摘要
为明确脱甲河溶存CH_4关键产生途径,明晰水系碳同位素组成及其分布特征,为小流域CH_4排放估算和减排提供数据支撑.利用双层扩散模型法估算了CH_4浓度和传输通量,研究了周年内脱甲河4级河段(S_1~S_4)水体CH_4通量的时空分布及其主控环境因子;运用稳定同位素方法探究了溶存CH_4关键产生途径,分析了溶解CH_4、悬浮颗粒物和沉积物有机质δ^(13)C分布特征.结果表明:水体pH均值为(7.27±0.03),各河段四季差异均显著;溶解氧(DO)在0.43~13.99 mg·L^(-1)内变化,S_1河段DO浓度最高且夏、秋季差异显著,其他河段均为冬与春、夏、秋季差异显著;可溶性有机碳(DOC)变化范围是0.34~8.32 mg·L^(-1),由S_1至S_4河段总体呈递增趋势;水体电导率(EC)和氧化还原电位(ORP)变化范围分别是17~436μS·cm^(-1)和-52.30~674.10 mV,各河段差异明显;铵态氮(NH_4^+-N)、硝态氮(NO_3^--N)浓度分别在0.30~1.35(平均0.90±0.10)mg·L^(-1)和0.82~2.45(平均1.62±0.16)mg·L^(-1)内变化.溶存CH_4浓度和传输通量变化范围分别是0~5.28(平均0.46±0.06)μmol·L^(-1)和-0.34~619.72(平均53.88±7.15)μg C·m^(-2)·h^(-1);均存在时空变化且变异规律相似,为春季>冬季>夏季>秋季,S_2>S_3>S_4>S_1.通量与水体铵态氮和DOC浓度均呈显著正相关.各级河段均以乙酸发酵产甲烷途径为主导,但不同河段差异明显,乙酸发酵途径产CH_4贡献率以S_1河段最高(87%),其次为S_4(81%),S_2、S_3分别达到78%和76%.溶存CH_4、悬浮颗粒物和沉积物有机质的δ^(13)C均值分别为-41.64‰±1.91‰、-14.07‰±1.06‰和-26.20‰±1.02‰,溶存甲烷δ^(13)C与沉积物有机质的δ^(13)C呈显著正相关,与其传输通量呈极显著负相关.
This study aimed at exploring the key pathway of methane production and clarifying the composition and distribution of carbon(C） isotopes in the Tuojia River waterbody in Hunan Province. We estimated CH4 concentrations and fluxes of four reaches(S1,S2,S3 and S4） by a twolayer diffusion model and gas chromatography. The spatial and temporal distribution of CH4 flux and its relationship with environmental factors were examined. The key pathway of CH4 production was investigated by stable C isotope method to analyze the distribution characteristics of13C isotope(δ13C） of water dissolved CH4 and seston/benthic organic matter. There was significant seasonal variability in water pH,with mean value of(7. 27 ± 0. 03）. The concentration of dissolved oxygen(DO） showed strong seasonal and spatial variations,with the range of 0.43-13.99 mg·L^（-1）. The maximum value of DO occurred in S1 and differed significantly in summer and autumin. In addition,DO differed significantly in winter and other seasons in S2,S3 and S4. The concentration of dissolved organic carbon(DOC） showed a gradual increasing trend from source to estuary. The highest concentration of DOC(8.32 mg·L^（-1）） was found in S2,while the lowest was observed in S1(0.34 mg·L^（-1））. The electrical conductivity(EC） and oxidation-reduction potential(ORP） of water ranged from 17 to 436 μS·cm^（-1） and from-52.30 to 674.10 mV,respectively,which were significantly different among the four reaches(P〈0. 05）. Water ammonium nitrogen(NH4＋-N） and nitrate nitrogen(NO3--N） concentrations were in the ranges of 0.30-1.35(averaged 0.90 ± 0.10）mg·L^（-1） and 0.82-2.45(averaged 1.62±0.16） mg·L^（-1）,respectively. The dissolved concentration and diffusion flux of CH4 ranged from 0 to 5.28 μmol·L^（-1） and from-0.34 to 619.72 μg C·m^（-2）·h^（-1）,respectively,with significant temporal and spatial variations. They showed a similar trend among reaches. Their values were highest in spring,followed by in winter and lowest in summer and autumn. Spatially,the CH4 concentration and flux followed the order of S2S3S4S1. The correlation analysis showed that CH4 flux was positively correlated with NH4-＋-N and DOC. The pathway of CH4 production of all reaches was dominated by acetic acid fermentation,while there were obvious differences among the four reaches. The contribution of CH4 from acetic acid fermentation was greatest(87%） in S1,followed by S4(81%）,S2(78%） and S3(76%）. The mean value of the δ13C for dissolved CH4,seston organic matter and benthic organic matter was-41. 64‰ ± 1. 91‰,-14.07‰±1.06‰ and-26. 20‰ ± 1. 02‰,respectively. There was a positive correlation between the δ13C of dissolved CH4 and benthic organic matter,whereas the δ13C value of dissolved CH4 was negatively correlated with CH4 flux.
作者
赵强
吕成文
秦晓波
吴红宝
万运帆
廖育林
鲁艳红
王斌
李勇
ZHAO Qiang1＇2, LYU Cheng-wen2, QIN Xiao-boi , WU Hong-bao, WAN Yun-fan, LIAO Yu-lin3, LU Yan-hong3, WANG Bin1, LI Yong4(1.Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agricultural Environment, Ministry of Agriculture, Beijing 100081, China ; 2 College of Territorial Resources and Tourism, Anhui Normal University, Wuhu 241002, Anhui , China; 3 Hunan Institute of Soil and Fertilizer, Changsha 410125, China; 4Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China)
出处
《应用生态学报》
CAS
CSCD
北大核心
2018年第5期1450-1460,共11页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(41475129
41775157)
国家发改委CDM基金项目(2014081)资助~~
关键词
脱甲河
CH4
扩散
产生途径
稳定碳同位素
Tuojia River
CH4
diffuse flux
production pathway
stable carbon isotope.
