长江河口盐度锋

根据1988－1991年河口锋面现场调查、上海市海岸带调查及历次标准断面调查资料对长江盐度场及盐度锋进行了分析，提出了由口门至外海纵向上存在着三级锋面现象：内侧锋面即长江河口锋为长江河口水与长江冲淡水的界面；羽状锋是长江口羽状流水与口外混合水的界面，它是长江口最主要的盐度锋面，也是长江口一个重要的生物地球化学带，对河口沉积过程及水下三角洲发育具有重要的影响。外侧锋面即海洋锋，是长江冲淡水的最外边缘。     

Nutrient composition and distributions in coastal waters impacted by the Changjiang plume

Four cruises were conducted during 2002--2003 in the Changjiang Estuary and adjacent coastal areas. The data presented show a clear coast to open sea gradient in nutrients related to the river inputs. Maximum values of chlorophyll a were typically observed at intermediate salinities at surface water and coincided with non-conservative decreases in nutrients along the salinity gradient, indicating that removal of nutrients was related to phytoplankton uptake. The seasonal variations of nutrient concentrations were just opposite to those of chlorophyll a, indicating that the seasonal variations of nutrients were mainly controlled by phytoplankton uptake, whereas riverine inputs merely weakened or balanced its extent. During the estuarine mixing, phosphate demonstrated some remobilization during all the four cruises; whereas both conservative and non-conservative behaviors for dissolved inorganic nitrogen and silicate were observed in the study area, indicating that both biotic and abiotic events may affect their behaviors during the estuarine mixing. Under the influence of freshwater inputs with high value of ratio of nitrogen to phosphorus, the estuarine and coastal waters impacted by the Changjiang plume were high （ 〉 30） in ratio of nitrogen to phosphorus, but rates of primary production were apparently not constrained by any kind of nutrient elements. However, the low （ 〈 1 ） ratio of silicate to nitrogen in most of the study area might be linked with the rapidly increasing frequency of harmful algal bloom （HAB） incidents in recent years in the coastal waters impacted by the Changjiang plume.     

Chemical forms of iron in the Connecticut River estuary

The ‘dissolved’ iron (that passed through a 0·4-μm filter) varied nonconservatively with salinity in the Connecticut River estuary. However, the total iron appeared to be conservative. Measurements of Fe(II) and Fe(III) showed that oxidation of Fe(II) was not a factor in the decrease of ‘dissolved’ iron in the low salinity region. A solubility model and analyses based on different pore-size filters indicated that a substantial amount of the ‘dissolved’ iron in the low salinity region was colloidal iron. The coagulation of fine colloidal particles led to the non-conservative behavior of ‘dissolved’ iron during estuarine mixing, but it did not necessarily lead to removal of total iron from the waters. Particulate iron was 80–90% of the total iron and it covaried with the total suspended matter during mixing and sediment resuspension. The residence time of water in the Connecticut River estuary was too short to allow removal of iron from the water column within the estuary.     

Temporal and spatial distribution of dissolved copper, lead, zinc and cadmium in the Changjiang Estuary and its adjacent waters

Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters. Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper, lead, zinc and cadmium in the study waters are 1.01 - 6.86, 0. 10 - 0.39,3.17 - 9.12 and 0.011 - 0. 049 μg/dm^3 , respectively. Similar to zinc, the behavior of dissolved copper was essentially conservative, but high scatter has been observed for high salinity samples, which can be attributed to the decomposition or mineralization of organic matter by bacteria. Dissolved lead may have active behavior with an addition at high salinity. Overall concentrations of dissolved cadmium increase with salinity. The mean values of these dissolved metals calculated for the surface waters were higher than those for the middle and bottom ones. External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values. The maximum seasonal average values of dissolved copper and zinc were found in summer, reflecting higher amounts of riverine input in this season. In contrast, the maximum seasonal average values of dissolved lead and copper were found in winter and the lowest ones in summer, respectively, which might be asso- ciated with a combination of low concentration with heterogeneous scavenging. Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers, except for cadmium. Compared with observations for the Changjiang Estuary in the last two decades, it is clear that the Changjiang estuarine waters has been contaminated with copper, lead, zinc and cadmium during China＇ s industrialization, but concentrations of them have decreased in the last few years.     

