乳山湾邻近海域低氧现象及成因浅析

根据2009-06-2009-09及2010-05-2010-06在乳山湾及其毗邻海域的综合调查,分析了该海域溶解氧的变化,初步探讨了影响溶解氧变化及底层低氧形成的原因。结果表明,夏季乳山湾邻近海域存在季节性低溶解氧区,溶解氧在6,7月份相对较高,而在8,9月份相对较低,最低值出现在8月份,为3.21mg/L(饱和度为35.5%),表观耗氧量为5.82mg/L。乳山湾外邻近水域溶解氧略高于湾口和湾内。底层溶解氧水平受到潮汐的影响,具有较大的周日波动性,变化范围介于3.74～8.26mg/L;在落潮时质量浓度降低而在涨潮时质量浓度升高。在这一区域存在较为强烈的温、盐跃层,从而限制了表、底层溶解氧的交换,而COD质量浓度的升高为这一区域的耗氧过程提供了一定的物质基础。潮汐、黄海冷水团的顶托作用、有机物质在底层水域的氧化作用以及底泥耗氧过程导致底层溶解氧的亏损。     

长江口邻近海域溶解氧的时空分布及影响因素研究

基于2018年早春和夏季长江口邻近海域的调查数据,分析溶解氧(DO)的时空分布,并讨论其影响因素.结果表明,夏季DO浓度变化范围为1.58～9.37 mg/L,浮游生物光合作用产生的DO是夏季表层水体过饱和的主要因素;夏季调查海域受台湾暖流北上引起海水层化加强,同时水体富营养化导致表层生物大量繁殖所引起有机碎屑的沉降和耗氧分解作用是底层低氧区存在的主要因素.夏季在台湾暖流影响下底层水体表观耗氧量(AOU)与营养盐成正相关关系,底层有机物耗氧降解过程与营养盐的再生密切相关.早春DO浓度变化范围为7.90～10.1 mg/L,长江口外北部海域和浙江近岸海域海水混合均匀,DO浓度主要受温度控制,而台湾暖流影响区海水出现层化现象,其低DO含量也为低氧区的形成奠定了基础.     

基于改进的RCA水质模型对珠江口夏季缺氧及初级生产力的数值模拟研究

针对珠江口藻类生长受泥沙遮光限制明显的问题, 对RCA(row and column of Aesop)三维水质模型进行改进, 加入泥沙模块及悬沙遮光对藻类生长的限制作用。应用改进的RCA水质模型, 对珠江口的营养盐、浮游植物及溶解氧进行模拟研究, 结果显示, 改进的RCA水质模型较好地再现了洪季珠江口营养盐、浮游植物和溶解氧在水平及垂向上的空间分布, 这表明该水质模型能较好地反映珠江河口中生态因子的关键过程。珠江口的缺氧现象在物理和生化过程的共同作用下, 被限制在伶仃洋的西滩和中滩及磨刀门海域。在洪季, 大量冲淡水进入珠江口形成锋面, 颗粒态有机物(particulate organic matter, POM)在锋面的影响下, 大量集中沉降在伶仃洋的西滩及中滩特定区域及磨刀门外, 产生较高的底泥耗氧率(sediment oxygen demand, SOD)。而在高SOD的区域, 水体分层通常也较明显, 因而产生缺氧现象。另一方面, 伶仃洋水体中磷的限制作用明显, 加上悬浮泥沙的遮光作用, 不利于浮游植物生长, 使得初级生产力低; 而在陆架上, 悬沙浓度减少使初级生产力增加, 但由于海源颗粒有机碳(particulate organic carbon, POC)的沉积分散于整个陆架上, 无法产生伶仃洋内的高SOD区域, 加上水体分层不明显, 并没有产生缺氧现象。     

