Accumulation of mercury in estuarine food chains
Accumulation of mercury in estuarine food chains
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DOI：
10.1023/a:1005959211768
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发表时间：
1998-03-01
期刊：
影响因子：
4
通讯作者：
Mason, RP
中科院分区：
文献类型：
--
作者：
Lawson, NM;Mason, RP
为了解无机汞和甲基汞在河口食物链底层的积累情况，进行了浮游植物（Thalassiosira weissfloppellum）对无机汞和甲基汞的吸收和形态分析实验。甲基汞-二硫化物的甲基汞络合降低了浮游植物的吸收率，而甲基汞-半胱氨酸和硫脲络合物的吸收率随着这些配体络合作用的增加而增加。此外，我们的研究结果表明，虽然不同的配体影响无机汞/甲基汞的浮游植物细胞的吸收，配体络合物没有重大影响，无论是在那里的汞被隔离在浮游植物细胞内，也没有桡足类的汞同化效率。无机汞/甲基汞的桡足类和端足类的藻类细胞喂养的同化效率进行了比较，这两种生物更有效地吸收甲基汞，甲基汞的相对同化效率为2.0桡足类和2.8端足类无机汞。相对同化作用在某种程度上取决于浓度，因为实验表明，随着接触浓度的增加，在浮游植物细胞的细胞质中发现的甲基汞百分比增加，从而导致以这些细胞为食的桡足类中的甲基汞浓度增加。此外，食物质量影响无脊椎动物的同化作用。在T.在作为无脊椎动物食物的weissflocculus养殖中，桡足类从食物中吸收甲基汞的能力越来越弱，而即使在腐烂的晚期，片足类也能够从食物中吸收大量汞。最后，以桡足类为食的鱼类吸收甲基汞的效率高于无机汞，因为在桡足类的软组织中发现的甲基汞比例较大。
To understand the accumulation of inorganic mercury and methylmercury at the base of the estuarine food chain, phytoplankton (Thalassiosira weissflogii) uptake and mercury speciation experiments were conducted. Complexation of methylmercury as methylmercury-bisulfide decreased the phytoplankton uptake rate while the uptake rate of the methylmercury-cysteine and -thiourea complexes increased with increasing complexation by these ligands. Furthermore, our results indicated that while different ligands influenced inorganic mercury/methylmercury uptake by phytoplankton cells, the ligand complex had no major influence on either where the mercury was sequestered within the phytoplankton cell nor the assimilation efficiency of the mercury by copepods. The assimilation efficiency of inorganic mercury/methylmercury by copepods and amphipods feeding on algal cells was compared and both organisms assimilated methylmercury much more efficiently; the relative assimilation efficiency of methylmercury to inorganic mercury was 2.0 for copepods and 2.8 for amphipods. The relative assimilation is somewhat concentration dependent as experiments showed that as exposure concentration increased, a greater percentage of methylmercury was found in the cytoplasm of phytoplankton cells, resulting in a higher concentration in the copepods feeding on these cells. Additionally, food quality influenced assimilation by invertebrates. During decay of a T. weissflogii culture, which served as food for the invertebrates, copepods were increasingly less able to assimilate the methylmercury from the food, while even at advanced stages of decay, amphipods were able to assimilate mercury from their food to a high degree. Finally, fish feeding on copepods assimilated methylmercury more efficiently than inorganic mercury owing to the larger fraction of methylmercury found in the soft tissues of the copepods.