Land inputs,behaviour and contamination levels of copper in a ria estuary (NW Spain)

Copper concentrations were measured in the sediments and dissolved phase of the water column in the Lérez Estuary (Pontevedra Ria, Galicia), NW Spain, and in the freshwater-sewage inputs to the estuary. Dissolved copper fluxes in the estuary were quantified. Results show that the freshwater end-member in the Lérez Estuary has minimal copper contamination ([Cu](Dissolved)=7+/-4 nM, Sediment Enrichment Factor=1) and the source of dissolved copper inputs is localized in the saline end-member ([Cu](Dissolved)=20-55 nM, Sediment Enrichment Factor=6-7). A non-conservative behaviour of dissolved copper showing a net addition during estuarine mixing was observed. The budgetary calculations and the copper sediment distribution suggest that the major copper input to the estuary-ria system is located at the Marín-Placeres transect, playing an important role in the net addition of copper within the estuarine mixing. The importance of upwelling in the renewal of the Galician coastal waters and dilution of continental inputs is discussed.     

长江口盐度梯度下不同形态碳的分布、来源与混合行为

河口碳的生物地球化学过程是全球碳循环的重要组成。通过测定溶解无机碳（DIC）及其稳定同位素丰度（δ13C_DIC），溶解有机碳（DOC），有色溶解有机物（CDOM），颗粒有机碳（POC）及其稳定同位素丰度（δ13C_POC）与元素比值（N/C）及相关指标，研究了2014年7月长江口盐度梯度下不同形态碳的分布、来源和混合行为。结果表明，DIC浓度、DOC浓度、POC含量分别为1 583.2~1 739.6 μmol/L，128.4~369.4 μmol/L和51.2~530.8 μmol/L，这些不同形态碳及CDOM的荧光组分的分布模式相似，均是从口内到口外，整体呈现先增大后减小的趋势，并与盐度呈现非保守混合行为。添加作用主要发生在在口门处最大浑浊带附近。与含量相反，从口内到口外，δ13C_DIC和δ13C_POC均呈现逐渐减小再增大的趋势，在口门附近达到最低值，分别为-9.7‰和-26.7‰。在口门附近不同形态碳含量上升及δ13C_DIC、δ13C_POC的降低可能主要与沉积物再悬浮及微生物作用有关。基于蒙特卡洛模拟的三端元混合模型的结果显示，河口内外POC来源变化明显，口内POC以陆源有机碳贡献为主，平均为62.3%，口外海源贡献逐渐增加。CDOM相关参数结果表明长江口CDOM主要来自陆源输入，海源及人类活动等也对其产生影响。     

长江口区河海划界自然条件及方案探讨

河口是河流与海洋交互作用的过渡区域,河口水域河海划界是一个十分复杂而敏感的问题.通过对长江河口段自然条件的分析,选取了相对比较稳定的几个相关参数:水域性质、潮汐特征、盐水入侵、悬沙浓度、河槽特性和沙岛形成过程等,作为长江口区河海划界的指标.水域性质是宏观上确定河海划界范围最基本的自然参数.潮汐特征的沿程分布和变化是河海划界的重要要素.盐水入侵是河口地区的普遍现象.悬沙浓度的沿程变化从一个侧面反映了径、潮流共同作用的产物,也可作为河海划界的参数之一.南支以上河段,河床纵断面变化显著,深槽浅滩起伏分布;南支河槽在浏河口以下,水深变化不大,一般在20 m之内,床面较平坦、起伏甚小,至口门一带水深均在10 m之内,明显反映了径、潮流共同作用的结果,显示了这一带是河海过渡段的特点.河口沙岛是河海相互作用下的沉积地貌,其推进状况也是河海划界的重要标志之一.从历史的角度看,随着长江口沙岛的形成和推进,河海界线有不断下移的趋向.据此探讨性地提出河海划界的3种方案:方案Ⅰ位于河口段的中部,界线的中部走向基本上是长江口第一代沙岛(崇明岛)与第二代沙岛(长兴、横沙)的分界线;方案Ⅱ以浏河口-崇明岛上口-北支沪苏分界线;方案Ⅲ位于口门附近.推荐方案Ⅰ作为上海市(长江口)河海划界的界线,仅供有关部门参考.     

入海泥沙的减少对长江口赤潮增加有贡献吗?

