Hogan Alicia C, van Dam Rick A, Houston Melanie A, Harford Andrew J, Nou Suthidha
Department of the Environment, Water, Heritage, and the Arts, Environmental Research Institute of the Supervising Scientist, Darwin, NT, 0801, Australia.
Arch Environ Contam Toxicol. 2010 Aug;59(2):204-15. doi: 10.1007/s00244-010-9465-x. Epub 2010 Feb 3.
The discharge of catchment-management water from the Ranger uranium (U) mine into Magela Creek upstream of the Ramsar-listed Magela Floodplain in Kakadu National Park is an important part of the mine's water-management system. Because U is one of the primary toxicants associated with this water, a receiving-water trigger value (TV), based on chronic toxicity data from five local native species, was derived for U. To strengthen the data set underpinning the derivation of the TV, the chronic toxicity of U to two additional tropical freshwater species, duckweed Lemna aequinoctialis (96-hour growth rate), and pulmonate gastropod, Amerianna cumingi (96-hour reproduction), was determined. The fate of U within the test systems was an important component of the study because analysis of U concentrations during the snail tests indicated that a substantial proportion of U (approximately 25%) was being lost from the test solutions when integrated during the entire test duration. Analysis of the snails and their food for U indicated that only a small proportion that was lost from solution was being taken up by the snails. Therefore, the majority of U that was lost was considered unavailable to the snails, and thus the exposure concentrations used to calculate the toxicity estimates were adjusted downward. Integrating the loss of U from the L. aequinoctialis test solutions over time showed that only a small proportion (6% to 13%) was lost during the test: Of that, almost half (2-5%) was taken up by the plants (constituting exposure). Uranium was only moderately toxic to L. aequinoctialis, with no observed-effect concentrations, lowest observed-effect concentrations, and inhibition concentrations causing 10% and 50% effects (IC10 and IC50) values of 226, 404, 207, and 1435 microg/l, respectively. A. cumingi was found to be more sensitive to U than L. aequinoctialis, with NOEC, LOEC, IC10, and IC50 values of 60, 61, 15, and 278 microg/l, respectively. The data for these two additional species will be used to revise the current TV for U in Magela Creek.
从兰杰铀矿排放的集水区管理用水进入卡卡杜国家公园内被列入《拉姆萨尔公约》的马盖拉洪泛平原上游的马盖拉溪，这是该矿水管理系统的重要组成部分。由于铀是与这种水相关的主要有毒物质之一，基于来自五种当地本土物种的慢性毒性数据得出了铀的受纳水体触发值（TV）。为了加强支撑触发值推导的数据集，测定了铀对另外两种热带淡水物种的慢性毒性，即浮萍（96小时生长率）和肺螺亚纲腹足动物美洲大蜗牛（96小时繁殖率）。铀在测试系统中的归宿是该研究的一个重要组成部分，因为在蜗牛测试期间对铀浓度的分析表明，在整个测试期间进行综合分析时，相当一部分铀（约25%）正从测试溶液中流失。对蜗牛及其食物中的铀进行分析表明，从溶液中流失的铀只有一小部分被蜗牛吸收。因此，大部分流失的铀被认为蜗牛无法利用，因此用于计算毒性估计值的暴露浓度向下调整。随着时间的推移对浮萍测试溶液中铀的流失进行综合分析表明，在测试期间只有一小部分（6%至13%）流失：其中，几乎一半（2%至5%）被植物吸收（构成暴露）。铀对浮萍的毒性只是中等程度，无观察效应浓度、最低观察效应浓度以及引起10%和50%效应的抑制浓度（IC10和IC50）值分别为226、404、207和1435微克/升。发现美洲大蜗牛对铀比浮萍更敏感，其无观察效应浓度、最低观察效应浓度、IC10和IC50值分别为60、61、15和278微克/升。这两种额外物种的数据将用于修订马盖拉溪目前的铀触发值。
