三种主养草鱼池塘沉积物-水界面碳通量的研究

为了探讨环境因子和底栖配养生物对碳通量的影响,采用实验室培养方法,测定并比较了不同混养模式下沉积物-水界面各形态碳的通量,监测了8月沉积物-水界面上覆水中各形态碳含量的昼夜变化。3种主养草鱼池塘的养殖模式为草鱼、鲢和鳙混养(GSB),草鱼、鲢、鳙和凡纳滨对虾混养(GSBL),草鱼、鲢、鳙和鲤混养(GSBC)。主要实验结果如下:(1)在养殖周期内,3种混养模式沉积物-水界面可溶性无机碳(DIC)通量范围为0.65~16.90 mg/(m²·d),可溶性有机碳(DOC)通量范围为0.16~13.49 mg/(m²·d),颗粒性有机碳(POC)通量范围为-2.29~3.32 mg/(m²·d);GSB和GSBC模式各形态碳通量均以8月最高,GSBL模式则以7月最高。(2)在养殖周期内,3种混养模式沉积物对DIC和DOC均表现为释放,而对POC在4-6月以吸收为主,其余时间表现为释放。(3)在养殖的中后期,3种混养模式的DIC、DOC和POC通量存在一定差异。其中,GSBL和GSBC模式中各形态碳通量值显著高于GSB模式(P<0.05)。(4)8月上覆水中DIC和DOC的含量在4:00达到最大值,POC含量则表现为GSBL模式在4:00达到最大值,12:00达到最小值,而GSBC模式在4:00达到最小值,12:00达到最大值。(5)各形态碳通量的变化与上覆水中的DO、pH呈显著负相关关系,而与水温呈显著正相关关系。

Carbon fluxes across sediment-water interface in different grass carp poly-culture models

To investigate the seasonal variance of carbonic exchange in different grass carp ponds and explore the relationship between carbonic fluxes and environment factors of overlying water,three poly-culture systems,i.e.(1)GSB group:grass carp Ctenopharyngodon idellus,silver carp Hypophthalmictuthys molitrix and big head carp Aristichthys nobilis,(2)GSBL group:grass carp,silver carp,big head carp and Litopenaeus vannamei,(3)GSBC group:grass carp,silver carp,big head carp and carp Cyprinus carpio,were studied by simulation in the laboratory from April to September,2013.The changes of benthic fluxes of carbon across the sediment-water interface with time were studied,as well as the diurnal variation of carbon in the overlying water in August.The results showed that dissolved inorganic carbons(DIC)fluxes ranged from 0.65 mg/(m²·d)to 16.90 mg/(m²·d),while dissolved organic carbons(DOC)fluxes and particulate organic carbon(POC)fluxes ranged from 0.16 mg/(m²·d)to 3.49 mg/(m²·d),-2.29 mg/(m²·d)to 3.32 mg/(m²·d),respectively.Different carbon fluxes were all maximum in August for GSB and GSBC groups,but in July for GSBL group.During our experiments,the ex-fluxes of DIC and DOC were observed in every month.POC was up-taken by the sediments from April to June,but released from the sediments in other months.In the mid-to-late cultivation time,the benthic fluxes of DIC,DOC and POC in GSBL and GSBC groups were significantly higher than those in GSB group(P<0.05).The diurnal variation of carbons had obvious characters in August,with the content of DIC and DOC being maximum at 4:00 am.The content of POC in the GSBL got the maximum value at 4:00 am and the minimum value at 12:00 am,which was opposite to that of GSBC group.The results demonstrated a significantly negative correlation of carbon fluxes with DO and pH in overlying water,but a significantly positive correlation with overlying water temperature.