不同水分梯度下UV-B辐射对2个稻田土壤碳氮转化的影响  

Effects of UV-B Radiation on Soil Carbon and Nitrogen Transformation under Different Soil Moisture Contents from Two Paddy Fields

作　　者：蒋梦蝶 王秋敏[1,2] 徐鹏 周维[1] 邬磊[1] 胡荣桂[1,3] JIANG Meng-die;WANG Qiu-min;XU Peng;ZHOU Wei;WU Lei;HU Rong-gui(College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China;Xiangyang Environmental Monitoring Station, Xiangyang 441000, China;Eeologieal Environment Center, Huazhong Agricultural University, Wuhan 430070, China)

机构地区：[1]华中农业大学资源与环境学院,武汉430070 [2]湖北省襄阳市环境保护监测站,襄阳441000 [3]华中农业大学环境生态中心,武汉430070

出　　处：《环境科学》2017年第11期4819-4827,共9页Environmental Science

基　　金：国家重点基础研究发展规划(973)项目(2012CB417100);中央高校基本科研业务费专项(2662016PY098)

摘　　要：UV-B辐射对土壤碳氮转化的影响与土壤物理化学性质有关,为明确土壤水分状态对UV-B辐射的影响,以有机质含量不同的两个水稻土(有机质含量低的记为L,高的记为H)为研究材料,在室内研究了含水量为25%(W1)、50%(W2)和100%(W3)时,UV-B辐射对土壤总有机碳(TOC)、可溶性有机碳(DOC)、铵态氮(NH_4^+-N)、硝态氮(NO_3^--N)以及累积净矿化氮量的影响.结果表明:120 h后,与避光(对照,CK)相比,UV-B辐射显著降低了土壤TOC的含量(P<0.05);UV-B辐射下,水分从低到高,L土壤的TOC分别降低了9.9%、4.5%和6.3%,H土壤降低了10.9%、5.6%和6.3%.但与对照相比,UV-B辐射却促使土壤DOC增加;且在UV-B辐射下水分为100%的处理中,土壤DOC含量高于25%和50%的处理,120 h时,L土壤的DOC分别增加了21.5%(W1)、9.4(W2)和26.3%(W3),H土壤分别降低了26.7%(W1)、14.2%(W2)和33.8%(W3).与对照相比,UV-B辐射使NH_4^+-N含量有所下降;且在UV-B辐射中,NH_4^+-N含量的变化幅度在不同水分条件下的整体表现为W1<W2<W3.较对照处理,UV-B辐射促进NO_3^--N的累积,NO_3^--N变化幅度在不同水分条件下的表现为:W1<W3<W2.24 h后与对照相比,UV-B辐射对土壤累积净矿化氮量有显著影响(P<0.05),且UV-B辐射下累积净矿化氮量在不同水分之间差异显著(P<0.05).这表明光降解在土壤有机质的稳定中扮演着重要角色,UV-B辐射会加速土壤有机碳的损失,影响土壤矿质态氮的转化,且水分不同,UV-B辐射对土壤碳氮转化的影响存在一定差异.Carbon and nitrogen in soils play an important role in the global carbon and nitrogen cycle.The enhancement of ultraviolet radiation（predominantly UV-B） resulting from the depletion of stratospheric ozone has raised significant concern.The effects of UV-B radiation on soil carbon and nitrogen transformation is connected directly to the physical and chemical properties of the soil.In order to clearly understand the effects of soil moisture on UV-B radiation,this study collected soil samples from two paddy fields with different levels of organic matter in a subtropical region of China.The response of the total organic carbon（TOC）,dissolved organic carbon（DOC）,ammonia nitrogen（NH4^＋-N）,nitrate nitrogen（NO3^--N） and cumulative net nitrogen mineralization to UV-B radiation under three different moisture gradients（W1 = 25%,W2 = 50%,and W3 = 100%） were monitored in laboratory for 120 h.After this period,the results were compared with a control treatment（CK） and it was found that： the TOC content had significantly decreased under UV-B radiation（p〈0.05）.From low to high moisture content（W1,W2 and W3）,the TOC decreased by 9.9%,4.5% and6.3%,respectively for soil with low organic matter（L）,and by 10.9%,5.6% and 6.3%,respectively for soil with high organic matter（H）,under UV-B radiation.However,UV-B radiation was found to enhance the DOC content in the soil compared with the CK.Furthermore,the DOC for soil moisture contents under 100%（W3） was higher than for other moisture contents（W1,W2）.The measured DOC increased by 21.5%（W1）,9.4%（W2）,and 26.3%（W3） for soil with L.In addition,the measured DOC increased by 26.7%（W1）,14.2%（W2） and 33.8%（W3） for soil with H under UV-B radiation after 120 h.Compared with control treatment（CK）,UV-B radiation decreased the NH4^＋-N content significantly,but there was an increased NO3^--N content.The decrease of the NH4^＋-N content was largest for W3 and smallest for W1.The increase in NO3^--N content was larg

关 键 词：UV-B辐射 水分 TOC DOC 矿质态氮 

分 类 号：X53[环境科学与工程—环境工程]