Chloride Loss in Fine Aerosols over the Atmosphere of Pearl River Estuary

The biogeochemistry of inorganic carbon and nutrients in the Pearl River estuary and the adjacent Northern South China Sea

The Western Pacific Coasts (WPC) are the outlets of many large Asian rivers. In recent years, the interplay of climate changes and human activities has persistently altered the suspended sediment concentrations (SSC) in the WPC, triggering substantial shifts in coastal ecosystems. However, the scarcity of coastal observation stations hampered comprehensive investigations at large scales. This study employed three representative SSC retrieval models and utilized Landsat images acquired from 1990 to 2020 to estimate the SSC in the WPC with a focused endeavor to dissect the intricate spatial and temporal variability of SSC in the region. The findings revealed the following insights: (1) The outcomes derived from the three distinct SSC models consistently manifested a discernible decreasing pattern in SSC changes over the past three decades across all six major estuaries (Liao River Estuary, Yellow River Estuary, Yangtze River Estuary, Hangzhou Bay, Pearl River Estuary, and Mekong River Estuary). (2) The seasonal attributes of the six major estuaries differed, primarily due to distinct dominant influencing factors like precipitation, upstream sediment load, wind, and tides. (3) Collectively, SSC tends to be relatively higher in the Yangtze River Estuary, Hangzhou Bay, and Yellow River Estuary, while the Pearl River and Mekong River Estuaries exhibit relatively lower levels. Notably, the SSC exhibited distinct spatial traits along the coastlines of different estuaries. (4) SSC in the non-estuarine regions along the WPC, a similar significant declining trend in SSC is observed as in the estuaries, albeit the rate of decline generally appeared to be less pronounced. Furthermore, regions with faster rates of SSC reduction are typically concentrated near major estuaries in the northern part of the Coasts. The decline in estuarine SSC plays an important role in the overall decrease in SSC across the WPC. These study outcomes held substantial significance for advancing the stability and sustainable evolution of the WPC.

Distribution of dissolved iron in the Pearl River (Zhujiang) Estuary and the northern continental slope of the South China Sea

Modeling the mass flux budgets of water and suspended sediments for the river network and estuary in the Pearl River Delta, China

Seasonal variations in the inorganic carbon system in the Pearl River (Zhujiang) estuary

Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China

The Pearl River and its estuary are highly exposed to anthropogenic disturbance. Because bacterial communities play an indispensable role in aquatic ecosystems, there has been an increased research focus on the statuses of these communities under human-induced perturbations. This study investigated the composition, diversity, and structure of bacterial communities across 29 sites from the Guangzhou section of the Pearl River (GZ) to the Pearl River Estuary (PRE) using 16S rRNA gene amplicons. The results revealed similar dominant phyla of bacteria in both GZ and PRE, as well as significant differences in bacterial community composition and diversity between the two sections. Proteobacteria and Cyanobacteria were identified as the primary drivers of compositional differences between GZ and PRE. The Cyanobacteria Dolichospermum_NIES41 and Cuspidothrix issatschenkoi were only present in GZ, whereas the marine Gram-negative bacteria of Porticoccus litoralis and Thalassolituus oleivorans were unique to PRE. Bacterial community composition and diversity exhibit both similarities and differences between GZ and PRE; Proteobacteria and Cyanobacteria are key factors underlying these variations. Bacterial communities in both GZ and PRE are strongly influenced by human activities, and salinity is an important factor in controlling their differences. This study provides a comprehensive analysis of the bacterial communities in GZ and PRE, establishing a foundation for better management of aquatic ecosystems impacted by anthropogenic activities.

