氧化还原环境变化对河口沉积物硅影响的模拟
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摘要
氧化还原环境变化是水生态系统中普遍存在的环境现象,并可能对营养盐迁移转化产生显著影响.本文通过模拟分析好氧/缺氧状态下,典型河口沉积物硅释放及其赋存形态的差异,揭示了氧化还原环境变化对河口沉积物活性硅迁移转化的影响.研究结果表明,厌氧环境下,上覆水中溶解态硅的含量持续上升,在第30天可达4.23 mg·L-1;而好氧环境下上覆水中溶解态硅的含量维持在2.30 mg·L-1左右.其原因可能是厌氧环境下,表层沉积物中Fe/Mn氧化物发生生物还原,氧化层被逐渐破坏,促进溶解态硅的释放.另外,在短期培养过程当中,对于生物硅含量较低且其早期成岩改变程度较高的长江口沉积物而言,厌氧环境并不能有效促进沉积物生物硅的溶解.
Transition between oxic and anoxic conditions is a widespread phenomenon in the aquatic ecosystem,which could significantly affect the migration and transformation of the nutrients. In present study,the effects of redox conditions on the release patterns of dissolved silica(DSi) from benthic sediments,the variations of Si speciations of the sediments and mechanism behind these were be explored through simulation experiments using Yangtze Estuary sediments incubated under oxic and anoxic conditions. The DSi in the overlying water under anoxic incubation was increased gradually and could come 4.23 mg·L-1 at the end of the incubation(30 days),while the DSi under oxic incubation was stayed steady at 2. 30 mg·L-1. Under anoxic conditions,the oxic layer in the surface sediment was destroyed gradually due to the reduction-reaction of the Fe/Mn oxides,and thus resulted in the release of significant amount of Si into the overlying water. Moreover,the anoxic incubation did not significantly stimulate the dissolution of biogenic silica particles within the experimental period,which may be due to the high extent diagenetic alteration and low contents of biogenic silica particles in the Yangtze estuary sediments.
Transition between oxic and anoxic conditions is a widespread phenomenon in the aquatic ecosystem,which could significantly affect the migration and transformation of the nutrients. In present study,the effects of redox conditions on the release patterns of dissolved silica(DSi) from benthic sediments,the variations of Si speciations of the sediments and mechanism behind these were be explored through simulation experiments using Yangtze Estuary sediments incubated under oxic and anoxic conditions. The DSi in the overlying water under anoxic incubation was increased gradually and could come 4.23 mg·L-1 at the end of the incubation(30 days),while the DSi under oxic incubation was stayed steady at 2. 30 mg·L-1. Under anoxic conditions,the oxic layer in the surface sediment was destroyed gradually due to the reduction-reaction of the Fe/Mn oxides,and thus resulted in the release of significant amount of Si into the overlying water. Moreover,the anoxic incubation did not significantly stimulate the dissolution of biogenic silica particles within the experimental period,which may be due to the high extent diagenetic alteration and low contents of biogenic silica particles in the Yangtze estuary sediments.
引文
[1]SMITH V H.Eutrophication of freshwater and coastal marine ecosystems:A global problem[J].Environmental Science and Pollution Research,2003,10(2):126-139.
[2]GOODAY A J,JORISSEN F,LEVIN L A,et al.Historical records of coastal eutrophication-induced hypoxia[J].Biogeosciences,2009,6(8):1707-1745.
[3]HOWARTH R,CHAN F,CONLEY D J,et al.Coupled biogeochemical cycles:eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems[J].Frontiers in Ecology&the Environment,2010,9(1):18-26.
[4]WANG C,ZHU H,WANG P,et al.Early diagenetic alterations of biogenic and reactive silica in the surface sediment of the Yangtze Estuary[J].Continental Shelf Research,2015,99:1-11.
[5]ZHU H,WANG C,WANG P,et al.Speciation of potentially mobile Si in Yangtze Estuary surface sediments:estimates using a modified sequential extraction technique[J].Environmental Science&Pollution Research,2016,23(18):1-14.
[6]SIIPOLA V,LEHTIMKI M,TALLBERG P.The effects of anoxia on Si dynamics in sediments[J].Journal of Soils and Sediments,2016,16(1):266-279.
[7]EKEROTH N,KONONETS M,WALVE J,et al.Effects of oxygen on recycling of biogenic elements from sediments of a stratified coastal Baltic Sea basin[J].Journal of Marine Systems,2016,154:206-219.
[8]KORON N,OGRINC N,METZGER E,et al.The impact of induced redox transitions on nutrient diagenesis in coastal marine sediments(Gulf of Trieste,northern Adriatic Sea)[J].Journal of Soils and Sediments,2015,15(12):2443-2452.
[9]BELIAS C,DASSENAKIS M,SCOULLOS M.Study of the N,P and Si fluxes between fish farm sediment and seawater.Results of simulation experiments employing a benthic chamber under various redox conditions[J].Marine Chemistry,2007,103(3-4):266-275.
