。结果显示未检测到Cr(VI)的浓度，因此没有可测量的总铬氧化为Cr(VI)的可能性。此外，在氧化和悬浮实验中，从沉积物释放到淘析水中的总铬浓度范围从低于检测限(<0.01 mg/L)到0.18 mg/L，低于Cr(III)的淡水国家推荐水质标准(NRWQC)0.57 mg/L。这些结果支持了哈肯萨克河下游沉积物中铬的原位地球化学环境稳定的结论。结果表明，除Cr(VI)外的其他化学物质，包括铜、铅、汞、锌和多氯联苯，释放水平可能对生态产生潜在不利影响。
