受扰动海域大型底栖动物群落特征及基于AMBI和M-AMBI指数的生态健康评价：以山东烟台辛安河口为例

To understand the ecological status and macrobenthic assemblages of the Xin'an River Estuary and its adjacent waters, a survey was conducted for environmental variables and macrobenthic assemblage structure in September 2012(Yantai, China). Several methods are adopted in the data analysis process: dominance index,diversity indices, cluster analysis, non-metric multi-dimentional scaling ordination, AMBI and M-AMBI. The dissolved inorganic nitrogen and soluble reactive phosphorus of six out of eight sampling stations were in a good condition with low concentration. The average value of DO((2.89±0.60) mg/L) and p H(4.28±0.43) indicated that the research area faced with the risk of ocean acidification and underlying hypoxia. A total of 62 species were identified, of which the dominant species group was polychaetes. The average abundance and biomass was577.50 ind./m2 and 6.01 g/m2, respectively. Compared with historical data, the macrobenthic assemblage structure at waters around the Xin'an River Estuary was in a relatively stable status from 2009 to 2012.Contaminant indicator species Capitella capitata appeared at Sta. Y1, indicating the animals here suffered from hypoxia and acidification. AMBI and M-AMBI results showed that most sampling stations were slightly disturbed,which were coincided with the abiotic measurement on evaluating the health conditions. Macrobenthic communities suffered pressures from ocean acidification and hypoxia at the research waters, particularly those at Stas Y1, Y2 and Y5, which displays negative results in benthic health evaluation.     

1959～2013年长江河口南槽动力地貌演变过程

南槽作为长江口入海四口之一,是长江水沙输运向海的主要通道。在长江入海水沙急剧变化和长江口大型涉水工程的影响下,南槽的动力地貌过程成为当前长江河口研究的重点内容之一。分析和揭示近50年来南槽的动力地貌变化过程对理解长江河口响应人类活动和自然驱动作用的变化具有重要意义。基于此,本文通过1959~2013年长时间序列的南槽地形资料,研究长江入海水沙变化及南槽落潮分流分沙比影响下的南槽动力地貌演变过程。结果表明,南槽在1989年江亚南沙并滩前后呈现两种不同的地貌演化阶段:江亚南沙并滩前,南槽普遍发生淤积,两侧浅滩不断淤涨,河槽总体呈缩小态势,河槽拦门沙呈现"双峰"状态;江亚南沙并滩后,南槽呈现出"上段冲蚀加深、中段微冲、下段河槽束窄、两侧浅滩淤积"的状态,拦门沙向"单峰"发展。此外,周边涉水工程的实施对近期南槽地貌的冲淤演变过程有较大的影响。     

长江口水下三角洲沉积物粒度组成及其在减沙背景下的响应

近年来长江口水下三角洲对入海泥沙减少的响应问题越来越受到关注。通过分析长江水下三角洲百年沉积速率的分布特征及位于水下三角洲泥质沉积区不同位置4个浅孔的粒度、~(210)Pb和~(137)Cs数据,探讨其对流域入海水沙变化及水动力变化的响应。研究结果显示,1954年后长江口北支萎缩是导致CDZS10孔所在区域沉积物粒度较其他3孔明显粗的主要原因。而CDZS10孔沉积物上粗下细则是由20世纪80年代三峡蓄水后长江入海泥沙显著下降、海洋动力明显增强引起的。另外,北支萎缩及三峡水库调蓄作用导致泥质区南移,并向杭州湾和嵊泗列岛延伸发展。     

Nitrate δ15N and δ18O evidence for active biological transformation in the Changjiang Estuary and the adjacent East China Sea

The Changjiang Estuary has been considered as one of the most polluted estuaries in the world due to high nitrate (NO-3) input, especially in spring and summer. In this study, δ15N and δ18O of NO-3 , along with other chemical parameters in this area, were measured in spring to evaluate NO-3 biogeochemical processes. A simple two end-members mixing model was used to examine the relative contribution of the Changjiang River Diluted Water and marine water to NO-3 sources in the Changjiang Estuary and the adjacent East China Sea. The isotopic signals show that NO-3 behaved relatively and conservatively in Transect F and Transect P where assimilation was weak possibly due to vertical mixing, while active assimilation and weak nitrification occurred in Transect D. Spatial difference in assimilation was indicated by the～1:1 enrichment of δ15N and δ18O in the three transects, while spatial difference in nitrification was reflected by deviations of δ15 N and δ18O from assimilation line. Our results suggest that the input of the Changjiang River Diluted Water promoted NO-3 assimilation possibly by stratifying the water column which favored the phytoplankton growth.     

伶仃洋夏季叶绿素a时间变化特征及分析

文章使用2019年7月5日—20日在珠江河口伶仃洋定点连续观测的海表面叶绿素a质量浓度、海表面气温、气压、风速、风向、海表温度、盐度、流速、流向、遥感降雨量数据和中等分辨率成像光谱仪可见光波段影像, 利用小波分析和集成经验模态分解方法分析了观测期间内伶仃洋海表面叶绿素a的时间变化特征及其影响因子。分析结果表明, 观测期间海水表层叶绿素a质量浓度的变化范围为0.44~1.75µg·L^-1, 平均值为0.80µg·L^-1, 其变化周期主要为6h、12h和24h。其与相对应周期的潮流存在明显的相位关系, 并且在降雨后两者的相位关系发生了转换。7月5日—12日, 叶绿素a与潮流基本呈反相位关系, 涨急时叶绿素a质量浓度低, 落急时叶绿素a质量浓度较高, 浓度相差约为0.3µg·L^-1。珠江流域在7月8日—13日发生了一次强降雨过程, 降雨前后海水表层叶绿素a质量浓度在6h、12h和24h周期波段的振幅由0.02~0.09µg·L^-1增加到0.15µg·L^-1左右。同时, 降雨对珠江河口的叶绿素a质量浓度造成了一个持续80h的增加过程, 浓度增加了0.3µg·L^-1。发生降雨后, 7月13日—20日期间潮流滞后于叶绿素a约6h, 水位最高时叶绿素a质量浓度最低, 水位最低时叶绿素a质量浓度最高。由以上结果可以看出, 降雨不仅引起了河口区叶绿素a质量浓度的增加, 还造成了叶绿素a和潮流间相位关系的转换。     

