Progress in research of hypoxia in estuaries and coastal areas in China

对长江、珠江等河口及其近海水域缺氧现象与影响因素进行研究,结果表明,主要分布于长江与珠江河口及其邻近海域的缺氧现象,夏季(6-8月)达到最盛,秋; 冬季消失;长江口的缺氧区域主要位于30.75°N~32°N,122.5°E~123.25°E附近海域,具有南北2个缺氧中心;珠江口缺氧程度相对较; 轻,缺氧区域主要在广州黄埔区河段至虎门水域和伶仃洋;辽河、钱塘江、海河等河口区域也时而出现零星的缺氧现象;水体缺氧受控于多项环境要素,物理层化作; 用是缺氧产生的最初诱因之一,陆源污染物的分解则是重要的耗氧负荷;各河口区特征各异,潮汐、洋流、营养盐、叶绿素a等要素对缺氧区的范围、程度和持续时; 间影响程度不一。In order to study hypoxia in the main estuaries and adjacent coastal; areas in China, we compared the hypoxia in the estuaries of the Yangtze; River, the Pearl River, and other rivers, and analyzed the factors. We; found that hypoxia mainly occurred in the estuaries of the Yangtze; River, the Pearl River, and the adjacent coastal areas; it had the most; significant increase in the summer (from June to August) and disappeared; in the autumn and winter. The hypoxia zone in the Yangtze River Estuary; was mainly located in the area with latitudes from 30.75°N to 32°N and; longitudes from 122.5°E to 123.25°E, and there were two hypoxia centers; in the south and north, respectively. The degree of hypoxia in the Pearl; River Estuary was relatively moderate, and hypoxia mainly occurred from; the Huangpu section to Humen waters in Guangzhou and in the Lingdingyang; Channel. In addition, hypoxia occasionally occurred in the estuaries of; the Liaohe River, Qiantang River, and Haihe River. We also found that; hypoxia was subjected to many environmental factors, of which the; stratification of water was one of the initial factors and the; decomposition of terrigenous pollutants was a major factor of oxygen; consumption. Tides, upwellings, nutrients, and chlorophyll-a had; different influences on the scale, degree, and duration of hypoxia, due; to the various characteristics of the estuaries

闽江下游及河口溶解无机氮的季节分布及组成

为研究闽江下游及河口区溶解无机氮（DIN）的季节分布及组成,采集并分析了四季的表层水样。平面分布上,NO3-N不同季节有所不同;NH4-N及NO2-N不同季节分布特征基本一致,仓山区、鼓楼区附近的站位受城市污水影响而含量偏高。季节变化上,NO3-N南北段春季最高,河口段冬季最高;NH4-N南北段秋季远高于其它三个季节,河口段季节变化不大;NO2-N南北段及河口段季节变化不大。DIN组成上,南北段不同季节占比相似,DIN组成上未达到热力学平衡;河口段DIN组成季节变化不大,三态间基本达到热力学平衡。DIN[2]转化上,北段三氮之间相关性总体较弱,且与DO的相关性变化较大,三氮关系受复杂的来源、人类活动及生物化学过程影响;南段三氮之间的相关性较显著也较复杂;河口段三氮及DO之间的关系季节差异比较明显。此外,闽江下游及河口DIN年际增高及超标现象较严重。国家自然科学基金(41376050

闽江下游及河口沉积物总碳的地球化学特征

分析了闽江下游及河口区的表层水质、悬浮物和沉积物样品,探讨了沉积物总碳的地球化学特征和影响因素,及与其他河流的异同.结果表明,对于相同站位,夏季沉积物总碳占比平均为1.74%,略高于秋季的1.70%,两者差异不明显.研究区沉积物总碳占比为1.21%~4.84%,平均为1.82%,从水口水库至福州市区河段,其含量逐渐升高,在北港达到最高值,而后由河口向外海逐渐降低,呈现\"低-高-低\"的分布特征.秋季悬浮物含量和化学需氧量(COD)高值区范围大于夏季,且含量也更高.研究区悬浮物含量、COD、颗粒态总碳均呈现先升后降的分布特征,悬浮物中总碳的含量则呈现从库区经河口向外海减少的趋势.沉积物总碳与悬浮物总碳、悬浮物含量、COD总体显著相关,悬浮物的沉降-再悬浮-再沉降过程是影响沉积物总碳分布的重要因素;人类活动产生的污水、农田和畜禽水产养殖废物是有机物的主要来源.闽江口沉积物总碳含量低于黄河、长江,而与其他中小型河口相近,处于国内河口较低水平,这与流域内源岩特性、有机物输入量以及沉积物粒度等相关.北港段沉积物总碳含量显著高于其他河流,有机污染较为严重,将成为影响水体水质的潜在因素.国家自然科学基金资助项目(41376050

