Swedish University of Agricultural Sciences, Department of Microbiology, Box 7025, 750 07 Uppsala, Sweden.
Swedish University of Agricultural Sciences, Department of Microbiology, Box 7025, 750 07 Uppsala, Sweden.
Water Res. 2015 Nov 15;85:377-83. doi: 10.1016/j.watres.2015.08.060. Epub 2015 Sep 3.
Reactive nitrogen (N) species released from undetonated ammonium-nitrate based explosives used in mining or other blasting operations are an emerging environmental problem. Wetlands are frequently used to treat N-contaminated water in temperate climate, but knowledge on plant-microbial interactions and treatment potential in sub-arctic wetlands is limited. Here, we compare the relative importance of plant uptake and denitrification among five plant species commonly occurring in sub-arctic wetlands for removal of N in nitrate-rich mine drainage in northern Sweden. Nitrogen uptake and plant associated potential denitrification activity and genetic potential for denitrification based on quantitative PCR of the denitrification genes nirS, nirK, nosZI and nosZII were determined in plants growing both in situ and cultivated in a growth chamber. The growth chamber and in situ studies generated similar results, suggesting high relevance and applicability of results from growth chamber experiments. We identified denitrification as the dominating pathway for N-removal and abundances of denitrification genes were strong indicators of plant associated denitrification activity. The magnitude and direction of the effect differed among the plant species, with the aquatic moss Drepanocladus fluitans showing exceptionally high ratios between denitrification and uptake rates, compared to the other species. However, to acquire realistic estimates of N-removal potential of specific wetlands and their associated plant species, the total plant biomass needs to be considered. The species-specific plant N-uptake and abundance of denitrification genes on the root or plant surfaces were affected by the presence of other plant species, which show that both multi- and inter-trophic interactions are occurring. Future studies on N-removal potential of wetland plant species should consider how to best exploit these interactions in sub-arctic wetlands.
未爆炸的含硝酸铵的爆炸物在采矿或其他爆破作业中释放的活性氮 (N) 物种是一个新兴的环境问题。湿地经常被用于处理温带气候下受 N 污染的水，但在亚北极湿地中，有关植物-微生物相互作用和处理潜力的知识有限。在这里，我们比较了在富硝酸盐的矿山废水中，五种常见于亚北极湿地的植物物种的植物吸收和反硝化作用的相对重要性。在瑞典北部，我们通过对生长在原位和在生长室中培养的植物进行定量 PCR 分析，确定了与硝酸盐吸收相关的潜在反硝化活性和基于反硝化基因 nirS、nirK、nosZI 和 nosZII 的反硝化遗传潜力。生长室和原位研究产生了相似的结果，这表明生长室实验的结果具有高度的相关性和适用性。我们确定反硝化作用是 N 去除的主要途径，反硝化基因的丰度是植物相关反硝化活性的有力指标。不同植物物种之间的影响大小和方向存在差异，与其他物种相比，水生藓类植物 Drepanocladus fluitans 的反硝化和吸收速率之间的比值异常高。然而，要获得特定湿地及其相关植物物种的 N 去除潜力的现实估计，需要考虑总植物生物量。植物物种特有的根或植物表面的 N 吸收和反硝化基因丰度受到其他植物物种的存在的影响，这表明多营养和互营养相互作用都在发生。未来关于湿地植物物种 N 去除潜力的研究应考虑如何在亚北极湿地中最好地利用这些相互作用。
