Accumulation of inorganic and methylmercury by freshwater phytoplankton in two contrasting water bodies
Accumulation of inorganic and methylmercury by freshwater phytoplankton in two contrasting water bodies
复制标题
DOI：
10.1021/es060966w
复制
发表时间：
2007-01-01
影响因子：
11.4
通讯作者：
Fisher, Nicholas S.
中科院分区：
文献类型：
--
作者：
Pickhardt, Paul C.;Fisher, Nicholas S.
浮游植物从其水体环境中浓缩汞，是汞在水生食物网中的主要进入点。我们使用 Hg-203 比较了两种含有不同浓度溶解有机碳 (DOC) 的水中四种浮游植物（硅藻、叶绿藻、隐植物和蓝藻）对无机汞 (Hg(II)) 和甲基汞 (MeHg) 的吸收情况。在稳定状态下，四种水体中 Hg(II) 的体积浓度因子 (VCF) 相似，范围为 0.5 至 5 x 10(4)，而 MeHg 的 VCF 超过 Hg(II)，范围为 1.3 至 14.6 x 10(5)。高 DOC 水中的三种真核细胞中 MeHg 的 VCF 比低 DOC 水中的大 2-2.6 倍，但原核生物的 VCF 在两种水中相似。较高的细胞表面积与体积比与 MeHg 浓度增加相关，但与 Hg(II) 无关。在这两种水类型中，活细胞和热灭活细胞的 Hg(II) VCF 相似，但活细胞中 MeHg 的 VCF 高 1.5-5.0 倍，表明 MeHg 存在主动吸收成分。 Hg(II)和MeHg完全结合在死细胞的细胞表面，而活细胞中59-64%的MeHg和9-16%的Hg(II)进入细胞质。
Phytoplankton concentrate mercury from their aqueous surroundings and represent the primary entry point for Hg in aquatic food webs. We used Hg-203 to compare the uptake of inorganic mercury, Hg(II), and methylmercury, MeHg, in four phytoplankton species (a diatom, a chlorophyte, a cryptophyte, and a cyanobacterium) in two waters containing different concentrations of dissolved organic carbon (DOC). At steady state, volume concentration factors (VCFs) for Hg(II) in the four species were similar and ranged from 0.5 to 5 x 10(4) for both water types, whereas VCFs for MeHg exceeded those for Hg(II) and ranged from 1.3 to 14.6 x 10(5). The VCFs for MeHg in the three eukaryotic cells in the high DOC water were 2-2.6 times greater than those in the low DOC water, but the VCFs for the prokaryote were similar in both waters. Higher cell surface area to volume ratios correlated with increased MeHg concentrations but not with Hg(II). In both water types, VCFs of Hg(II) were similar for living and heat-killed cells, but the VCFs of MeHg were 1.5-5.0 times greater in living cells, suggesting an active uptake component for MeHg. Hg(II) and MeHg were entirely bound to cell surfaces of the dead cells, whereas 59-64% of the MeHg and 9-16% of the Hg(II) in living cells entered the cytoplasm.