Temporal-spatial Distribution and Its Influencing Factors of Suspended Particulate Matters in Minjiang Lower Reaches and Estuary

为了解闽江下游及河口悬浮物的时空变化特征和影响因素,于2014~2015年采集了研究区4个季节的水样,并在河口进行了冬、春季2次加密采样。结果表明：从闽江水口水库经河口至外海,悬浮物浓度呈现＂低→高→低＂的分布特征,并具有春、夏季高于秋、冬季的季节变化特征;河口悬浮物浓度从涨潮至低潮阶段,总体呈现由河端向海端降低的特征,且其浓度冬季高于春季;河口冬季水体混合作用较强,盐度分层不明显;春季盐度分层显著,且涨潮和高潮时河口盐水楔活动影响悬浮物分布;河口最大浑浊带的规模呈现枯兴洪衰的趋势,其位置随潮汐的涨落上下摆动,通常秋、冬季偏上游,而春、夏季偏下游;闽江河口悬浮物时空分布受径流、潮流及盐度分布等影响显著,且强潮流、分支水道、盐水楔等因素对悬浮物的影响被放大,中小型河口更多地反映出各因素及其河口自身特征的综合影响;与中国其他河流相比,闽江河口悬浮物浓度远低于黄河河口,与长江河口相近,高于位于其南侧的珠江河口;闽江河口悬浮物的季节变化特征与其他河流相反;各河口悬浮物随潮周期的变化规律类似;闽江河口总体呈冲刷状态,水动力增强,悬浮物浓度呈上升趋势,对河口地貌、河口生态和港口航运等产生影响。For understanding the temporal-spatial distribution and its influencing factors of suspended particulate matters（SPM）in Minjiang lower reaches and estuary,the water samples during spring,summer,autumn and winter were collected from 2014 to 2015,and the intensive samples during spring and winter were carried out in estuary.The results show that the concentrations of SPM present the characteristics of ＂low-high-low＂ from Shuikou reservoir in Minjiang to the sea,and the concentrations during autumn and winter are higher than those during spring and summer;from high tide to low tide,the concentrations of SPM in estuary decrease from the river side to the sea side,and the concentrations during winter are higher than those during spring;the water is mixed and the salinity stratification is not obvious in estuary during winter,but the salinity stratification coefficient is significant,and the activity of saline wedge in estuary during flood and high tide has an effect on the distribution of SPM duringspring;the turbidity maximum zone in estuary forms during dry season and declines during flood,and the location floats up and down with a tidal,usually upstream during autumn and winter and downstream during spring and summer;the influences of runoff,tide and salinity on the temporal-spatial distribution of SPM in estuary are obvious,meanwhile the influences of tide race,branch channel,saline wedge and other factors on SPM are magnified;the small and medium-sized estuaries reflect much more about the comprehensively effects of factors and their own characteristics on the distribution of SPM;compared to other great rivers in China,the concentration of SPM in Minjiang estuary is much lower than that in Yellow River estuary,and similar to that in Yangtze River estuary,while higher than that in Pearl River estuary which located in the south of Minjiang;the seasonal variation characteristics of SPM in Minjiang estuary are contrary to those great rivers,but the changing processes of SPM with tidal cycle are similar to the国家自然科学基金项目（41376050

Distribution,composition of dissolved inorganic nitrogen and relationships with the environmental factors in Quanzhou Bay