Distribution, source and enrichment of some chemical elements in sediments of the Pearl River Estuary, China

Objective Acoustic telemetry was used to examine the spatial-temporal distribution and anadromous migration pattern of juvenile Gulf Sturgeon Acipenser desotoi within the Pearl River and associated coastal estuaries of Louisiana and Mississippi. Methods Acoustic transmitters were surgically implanted in 52 juvenile Gulf Sturgeon (<890 mm fork length) from the Pearl River between 2016 and 2019. Sturgeon were monitored on 247 acoustic receivers in the lower Pearl River and adjacent estuaries across numerous partnering arrays. Result Juveniles were detected on receivers from Lake Pontchartrain, Louisiana, east to Bay St. Louis, and Biloxi Bay, Mississippi. The 3-year study found that juvenile Gulf Sturgeon migration in the Pearl River occurred on cycles similar to those reported from other populations. Juveniles were rarely observed in the estuary and nearshore marine environments from May through mid-October of each year, during which time most sturgeon inhabited the Pearl River. Conversely, most of the juveniles inhabited coastal estuaries from December through February of each year and were rarely observed in freshwater environments during this period. Migration from the river into the estuary occurred during late-October through November, and migration from the estuary into the river occurred in March and April. Distribution patterns varied spatially within the river and estuary ecosystems during each phase of migration. Tagged juveniles occupied the lowest 40 km of the Pearl River while in freshwater, and they occupied the northeastern shoreline of Lake Pontchartrain and Bay St. Louis while in the estuary. Interestingly, juveniles seemed to target specific areas in the estuary during winter that were farther away from the mouth of natal rivers than has been previously reported. Conclusion This study provides a new assessment of juvenile Gulf Sturgeon migration and seasonal distribution for the Pearl River and provides important information for designing and assessing the potential benefits and challenges of habitat restoration for Gulf Sturgeon.

PDF HTML阅读 XML下载 导出引用 引用提醒 极端天气陆地河流面源污染对珠江河口叶绿素分布的影响——评价方法构建与应用 DOI: 10.5846/stxb202103130681 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 南方海洋科学与工程广东省实验室（广州）人才团队引进重大专项（GML2019ZD0303）；热带海洋环境国家重点实验室自主研究项目（LTOZZ2103）；国家自然科学基金面上项目（42077057，41876136） Impacts of non-point source pollutants from river on chlorophyll distribution in the Pearl River Estuary under the extreme weather conditions: the framework and application Author: Affiliation: Fund Project: 100 Talents Program of the Chinese Academy of Sciences，The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan), Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) talent team introduced major special projects 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:近十年来，随着我国粤港澳大湾区的建设，珠江流域人口增长十分迅速，食品和能源需求急剧增加，导致流域上游省份农业用地面积增加，下游省份城市化进程加速，随之导致含农业化肥的农田灌溉用水和生活污水排放大幅度增加。流域的面源污染物进入珠江河口，导致河口海域赤潮发生频率明显增高。此外，全球变暖加剧了南海和西太台风等极端天气事件的发生频率，大量的台风在珠江口附近登陆，对人类活动产生的营养盐在海水中再分布产生较大影响。现场及卫星观测表明，台风等极端天气影响浮游植物时空分布的4个主要影响因子为：海水的垂直混合、流域的降水增加、河流淡水及营养盐的大量输入及风场变化。但是，尚未对这些因子如何影响叶绿素分布进行过清晰阐释。研究构建了粤港澳大湾区陆海气集成模拟系统，一方面通过控制实验来对模式敏感性进行测试，另一方面以台风"天鸽"过境珠江口为例，来对台风过境期间海表叶绿素时空变化机理进行探究。结果表明，陆地模式径流分辨率的提高对模拟结果有很大影响，台风"天鸽"过境时，向岸的风抑制了珠江冲淡水排出，促进外海水涌入，提高海表盐度，降低叶绿素浓度。而台风所致的陆地降水在过境后四天（8月27日）通过径流输出至河口，此次剧烈的增水向珠江口输入大量的营养盐，促进浮游植物持续生长，使叶绿素浓度在台风过境两周（9月1日）后仍在增加。研究所构建的集成模拟系统可适于其它受河口面源污染影响的海湾及近海系统。为未来实现赤潮、缺氧等生态灾害预报提供可能性。 Abstract:Over the last 10 years, progressive development of the Guangdong-Hong Kong-Macau Greater Bay area in our country has caused rapid population growth within the Pearl River watershed. In the meantime, demand for food and energy has increased dramatically. These result an expansion of agriculture land in the upper reaches of the Pearl River catchment and an increase in the rate of urbanization in the downstream area. As a result, groundwater and surface runoff entering the Pearl River up-stream now contains higher levels of fertilizer than previous, whilst in urban areas sewage and effluent production has increased considerably. A side effect of these changes is that the amount of pollution entering the estuary in a non-point source manner has increased, leading to widespread eutrophication there. Besides, global warming increased typhoons from South China Sea and Western Pacific making landfall near the Pearl River estuary, resulting in the enhanced redistribution of anthropogenic nutrients into the oceanic water. Both in-situ and satellite have been used to investigate the impact these typhoons have on Pearl River phytoplankton dynamics. They identified four factors impacting the redistribution of phytoplankton include the vertical mixing of oceanic water, high precipitation in the watershed, the large freshwater discharge and nutrients loading, and the variation of wind fields. To date, there have been no studies address how these four factors work together to influence the distribution of chlorophyll in the Pearl River estuary. In this research, we built a land-ocean-atmosphere modeling system for the China Great Bay Area. We conducted numerous controlled experiments to examine the sensitivity of the system to multiple forcing conditions. We also investigated the effect of each controlling mechanism has on phytoplankton dynamics, using the incidence of Hurricane Hato's arrival in the area as an opportunity to collect first-hand, real-time observations. Our results show that the temporal resolution of river runoff data used in the modeling system has a profound impact on the simulation results. Using daily river runoff data from land surface models produced very different results from those using monthly data. As Hato passed by, strong onshore winds inhibited the spread of freshwater from the Pearl River, increasing the influx of seawater which in turn increased sea surface salinity and reduced the concentration of surface chlorophyll. Four days (August 27th) after Hato had passed by, water that had fallen on land as precipitation during the typhoon entered the Estuary as runoff. The dramatic increase of river discharge coincident with this event enhanced the level of nutrient loading and caused dramatic phytoplankton growth. Chlorophyll levels were still increasing two weeks after the typhoon Hato passing by (September 1st). The land-ocean-atmosphere modeling system built for the Pearl River Estuary in our research could be adapt to other estuarine and coastal regions and would ultimately help predict algal blooms, hypoxia within the aquatic environment, and other ecological hazards in the future. 参考文献 相似文献 引证文献

