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1.
夏季长江口潮间带CH4、CO2和N2O通量特征 总被引：5，自引：0，他引：5
使用原位静态箱现场采样,对夏季(7月和8月)长江口崇明东滩湿地3种主要温室气体CO2、CH4和N2O的界面通量进行了同步观测.结果表明,夏季低潮滩是大气CH4的排放源(40.2 μg/(m2·h)),CO2和N2O的吸收汇(通量值分别为-86.3 mg/(m2·h),-27.6 μg/(m2·h)).7月和8月中潮滩是3种温室气体的排放源,CH4日平均排放速率达到6.56 mg/(m2·h),CO2为301 mg/(m2·h),N2O为69.9 μg/(m2·h).温度(气温和不同深度地温)、沉积物有机碳含量以及潮滩植被海三棱藨草和沉积物表层藻类的光合和呼吸是决定CH4、CO2、N2O产生、排放和吸收的主要因素.相关分析表明中潮滩气体排放通量与温度(气温和不同深度地温)呈显著正相关关系,但在低潮滩气体通量与温度的相关关系不明显. 相似文献
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赤道东北太平洋表层沉积物间隙水中营养盐的剖面分布及其海底扩散通量 总被引：3，自引：0，他引：3
对赤道东北太平洋海域表层沉积物间隙水中硅酸盐、磷酸盐和硝酸盐等营养盐的剖面分布三个航次的研究表明,研究区在采样深度内沉积物中有机质的分解以硝化作用为主.在水-沉积物界面附近硅酸盐、磷酸盐和硝酸盐都存在着极陡的浓度梯度, Fick扩散定理的计算结果表明,研究区内硅酸盐、磷酸盐和硝酸盐的海底扩散通量分别为- 886.45～ 42.62 μ mol/(m2· d)、- 3.04～ 5.83 μ mol/(m2· d)和- 189.43～ 21.05 μ mol/(m2· d),且硅酸盐和硝酸盐主要是从沉积物向底层水体扩散,是底层水体营养盐的来源之一;研究区内硅酸盐、磷酸盐和硝酸盐的海底扩散通量存在着一定的时间和空间变化, 这可能与因全球气候变化而导致的沉积环境的改变有关. 相似文献
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根据2012年9月在黄河口及莱州湾取得的悬浮体和水文调查资料,探讨了非调水调沙期间黄河15及莱州湾颗粒有机碳（POC）的地球化学特征及其影响因素。结果表明：（1）2012年秋季黄河口及莱州湾POC浓度介于42．25-1018．87gg／L之间,平均为316．35μg／L,底层POC浓度高于表层,这与沉积物再悬浮有直接关系;（2）黄河口POC呈现近岸区高,远岸区低的趋势,高值区出现在新、老两个河口区域,指示了陆源输入对河口区POC的直接控制作用;（3）在盐度为26～28（psu）之间黄河口POC有高值,表明絮凝沉降作用对POC空间分布的影响;底层POC与浊度显著相关,表明海底沉积物再悬浮对研究区POC空间分布的直接影响;悬浮物含量超过20mg／L时,生命态颗粒有机碳对总颗粒有机碳的贡献明显下降;（4）POC／PN值显示黄河15及莱州湾POC来源的复杂性,生物作用、沉积物再悬浮和黄河水沙输入对研究区的POC生物地球化学过程都有一定的影响。 相似文献
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南极普里兹湾北部深海沉降颗粒物通量的季节性变化 总被引：4，自引：1，他引：4
利用1998～2000年中国南极科学考察期间(第15和16航次)在南极普里兹湾北部海域所获得的沉积物捕获器样品的资料,对南极普里兹湾北部海域颗粒物的有机地球化学特征进行了调查,并重点开展了该海域颗粒物通量及其季节性变化特征的研究。研究结果表明,在1000m深度,颗粒物通量呈现明显的季节性变化,最高通量出现在南极夏季的1月份,最低通量出现在4～7月份;通量的变化范围为13.00～334.59mgd-1m-2。捕获器中颗粒物的主要成分为生源物质(生物硅、有机质和碳酸钙),占总通量的50.62%～92.06%,而生源组分中又以生物硅为主要成分,其值介于9.30～136.33mgd-1m-2之间,占总通量的40.74%～74.21%。有机质和碳酸钙的通量远小于生物硅,分别平均占总通量的9.06%±4.26%和4.42%±2.14%。颗粒物中各组分通量的变化趋势与总通量明显相似,均呈现明显的季节性变化,这主要归因于研究海域海冰的形成与消退。在垂向变化上,1月份1000m深度颗粒物通量高于2000m深度,这表明该海域颗粒物的转化主要发生在上层水体。 相似文献
