氮负荷增强对闽江河口短叶茳芏湿地土壤碳氮含量变化的影响  

Effects of enhanced nitrogen load on variations of carbon and nitrogen contentsin soils of Cyperus malaccensis marsh in the Minjiang estuary

作　　者：姚钦予 孙志高[1,2,3] 宋振阳 贺攀霏 武慧慧 方冠荣 YAO Qinyu;SUN Zhigao;SONG Zhenyang;HE Panfei;WU Huihui;FANG Guanrong(Fujian Provincial Key Laboratory for Subtropical Resources and Environment,Fujian Normal University,Fuzhou 350117;Key Laboratory of Humid Subtropical Eco˗geographical Process(Fujian Normal University),Ministry of Education,Fuzhou 350117;Fujian Minjiang Estuary Wetland Ecosystem National Observation and Research Station,National Forestry and Grassland Administration,Fuzhou 350215)

机构地区：[1]福建师范大学福建省亚热带资源与环境重点实验室,福州350117 [2]福建师范大学湿润亚热带生态地理过程教育部重点实验室,福州350117 [3]福建闽江河口湿地生态系统国家定位观测研究站,国家林业和草原局,福州350215

出　　处：《环境科学学报》2025年第2期462-475,共14页Acta Scientiae Circumstantiae

基　　金：福建省自然科学基金重点项目(No.2023J02012);国家自然科学基金面上项目(No.42371105,41971128);福建省“闽江学者奖励计划”项目。

摘　　要：选择闽江河口短叶茳芏(Cyperus malaccensis)湿地为研究对象,基于野外氮负荷增强模拟实验,对比研究了输氮4个月(T4)和16个月(T16)后不同氮负荷水平下(NNT,对照处理,0 g·m^(-2)·a^(-1);LNT,低氮处理,12.5 g·m^(-2)·a^(-1);MNT,中氮处理,25.0 g·m^(-2)·a^(-1);HNT,高氮处理,75.0 g·m^(-2)·a^(-1))湿地土壤碳氮含量的动态变化特征.结果表明,氮负荷增强条件下湿地SOC含量在不同时期差异明显.由于氮负荷增强可能促进了植物生长和残体分解并明显改变了主要环境因子的原因,使得SOC含量在较短时期(T4)以MNT和HNT处理较高,LNT处理较低;而在较长时期(T16)以LNT处理较高,MNT和HNT处理较低.相比T4时期,T16时期的SOC含量在LNT、MNT和HNT处理下分别增加了18.72%、7.73%和4.00%,原因可能与不同氮负荷处理下土壤C/N随氮负荷时间的延长整体均增加有关.氮负荷增强条件下湿地土壤TN、NH_(4)^(+)-N和NO_(3)^(-)-N含量在不同时期亦差异较大.在残体分解、氮矿化及脱氮作用的综合影响下,TN、NH_(4)^(+)-N和NO_(3)^(-)-N含量在T4时期均以LNT和MNT处理较高,HNT处理较低;而在T16时期,不同处理下的TN和NH_(4)^(+)-N含量均较低,而NO_(3)^(-)-N含量均较高.相比T4时期,T16时期的TN含量在MNT和HNT处理下分别增加了4.85%和0.56%,在LNT处理下降低了1.06%;NH_(4)^(+)-N含量在LNT、MNT和HNT处理下分别降低了30.93%、41.51%和19.24%;而NO_(3)^(-)-N含量在LNT和MNT处理下分别降低了24.93%和52.26%,在HNT处理增加了14.97%.随着氮负荷时间的延长,影响SOC含量变化的关键因素从pH、EC转变为含水量(MC),而影响TN、NH_(4)^(+)-N和NO_(3)^(-)-N含量变化的主导因素从pH、EC转变为MC、C/N和SOM.研究发现,随着氮负荷时间的延长,低氮处理下SOC转化受到的抑制程度可能较高,而这有助于提升闽江河口湿地土壤的储碳功能.This study focused on typical Cyperus malaccensis marsh in the Minjiang estuary and conducted field N load experiment with four N load levels:NNT(no N treatment,0 g·m^(-2)·a^(-1)),LNT(low N treatment,12.5 g·m^(-2)·a^(-1)),MNT(medium N treatment,25 g·m^(-2)·a^(-1)),and HNT(high N treatment,75 g·m^(-2)·a^(-1)).The dynamic variations in soil organic carbon(SOC),total nitrogen(TN),ammonium nitrogen(NH_(4)^(+)-N)and nitrate nitrogen(NO_(3)^(-)-N)contents in marsh soils of different N load levels were comparatively investigated after 4(T4)and 16 months(T16)of N import.Results showed that enhanced N load might promote plant growth and litter decomposition and significantly alter the key environmental factors in marsh soils,which significantly altered the SOC contents between the two sampling periods.At T4 period,SOC contents were generally higher in the MNT and HNT treatments while those in the LNT treatment were much lower.In comparison,SOC contents in the LNT treatment at T16 were generally higher whereas those in the MNT and HNT treatments were much lower.Compared to T4,SOC contents in the LNT,MNT and HNT treatments at T16increased by 18.72%,7.73%and 4.00%,respectively,which might be ascribed to the increase of C/N ratios in soils of different treatments with theprolonged N load time.Under N load conditions,the TN,NH_(4)^(+)-N and NO_(3)^(-)-N contents in marsh soils also varied greatly in different periods due to thecombined influences of litter decomposition,organic-N mineralization and denitrification,with the LNT and MNT treatments being higher and the HNTtreatment being lower at T4.At T16,the contents of TN and NH_(4)^(+)-N in soils of different treatments were generally lower while those of NO_(3)^(-)-N weremuch higher.Compared to T4,the TN contents in the MNT and HNT treatments at T16 increased by 4.85%and 0.56%,respectively,while the valuesin the LNT treatment decreased by 1.06%;the NH_(4)^(+)-N contents in the LNT,MNT and HNT treatments decreased by 30.93%,41.51%and 19.24%,respectively;the NO_(3)^(-)

关 键 词：氮负荷 土壤有机碳 全氮 短叶茳芏湿地 闽江河口 

分 类 号：X171[环境科学与工程—环境科学]