海洋学报（中文版）
海洋學報（中文版）
해양학보（중문판）
ACTA OCEANOLOGICA SINICA
2015年
4期
1-15
,共15页
潘慧慧%姚鹏%赵彬%孟佳%李栋%王金鹏
潘慧慧%姚鵬%趙彬%孟佳%李棟%王金鵬
반혜혜%요붕%조빈%맹가%리동%왕금붕
长江口%悬浮颗粒物%水淘选法%粒径分级%有机碳%稳定碳同位素
長江口%懸浮顆粒物%水淘選法%粒徑分級%有機碳%穩定碳同位素
장강구%현부과립물%수도선법%립경분급%유궤탄%은정탄동위소
Changjiang Estuary%suspended particulate matter%water elutriation%size fractionation%organic carbon%stable carbon isotope
从分粒级的角度研究大河河口颗粒有机碳的输送特征是深刻理解河口淡咸水混合过程中有机碳的生物地球化学过程的关键。于2011年6月采集了长江口最大浑浊带附近盐度梯度下的表层悬浮颗粒物，采用水淘选方法对其按照水动力直径大小进行了分级分离，分析了这些颗粒物的有机碳含量、稳定碳同位素组成及颗粒物比表面积等参数，讨论了不同粒级颗粒物上有机碳的来源、分布和保存随盐度的变化特点及其影响因素。结果表明，随着盐度的增加和粒径的增大，长江口最大浑浊带附近分级颗粒有机碳逐渐降低，颗粒有机碳含量主要集中在小于32μm 的粒级。相对于长江干流，长江口颗粒有机碳含量偏低，可能归因于河口最大浑浊带附近特殊的生物地球化学作用，如细颗粒物絮凝－沉降、微生物分解等。基于蒙特卡洛模拟的三端元混合模型的计算表明长江口分级颗粒有机碳主要来源于河流和三角洲输入，海洋来源贡献较小，三者的平均贡献比例分别为40％、35％和25％。在河口盐度梯度的淡水端，不同粒级颗粒物上三角洲来源的有机碳比例均随着盐度升高而增加，而在咸水端，海源有机碳的贡献比例升高，尤其是在16～32μm 粒级，最高达39％。32～63μm 粒级的颗粒物单位比表面积有机碳含量均大于1．0 mg／m2，小于32μm 的颗粒物单位比表面积有机碳含量均在0．4～1．0 mg／m2的范围之内，符合河流颗粒物的一般特点，同时也说明细颗粒物上的有机碳可能已经发生了一定程度的分解，不过相对于长江口表层沉积物，颗粒物单位比表面积有机碳含量普遍较高，表明这些颗粒有机碳在沉降过程中或沉积之后还要经历进一步的再矿化分解，初步的估算表明，长江所输送的陆源有机碳约71％会在沉积过程中损失掉。本研究有助于深入了解大河河口不同粒级颗粒物在有机碳迁移转化过程中的作用，深化对高浊度河口有机碳生物地球化学过程的认识。
從分粒級的角度研究大河河口顆粒有機碳的輸送特徵是深刻理解河口淡鹹水混閤過程中有機碳的生物地毬化學過程的關鍵。于2011年6月採集瞭長江口最大渾濁帶附近鹽度梯度下的錶層懸浮顆粒物，採用水淘選方法對其按照水動力直徑大小進行瞭分級分離，分析瞭這些顆粒物的有機碳含量、穩定碳同位素組成及顆粒物比錶麵積等參數，討論瞭不同粒級顆粒物上有機碳的來源、分佈和保存隨鹽度的變化特點及其影響因素。結果錶明，隨著鹽度的增加和粒徑的增大，長江口最大渾濁帶附近分級顆粒有機碳逐漸降低，顆粒有機碳含量主要集中在小于32μm 的粒級。相對于長江榦流，長江口顆粒有機碳含量偏低，可能歸因于河口最大渾濁帶附近特殊的生物地毬化學作用，如細顆粒物絮凝－沉降、微生物分解等。基于矇特卡洛模擬的三耑元混閤模型的計算錶明長江口分級顆粒有機碳主要來源于河流和三角洲輸入，海洋來源貢獻較小，三者的平均貢獻比例分彆為40％、35％和25％。在河口鹽度梯度的淡水耑，不同粒級顆粒物上三角洲來源的有機碳比例均隨著鹽度升高而增加，而在鹹水耑，海源有機碳的貢獻比例升高，尤其是在16～32μm 粒級，最高達39％。32～63μm 粒級的顆粒物單位比錶麵積有機碳含量均大于1．0 mg／m2，小于32μm 的顆粒物單位比錶麵積有機碳含量均在0．4～1．0 mg／m2的範圍之內，符閤河流顆粒物的一般特點，同時也說明細顆粒物上的有機碳可能已經髮生瞭一定程度的分解，不過相對于長江口錶層沉積物，顆粒物單位比錶麵積有機碳含量普遍較高，錶明這些顆粒有機碳在沉降過程中或沉積之後還要經歷進一步的再礦化分解，初步的估算錶明，長江所輸送的陸源有機碳約71％會在沉積過程中損失掉。本研究有助于深入瞭解大河河口不同粒級顆粒物在有機碳遷移轉化過程中的作用，深化對高濁度河口有機碳生物地毬化學過程的認識。
종분립급적각도연구대하하구과립유궤탄적수송특정시심각리해하구담함수혼합과정중유궤탄적생물지구화학과정적관건。우2011년6월채집료장강구최대혼탁대부근염도제도하적표층현부과립물，채용수도선방법대기안조수동력직경대소진행료분급분리，분석료저사과립물적유궤탄함량、은정탄동위소조성급과립물비표면적등삼수，토론료불동립급과립물상유궤탄적래원、분포화보존수염도적변화특점급기영향인소。결과표명，수착염도적증가화립경적증대，장강구최대혼탁대부근분급과립유궤탄축점강저，과립유궤탄함량주요집중재소우32μm 적립급。상대우장강간류，장강구과립유궤탄함량편저，가능귀인우하구최대혼탁대부근특수적생물지구화학작용，여세과립물서응－침강、미생물분해등。기우몽특잡락모의적삼단원혼합모형적계산표명장강구분급과립유궤탄주요래원우하류화삼각주수입，해양래원공헌교소，삼자적평균공헌비례분별위40％、35％화25％。재하구염도제도적담수단，불동립급과립물상삼각주래원적유궤탄비례균수착염도승고이증가，이재함수단，해원유궤탄적공헌비례승고，우기시재16～32μm 립급，최고체39％。32～63μm 립급적과립물단위비표면적유궤탄함량균대우1．0 mg／m2，소우32μm 적과립물단위비표면적유궤탄함량균재0．4～1．0 mg／m2적범위지내，부합하류과립물적일반특점，동시야설명세과립물상적유궤탄가능이경발생료일정정도적분해，불과상대우장강구표층침적물，과립물단위비표면적유궤탄함량보편교고，표명저사과립유궤탄재침강과정중혹침적지후환요경력진일보적재광화분해，초보적고산표명，장강소수송적륙원유궤탄약71％회재침적과정중손실도。본연구유조우심입료해대하하구불동립급과립물재유궤탄천이전화과정중적작용，심화대고탁도하구유궤탄생물지구화학과정적인식。