Temporal and spatial distribution of dissolved oxygen in the Pearl River Estuary and adjacent coastal waters

Some estuarine ecosystems appear to be more resistant to eutrophication than others, but the mechanisms are not well understood. The Pearl River is the second largest river in China and little is known about the long-term nutrient enrichment processes in the Pearl River estuary and adjacent coastal waters of Hong Kong. Seasonal monsoons are a climatic feature of tropical and subtropical regions. However, monsoonal influences on seasonal dynamics of nutrients and phytoplankton biomass have been little studied. This is the first report of such a study using time series of water quality data at stations around Hong Kong from 1991 to 2000. There was a strong seasonality and spatial gradient in salinity, nutrients and phytoplankton biomass around Hong Kong waters. In winter, when the NE monsoon prevailed (winds were stronger), coastal waters and the eastern part of the Pearl River estuary were dominated by high salinities (>30) low nutrients and low phytoplankton biomass. In summer, the coastal plume from the Pearl River estuary on the west moved across the southern waters of Hong Kong to the eastern waters of Hong Kong, as the SW monsoon (winds were weaker) dominated and the Pearl River discharge was maximal. Concentrations of nitrate were high (>60 卩 during summer in the Pearl River estuary, decreased (<30 卩 in the coastal plume south of Hong Kong and were low (<10 卩 in the eastern waters. Chlorophyll a (chl a) concentrations were low, high and low, respectively, in the corresponding waters. Because PO4 oncentrations were low (<1 卩 in all waters, nutrient ratios of N:P and N:Si (N = total inorganic nitrogen, P = PO4) displayed seasonal and spatial changes. In winter, N:P and N:Si were low (near or <16:1 and 1:1, respectively). In summer, however, the N:P ratio increased markedly (>64:1) in the southern waters of Hong Kong and was even higher than in the estuary. Low chl a relative to high N concentrations suggests that the eutrophication effect is not as severe as one would expect from N over enrichment. These results suggest an important role of P limitation in controlling phytoplankton biomass production. It appears that seasonal monsoons serve as a flushing mechanism in 2 ways: (1) monsoons reduce seasonal eutrophication effects by nutrient enrichment during summer; and (2) they prevent long-term (yr) accumulation of organic matter in the sediments due to nutrient enrichment in the region. In summer, when coastal upwelling resulting from the SW monsoon causes offshore movement of the coastal plume in the surface layer, the continental shelf oceanic waters moving shoreward at the bottom flush the coastal waters. In winter, coastal waters with low nutrients replace the entire coastal water of Hong Kong. Due to the monsoon-influenced processes and low phosphorus in the Pearl River estuary, the Pearl River estuary and adjacent coastal waters of Hong Kong appear to be more resilient to enrichment of N.