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近海营养盐和微量元素的大气沉降 总被引：3，自引：1，他引：2
受气候变化和人类活动的影响,传输和沉降到全球近海的大气污染物急剧增加.1997年后对近海营养盐和微量元素大气沉降的众多研究表明,通过大气沉降至近海的氮和磷分别为13～73 mmol N/(m2·a)和0.11～1.6 mmol P/(m2·a),微量元素的沉降通量具有显著的时空变化特征,在不同海区最高可相差3个数量级.对于很多近海包括东海(East China Sea)和黄海(Yellow Sea),大气沉降的营养盐和部分微量元素可能超出了其河流输入量.大气沉降除了对近海富营养化有重要贡献之外,其事件性特征可使初级生产力在短期内大幅度增加,从而影响赤潮发生.微量元素沉降还可能抑制某些藻类生长,对初级生产力和生态系统结构产生更为复杂的影响.未来研究重点是准确估算近海各物质的大气沉降通量,了解其对浮游植物生长的影响机制. 相似文献
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为有效控制湖泊内源营养盐的释放,探讨了不同物理改良措施(覆沙、底质疏松)对沉积物-水界面营养盐的释放通量控制效果。利用原位孔隙水采样技术(Peeper)来获得沉积物孔隙水剖面,对改良后湿地沉积物孔隙水营养盐的垂向分布及其扩散通量进行了研究。结果发现,改良后沉积含水率、孔隙率分别提高了91%和54%。水土界面附近,随剖面深度增加,孔隙水中PO43-、NH4+、NO3-及NO2-浓度分布符合指数关系,PO43-、NH4+在8 cm左右达到最大值。种植芦苇后沉积物孔隙水中PO43-、NH4+均有不同程度的下降,改良措施能有效降低表层弱结合态磷在总磷中比例但增加铁磷的比例,种植芦苇可强化这一效应。运用Fick第一定律对剖面孔隙水营养盐的扩散通量进行估算,发现沉积物经疏松后,NH4+、PO43-的扩散通量由57.47~72.19μg/(m2·d)和2.55~3.21μg/(m2·d)变为-95.54~-130.94μg/(m2·d)和1.50~2.05μg/(m2·d),可考虑疏松沉积物-水界面附近沉积物来作为控制湖泊内源污染的有效手段之一。 相似文献
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东海海—气界面二氧化碳通量的季节变化与控制因素研究进展 总被引：1，自引：0，他引：1
通过对东海海—气界面二氧化碳(CO2)交换有关研究的总结,剖析了东海表层海水CO2分压(pCO2)的区域分布特征,探讨了海—气界面CO2通量(FCO2)的季节变化规律,诠释了影响海—气界面CO2转移的主要因素.结果表明,东海表层海水pCO2的区域分布具有明显的季节变化,可将其分为冬季、夏季、过渡季节(春季、秋季)3个时段.冬季西部近岸海域由于水体垂直交换强烈,造成表层水体pCO2较高,而中、东部陆架海域由于浮游生物的光合作用使得pCO2较低.夏季近岸河口海域由于陆源输入的影响导致pCO2较高,中、东部陆架海域受温跃层、长江冲淡水、浮游植物的综合作用pCO2较低.春季、秋季为过渡时段,表层海水pCO2分布变化剧烈,受控因素较为复杂.东海全年表现为大气CO2的净汇,其中冬、春、夏为碳汇,其海—气界面FCO2分别为(-6.68±6.93),(-4.94±0.80),(-3.67±1.09)mmol/(m2·d).秋季表现为碳源,通量约为(1.50±8.37)mmoL/(m2·d).东海全年平均通量约为-3.16 mmol/(m2·d),共可吸收CO2约为6.92×106 t C/a.不同季节海—气界面FCO2的年际变化凸显了人为因素的影响,近海富营养化加剧,三峡工程的运行都可能是造成东海冬季碳汇量减少、秋季碳源/汇格局转变的原因. 相似文献
9.
