The acute and chronic toxicity of lanthanum to Daphnia carinata
The acute and chronic toxicity of lanthanum to Daphnia carinata
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DOI：
10.1016/s0045-6535(00)00091-6
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发表时间：
2000-11-01
期刊：
影响因子：
8.8
通讯作者：
Meehan, BJ
中科院分区：
文献类型：
--
作者：
Barry, MJ;Meehan, BJ
稀土元素（RE）越来越多地被用作农业中的微量补充剂。研究了稀土元素镧（La）对隆线蚤（Daphnia carinata）的急性和慢性毒性。在三种不同组成和硬度的介质中测定了La对水蚤的48小时EC_（50）。镧在软自来水中对水蚤的毒性最大，急性48小时EC 50为43 μ g/l，而在ASTM硬水中为1180 μ g/l。在第三daphnid生长培养基（DW），稀释的海水的基础上，急性48小时EC 50为49微克镧/升，但是，有显着的沉淀La在此媒体。在DW和ASTM介质中测定了La对水蚤的慢性毒性。标称接触浓度为100、200、400、600、800和1000 μ g La/l。在两项慢性实验中，死亡率是比生长或繁殖更敏感的终点。在24小时后，在任一培养基中检测到非常少的La，并且通过标称值和测量值的对数平均值估计以下测量浓度。在使用DW培养基的实验的第六天，浓度大于或等于80 μ g La/l（标称400 μ g/l）时有100%的死亡率，但在较低浓度下对存活生长或繁殖没有影响。在ASTM介质中，La在浓度大于或等于39 μ g/l（标称值为208 μ g/l）时对水蚤造成显著死亡，然而，在每个测试浓度下，至少有一只动物存活至研究结束。有没有影响的La生存水蚤的生长浓度小于或等于57微克/升（400克/升），但是，第二窝的大小显着增加30; 39，和57微克/升（100，200，400克/升标称）与对照组相比。镧还导致水蚤的成熟延迟。(C)2000爱思唯尔科技有限公司版权所有。
The rare earth elements (REEs) are increasingly being used as trace supplements in agriculture. This study measured the acute and chronic toxicity of one REE, lanthanum (La), to Daphnia carinata. The 48-h EC50 of La to Daphnia was measured in three media of differing composition and hardness. Lanthanum was most toxic to Daphnia ih soft tap water (TW) with an acute 48-h EC50 Of 43 mu g/l compared with 1180 mu g/l in ASTM hard water (ASTM). In the third daphnid growth medium (DW), based on diluted sea water, the acute 48-h EC50 was 49 mu g La/l, however, there was significant precipitation of La in this media. The chronic toxicity of La to Daphnia was measured in the DW and ASTM media. Nominal exposure concentrations were 100, 200, 400, 600, 800, and 1000 mu g La/l. Mortality was a more sensitive endpoint than growth or reproduction in both chronic experiments. Very little La was detected in either media after 24 h and the measured concentrations below were estimated by logarithmic mean of nominal and measured values. There was 100% mortality at concentrations greater than or equal to 80 mu g La/l (400 mu g/l nominal) by day six of the experiment using DW media, but no effect on survival growth or reproduction at lower concentrations. In the ASTM media, La caused significant mortality to Daphnia at concentrations greater than or equal to 39 mu g/l (208 mu g/l nominal), however, at least one animal survived to the end of the study at each of the tested concentrations. There was no effect of La on growth of surviving daphnids at concentrations less than or equal to 57 mu g/l (400 g/l), however, second brood clutch sizes were significantly increased at 30; 39, and 57 mu g/l (100, 200, 400 g/l nominal) compared with controls. Lanthanum also caused a delayed maturation in Daphnia. (C) 2000 Elsevier Science Ltd. All rights reserved.