黄河口埕岛油田周边海域的生态环境特征及变化趋势

为了了解黄河口埕岛油田周边海域的生态环境特征及变化趋势,采用单因子质量指数法和综合指数法对该油田周边海域海水和沉积物历年跟踪监测结果进行了评价,并对该油田周边海域海洋生物的变化情况进行了分析。结果表明:除2009—2011年无机氮,2011年磷酸盐外,埕岛油田周边海域历年监测水质要素均符合《海水水质标准》中第二类水质标准;历年监测沉积物要素均符合《海洋沉积物质量》中的一类标准。2006—2011年调查海域水质和沉积物油类含量的变化趋势与埕岛油田年产油量具有良好的对应关系。调查海域生物环境状况整体水平有所下降,海洋石油开发对埕岛油田周边海域的海洋环境造成了一定的负面影响。     

Early warning indicators for river nutrient and sediment loads in tropical seagrass beds: a benchmark from a near-pristine archipelago in Indonesia

In remote, tropical areas human influences increase, potentially threatening pristine seagrass systems. We aim (i) to provide a bench-mark for a near-pristine seagrass system in an archipelago in East Kalimantan, by quantifying a large spectrum of abiotic and biotic properties in seagrass meadows and (ii) to identify early warning indicators for river sediment and nutrient loading, by comparing the seagrass meadow properties over a gradient with varying river influence. Abiotic properties of water column, pore water and sediment were less suitable indicators for increased sediment and nutrient loading than seagrass properties. Seagrass meadows strongly responded to higher sediment and nutrient loads and proximity to the coast by decreasing seagrass cover, standing stock, number of seagrass species, changing species composition and shifts in tissue contents. Our study confirms that nutrient loads are more important than water nutrient concentrations. We identify seagrass system variables that are suitable indicators for sediment and nutrient loading, also in rapid survey scenarios with once-only measurements.     

Potential effect of sedimentary iron-phosphorus accumulation on frequent algal bloom in the Pearl River Estuary

Based on laboratory culture of harmful alga on iron and phosphorus uptake, and the study of accu-mulation of iron-phosphorus in cores and release of iron and phosphorus from surficial sediments collected in the Pearl River Estuary, the reasons of the high frequency of phytoplankton bloom therein are discussed. The results show that Fe starvation can make algal growth rate slow down and the peak of cell number decrease. Fe and P contents in algal cell bear a significant correlation and the molar ratio of P:Fe is ~356:1, suggesting that algal uptake of Fe and P is synergistic. Total Fe and total P in sediments are positively correlated and Fe-P is the main species of inorganic sedimentary P. Through continuous leaching with agitation, 34.26%―80.21% of exchangeable P and 4.04%―22.52% of ex-changeable Fe are released from surficial sediments, implying that the accumulation of Fe-P in sedi-ments is available for providing nutrients (P and essential Fe) for the demand of phytoplankton bloom. These factors might be responsible for a higher frequency of red tides than other marine regions.     

利用WAVEWATCH和SWAN嵌套计算珠江口附近海域的风浪场*

基于CCMP(Cross Calibrated Multi-platform)卫星遥感海面风场数据,通过将WAVEWATCH和SWAN (Simulating WAves Nearshore)模型嵌套的方法,数值模拟了珠江口附近海域的风浪场。将总计10个月的数值模拟的有效波高、波周期和波向分别与相应的观测值进行了定量比较。结果说明,有效波高的平均绝对误差为15.4cm,分散系数SI为0.240,相关系数为0.925;波周期的平均绝对误差为1.9s,分散系数SI为0.433,相关系数为0.636;波向的平均绝对误差为23.9°。计算的波高和波向与观测结果的变化趋势相吻合。由于第三代海浪模式本身的缺陷,导致所计算的波周期偏小。总体说来,本文所采用的数值模式能较好地模拟珠江口附近海域的风浪场。另外,还设计了6个算例以探讨采用不同的计算方法和风场对计算结果精度的影响。结果表明使用本文的数值方法和高精度的CCMP风场确实可以提高计算结果的精度。     

Multi-source water pollution in a highly anthropized wetland system associated with the estuary of Huelva (SW Spain)

Major ions, nutrients, trace elements and pesticides distribution were studied in a coastal wetland heavily impacted by human development in Spain. Past land use has altered the local hydrodynamics leading to the partitioning of the ecosystem into a tideland subject to marine influence, and an artificial freshwater reservoir created by stream impoundment. The tideland stretch is flooded twice a day with a heavy metal plume that emerges from the mine-polluted estuary of Huelva and propagates landward depicting the same dispersal trend of major seawater ions. Additionally, the tidal channel receives acid discharges from industrial point sources that contribute to metal enhancement. The impounded area and stream tributaries are affected by agrochemicals runoff (nitrate, phosphate, pendimethalin, simazine, diuron and therbuthylazine) from surrounding agricultural lands. The tidal regime plays a crucial role in the transport and dispersion of pollutants, except in the artificial reservoir where freshwater exhibits a seasonal mineralization pattern.