不同养殖密度对我国热带地区集约化养殖凡纳滨对虾水质和成活率的影响

报道了在我国热带地区集约化养殖凡纳滨对虾Litopenaeus vannamei不同放养密度下水体pH值、溶解氧(DO)、总碱度(TA)、化学需氧量(COD)、生物化学需氧量(BOD)、硫化氢(H2S)、亚硝酸态氮(NO2-NT)、氨态氮(NH4-NT)及弧菌活菌总浓度(Concentration of Live Vibrio,CLV)的变化特征及其与对虾死亡之间的关系,并比较了70、100、120、150尾.m-2不同养殖密度下的养殖成活率。通过几种主要水质因子变化与对虾死亡数之间的相关性分析,结果表明,DO、H2S、NO2-NT、NH4-NT和CLV等5种水质指标与对虾大量死亡存在显著的线性相关,其中DO为负相关,其余为正相关。而pH、TA、COD、BOD与对虾死亡数无显著相关性。4种养殖密度下的成活率分别为80.44%、75.16%、51.74%和44.43%。建议我国热带地区集约化养殖凡纳滨对虾的合理密度为70—100尾.m-2。     

烟台-威海北部海洋牧场底层溶解氧浓度的季节变化研究

基于2021年4~12月山东半岛烟台-威海北部海洋牧场区域4处连续观测站的长期观测数据, 研究了该海域底层溶解氧(dissolved oxygen, DO)浓度的季节变化特征, 并探讨了物理机制。该海域底层DO从春季到夏季逐渐降低, 而从夏季到秋季逐渐升高, 主要受温度控制; 各观测站DO均在8月达到最低值, 受垂向层结增强和底层生物化学耗氧增多的共同影响。底层DO浓度在东西方向差异较小, 而在南北方向上差异明显; 在春季和秋季DO浓度南高北低, 是由于层结较弱, 海水垂向混合向底层提供DO, 且南边水深更浅, DO更容易达到饱和或过饱和状态, 而水深更深处DO仍处于不饱和状态; 夏季DO浓度南边大于北边是季节性层结强度的空间差异所致, 同时南边底层DO浓度下降更快, 使其南北差异在夏季有所减小。在11月中旬, 近岸3个观测站底层DO快速增多, 可能是由于此前的大风过程引起浮游植物繁殖, 晴朗天气促进其光合作用使海水中DO增多, 之后海水层结消失, 海水充分垂向混合使丰富的DO到达底层。     

Distribution of dissolved oxygen and causes of maximum concentration in the Bering Sea in July 2010

According to data obtained in the Bering Sea during the 4th Chinese National Arctic Research Expedition, the distribution of dissolved oxygen(DO) was studied, causes of its maximum concentration were discussed, and the relationships between DO and other parameters, such as salinity, temperature, and chlorophyll a were analyzed. The results showed DO concentration ranged from 0.53 to 12.05 mg/L in the Bering Sea basin. The upper waters contained high concentrations and the maximum occurred at the depth range from 20 to 50 m. The DO concentration decreased rapidly when the depth was deeper than 200 m and reached the minimum at the depth range from 500 to 1 000 m, and then increased slowly with the depth increasing but still kept at a low level. On the shelf, the DO concentration ranged from 6.53 to 16.63 mg/L with a mean value of 10.75 mg/L, and showed a characteristic of decreasing from north to south. The DO concentration was higher in the area between the Bering Sea and Lawrence Island and was lower in the southeast and southwest of Lawrence Island at the latitude of 62°N. The formation of maximum DO concentration was concerned with phytoplankton photosynthesis and formation of the themocline. To the south of Sta. B07 in the Bering Sea basin, the oxygen produced by photosynthesis permeated to the deeper water and the themocline made it difficult to exchange vertically, and to the north of Sta. B07, the maximum DO concentration occurred above the themocline due to phytoplankton activities. On the shelf, the oxygen produced by phytoplankton photosynthesis gathered at the bottom of the thermocline and formed the DO maximum concentration. In the Bering Sea basin, the DO and salinity showed a weak negative correlation(r=0.40) when the salinity was lower than 33.1, a significant negative correlation(r=0.92) when the salinity ranged from 33.1 to 33.7, and an irregular reversed parabola(r=0.95) when the salinity was greater than 33.7.     