[10]VORHIES J S,GAINES R R.Microbial dissolution of clay minerals as a source of iron and silica in marine sediments[J].Nature Geoscience,2009,2(3):221-225.
[11]LIU J P,LI A C,XU K H,et al.Sedimentary features of the Yangtze River-derived along-shelf clinoform deposit in the East China Sea[J].Continental Shelf Research,2006,26(17-18):2141-2156.
[12]宋金明.海底铁锰氧化还原过程的模拟研究[J].环境化学,1993,12(1):29-35.SONG J M.Simulation study of redox processes of iron and manganese in marine bottom[J].Environmental Chemistry,1993,12(1):29-35(in Chinese).
[13]MELTON E D,SWANNER E D,BEHRENS S,et al.The interplay of microbially mediated and abiotic reactions in the biogeochemical Fe cycle[J].Nature Reviews Microbiology,2014,12(12):797-808.
[14]LOVLEY D R,PHILLIPS E J P.Competitive mechanisms for inhibition of sulfate reduction and methane production in the zone of ferric iron reduction in sediments[J].Applied and Environmental Microbiology,1987,53:2636-2641.
[15]邹建军,石学法,李乃胜,等.长江口氧化还原敏感元素的早期成岩过程[J].地球科学—中国地质大学学报,2010,35(1):31-42.ZOU J J,SHI X F,LI N S,et al.Early diagenetic processes of redox sensitive elements in Yangtze Estuary[J].Earth Science—Journal of China University of Geosciences,2010,35(1):31-42(in Chinese).
[2]GOODAY A J,JORISSEN F,LEVIN L A,et al.Historical records of coastal eutrophication-induced hypoxia[J].Biogeosciences,2009,6(8):1707-1745.
[3]HOWARTH R,CHAN F,CONLEY D J,et al.Coupled biogeochemical cycles:eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems[J].Frontiers in Ecology&the Environment,2010,9(1):18-26.
[4]WANG C,ZHU H,WANG P,et al.Early diagenetic alterations of biogenic and reactive silica in the surface sediment of the Yangtze Estuary[J].Continental Shelf Research,2015,99:1-11.
[5]ZHU H,WANG C,WANG P,et al.Speciation of potentially mobile Si in Yangtze Estuary surface sediments:estimates using a modified sequential extraction technique[J].Environmental Science&Pollution Research,2016,23(18):1-14.
[6]SIIPOLA V,LEHTIMKI M,TALLBERG P.The effects of anoxia on Si dynamics in sediments[J].Journal of Soils and Sediments,2016,16(1):266-279.
[7]EKEROTH N,KONONETS M,WALVE J,et al.Effects of oxygen on recycling of biogenic elements from sediments of a stratified coastal Baltic Sea basin[J].Journal of Marine Systems,2016,154:206-219.
[8]KORON N,OGRINC N,METZGER E,et al.The impact of induced redox transitions on nutrient diagenesis in coastal marine sediments(Gulf of Trieste,northern Adriatic Sea)[J].Journal of Soils and Sediments,2015,15(12):2443-2452.
[9]BELIAS C,DASSENAKIS M,SCOULLOS M.Study of the N,P and Si fluxes between fish farm sediment and seawater.Results of simulation experiments employing a benthic chamber under various redox conditions[J].Marine Chemistry,2007,103(3-4):266-275.
[10]VORHIES J S,GAINES R R.Microbial dissolution of clay minerals as a source of iron and silica in marine sediments[J].Nature Geoscience,2009,2(3):221-225.
[11]LIU J P,LI A C,XU K H,et al.Sedimentary features of the Yangtze River-derived along-shelf clinoform deposit in the East China Sea[J].Continental Shelf Research,2006,26(17-18):2141-2156.
[12]宋金明.海底铁锰氧化还原过程的模拟研究[J].环境化学,1993,12(1):29-35.SONG J M.Simulation study of redox processes of iron and manganese in marine bottom[J].Environmental Chemistry,1993,12(1):29-35(in Chinese).
[13]MELTON E D,SWANNER E D,BEHRENS S,et al.The interplay of microbially mediated and abiotic reactions in the biogeochemical Fe cycle[J].Nature Reviews Microbiology,2014,12(12):797-808.
[14]LOVLEY D R,PHILLIPS E J P.Competitive mechanisms for inhibition of sulfate reduction and methane production in the zone of ferric iron reduction in sediments[J].Applied and Environmental Microbiology,1987,53:2636-2641.
[15]邹建军,石学法,李乃胜,等.长江口氧化还原敏感元素的早期成岩过程[J].地球科学—中国地质大学学报,2010,35(1):31-42.ZOU J J,SHI X F,LI N S,et al.Early diagenetic processes of redox sensitive elements in Yangtze Estuary[J].Earth Science—Journal of China University of Geosciences,2010,35(1):31-42(in Chinese).