过去几十年来全球近海有害藻华（又称赤潮）发生频率持续增加。人类活动造成的河口-近海富营养化程度的加剧,被认为是导致全球有害藻华增加的主要原因。但是,富营养化程度的加剧可能不是全球有害藻华增加的惟一原因。河流入海的非营养盐类的其他物质通量变异（如泥沙）,也可能显著影响河口-近海的生物活动乃至赤潮的发生。过去40年来随着长江入海营养盐通量的增加,长江入海泥沙通量减少了70%。长期观测资料显示,由于泥沙减少使得长江口羽状流区光照条件显著改善,长江口浮游植物生物量最大值区已扩展至更低盐度的区域。此外,过去40年来长江口赤潮发生频率变化与长江入海泥沙通量变化呈现镜像关系,且二者呈显著的负相关关系。因此认为,长江入海泥沙的剧烈减少降低了羽状流区水体浊度,从而对长江口区赤潮频率的增加有一定贡献。     

长江分汊河口涨、落潮悬沙不对称特征及季节性差异

入海河口由于径流的存在以及河口地貌形态的影响，存在涨、落潮水动力、悬沙以及盐度分布等不对称现象，同时这一不对称现象还存在显著的区域性和季节性差异。根据2013年7月和2014年1月洪、枯季长江口定点准同步水文泥沙调查结果，发现长江口分汊型河槽悬沙浓度在时间上存在洪枯季、大小潮不对称特征，在空间上存在东西向沿程分布、南北向横向分布以及垂向上表底层分布不对称特征。河势演变形成南、北支河口涨、落潮悬沙浓度不对称分布的整体格局；洪、枯季变化影响河口涨、落潮悬沙分布的再分配过程；大潮涨、落潮过程对悬沙分布不对称影响显著大于小潮；季节性风浪作用影响河口最大浑浊带涨、落潮悬沙不对称南北差异；底部高含沙浓度对口门段涨、落潮悬沙不对称性贡献显著。     

基于GOCI影像的长江口及其邻近海域CDOM遥感反演及其日内变化研究

采用静止轨道海洋水色卫星（GOCI）数据对长江口及其邻近海域有色溶解有机物（CDOM）反演。以QAA-CDOM算法为基础,根据实测数据,利用BP神经网络模型来拟合QAA-CDOM算法中需要针对长江口水体进行优化的悬浮颗粒后向散射系数b_bp与吸收系数a_p的关系,从而准确估算CDOM的浓度。结果表明,反演结果准确度较高,平均相对误差为0.35。基于GOCI日内连续成像的优势,选取2014年3月15日8景GOCI影像,利用优化后的QAA-CDOM-BP算法,对长江口及其邻近海域CDOM的日内变化进行反演和分析,得到的变化规律如下:长江口及其邻近海域的CDOM日变化主要受潮流、长江径流等共同影响。长江口内CDOM浓度在涨潮期高于退潮期,由于受长江冲淡水的作用,CDOM从口外往外海区呈现逐渐递减趋势。     

九龙江河口区稀土元素地球化学特征

用电感耦合等离子体质谱（ICP-MS）对2007年10月航次采集的九龙江河口区溶解态、悬浮颗粒态、沉积物样品中的稀土元素（REEs）进行了测定,对REEs的地球化学特征进行研究.结果表明,REEs在各相态中的含量范围如下：溶解态的为0.1 ng/dm^3（Eu）～1.96μg/dm^3（Ce）,悬浮颗粒态的为0.28（Tm）～142.83（Ce）mg/kg,沉积物的为0.25（Tm）～99.65（Ce）mg/kg;溶解态、悬浮颗粒态及沉积物中REEs球粒陨石标准化配分曲线均表现为负斜率型,九龙江河口为LREE相对HREE富集型河口.九龙江河口溶解态、悬浮颗粒态、沉积物三相态中REEs含量受流域土壤、地表径流等源区因素影响较大.Ce异常值在各相态中表现为负异常.     