分析了泉州湾溶解无机氮(DIN)春季的含量分布、组成、潮周期及其与环境因子的关系.根据高值区判断洛阳江口以县区农田养殖输入硝酸氮(NO_3~-; -N)为主,而晋江口以市区生活污水输入氨氮(NH_4~+ -N)为主,DIN含量的平面分布受NO_3~- -N与NH_4~+ -N共同控制.; DIN的平均组成为NO_3~- -N最高,NH_4~+ -N其次,NO_2~- -N远低于二者,NH_4~+; -N平均占比达35%左右,DIN的组成未达到热力学平衡.根据DIN含量与溶解氧(DO)及化学需氧量(COD)的相关性分析,推测三氮转换不仅受到氧; 化还原过程的影响,还受更为复杂的来源、人类活动及生物过程等的影响;根据DIN含量与盐度的关系,NO_3~- -N及NO_2~-; -N均呈现保守行为,NH_4~+ -N淡水端有一定的增加现象,DIN含量与盐度的关系受NO_3~- -N和NH_4~+ -N共同控制;; DIN含量还受到悬浮物含量、温度、盐度及pH值等环境因子的控制,结合DIN含量与叶绿素a的相关性及分布情况,可推测春季DIN主要来源不是浮游植物; 分解.不同站位DIN含量的潮期变化相似,基本上都表现为涨潮冲淡作用下含量降低而落潮后回升.除此之外,泉州湾DIN含量的年际增长及超标均比较严重,; 需要采取相应的治理措施.In this paper we study the relations of distribution and composition of; dissolved inorganic(DIN)with tidal change and other factors in spring of; Quanzhou Bay. The result shows that Luoyang River inputted more NO_3~-; -N from cropland aquaculture while Jinjiang River inputted more NH_4~+; -N from municipal sewage to the bay according to the nutrient content.; The horizontal distribution of DIN was controlled both by NO_3~- -N and; NH_4~+ -N. The average percentage of NH_4~+ -N reached 35%,so the; composition of DIN didn't balanced by the thermodynamic equilibrium in; Quanzhou Bay. The relationships among different nitrogen species were; affected by complicated nitrogen sources, human activities and; biochemical processes according to the correlations between DIN and; DO,COD. According to the linear regressions between DIN and salinity,the; mixing behavior of NO_3~- -N and NO_2~- -N is suggested to be con; servative besides some NH_4~+ -N from the fresh water end. Also,the; mixing behaviors of DIN were controlled by both NO_3~- -N and NH_4~+ -N.; DIN was also controlled by environmental factors such as suspended; solids,temperature,salinity, pH and chla. According to the distribution; of DIN and its correlations with chl a,we suggest that the main source; of NO_3~- -N is from human input. Tidal cycle variation of DIN at; different stations were similar,both showed a decreasing trend during; the tide rising due to the seawater dilution and an increasing trend; during the tide falling. Moreover,the excess and annual increment of DIN; concentrations was much serious in Quanzhou Bay where more attentions; should be paid.国家自然科学基金资助项

Distribution of Dissolved Oxygen in the Surface Water and Its Influencial Factors in Quanzhou Bay During Spring and Summer

