Responses of dissolved organic C and N in paddy field water to elevated atmospheric CO2
稻田水体可溶性有机碳与可溶性氮对大气CO2浓度增高的响应

In order to enhance our understanding of carbon and nitrogen cycle in wetland ecosystem, total organic carbon (TOC), total nitrogen (TN), dissolved organic carbon (DOC) and dissolved nitrogen (DN) in the paddy field water were monitored dynamically by Free Air CO2 Enrichment (FACE) of paddy field(started in 2004, located in Jiangdu County, Jiangsu province). The results showed that elevated atmospheric CO2 significantly increased TOC, TN, DOC and DN by 31.2%, 25.9%, 28.3% and 25.6% on average, respectively, than those in ambient plots (P<0.01). There were significantly differences in TOC, TN, DOC and DN between different rice growing stages (P<0.01). The results also indicate that elevated atmospheric CO2 could threat rice security production through eutrophicating paddy field water and increase aquatic DOC and DN. Therefore elevated atmospheric CO2 may influence the rice ecosystem C and N cycle and soil productivity through field drainage and rainstorms at the early stage of rice.