Natural organic matter facilitates formation and microbial methylation of mercury selenide nanoparticles,Environmental Science: Nano

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Natural organic matter facilitates formation and microbial methylation of mercury selenide nanoparticles
Environmental Science: Nano ( IF 5.8 ) Pub Date : 2020-12-9 , DOI: 10.1039/d0en00992j
Qing Chang _{1,

2,

3,

4,

5} , Zhanhua Zhang _{1,

2,

3,

4,

5} , Yunyun Ji _{1,

2,

3,

4,

5} , Li Tian _{1,

2,

3,

4,

5} , Wei Chen _{1,

2,

3,

4,

5} , Tong Zhang _{1,

2,

3,

4,

5}

Affiliation

Due to their extremely low solubility, mercury selenide (HgSe) minerals are long considered as environmental sinks of mercury that pose minimal risks to ecological systems. Thus, selenium amendments have been widely applied in agricultural soils to mitigate mercury contamination and produce Se-rich crops. Here, we demonstrate that co-precipitation of ubiquitous natural organic matter (NOM), divalent mercury and selenium leads to the formation of nanoscale tiemannite (HgSe) particles, which are rapidly converted into bioaccumulative neurotoxin, methylmercury, upon exposure to methylating bacteria. The methylation potential of these tiemannite nanoparticles decreases during aging and yet remains to be significantly greater than that of bulk-HgSe formed in the absence of NOM. Nano-tiemannite formed with fulvic acid appears to be smaller in size and more available for methylation, compared with nano-tiemannite formed with humic acid. This trend may be explained by the different extents of chemical binding, likely through inner-sphere coordination between surface mercury atoms of HgSe and NOM carboxyl moieties. Our findings point out the potential risks to food safety by the application of mercury–selenium antagonism in agricultural practices, and add new perspectives to understanding the occurrence and impact of an emerging group of mercury species, mercury-containing nanominerals, that may substantially contribute to mercury biogeochemistry.

中文翻译：

天然有机物促进硒化汞纳米颗粒的形成和微生物甲基化

由于硒化汞（HgSe）矿物的溶解度极低，长期以来一直被认为是汞的环境汇聚区，对生态系统的危害最小。因此，硒改良剂已广泛应用于农业土壤中，以减轻汞污染并生产富硒作物。在这里，我们证明了普遍存在的天然有机物（NOM），二价汞和硒的共沉淀导致纳米级铁锰矿（HgSe）颗粒的形成，这些颗粒在暴露于甲基化细菌后会迅速转化为生物蓄积性神经毒素甲基汞。这些铁锰矿纳米颗粒的甲基化潜力在老化过程中下降，但仍要比不存在NOM时形成的本体HgSe的甲基化潜力大得多。与由腐殖酸形成的纳米铁锰矿相比，由黄腐酸形成的纳米铁锰矿似乎尺寸更小且可用于甲基化。这种趋势可能是由于化学结合程度不同而引起的，很可能是由于HgSe和NOM羧基表面汞原子之间的内球配位。我们的研究结果指出了将汞-硒拮抗作用应用于农业实践对食品安全的潜在风险，并增加了新的视角来理解新兴的汞物种（含汞的纳米矿物）的发生和影响，这可能对汞生物地球化学。可能是由于HgSe和NOM羧基部分的表面汞原子之间的内球配位。我们的研究结果指出了将汞-硒拮抗作用应用于农业实践对食品安全的潜在风险，并增加了新的视角来理解新兴的汞物种（含汞的纳米矿物）的发生和影响，这可能对汞生物地球化学。可能是由于HgSe和NOM羧基部分的表面汞原子之间的内球配位。我们的研究结果指出了将汞-硒拮抗作用应用于农业实践对食品安全的潜在风险，并增加了新的视角来理解新兴的汞物种（含汞的纳米矿物）的发生和影响，这可能对汞生物地球化学。

更新日期：2020-12-24

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