Knowledge of the transport of particulate organic carbon in large-river estuaries from the perspective of size-fractionation is key to better understand the biogeochemical processes of organic carbon during the mixing of freshwa-ter and seawater.Suspended particulate matters (SPM)in surface water were collected along a salinity gradient in the turbidity maximum zone of the Changjiang Estuary in June 2011,and then were separated into different size fractions using the water elutriation method.Organic carbon (OC)and nitrogen,stable carbon isotopic composition and specific surface area (SSA)of these size-fractionated particles were analyzed to discuss the variation of sources,distribution and preservation of OC with the increasing salinity and their impact factors.The results showed that with the increase of salinity and particle size,the size-fractionated particulate OC (POC)gradually reduced and mainly concentrated in less than 32 μm fractions.The POC in the estuary was lower than those in the main stream,perhaps due to the special bio-geochemical processes around the maximum turbidity zone,such as flocculating and settling of fine particles,microbial decomposition,etc.The results of the three end-member mixing model based on Monte-Carlo simulation indicated that the POC was mainly from riverine and deltaic sources,whereas the contribution from marine end-member was relative-ly small,and the average fractions of these three end-members were 40%,35% and 25%,respectively.In the freshwa-ter end,deltaic OC of the size fractions increased with the increase of salinity,but in the seawater end,the contribution of marine OC increased,especially in the 16-32 μm fractions,with the maximum value of 39%.The SSA normalized OC contents of the 32—63μm fractions were all larger than 1.0 mg/m2 ,while the OC/SSA ratios of less than 32 μm fractions were in the range of 0.4 to 1.0 mg/m2 ,consistent with the typical characteristics of river suspended particu-lates.Furthermore,the OC/SSA ratios also indicated that OC in fine particulates could have been decomposed in a cer-tain degree.However,these ratios were generally higher than those of the surface sediments in the Changjiang Estuar-y,which indicated that particulate OC may go through further remineralization during or after sedimentation.Prelimi-nary estimate showed that 71% of the terrigenous OC delivered by the Changjiang was lost during sedimentation.This study helps to deeply understand the role of particulate matters with different sizes in the transport and transformation of OC in large-river estuaries,and deepen the knowledge of biogeochemical processes of OC in high turbidity estuary.