北京市有机氯农药填图与风险评价 总被引：2，自引：0，他引：2
采用1个样/km2的密度、1个分析组合样/16km2的方法,对北京市784km2范围内的土壤、大气干湿沉降物、大气颗粒物中HCH、DDT的含量和空间分布特征进行有机氯农药填图.查明2000年北京市地表土壤HCH和DDT的平均含量分别为8.80±11.83ng/g、108.99±301.90ng/g.2006年大气干湿沉降物中HCH和DDT平均含量分别为10.09±9.60ng/g、12.99±13.51ng/g,HCH和DDT的年沉降通量分别为996.57±939.96g/a·km2、1291.53±1342.28g/a·km2.2006年大气颗粒物PM10和PM2.5中的HCH含量分别为0.294±0.205ng/m3和0.217±0.137ng/m3,DDT的平均含量分别为1.037±1.301ng/m3和0.522±0.773ng/m3,显著高于2002-2003年度大气颗粒物中HCH(PM100.01786ng/m3,PM250.01731ng/m3)和DDT(PM100.01672ng/m3,PM2.50.02353ng/m3)的含量,表明北京市或周边地区仍在使用含HCH和DDT化学成分的农药.以2000年北京地表土壤和2006年大气干湿沉降物中HCH和DDT的含量为基础,对2020年土壤中HCH和DDT的时空演变的预测显示,即使干湿沉降物中HCH和DDT的沉降通量每年以5%的速率递减,到2020年土壤中HCH和DDT的环境质量仍不能显著改善,而控制和削减北京及周边地区含HCH和DDT成分农药的使用将是改善北京地表土壤环境质量的关键措施. 相似文献
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本文根据钻井、地层剖面等资料,利用Surfer8.0软件编制出晚三叠世以来龙门山前陆盆地各构造层序的残留地层等厚图,计算出6个构造层序地层的沉积总量、沉积通量.沉积通量分别为:300.2g/(m2·ka)、66.5g/(m2·ka)、71.7 g/(m2 ·ka)、38.5 g/(m2·ka)、113.0 g/(m2·ka)、1204.6 g/(m2·ka).利用物质平衡法将各阶段沉积物回剥至物源区,计算各阶段物源区剥蚀速率分别为:167.3 mm/ka、22.5 mm/ka、22.9 mm/ka、9.8mm/ka、22.9 mm/ka、319.4 mm/ka.计算结果表明,晚三叠世以来,物源区的剥蚀速率和沉积区的沉积速率均具有先减小后增大的变化规律,晚三叠世和晚新生代是剥蚀一沉积过程最强烈的两个阶段,可能对应了龙门山强烈隆升的两个时期.根据对盆地沉积物总量的估算,利用物质平衡的原理,可以推算出龙门山自晚三叠世开始隆升到现在,龙门山冲断带的地壳隆升幅度大于10 ～ 12km,平均剥蚀厚度超过7.05km. 相似文献
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Loreta Fernandes Fraddry D’Souza S. G. P. Matondkar Narayan B. Bhosle 《Journal of Earth System Science》2006,115(3):363-370
Amino sugars (AS) are important constituents of organic matter. However, very little is known about their cycling in marine
waters. In this research, we assessed the distribution and cycling of these compounds in waters of the Bay of Bengal. For
this purpose, samples of suspended particu late matter (SPM) were collected from 8 depths (surface to 1000 m) at 6 locations
during the 166th cruise of the ORV Sagar Kanya in the Bay of Bengal in July/August 2001. The SPM samples were analysed for
particulate organic carbon (POC), particulate nitrogen (PN) and AS concentrations and composition. The AS varied between 0.4
and 17.5 nmol/l. Concentrations were high in the surface waters and generally decreased with increasing depth. AS concentration
decreased from the south to north. AS accounted for 0.01 to 0.71% and 0.05 to 2.37% of POC and PN, respectively. Rapid decrease
in AS-C% and AS-N% with depth indicates that these compounds were preferentially degraded relative to bulk POC and PN. The
composition of AS suggests that glucosamine (GLU-N) and galactosamine (GAL-N) were present in the surface SPM samples, and
their abundance decreased from surface downwards. Relatively, low values of GLU-N/GAL-N ratio indicate that the organic matter
was mostly derived from the detritus of micro-organisms. Our data suggest that chitin, a polymer of the glucosamine produced
by many marine organisms was not the major source of AS in the Bay. Rapid cycling of these compounds indicates their importance
