School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
Environ Pollut. 2018 Dec;243(Pt A):713-722. doi: 10.1016/j.envpol.2018.09.024. Epub 2018 Sep 6.
Heavy metal contamination of soil in the vicinity of mining sites is a serious environmental problem around the world when mining residue (slag) is dispersed as dust. We conducted an incubation experiment to investigate the effect of a slag containing high levels of Pb and Zn (62.2 and 33.6 g kg slag as PbO and ZnO, respectively, sampled from a site formerly used as a lead and zinc mine) on the nitrogen cycle when mixed with soil (0-0.048 g slag g soil). The nitrogen cycle provides many life supporting-functions. To assess the quality of the soil in terms of the nitrogen cycle we focused on the dynamics of nitrate and ammonium, and bacterial community structure and functions within the soil. After two weeks of pre-incubation, N-labeled urea (500 mg N kg) was added to the soil. Changes in soil pH, the concentration and N ratio of nitrate (NO-N) and ammonium, and bacterial relative abundance and community structure were measured. Results indicated that increasing the ratio of slag to soil had a stronger negative effect on nitrification than ammonification, as suggested by slower nitrate accumulation rates as the slag:soil ratio increased. In the treatment with the highest amount of slag, the concentration of NO-N was 50% of that in the controls at the end of the incubation. Regarding the bacterial community, Firmicutes had a positive and Planctomycetes a negative correlation with increasing slag concentration. Bacterial community functional analysis showed the proportion of bacterial DNA sequences related to nitrogen metabolism was depressed with increasing slag, from 0.68 to 0.65. We concluded that the slag impacted the soil bacterial community structure, and consequently influenced nitrogen dynamics. This study could form the basis of further investigation into the resistance of the nitrogen cycle to contamination in relation to soil bacterial community.
矿区附近土壤的重金属污染是一个严重的环境问题，尤其是当采矿残渣（炉渣）作为粉尘散布时。我们进行了一项孵化实验，研究了一种含高浓度 Pb 和 Zn 的炉渣（从以前用作铅锌矿的地点采集的炉渣，PbO 和 ZnO 的含量分别为 62.2 和 33.6 g kg 炉渣）与土壤混合时对氮循环的影响（土壤中 0-0.048 g 炉渣 g 土壤）。氮循环提供了许多生命支持功能。为了评估土壤在氮循环方面的质量，我们专注于硝酸盐和铵的动态，以及土壤中的细菌群落结构和功能。经过两周的预孵化，向土壤中添加了 N 标记的尿素（500 mg N kg）。测量了土壤 pH 值、硝酸盐（NO-N）和铵的浓度和 N 比以及细菌相对丰度和群落结构的变化。结果表明，随着炉渣与土壤比例的增加，对硝化的负面影响强于氨化，这表明随着炉渣与土壤比例的增加，硝酸盐积累速率较慢。在添加炉渣量最高的处理中，NO-N 的浓度在培养结束时仅为对照的 50%。关于细菌群落，厚壁菌门与炉渣浓度呈正相关，而浮霉菌门则呈负相关。细菌群落功能分析表明，随着炉渣的增加，与氮代谢相关的细菌 DNA 序列的比例从 0.68 下降到 0.65。我们得出结论，炉渣影响了土壤细菌群落结构，从而影响了氮动态。本研究可以为进一步研究土壤细菌群落对氮循环污染的抵抗力奠定基础。