水体中的溶解氧(dissolved; oxygen,DO)分布受控于复杂的生物地球化学过程,对区域生态环境保护和修复有重要意义.泉州湾表层水体DO的分析结果表明,春、夏季DO的质量浓; 度分别为6.37~8.24mg/L和2.76~7.62mg/L,两季差异主要是由于水温和DO消耗强度的变化.受入海径流和潮汐的影响,DO呈现从湾; 内向湾口增加的趋势,其中春季DO总体变化较小,在西南部海域的变化幅度比海湾中部至湾口更明显,而夏季反之.泉州湾的表观耗氧量(apparent; oxygen utilization,AOU)与化学需氧量(chemical oxygen; demand,COD)呈显著正相关,与盐度和pH均呈显著负相关,与营养盐的相关性在各潮期有异.总体而言,AOU分布在春、夏季均受有机物降解的强烈; 影响;夏季浮游生物生长旺盛,其耗氧过程对AOU分布的影响大于春季;春季浮游生物活动较弱,水动力条件对AOU的影响大于夏季.Distribution of dissolved oxygen(DO)in water,which is influenced by; complicated geochemical processes,plays an important role in ecological; environment protection and restoration.We analyzed the DO concentrations; in the surface water of Quanzhou Bay during spring and summer.The; results showed that DO concentrations were 6.37-8.24mg/L and; 2.76-7.62mg/L during spring and summer,respectively,and the seasonal; difference was attributed to the differences of water temperature and; oxygen consumption.DO concentrations increased from the inner bay to the; bay mouth,and varied more significantly during spring than; summer.Furthermore,DO concentrations varied more obviously in the; southwestern waters than in the central of bay during spring,while; varied in an opposite way during summer,which was mainly due to the; effects of runoffs and tide.Apparent oxygen; utilization(AOU)concentrations were significantly positively correlated; with chemical oxygen demand(COD)and negatively correlated with salinity; and pH,and the correlations between AOU and nutrients were different; during various tidal periods.Generally, AOU distributions in Quanzhou; Bay are influenced by organic matter degradation,plankton activities and; mixture of runoffs and tide.The effects of plankton activities on AOU; are greater during summer than spring,and the influences of runoffs and; tide are stronger during spring than summer.国家自然科学基

Characters of magnetic susceptibility of surface sediments and their significance in the lower reach and estuary of Minjiang River

闽江是中国东南沿海最大的河流,具有落差大、水动力强等典型的山溪型河流特征.本研究对采自闽江流域的43个表层沉积物样品进行了磁学参数分析,结果显示,低频磁化率(χ_(lf))、高频磁化率(χ_(hf))分别为0.79×10~(-8)~24.97×10~(-8)、0.74×10~(-8)~24.80×10~(-8)m~3/kg,与长江、黄河相比低一个数量级;频率磁化率(χ_(fd))为0.06%~7.20%,大多小于5.00%,沉积物中超顺磁颗粒含量较低.χ_(lf)和χ_(fd)总体呈现从下游到河口增长的趋势,并在北港、南港、闽侯、大樟溪等人口密集区域受到不同程度的人为影响,分析表明研究区磁化率受控于源岩特征、水动力条件、沉积作用和人为活动等因素.在p<0.01时,χ_(lf)与Al2O3、Fe2O3、Na2O、Mg O、Ti O_2、Ca O等氧化物显著正相关,与Si O_2显著负相关,说明其受控于源岩成分.此外,χ_(lf)与Si/Al值显著负相关,与化学风化指数(CIA)正相关,表明磁化率可以作为现代沉积物风化程度的替代指标.χ_(lf)与溶解态As含量、χ_(fd)与溶解态Cd含量均在p<0.05时相关,表明磁学参数可作为指示研究区水体的As和Cd污染的参考指标.Minjiang River is the largest river in South-east coastal area of China and it is,as a mountain river,characteristic of large elevation gradient and strong hydrodynamics. Low frequency magnetic susceptibility( χ_(lf)),high frequency magnetic susceptibility( χ_(hf)) and frequency magnetic susceptibility( χ_(fd)) of 51 surface sediment samples collected from the Minjiang River were measured with Bartington MS2. The results shows that χ_(lf)ranges from 0. 79× 10~(-8)to 24. 97 × 10~(-8)m~3·kg~(-1),which is an order less than those of the Changjiang River and Huanghe River sediment. Most of the value of χ_(fd)are lower than 5. 0%,indicating that the content of superparamagetism particles in surface sediment samples are low. In general,the values of χ_(lf)and χ_(fd)progressively increase from low reach to estuary,with significant influence of anthropogenic impact in densely populated areas of the North and the South port,Minhou Country and Dazhangxi Brook. It suggests that magnetic susceptibility is controlled by the source rock differences,hydrodynamics,sedimentation and anthropogenic impact. Magnetic susceptibility can be taken as indicators of source rock differences and weathering intensity,considering its remarkable correlation with major element abundance and ratios of Si / Al( p < 0. 01). χ_(lf)and χ_(fd)are also positively correlated with As and Cd abundance in water,which it means that χ_(lf)and χ_(fd)could be used as a simple proxy of As and Cd contamination in water.国家自然科学基金资助项目(41076122,40976037,41376050