in the cycling of nitrogen in marine waters 相似文献
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The major problems encountered in studying estuarine particulate organic matter (POM) are the characterization and quantitation of different kinds of materials (e.g. detrital and living matter, algal and bacterial matter…) each type contributing a specific role in the ecosystem. The study of the activity of the electron transport system (ETS) is proposed as a tool for resolving these problems. Results obtained in our laboratory with cultures of planktonic algae and bacteria provided us with numerical relationships between ETS activity and various organic components such as chlorophyll, carbon and protein. These relationships were: ETS activity/chlorophyll = 2.6, carbon/ETS activity = 17.3, protein/ETS activity = 9.6 in algae; carbon/ETS activity = 5.9, protein/ETS activity = 7.7 in bacteria (ETS activity expressed in /i2h−1 at 20°C; chlorophyll, carbon and protein in μg). Such data can be applied in field studies to characterize the living algal and bacterial matter and, by difference, the detrital organic matter. We report here a study of the Loire estuary as an example. 相似文献
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A conceptual isotopic/geochemical model is presented to explain the variation of major, trace and rare earth element (REE)
geochemistry and Sr isotope systematics in suspended particulate matter (SPM) as a function of particle/colloid size. This
conceptual model is an extension of a previous investigation of the origin of SPM in the Murray-Darling River system (MDRS)
that utilised Sr isotope systematics to examine aspects of SPM (particle/colloid) origin, structure and mineralogy. The geochemical
processes that give rise to the often coherent trends in major, trace and REE geochemistry and Sr isotopic signature as a
function of particulate (<1 μm) and colloidal (>1 μm) size in the MDRS have been identified using an enhanced SPM size fractionation
technique as a basis to not only obtain a broad range of particle/colloid size ranges, but also to provide sufficient material
for subsequent geochemical and isotopic analysis. The conceptual isotopic/geochemical model proposed here contains three major
components: (i) the differential weathering of micas and alkali (K-) feldspars to form the majority of the particulate (<1
μm) fractions (high 87Sr/86Sr ratio), which have a geochemical and Sr isotopic signature that closely resembles precursor
mineralogies, (ii) the differential weathering of Na, Ca-feldspars (plagioclase) which decompose to form clay minerals in
the colloidal (>1 μm) fractions (low 87Sr/86Sr ratio), with a range of geochemical signatures related to the relative proportions
of inorganic and organic constituents, and (iii) the presence of natural organic matter as coatings on the particulate (<1
μm) and colloidal (>1 μm) matter and possibly as organo-colloids which exert an increasing influence in particular on bulk
