Background quality for coastal marine waters of the North West Shelf, Western Australia

Water quality surveys were undertaken in February and June of 2003 to determine dissolved concentrations of cadmium, chromium, copper, lead and zinc, total mercury, polyaromatic hydrocarbons, phenols, BTEX chemicals and petroleum hydrocarbons in and around the Dampier Archipelago and Port Hedland. Most sampling sites were located in areas unlikely to be contaminated from anthropogenic sources, but for comparative purposes some sites were also located in potentially contaminated areas. This work was undertaken to provide an estimate of background concentrations for selected metals and organics in the marine waters of the North West Shelf, and to ascertain whether the guideline trigger values from ANZECC & ARMCANZ (2000) are relevant to the region. The results of this study indicate that the coastal waters of the North West Shelf are generally of very high quality. The concentrations of metals were low by world standards, with localised elevations of some metals adjacent to industrial centres and ports. Metal concentrations at the time of sampling met the environmental quality guidelines for a very high level of ecological protection (99% species protection) throughout the sampled area, with the exception of the inner harbour at Port Hedland, where copper and zinc levels were elevated above background, but below the 95% species protection guidelines, which represent a high level of ecological protection. No organic chemicals were detected in any of the samples. The reporting limits were well below the guideline trigger values recommended in ANZECC & ARMCANZ (2000) for a very high level of ecological protection for the five organics for which guideline values were available. The findings of this study suggest that ANZECC & ARMCANZ (2000) 99% species protection guidelines are relevant to the region for all metals analysed, except cobalt, for which the 95% species protection guideline is recommended for use. A set of Environmental Quality Criteria is proposed.

2003年2月与6月，研究人员针对丹皮尔群岛（Dampier Archipelago）与黑德兰港（Port Hedland）及其周边海域开展水质调查，旨在测定镉、铬、铜、铅、锌、总汞、多环芳烃（polyaromatic hydrocarbons）、酚类、BTEX化学品（BTEX）以及石油烃的溶解态浓度。多数采样点位设置于受人为源污染可能性极低的区域，同时为开展对照研究，部分点位布设至潜在污染区域。本研究旨在估算西北陆架（North West Shelf）海域选定金属与有机物的背景浓度，并探明ANZECC & ARMCANZ（2000）发布的导则触发值是否适用于该区域。研究结果显示，西北陆架近岸海域整体水质优良。从全球标准来看，该海域金属浓度普遍偏低，仅在工业中心与港口邻近区域出现部分金属浓度局部升高的情况。采样期间的金属浓度在全部采样区域均符合极高生态保护等级（对应99%物种保护）的环境质量导则要求，仅黑德兰港内港区域例外：该区域铜与锌浓度高于背景值，但仍低于代表高生态保护等级的95%物种保护导则阈值。所有样品均未检出有机污染物。对于已有导则值的5类有机物，本研究的检出限远低于ANZECC & ARMCANZ（2000）中针对极高生态保护等级设定的导则触发值。本研究结果表明，ANZECC & ARMCANZ（2000）的99%物种保护导则适用于本次分析的所有金属，仅钴元素除外，该元素建议采用95%物种保护导则。本研究同时提出了一套环境质量标准建议。