长江河口南支水域溶解氧动力学模型的应用

应用Netherlands Instilute of Ecology (NIOO)的环境生态动力学模型Femme，在长江河口南支河段建立了1个一维的溶解氧动力学预测模型。运用此模型得出该区域深解氧和有机物时空分布情况并加以分析，结果显示该区域的有机物污染并不严重，其分布趋势大体为：排污口附近污染较多，枯水期更为明显；丰水期由于长江径流的稀释作用，有机物浓度大大降低；黄浦江、上海竹园排污口处有机物浓度最大。此结果同各种参考文献中提供的资料和观测值基本一致，也基本证实这是1个可行的预测溶解氧的模式。     

海南红树林湿地沉积物耗氧及其相关因素

于2009年8月在海南省东寨港、亚龙湾青梅港和三亚河口红树林区,分别采用自行研制的沉积物耗氧量(Sediment oxygen demand,SOD)测定装置,对红树林湿地SOD和相关环境因子进行研究。结果表明,红树林湿地沉积物耗氧主要分为2个阶段,即瞬时耗氧阶段和渐缓耗氧阶段。3个站位的SOD值范围为102.2-157.7mg/(m2·h),其中瞬时耗氧占23.3%-45.5%。SOD与沉积物中的硫化物含量及上覆水中的化学耗氧量(Chemical oxygen demand,COD)、NH4+浓度有显著的相关性。研究结果表明,红树林湿地沉积物能对其上覆水释放有机物并消耗水体中的溶解氧,使水质变差,因此,用红树林湿地处理城市污水可能导致生态恶化。     

Modelling nitrogen and phosphorus cycles and dissolved oxygen in the Zhujiang Estuary Ⅰ. Model development

wrmcrloxHuman activities related to the population growth and developrnent of industry and rnwhci-pality have led to the incrouing hadings of various POllutants into estudries during the past fewdecades. These increasing edlutant lOadings have caused declined estuallne hedth which can bemereured by a vdriety of indices. In order to obtain solutions to environrnent problerns, re-sources manageTnnt apencies are supporting a holistic approach to envirorirnental management.An effcient strategy t…     

长江口及邻近海域表层水体溶解氧饱和度的季节变化和特征

根据“908”ST04区块调查的夏、冬、春、秋季四个航次和“908”补充调查的8月航次资料对长江口及邻近海区表层水体溶解氧及其饱和度进行了探讨.研究表明东海北部表层水体在夏季和春季以浮游植物光合作用为主要控制过程,特别是7、8月份长江口外、杭州湾外及浙江近海存在大范围的强光合作用区;秋季以有机质氧化分解过程为主,表层溶...     

珠江河口氮和磷循环及溶解氧的数值模拟 Ⅰ.模式建立

为了研究珠江河口营养物质循环和溶解氧,建立了一个生态型水质模式.在该水质模式中营养物质以溶解无机态、碎屑有机物质、底栖物质、浮游植物和浮游动物等5种形态出现,而每种形态均分氮和磷两种形式.水质模式采用三维形式,并与斜压水动力和泥沙模式联立运行.     

秦皇岛外海夏季溶解氧与pH的变化特征分析

溶解氧(DO)是海洋生物生存不可缺少的要素。随着人类活动的增加,全球近岸海域低氧情况愈发严重,已经成为威胁海洋生态系统健康的重要因素。通过对2017年5?9月秦皇岛外海区域的观测调查,探讨了该海域低氧与酸化的形成机制并计算了月平均耗氧速率。结果表明,5月秦皇岛外海水体混合较为均匀,表、底层DO浓度一致,均大于8 mg/L;6月开始形成密度跃层,与此同时底层DO浓度和pH开始下降;8月底层呈现明显的低氧和酸化状态,DO浓度下降至2～3 mg/L,pH下降至7.8以下;9月随着层化消失,底层水体DO浓度和pH逐渐升高。相关性分析显示,DO和叶绿素a (Chl a)以及pH具有良好的耦合性,说明秦皇岛外海区域的低氧发生过程主要为局地变化。同时表明DO浓度和pH主要受水体中浮游植物的光合作用和有机物有氧分解的影响。通过箱式模型计算得到2017年6?8月密度跃层以下水体及沉积物耗氧速率为951～1193 mg/(m2·d)[平均为975 mg/(m2·d)]。综合来看,水体分层是秦皇岛外海低氧和酸化发生的先决条件,跃层以下的有机物分解耗氧则是底层水体发生低氧和酸化的重要原因。     

