珊瑚海岛包气带中氮磷的迁移、转化和累积规律  

Studies on the migration,transformation and accumulation pattern of nitrogen and phosphorus in the vadose zone of coral islands

作　　者：李莉[1] 张盼[1] 赵志伟 张赛[1] 龚星 许庭浩 LI Li;ZHANG Pan;ZHAO Zhi-wei;ZHANG Sai;GONG Xing;XU Ting-hao(College of Environment and Ecology,Chongqing University,Chongqing 400045,China;College of Civil and Transportation Engineering,Guangdong University,Guangzhou 510006,China)

机构地区：[1]重庆大学环境与生态学院,重庆400045 [2]广东工业大学土木与交通学院,广东广州510006

出　　处：《中国环境科学》2024年第10期5776-5787,共12页China Environmental Science

基　　金：国家重点研发计划资助(“海洋环境安全保障与岛礁可持续发展”重点专项2021-01)。

摘　　要：珊瑚海岛包气带中氮磷的迁移转化直接影响海岛地下水质量和土壤结构.通过XRD和SEM分析,明确了珊瑚砂特殊的CaCO_(3)物相成分和多孔形貌特征.采用静态吸附实验明确了珊瑚砂对N、P的吸附机理;通过短期连续降雨和长期间歇降雨模拟柱实验分别研究了N、P在珊瑚砂中的运移机制和不同深度剖面N的转化和P的累积规律.结果表明,珊瑚砂对NH_(4)^(+)和DIP的平均吸附量为192mg/kg和2051.75mg/kg,吸附模型分别符合可逆线性吸附和Freundlich等温吸附模型;NH_(4)^(+)的运移机制可由线性平衡CDE模型解释,低浓度DIP的运移过程符合含衰减项的双点位化学非平衡模型;而高浓度DIP的运移过程无法由模型拟合,结合pH值推测了其与CaCO_(3)发生的溶解沉淀平衡反应.长期降雨条件下,结合微生物分析得出土壤中存在N_(2)→NH_(4)^(+)→NO_(2)^(-)→NO_(3)^(-)→N_(2)/DON的氮转化路径,存在地下水氮污染的风险,而DIP则以非溶解态磷形式被固定,其长期累积可能对土壤结构不利.简言之,N、P在珊瑚海岛包气带中的迁移、转化、累积方面具有特殊性,明确其规律可为海岛生态建设中的环境风险控制提供科学依据.The migration and transformation of nitrogen and phosphorus in the vadose zone of coral islands have a direct impact on the groundwater quality and soil structure of the islands.Through XRD and SEM analyses,the unique CaCO_(3) phase composition and porous morphology of coral sand were elucidated.Static adsorption experiments were conducted to clarify the adsorption mechanism of N and P in coral sand;short-term continuous rainfall simulation column experiments were used to investigate the transport mechanism of N and P in coral sand,while long-term intermittent rainfall simulation column experiments examined the N transformation and P accumulation in different depth profiles.The results showed that the average adsorption amounts of NH_(4)^(+)and DIP in coral sand were 192mg/kg and 2051.75mg/kg,respectively,with adsorption models conforming to reversible linear adsorption and Freundlich isothermal adsorption models.The transport mechanism of NH_(4)^(+)was explicable by the linear equilibrium CDE model,while the transport process of low-concentration DIP followed a two-point chemical nonequilibrium model with an attenuation term.The transport of high-concentration DIP could not be modeled,and a dissolution and precipitation equilibrium reaction with CaCO_(3) was speculated in conjunction with the pH value.Under long-term rainfall conditions,microbial analysis indicated a nitrogen pathway N_(2)→NH_(4)^(+)→NO_(2)^(-)→NO_(3)^(-)→N_(2)/DON in the soil,posing a risk of nitrogen contamination to groundwater.Meanwhile,DIP was fixated in the form of insoluble phosphorus,potentially negatively impacting soil structure through long-term accumulation.In conclusion,the unique characteristics of N and P migration,transformation,and accumulation in the vadose zone of coral islands provide a scientific basis for environmental risk management in island ecological development.

关 键 词：珊瑚砂 静态吸附 氮磷运移 HYDRUS-1D 微生物 

分 类 号：X53[环境科学与工程—环境工程]