Department of Environmental Hydrology & Microbiology, Zuckerberg Institute for Water Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Sede Boqer, Israel.
FEMS Microbiol Ecol. 2012 Jul;81(1):145-55. doi: 10.1111/j.1574-6941.2012.01347.x. Epub 2012 Mar 27.
Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater.
无衬砌粪肥池塘是在全球范围内的粘土地上建造的，用于管理农场废物。富含氨的液体渗滤液进入底层土壤会导致硝酸盐污染地下水。为了确定在这种缺氧环境中氨转化为硝酸盐的可能过程，我们研究了无衬砌粪肥池塘下氨转化微生物的多样性和丰度。氨氧化细菌和厌氧氨氧化细菌的数量在土壤剖面的顶部最丰富，并随着深度（0.5 米）显著减少，分别与土壤孔隙水中的氨浓度和土壤中的氨浓度相关。另一方面，氨氧化古菌的数量在整个土壤剖面中相对稳定（每克土壤 10(7)amoA 拷贝）。亚硝酸盐氧化菌主要存在于 0.2 米的表层土壤中。结果表明，粪肥池塘下包气带中硝酸盐的积累可能是完全好氧硝化（氨氧化为硝酸盐）的结果，也可能是厌氧氨氧化活性的副产物。尽管大部分氮在 0.5 米的土壤剖面中被去除，可能是通过联合厌氧氨氧化和异养反硝化，一部分产生的硝酸盐会淋入地下水。