The conservative and non-conservative behavior of chromophoric dissolved organic matter in Chinese estuarine waters

The spectral absorption properties of chromophoric dissolved organic matter (CDOM) and their distributions in two Chinese estuaries, the Yangtze River Estuary and the Jiulong River Estuary, were studied during August 2003 (wet season) and during different seasons between 2003−2005, respectively. The CDOM concentrations (a₃₅₅) of fresh end members in the Jiulong River Estuary varied seasonally, while its quality remained relatively stable. However, the a₃₅₅ of the marine end members exhibited less variability. Application of a conservative mixing model indicated that CDOM behaved conservatively in the Yangtze River Estuary. No photobleaching removal was observed at high salinity region of this estuary. Although CDOM showed conservative behavior for many cruises in the Jiulong River Estuary, there was evidence for removal in the low salinity regions during some cruises. Laboratory mixing experiments and a salt addition experiment suggested that particle sorption of CDOM maybe the possible reason for the removal. These results showed that absorption properties of CDOM can be used as a tool to observe the quantitative and qualitative dynamics of DOM during estuarine mixing.     

长江口溶解有机物光漂白和光矿化表观量子产率

溶解有机物(DOM)经太阳光照射导致其吸光度(光漂白)和溶解有机碳(光矿化)损失,从而影响水体生态系统光学特性及碳循环。本文通过测定冬季长江口及其邻近海域DOM光降解表观量子产率(AQY),初步探讨了DOM光反应活性在河口及陆架海的变化特征。DOM光降解AQY由口内至口外逐渐递减,且有色溶解有机物(CDOM)光漂白速率是溶解有机碳(DOC)光矿化速率的10倍。Φ_ble(CDOM光漂白表观量子产率)和Φ_min(DOC光矿化平均量子产率)在最大浑浊带以东海域与盐度和SUVA₂₅₄分别呈显著的线性负相关与正相关,表明DOM光反应活性在长江口外受物理混合影响为主,且陆源DOM光反应活性比海源高。此外,最大浑浊带下游DOM光降解AQY显著低于上游。DOM光降解速率随波长的变化呈现非高斯分布,且峰值出现在330 nm,积分结果表明UVA是DOM光降解的主要贡献者。本研究结果将为完善我国东海碳通量模型提供帮助。     

The removal of dissolved humic acid during estuarine mixing

A simple method for the determination of dissolved humic acid based on carbon analysis is presented. This method was used to measure the distribution of dissolved humic acids in seven coastal plain estuaries located in the middle-Atlantic United States. Results indicate that 100% of the dissolved humic acid was removed during estuarine mixing, although concurrent measurements of dissolved organic carbon showed either production or conservative behavior in regions of the estuary where humic acid removal was observed. It is apparent from these observations that removal of dissolved humic acid is a minor part of the estuarine transport of dissolved organic carbon.Laboratory experiments carried out by mixing river water with sea water demonstrated that salt-induced removal of dissolved humic acid was insignificant in two of three estuaries studied. These results suggest in situ removal of dissolved humic acid may not be universally caused by increasing estuarine salinity.     

Tripod measured residual currents and sediment flux: Impacts on the silting of the Deepwater Navigation Channel in the Changjiang Estuary

Four bottom-mounted instrument-equipped tripods were deployed at two sections spanning the region characterized by severe sedimentation rates in the Deepwater Navigation Channel (DNC) along the North Passage of Changjiang Estuary in order to observe currents, near-bed suspended sediment, and salinity. Seaward residual currents predominated in the up-estuary section. In contrast, a classical two-layered estuarine circulation pattern occurred in the down-estuary section. Flow moved seaward in the upper layer and a heavier inflow, driven by the salinity gradient, moved landward in the lower layer. The near-bed residual currents in the up-estuary section and the down-estuary section acted in opposing directions, which implies that the region is a convergence zone of near-bed residual currents that trap sediment at the bottom. The maximum salinity gradient at the maximum flood current indicates the presence of a strong front that induces sediment trapping and associated near-bottom convergence of sediment, which explains the high sedimentation rates in this section of the estuary.     

环境因子对菲在黄河口沉积物上吸附的影响

为研究多环芳烃从河口到近海的环境归趋行为与生态风险,考察了沉积物质量浓度、溶解性有机质、温度、盐度4种典型环境因子对菲在黄河口沉积物上吸附的影响,比较了黄河口与近海两种沉积物对菲的吸附性能。研究结果表明,沉积物质量浓度越低,单位质量颗粒物的菲吸附量越高;共存的溶解性有机质对菲的吸附具有增促作用,且腐殖酸比黄腐酸的作用更显著;温度的升高不利于菲的吸附,而盐度的增加有利于菲的吸附。菲在沉积物上的吸附是分配作用与表面吸附两种行为的耦合,其中黄河口沉积物以表面吸附为主,而近海沉积物以分配作用为主。近海沉积物菲吸附量显著高于黄河口沉积物菲吸附量。基于此,菲从河口到近海的迁移过程中,更易于在沉积物表面发生吸附沉降,从而可能降低水相中的生态危害,但对近海底栖生物具有潜在的健康生态风险。     

