低剂量Cd对崇明东滩湿地不同覆被类型土壤反硝化速率的影响  

Effect of Low Dose Cadmium on Denitrification Intensity of Soil with Different Covers in Chongming Dongtan Wetland

作　　者：徐传红 韩金 程虎 韩建刚 XU Chuan-hong;HAN Jin;CHENG Hu;HAN Jian-gang(College of Biology and Environment,Nanjing Forestry University,Nanjing 210037,China;Co-Innovation Center for the Sustainable Forestry in Southern China,Nanjing Forestry University,Nanjing 210037,China;National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province,Hongze 223100,China)

机构地区：[1]南京林业大学生物与环境学院,江苏南京210037 [2]南京林业大学南方现代林业协同创新中心,江苏南京210037 [3]江苏洪泽湖湿地生态系统国家定位观测研究站,江苏洪泽223100

出　　处：《长江流域资源与环境》2021年第11期2703-2711,共9页Resources and Environment in the Yangtze Basin

基　　金：国家重点研发计划项目(2017YFC0505803);国家自然科学基金项目(41375149);江苏高校优势学科建设工程资助项目(PAPD)。

摘　　要：全球变暖及人为活动加速影响下,重金属对湿地生态系统反硝化(Den)的影响研究备受关注,但目前有关不同覆被类型下低剂量重金属的效应评估还很不充分。本文以崇明东滩湿地为例,采集光滩、互花米草(Spartina alterniflora)和芦苇(Phragmites australis)3种覆被下的土壤样品,外源添加不同剂量(0、0.05、0.1、0.3、0.5、1.0、3.0和5.0 mg·kg^(-1))的Cd,借助^(15)N同位素示踪技术观测土壤Den速率的变化。结果表明:芦苇覆被下土壤Den速率(9.2±0.3μg·kg^(-1)·h^(-1))>互花米草(4.7±0.5μg·kg^(-1)·h^(-1))。Cd的添加导致两种植被下土壤Den速率均显著降低(P<0.05),芦苇和互花米草下土壤Den速率分别降至6.3和3.2μg·kg^(-1)·h^(-1)。Cd胁迫下,Den速率的变化表现为剂量驱动下的“阶梯状”特征。即,低剂量(0.05~0.3 mg·kg^(-1))区间,Den的抑制率稳定保持在13.3%~14.8%。当Cd的剂量上升至0.3~0.5 mg·kg^(-1)时,Den的抑制率从14.8%增至50.0%。高剂量(0.5~5.0 mg·kg^(-1))下,Den的抑制率再次趋于稳定(50.0%~55.0%)。相关分析表明,Cd胁迫下,芦苇和互花米草植被下土壤NO_(3)^(-)-N含量与Den速率显著正相关(P<0.05)。这表明,低剂量Cd的存在并未改变NO_(3)^(-)-N对Den过程的主导。Effects of heavy metals on soil denitrification rates in wetland ecosystems has attracted much attentions with accelerated global warming and anthropogenic activities,but few studies have evaluated the low-dose effects under various plant types.In the present study,soils were collected from bare beach,Spartina alterniflora and Phragmites australis in Chongming Dongtan wetland,Shanghai,China.Gradient doses of Cd(0,0.05,0.1,0.3,0.5,1.0,3.0 and 5.0 mg·kg^(-1))were added into the soils,and the Den rates were determined based on ^(15)N isotope tracer technology.The results showed that mean Den rate in soils with Phragmites australis(9.2±0.3μg·kg^(-1)·h^(-1))was higher than that of Spartina alterniflora(4.7±0.5μg·kg^(-1)·h^(-1)).The presence of Cd resulted in the significant decrease of Den rates under the two vegetation(P<0.05).The soil Den rates under Phragmites australis and Spartina alterniflora decreased to 6.3μg·kg^(-1)·h^(-1) and 3.2μg·kg^(-1)·h^(-1),respectively.Under Cd stress,the change of Den rate showed a"step-like"mode with doses.In the low dose(0.05-0.3 mg·kg^(-1))interval,the inhibition rate of Den rates remained stable at 13.3%-14.8%.When the dose of Cd increased to 0.3-0.5 mg·kg^(-1),the inhibition rate increased from 14.8%to 50.0%.At high doses(0.5-5.0 mg·kg^(-1)),the inhibition rate reached a higher level and stabilized again(50.0%-55.0%).Correlation analysis showed that the soil NO_(3)^(-)-N contents were significantly positively correlated with Den rates under Spartina alterniflora and Phragmites australis(P<0.05).This indicated that the presence of low-dose Cd did not change the dominance of NO_(3)^(-)-N on the Den process in the coastal wetland.

关 键 词：低剂量 镉 反硝化 滨海湿地 

分 类 号：S153.6[农业科学—土壤学] X144[农业科学—农业基础科学] X171.1[环境科学与工程—环境科学]