北部湾北部海域潜在低氧分布及影响研究

通过对2011年北部湾北部海域春季和夏季溶解氧（DO）及其他环境要素进行分析讨论,发现DO的季节性差异较大,春季DO含量（平均8.11 mg/L）明显高于夏季（平均6.05 mg/L）。夏季北部湾底层部分区域存在DO低值,该低值区常年存在,并且DO最低值逐渐降低、低值区范围逐渐扩大。利用相关性分析和灰色关联度分析的方法,对夏季底层DO低值的成因进行分析发现：夏季底层水体浮游植物产氧作用较弱,海水层化作用强,阻碍了表底层DO的交换;另外底层有机质分解的耗氧作用明显,出现了氧气的净消耗,由此导致夏季底层水体出现DO的低值。同时,由于2011年之后北部湾北部海域陆源污染排放和赤潮的频发使得该海域低氧状况加剧,潜在低氧区逐渐发展为低氧区。     

对虾养殖池生态环境的人工调控及其特征

通过人工调控对虾养殖池的水色、透明度、溶解氧和COD,建立了较稳定的对虾养殖生态体系.其特征为,生产力水平高,物质循环速度快,各项水质指标在一定范围内的变化幅度和变化速度较快.提出了人工调控虾池生态环境应以维持稳定的浮游植物种群结构和数量为主要内容,同时,讨论了浮游植物种群结构及数量与相关因素的关系.     

春、秋季考洲洋海水质量状况及评价方法初探

文章利用2017年11月（秋季）和2018年4月（春季）对惠州考洲洋海域开展的两个航次水环境调查数据,分析了考洲洋海域表层溶解氧（DO）、化学需氧量(COD)、无机氮(DIN)、无机磷(DIP)和石油类（OIL）等典型水质因子的水平分布和季节变化情况。结果表明,秋季溶解氧、化学需氧量、石油类分别在盐洲岛以东附近海域、考洲洋湾顶海域和盐洲岛东南海域出现高值区,而无机氮在整个考洲洋无明显区域分布差异,无机磷含量呈现考洲洋内湾到湾口逐渐递减的趋势;春季化学需氧量、无机磷均在考洲洋湾顶出现高值区域,无机氮在盐洲岛以东附近海域出现高值区,而溶解氧和石油类无明显变化。从季节变化来看,秋季考洲洋海域溶解氧、化学需氧量和石油类平均含量均比春季高;无机氮、无机磷则相反,平均含量秋季低于春季。同时,文章还分别利用单因子和综合因子方法对海水有机污染状况进行评价并对其进行比较分析,结果表明,有机污染评价指数法可充分考虑多种水质因子,更适合对考洲洋水环境质量进行评价,得到较为客观的综合评价结果。     

Hydrography and budget of dissolved total nitrogen and dissolved oxygen in the stratified season in Mikawa Bay,Japan

Distributions of salinity, dissolved total nitrogen (DTN) and dissolved oxygen (DO) were observed once a month throughout a year in Mikawa Bay, one of the most eutrophic bays in Japan. Supply of freshwater, DTN and DO from the land and precipitation was estimated. Hydrography, circulation and transformation of DTN and DO during the stratified period were investigated simultaneously by a two-layered box model analysis dividing the bay into five boxes. The two-layered circulation was confirmed. In the upper layer of the river mouth regions, a high production of particulate organic nitrogen (PON) due to the strong upwelling together with the river inflow was found. On the other hand, in the lower layer of the bay mouth region, a high deposition of PON due to weak upwelling and sometimes downwelling and a high decomposition of PON due to the inflow of DO abundant water were also found. The reason why the eutrophication is more severe in the eastern part than in the north-western part of the bay is discussed.     

