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Dissimilatory nitrate reduction in the coastal area

沿海地区硝酸盐异化还原

基本信息

批准号：
20710011
负责人：
SENGA Yukiko
金额：
$ 2.66万
依托单位：
Rissho University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Young Scientists (B)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20710011/
关键词：
物質循環異化型硝酸還元 DNRA 脱窒沿岸域亜酸化窒素(N_2O)

项目摘要

Kushiro Mire is the largest mire in Japan and in 1980 was the first wetland in Japan registered under the Ramsar Convention. Recent reports indicate an increase in nutrient loading into Kushiro Mire from changes in land use. We measured vertical profiles of dissolved inorganic nitrogen (DIN ; NO_3^-, NO_2^-, NH_4^+), dissolved organic carbon (DOC), and various types of microbial activity in soil samples collected to approximately 1.5m depth at two sites in Kushiro Mire. We found an accumulation of NO_3^- and DOC in the deeper soil. Denitrifying activity was highest in the shallower soils, and decreased drastically with depth, whereas higher levels of fluoresceindiacetate hydrolysis and β-glucosidase, acid phosphatase, and xylosidase enzyme activity were found in the deeper layers. We also detected humic-like substances as components of the DOC. These results suggest that the DOC in the wetland soil cannot be used as a substrate for denitrification, causing denitrification to be suppressed in the deeper soil. In addition, denitrifying activity would be very low in the deeper layers due to low soil temperature. As a result, nitrogen inputs to the Mire have resulted in a large accumulation of NO_3^- in the deeper soil. This will eventually change the mire ecosystem through effects such as increased eutrophication and acidification.

Kushiro Mire是日本最大的沼泽，1980年是日本根据拉姆萨尔公约登记的第一个湿地。最近的报告表明，由于土地利用的变化，进入久路沼泽的养分负荷增加。我们测量了库什罗沼泽两个采样点约1.5米深度土壤样品中溶解无机氮(DIN；NO_3~-，NO_2~-，NH_4~+)、溶解有机碳(DOC)和各种微生物活性的垂直剖面。我们发现在更深的土壤中有NO3~-和DOC的积累。反硝化活性在浅层土壤中最高，并随深度的增加而急剧下降，而在深层土壤中有较高水平的吲哚乙酸盐水解酶和β-葡萄糖苷酶、酸性磷酸酶和木糖苷酶活性。我们还检测到类腐殖质物质作为DOC的成分。这些结果表明，湿地土壤中的DOC不能作为反硝化的基质，导致深层土壤中的反硝化作用受到抑制。此外，由于土壤温度较低，深层的反硝化活性很低。结果是，氮素输入到沼泽中，导致了土壤深层NO_3^-的大量积累。这最终将通过增加富营养化和酸化等效应改变沼泽生态系统。