colloid geochemistry with decreasing colloid size. This conceptual isotopic/geochemical model also accounts for the distinct
variation in major, trace and REE geochemistry and Sr isotopic systematics between the particulate (<1 μm) and colloidal (>1
μm) fractions, the variation being primarily a function of the distinctly different precursor mineralogies of the SPM fractions
and geochemical fractionation during the weathering and transport. Additionally, this model explains a systematic fractionation
of REE apparent within colloidal (>1 μm) fractions. Statisitcal (hierachical cluster) analysis of two particulate and three
colloidal fractions from 23 samples from the MDRS is used as a basis to investigate geochemical and mineralogical associations
within the particulate and colloidal size fractions and to provide additional supporting evidence for the conceptual isotopic/geochemical
model.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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2006年9~10月在长江采集悬浮颗粒物样品,应用改进后的SEDEX法对磷的赋存形态进行了分析.结果表明,自生磷灰石磷是长江悬浮颗粒物中磷的主要赋存形态.涪陵至万州江段,碎屑磷灰石磷的含量较高,弱吸附态磷和有机磷含量较低,磷的赋存形态主要受悬浮颗粒物含量的影响;香溪至葛洲坝下江段,弱吸附态磷和有机磷含量较高,碎屑磷灰石磷含量较低,磷的赋存形态主要受浮游植物生长及泥沙粒径的影响;城陵矶至大通江段,有机磷、碎屑磷灰石磷和铁结合态磷含量较高,弱吸附态磷含量较低,磷的赋存形态主要受泥沙粒径和洞庭湖输入的影响.长江悬浮颗粒物中生物可利用磷占颗粒态磷的45.6%,长江上游水体中生物可利用磷含量较低,下游含量较高. 相似文献
16.
A. Fuentes-Cid E. Chauvet H. Etcheber E. De-Oliveira A. Sottolichio S. Schmidt 《Geodinamica Acta》2013,26(1):60-66
The rates of decomposition of oak (Quercus robur) leaves have been examined using litter bags in a very high turbidity macrotidal estuary, the Gironde Estuary (S.W. France). The first experiments show a marked decrease in the decomposition rate of oak leaves at the water-sediment interface (mud-contact: anoxic conditions, reduced physical fragmentation) in comparison to the water column. The results point out the impact of hydrodynamic conditions on leaf litter degradation in such fluvio-estuarine systems. Regarding the aquatic-terrestrial linkage, our observations suggest direct changes in leaf decomposition kinetics and then, a potential delay on the recycling and transport processes of coarse particulate organic matter, especially in a context of modification of the natural water flow, due to global and land use changes. 相似文献
17.
贵州阿哈湖物质循环过程中的铁同位素地球化学及其指示意义 总被引：1，自引：0，他引：1
使用AGMP-1氯化物型阴离子交换树脂(100--200目)对夏季贵州阿哈湖流域水体悬浮颗粒物等样品进行了化学分离,并在多接收电感耦合等离子体质谱仪(MC-ICP-MS)上进行了铁同位素分析.分析结果表明,夏季阿哈湖湖水分层期间湖水悬浮颗粒物及各端员环境样品的铁同位素组成变化较大:湖水悬浮颗粒物的δ56Fe为负值,分布范围为-1.36‰～-0.10‰之间;各支流河水悬浮颗粒物的铁同位素组成在-0.88‰～-0.16‰之间;大气颗粒物的平均铁同位素组成为 0.06‰±0.02‰;而未经化学清洗的浮游藻类的铁同位素组成为 0.08‰.对比研究表明,湖水悬浮颗粒物的铁同位素组成不仅受各输入端员的影响,湖泊内部复杂的生物地球化学过程也对颗粒物的铁同位素组成产生了重要影响.陆源输入的颗粒有机结合态铁使得湖泊表层悬浮颗粒物的铁同位素组成偏低,而大气沉降颗粒物和湖泊表层的浮游藻类整体上对铁同位素组成的影响并不显著."ferrous wheel"铁循环对于氧化还原界面附近水层中铁同位素的重分配起到了主要的控制和影响作用.δ56Fe值与Fe/A1呈现良好的负相关关系,也显示出活性铁的循环迁移是造成氧化还原界面附近水层中悬浮颗粒物的铁同位素组成变化的重要原因,表明铁同位素与Fe/A1可能可以作为表征水体生物地球化学环境的良好指标. 相似文献
18.