To study the effect of mineralogical assemblages and chemical characteristics of clays mineral particles on absorption properties in coastal waters of China, we designed a tank experiment and measured the optical properties of suspensions of clay mineral particles for samples collected in Yellow River Estuary (YRE), Changjiang River Estuary (CRE) and Pearl River Estuary (PRE). We designed eight kinds of suspensions of clay mineral particles with concentration of 5, 10, 20, 30, 40, 50, 100 and 200mg/L. The absorption coefficient was measured for all the samples. The results show that the mass-specific absorption coefficient of clay mineral particles (am*) varies for samples collected respectively in YRE, CRE and PRE. The magnitude of am* is higher for samples collected in PRE compared with samples collected in YRE and CRE, especially in the blue band, with am*(410) for the sample collected in PRE 1.5 times higher than that collected in YRE and CRE. We discovered that the composition of clay mineral in PRE is obviously different from that in YRE and CRE. In addition, the content of iron element is higher for samples collected in PRE than that collected in YRE and CRE. The difference in the composition of clay mineral and higher content of iron element could be the reason that the magnitude of am* is significant different for the samples collected in PRE than that collected in YRE and CRE. It suggests that the absorption coefficient of clay mineral particles suspended in waters is not only connected to the SPM concentration, but also mineral and element composition, such as iron. Although the composition of clay mineral and concentration of iron could explain only part of variability observed in the absorption coefficient of clay mineral particles, it is of significant importance for further discover the inherent optical properties in coastal waters and can be helpful for improving the algorithm accuracy in ocean color remote sensing.

Aerosol ionic components at Mt. Heng in central southern China: Abundances, size distribution, and impacts of long-range transport

Water quality information in the coastal region of Hong Kong and the Pearl River Estuary (PRE) is of great concern to the local community. Due to great landuse-landcover (LULC) changes with rapid industrialization and urbanization in the Pearl River Delta (PRD) region, water quality in the PRE has worsened during the last 20 years. Frequent red tide and harmful algal blooms have occurred in the estuary and its adjacent coastal waters since the 1980s and have caused important economic losses, also possibly threatening to the coastal environment, fishery, and public health in Hong Kong. In addition, recent literature shows that water nutrients in Victoria Harbor of Hong Kong have been proven to be strongly influenced by both the Pearl River and sewage effluent in the wet season (May to September), but it is still unclear how the PRE diluted water intrudes into Victoria Harbor. Due to the cloudy and rainy conditions in the wet season in Hong Kong, ASAR images will be used to monitor the PRE river plumes and track the intruding routes of PRE water nutrients. In this paper, we first review LULC change in the PRD and then show our preliminary results to analyze water quality spatial and temporal information from remote observations with different sensors in the coastal region and estuary. The study will also emphasizes on time series of analysis of LULC trends related to annual sediment yields and critical source areas of erosion for the PRD region since the 1980s.