Seasonal and sub-seasonal oxygen and nutrient fluctuations in an embayment of an eastern boundary upwelling system: St Helena Bay

Seasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the 50-m depth contour. A mean coefficient of variation of 0.35 provided a measure of the relative variability of near-bottom DO concentrations along this contour. Consistently lower DO concentrations in the southern region of the bay in summer and autumn are attributed to enhanced retention. Across-shelf transects captured the seasonal development of hypoxia in relation to the distribution of phytoplankton biomass. Exceptional dinoflagellate blooms form extensive subsurface thin layers preceding the autumn DO minima in the south of the bay, prior to winter ventilation of the bottom waters. The seasonal decline in DO concentrations in the bottom waters was marked by sub-seasonal events of hypoxia, and ultimately anoxia linked to episodic deposition of organic matter, as indicated by increases in bottom chlorophyll-a concentrations. Seasonal changes in bottom water macronutrient concentrations followed trends in apparent oxygen utilisation (AOU), both of which mirrored DO concentrations. In the south of the bay, nitrogen loss through denitrification/anammox in suboxic waters was indicated by a dissolved inorganic N deficit in the bottom waters, which was most pronounced in autumn.     

Variation of dissolved organic matter and fluorescence characteristics before,during and after phytoplankton bloom

The variation of dissolved organic matter (DOM) and fluorescence characteristics during the phytoplankton bloom were investigated in Yashima Bay, at the eastern part of the Seto Inland Sea, Japan. We found significant accumulations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), chromophoric dissolved organic matter (CDOM) fluorescence, and UV₂₆₀ during the phytoplankton bloom period in 2005, although lower accumulations of DOC and DON and only increases of CDOM fluorescence were observed during the bloom period in 2006. Little or no correlation between DOM and phytoplankton abundance might be due to the composition of DOM, which is a complex mixture of organic materials. The 3D-EEM results revealed that the DOM produced around the phytoplankton bloom period contained tyrosine, tryptophan, and humic-like substances. Our results showed that the occurrence of phytoplankton bloom contributed to the production of DOM in coastal water but the DOM accumulation depended on the type of phytoplankton bloom, the phytoplankton species in particular. From our results, we concluded that phytoplankton have a great role in the dynamics of DOM as a producer in a coastal environment.     

An ecological-physical coupled model applied to Station Papa

A vertical one-dimensional ecosystem model was constructed and applied to Station Papa. The model has seven compartments (phytoplankton, nitrate, ammonium, zooplankton, particulate organic matters, dissolved organic matters, dissolved oxygen) and was coupled with a mixed layer model for calculating diffusion coefficient which appears in the governing equations. The mixed layer model was driven by SST, SSS data observed at Station Papa in 1980 and ECMWF wind data for 1980, and the ecosystem model was driven by fixing nitrate concentration in deep layer to an observational value. The phytoplankton maximum in March was reproduced by the model although the maximum in fall-winter could not be reproduced. The model also suggests the importance of studying nitrification. As a whole, the model could reproduce characteristic features at Station Papa such as the summer ammonium maximum at 50 m depth, the summer dissolved oxygen maximum at 70 m depth and the absence of remarkable phytoplankton bloom.     

Respiration partitioning in contrasting subtidal sediments: seasonality and response to a spring phytoplankton deposition

Biomass and respiration rates of bacteria, nematodes and macrobenthos were estimated in relation to the deposition of the spring phytoplankton bloom at two contrasting sites in the Southern North Sea: one with fine‐grained sediment close to the coastline and another with highly permeable sediments. Sediment community oxygen consumption (SCOC) was also measured. Bacterial biomass was relatively similar at both stations, whereas nematode and macrobenthic biomass were higher in fine‐grained sediment. In fine sediments, bacterial biomass increased quickly after deposition of the phytoplankton bloom, whereas the response of nematodes and macrobenthos was delayed. In coarser sediments, nematodes and macrobenthos also showed a fast response in terms of density and biomass. Respiration in permeable sediments was mainly dominated by bacteria at all periods of the year. Hence, nematode and macrobenthic respiration did not contribute strongly to SCOC. This is in contrast to the patterns observed in finer sediments, where both macrofauna and nematodes were important oxygen consumers as well. Macrobenthos contributed more to total SCOC than did nematodes in winter. However, shortly after the arrival of phytodetritus at the sea floor, nematodes and macrobenthos contributed equally to the total SCOC, indicating that all benthic size classes should be taken into account when investigating marine benthic respiration rates.