Department of Civil and Environmental Engineering, University of Maine, Orono, Maine 04469, USA.
Environ Sci Process Impacts. 2013 Oct;15(11):2104-14. doi: 10.1039/c3em00355h.
Mercury-specific diffusive gradient in thin films (DGTs) were used in laboratory microcosms as a biomonitoring tool to assess the lability of mercury (Hg) total and monomethylmercury Hg (MeHg), and to develop a relationship between chemical lability and bioavailability in estuarine sediments. Time-series deployment of DGTs in sediments showed that sediment-bound MeHg is more labile than sediment-bound inorganic Hg. In subsequent experiments, DGTs were deployed simultaneously with three benthic macroinvertebrates (the estuarine amphipod, Leptocheirus plumulosus; the estuarine polychaete, Nereis virens; and the marine clam, Macoma nasuta) in sediments for up to 55 days. All organisms and their co-deployed DGTs exhibited an initial period of rapid Hg uptake followed by slower uptake reaching apparent steady state. Strong correlative relationships were generally observed between paddle-type DGTs and macroinvertebrate tissue data (r(2) between 0.57 and 0.97). Further, %MeHg:Total Hg ratios for M. nasuta and N. virens (38.5 ± 12.2 and 19.2 ± 5.2) were similar to their corresponding ratios for the DGTs (33.1 ± 13.3 and 24.4 ± 11.0), and they were significantly higher than the same ratios for sediment (2.9 ± 0.3) and pore water (8.5 ± 4.9). The %MeHg:Total Hg ratios for L. plumulosus (68.5 ± 6.2) were significantly higher than those for the DGTs. This may be because the tissue and DGT data for this organism were not truly co-located as L. plumulosus burrows close to the sediment surface, and the DGTs sampled the sediment surface. Overall, our results suggest that for benthic macroinvertebrates in estuarine sediments studied here, (a) sediment MeHg is more bioavailable than inorganic Hg, (b) sediment and pore-water concentration measurements are not good predictors for the extent of bioaccumulation of Hg species, and (c) DGTs are an effective biomonitoring tool for the assessment of bioavailability of Hg species.
汞专用扩散梯度薄膜（DGT）在实验室微环境中用作生物监测工具，以评估汞总浓度和一甲基汞 Hg (MeHg) 的活性，以及在河口沉积物中建立化学活性与生物可利用性之间的关系。DGT 在沉积物中的时间序列部署表明，沉积物结合的 MeHg 比沉积物结合的无机 Hg 更具活性。在随后的实验中，DGT 与三种底栖大型无脊椎动物（河口端足类动物，Leptocheirus plumulosus；河口多毛类动物，Nereis virens；和海洋蛤，Macoma nasuta）同时部署在沉积物中长达 55 天。所有生物体及其同时部署的 DGT 都表现出快速摄取汞的初始阶段，然后摄取速度较慢，达到明显的稳定状态。DGT 与大型无脊椎动物组织数据之间通常观察到强相关关系（r(2) 介于 0.57 和 0.97 之间）。此外，M. nasuta 和 N. virens 的 %MeHg:总 Hg 比值（38.5 ± 12.2 和 19.2 ± 5.2）与 DGT 的相应比值（33.1 ± 13.3 和 24.4 ± 11.0）相似，并且明显高于沉积物（2.9 ± 0.3）和孔隙水（8.5 ± 4.9）的相应比值。L. plumulosus 的 %MeHg:总 Hg 比值（68.5 ± 6.2）明显高于 DGT 的比值。这可能是因为该生物的组织和 DGT 数据没有真正的共同定位，因为 L. plumulosus 靠近沉积物表面挖洞，而 DGT 则在沉积物表面取样。总体而言，我们的结果表明，对于本研究中河口沉积物中的底栖大型无脊椎动物，（a）沉积物中的 MeHg 比无机 Hg 更具生物可利用性，（b）沉积物和孔隙水浓度测量不能很好地预测 Hg 物种的生物积累程度，以及（c）DGT 是评估 Hg 物种生物利用度的有效生物监测工具。