Ching-man Carman IP Wing-yee Chloe TANG Xiang-dong LI 《中国地球化学学报》2006,25(B08):159-159
Marine water samples, including both surface and bottom samples, were collected from the five sampling sites in Victoria Harbour during December 2004 and February 2005. The concentrations of trace metals （Cd, Co, Cr, Cu, Ni, Pb and Zn） in the suspended particulate matter （SPM） and dissolved phases as well as the Pb isotopic compositions of the suspended particulates were determined to assess the potential sources and transport pathways of metal contaminants in the harbour. The results showed that sewage discharges along the harbour dominated the SPM loadings in water, particularly in the dry season. The total concentrations of Co, Cr, Cu, Ni and Zn in water showed a close association with the SPM loadings, indicating that SPM was important in transporting these metals in the coastal environment. Dissolved phase was predominant for Cd in Victoria Harbour. The particulate phase was the major form of Pb in marine water. 相似文献
19.
Particulate matter and interfacial sediment from a seasonally anoxic coastal salt pond were analyzed for fatty acids and sterols to examine variations in organic sources, and compositional changes across the oxic-anoxic interface in the water column and at the sediment-water interface. Fatty acid distributions in suspended particles varied seasonally and as a function of depth. Fatty acids of algal origin (e.g. 16:3, 16:4, 18:3, 18:4) were abundant in particles in oxic surface waters, but these labile components were depleted in particles from the anoxic zone which instead were enriched in bacterial fatty acids (e.g. 16:1Δ9, 18:1Δ11, anteiso-C15). Sterol distributionsvaried less than fatty acid distributions and particles throughout the water column reflected an upper water algal source with little in situ alteration. There was evidence for an in situ conversion of Δ5-stenols to 5(α)H-stanols in suspended particles in the anoxic zone. Sinking particles and the interfacial sediment were compositionally similar to each other, but different from suspended particles. These data reflect differences in particle source, transport and transformation processes occuring in the water column. 相似文献
20.
The Mfolozi Estuary on the KwaZulu-Natal coast of South Africa is the most turbid estuary in Natal due to poor catchment
management, leading to large quantities of suspended particulate matter (SPM) entering the estuary from the Mfolozi River.
This paper quantities some of the solute and sediment dynamics in the Mfolozi Estuary where the main documented environmental
concern is the periodic input of SPM from the Mfolozi Estuary to the St. Lucia system, causing reduction of light penetration
and endangering biological productivity in this important nature reserve. Synoptic water level results have allowed reach
mean bed shear stresses and velocities to be calculated for an observed neap tidal cycle. Results indicate that ebb velocities
dominate the sediment transport processes in the estuary when fluvial input in the Mfolozi River is of the order of 15–20
m3 s–1. Observed and predicted flood tide velocities are too low (<0.35 m s–1) to suspend and transport significant amounts of SPM. Observed results indicate that although the SPM load entering the estuary
is dominantly from the Mfolozi River, the Msunduzi River flow plays a major role in the composition of the estuary's salinity
and velocity fields. It is calculated that the Mfolozi Estuary would fill with sediment in 1.3 years if it was cut off from
the sea. The major fluvial flood events help maintain the estuary by periodically pushing sediment seawards (spit progrades
seawards 5 m yr–1) and scouring and maintaining the main flow channel in the estuary. During low fluvial flow conditions, tidal flow velocities
will become the dominant control on sediment transport in the estuary. Interchange of SPM between the St. Lucia and Mfolozi
estuaries under present conditions is complicated by the strong transverse velocity shear between the two systems at their
combined mouth. This is creating a salinity-maintained axial convergence front that suppresses mixing of solutes and SPM between
the systems for up to 10 h of the tidal cycle during observed conditions.
Received: 22 May 1995 · Accepted: 31 July 1995 相似文献