Birch Gavin, Nath Bibhash, Chaudhuri Punarbasu
School of Geosciences, University of Sydney, Sydney, NSW, 2006, Australia,
Environ Sci Pollut Res Int. 2015 Apr;22(8):6185-97. doi: 10.1007/s11356-014-3830-7. Epub 2014 Nov 18.
Industrial activities and urbanization have had a major consequence for estuarine ecosystem health and water quality globally. Likewise, Sydney estuary has been significantly impacted by widespread, poor industrial practices in the past, and remediation of legacy contaminants have been undertaken in limited parts of this waterway. The objective of the present investigation was to determine the effectiveness of remediation of a former Pb-contaminated industrial site in Homebush Bay on Sydney estuary (Australia) through sampling of inter-tidal sediments and mangrove (Avicennia marina) tissue (fine nutritive roots, pneumatophores, and leaves). Results indicate that since remediation 6 years previously, Pb and other metals (Cu, Ni and Zn) in surficial sediment have increased to concentrations that approach pre-remediation levels and that they were considerably higher than pre-settlement levels (3-30 times), as well as at the reference site. Most metals were compartmentalized in fine nutritive roots with bio-concentration factors greater than unity, while tissues of pneumatophores and leaves contained low metal concentrations. Lead concentrations in fine nutritive root, pneumatophore, and leaf tissue of mangroves from the remediated site were similar to trees in un-remediated sites of the estuary and were substantially higher than plants at the reference site. The situation for Zn in fine nutritive root tissue was similar. The source of the metals was either surface/subsurface water from the catchment or more likely remobilized contaminated sediment from un-remediated parts of Homebush Bay. Results of this study demonstrate the problems facing management in attempting to reduce contamination in small parts of a large impacted area to concentrations below local base level.
工业活动和城市化对全球河口生态系统健康和水质产生了重大影响。同样，悉尼河口过去也受到广泛存在的不良工业行为的严重影响，并且已经在这条水道的有限区域开展了遗留污染物的修复工作。本研究的目的是通过对潮间带沉积物和红树林（白骨壤）组织（细营养根、呼吸根和叶片）进行采样，来确定悉尼河口（澳大利亚）霍姆布什湾一个以前受铅污染的工业场地的修复效果。结果表明，自6年前进行修复以来，表层沉积物中的铅和其他金属（铜、镍和锌）浓度已升至接近修复前的水平，且远高于定居前的水平（3至30倍），也高于参考站点的浓度。大多数金属在细营养根中富集，生物富集系数大于1，而呼吸根和叶片组织中的金属浓度较低。来自修复场地的红树林细营养根、呼吸根和叶片组织中的铅浓度与河口未修复场地的树木相似，且远高于参考站点的植物。细营养根组织中锌的情况类似。金属的来源要么是集水区的地表水/地下水，要么更有可能是来自霍姆布什湾未修复区域重新活化的受污染沉积物。这项研究的结果表明，在试图将一个大面积受影响区域的小部分污染降低到当地基线水平以下时，管理工作面临诸多问题。