夏季长江口海域溶解态铁的分布及混合行为研究

本文基于2015年7月长江口的现场调查资料,分析讨论了长江河口区溶解态铁(DFe)的含量分布与混合行为及其影响因素。结果表明:长江径流携带大量的DFe入海,且口内区(Ⅰ)浓度高于混合区(Ⅱ)和外海区(Ⅲ),平均浓度分别为166.45±6.26nmol/L,14.04±8.80nmol/L和6.18±1.51nmol/L。受去除作用和海水稀释的影响,在河口区DFe的浓度下降率达到96.92%。DFe浓度与盐度的关系符合指数模型,由模型与理论稀释线估算的长江口海域DFe的理论最大去除率为97.75%,与实际测得的最大浓度下降率相近。长江冲淡水、苏北沿岸流和台湾暖流影响DFe的水平分布。受长江冲淡水影响,长江口外海域DFe浓度高达176.50nmol/L。苏北沿岸流主要影响研究区域北部的表层水,其携带的DFe浓度低于长江冲淡水。台湾暖流是导致研究区域东南部DFe浓度较低的主要原因,使得中层和底层水中浓度分别低至4.04nmol/L和4.79nmol/L。另外,在表层海水中DFe的分布受到叶绿素a、溶解有机碳和溶解氧的共同影响,DFe与叶绿素a、溶解氧呈显著负相关,与溶解有机碳呈显著正相关。     

Carbonate system and CO2 degassing fluxes in the inner estuary of Changjiang (Yangtze) River,China

We examined the carbonate system, mainly the partial pressure of CO₂ (pCO₂), dissolved inorganic carbon (DIC) and total alkalinity (TAlk) in the Changjiang (Yangtze) River Estuary based on four field surveys conducted in Sep.–Oct. 2005, Dec. 2005, Jan. 2006 and Apr. 2006. Together with our reported pCO₂ data collected in Aug.–Sep. 2003, this study provides, for the first time, a full seasonal coverage with regards to CO₂ outgassing fluxes in this world major river–estuarine system. Surface pCO₂ ranged 650–1440 μatm in the upper reach of the Changjiang River Estuary, 1000–4600 μatm in the Huangpujiang River, an urbanized and major tributary of the Changjiang downstream which was characterized by a very high respiration rate, and 200–1000 μatm in the estuarine mixing zone. Both DIC and TAlk overall behaved conservatively during the estuarine mixing, and the seasonal coverage of these carbonate parameters allowed us to estimate the annual DIC export flux from the Changjiang River as ∼ 1.54 × 10¹² mol. The highly polluted Huangpujiang River appeared to have a significant impact on DIC, TAlk and pCO₂ in the lower reaches of the inner estuary. CO₂ emission flux from the main stream of the Changjiang Estuary was at a low level of 15.5–34.2 mol m^− 2 yr^− 1. Including the Huangpujiang River and the adjacent Shanghai inland waters, CO₂ degassing flux from the Changjiang Estuary may have represented only 2.0%–4.6% of the DIC exported from the Changjiang River into the East China Sea.     

Ecology of benthic polychaetes in the heathcote estuary,New Zealand

The distributions of 19 species of polychaetes burrowing in the intertidal sand and mudbanks of the Heathcote Estuary, New Zealand, are related to salinity, sediment grade, and length of time of exposure at low tide. Only Nicon aestuariensis Knox and Scotecolepides benhami Ehlers appear to be truly estuarine species reaching their greatest population densities in low salinities. Incidental observations of feeding and reproduction are reported.     

The processes of dynamic sedimentation in the Changjiang Estuary

The characteristics of the mouth bar and subaqueous delta, and the water masses and water systems in the Changjiang Estuary and nearby coastal waters are examined. The hydrodynamics of the estuarine plume, and the fronts and turbidity systems are described with reference to their distribution and movement. Physical, chemical, biological and geological barrier effects of the estuarine mouth bar are evaluated. Through examination of the sediment distribution, sedimentation rate and depositional sequence, the sediment exchanges and evolution of the estuarine mouth bar and subaqueous delta are described.