模拟SO_4^(2-)沉降对闽江口淡水感潮野慈姑湿地N_2O通量的影响

Effects of simulated sulfate deposition on N_2O flux in freshwater tidal Sagittaria trifolia wetland in the Min River estuary

选取闽江口塔礁洲淡水感潮野慈姑(Sagittaria trifolia L.)湿地为研究对象,2015年12月—2016年10月,每月小潮日原位定期向实验样地施加2个沉降量水平的硫酸钾溶液:S60(60 kg·hm-2·a-1)和S120(120 kg·hm-2·a-1),运用静态箱-气相色谱法研究模拟硫酸根沉降对河口区淡水感潮湿地N2O通量的影响及主要环境影响因子.对照、S60和S120 3个处理下N2O通量分别为(58.06±23.07)、(23.50±22.85)和(20.75±7.83)μg·m-2·h-1,年尺度上,S120处理显著降低N2O通量(p<0.05),S60处理与CK处理差异不显著(p>0.05).闽江口淡水感潮野慈姑湿地整体上表现为大气中N2O源.野慈姑湿地N2O排放通量与间隙水盐度呈显著负相关关系.研究表明,对于亚热带河口区淡水感潮野慈姑湿地,施加量为120 kg·hm-2·a-1的模拟硫沉降显著降低其N2O排放通量.

Tile effects of simulated sulfate deposition on N20 fluxes were investigated in the freshwater tidal Sagittaria trifolia wetland in the Tajiaozhou of the Min River estuary. Monthly pulses of dissolved KaSO4 were added to the experiment sites on the neap days from December 2015 to October 2016. The treatments included the additions of dissolved K2SO4 at rates of 60,120 kg. hm^-2· a^-l and the control（CK）. The averaged N20 fluxes were （58.06±23.07） , （23.50±22.85） and （20.75±7.83） μg·m^-2·h^-1, respectively, in CK, 60 and 120 kg.hm^-2, a^-ltreatments. On the annual scale, 120 kg^-1·hm^-2·a^-1 treatment significantly decrease the N20 flux, however the 60 kg·hm 2 a i treatment had no significant inhibitory effect on N20 flux. In whole the freshwater tidal Sagittaria trifolia wetland in the Tajiaozhou of the Min River estuary is a source of N20 in the atmosphere. Simulated sulfate deposition increased the pore water SO2-concentration. N20 fluxes from the S. trifolia with simulated sulfate deposition demonstrated a significant negative correlation with pore water conductivity. The results indicate that higher dose of sulfate deposition （ 120 kg. hm^-2. a^-1 ） on the neap days suppresses N20 flux from freshwater tidal S. trifolia wetland in subtropical estuary, and exerts a positive feedback in relation to acid rain problem.