Chemical hydrography of coastal upwelling in the East China Sea

Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles and horizontal distributions of chemical and hydrographic variables. Results show that the coastal upwelling was year-round, but the areas and intensities of the upwelling were quite different in season. The coastal upwelling occurred in all of the coastal areas of the region in spring and summer, but in autumn only in the area off Zhejiang Province, and in winter in the area off Fujian Prov- ince. It was the strongest in summer and the weakest in winter. Geographically, it was the strongest in the area off Zhejiang Province and the weakest in the southmost or northmost parts of the East China Sea. The estimated nutrient fluxes upward into euphotic zone through coastal upwelling were quite large, es- pecially for phosphate, which contributed significantly to primary production and improved the nutrient structure of the coastal ecosystem in the East China Sea.

Hydrography and Circulation in the Eastern Tropical Indian Ocean during April-May 2011

The distribution of hydrography and circulation in the eastern tropical Indian Ocean(ETIO) during April-May 2011 were analyzed using cruise observations,satellite observations,and historic hydrographic data.It was observed that warm water(>28℃) occupies the upper 50-m layer in the ETIO.Low-salinity surface water was observed at the mouth of the Bay of Bengal(BOB),which further extends to the Arabian Sea and off Sumatra via the Sri Lanka coast and the eastern bay mouth.Arabian Sea high-salinity water(ASHSW) is carried eastward along the equator to around 90°E by the equatorial undercurrent(EUC).It also runs south of Sri Lanka(north to 3°N) and in the western bay mouth(west to 87°E) but is much shallower than its counterpart at the equator.It is suggested to be the residual of the ASHSW,which intrudes into the BOB during the preceding southwest monsoon.Our results also show that,in the south of Sri Lanka,just below this subsurface high-salinity water,very-low-salinity water(about 34.8) occurs at depths of 100-200 m.Further analysis suggests that this low-salinity water comes from the BOB.

Experimental evaluation of a hydrography surface vehicle in four navigation modes

Considering the effectiveness of maritime transportation,a large number of world’s trade is carried by sea and ports.Monitoring ports and harbors are essential for 24 hourly loading/unloading of ships.In this regard,bathymetry and monitoring of depth data especially in real time manner would be very valuable and worthy.To plot hydrography map of ports and harbors in the bureau as online and with low cost,a Surface Vehicle(SV)is designed and developed.This vehicle could navigate in four modes.Operator could seat on the boat and run by joystick or stand in slipway and control by Remote Controller(RC)or seat in the office and navigate by a user friend graphical interface.Finally the boat could navigate fully autonomous without any supervision.Comparison accuracy and precision of four mentioned navigation modes was the main objective of this research.Experimental results illustrated that autonomous mode with Standard Deviation(SD)of below 0.5 m was the most precision and comfortable mode,while RC is the more reliable and trustworthy.

Marine hydrographic spatial-variability and its cause at the northern margin of the Amery Ice Shelf

Conductivity, temperature and depth（CTD） data collected along a zonal hydrographic section from the northern margin of the Amery Ice Shelf on 25-27 February 2008 by the 24th Chinese National Antarctic Research Expedition （CHINARE） cruise in the 2007/2008 austral summer are analyzed to study thermohaline structures. Analysis reveals warm subsurface water in a limited area around the east end of the northern margin, where the temperature, salinity and density have east-west gradients in the surface layer of the hydrographic section. The localization of the warm subsurface water and the causes of the CTD gradients in the ＇surface layer are discussed. In addition, the results from these CTD data analyses are compared with those from the 22nd CHINARE cruise in the 2005/2006 austral summer. This comparison revealed that the thermoclines and haloclines had deepened and their strengths weakened in the 2007/2008 austral summer. The difference between the two data sets and the cause for it can be reasonably explained and attributed to the change in ocean-ice-atmosphere interactions at the northern margin of the Amery Ice Shell

The Sediment and Hydrographic Characteristics of Three Horseshoe Crab Nursery Beaches in Hong Kong

Horseshoe crab juveniles have been recorded from sand and sandy-mud nursery beaches at Pak Nai (western New Territories), San Tau and Shui Hau (Lantau Island), Hong Kong. In order to provide a better understanding of these beaches and to identify those plausible factors which have made them preferred by spawning horseshoe crabs, environmental parameters, including temperature, salinity, pH and dissolved oxygen content of the water, and particle size distribution and organic matter content of the sediments at the three sites, were determined and compared. The hydrographic and sediment data obtained for the three study sites have revealed some common environmental features. The three nursery beaches are relatively remote, and far (in Hong Kong terms) from urbanized and densely populated areas. The beaches are generally well sheltered from strong wave action and inundated regularly by estuarine waters. Horseshoe crab adults tend to select these beaches for spawning as their protected features ensures the laid eggs are less likely to be washed out of the sand, and hatched juveniles can feed on the meiofauna and grow. Sediments of the three beaches largely comprise medium-sized sand particles and are moderately sorted, suggesting medium porosity and good water permeability. Such a sand type, with the generally high oxygen levels in incursing waters, may help create a well-oxygenated micro-environment for the normal development of horseshoe crab eggs, larvae and juveniles. Lantau Island beaches at San Tau and Shui Hau are relatively free from organic pollution, as reflected in generally high dissolved oxygen level, and low BOD 5 and ammonia nitrogen values. Pak Nai is, however, more polluted.

Evaluation of the Quality for the Egyptian Red Sea Coastal Waters during 2011-2013

To assess the quality of the Egyptian Red Sea coastal waters for the sustainable use and development, due to its importance for the national income, four field campaigns were annually carried out during the period from 2011-2013 to investigate the hydrography, nutrient salts, heavy metals and petroleum hydrocarbons. Except for the area of Bir Shalatein, the results of beach litter cleared out that the shoreline of the studied area is not affected by man-made litter. No sewage could be observed. The results of the present study showed that water temperature followed seasonal changes in air temperature. Red Sea water is more saline than adjacent Arabian Sea. DO revealed high values and presence of well oxygenated waters. Minor changes in the distribution of pH, BOD, DOM and COD, revealed that limited effects of human impacts and depend mainly on the dynamics of its water as well as on the geographical location. Low Chl-a and TSM concentrations and high transparency revealed that also the effect of human impacts is almost negligible. Significantly higher sea water temperatures, TSM, pH, DO, BOD, DOM, and COD were observed in summer season compared to their corresponding values in winter season. Dissolved inorganic nitrogen concentrations were quite low because there is little nutrient input from soil, agriculture and pollution on land. Based on the annual mean values, the pattern concentrations of dissolved inorganic nitrogen forms followed the order: NO3 > NH4 > NO2. The Red Sea coastal waters are classified as oligotrophic to mesotrophic state. A remarkable increase of PO4 concentration was observed in the middle Red Sea stations due to huge amounts of effluents enriched with phosphate from the main shipping and industry of Phosphate Companies. SiO4 displayed a large variability due to the supply of SiO4, which flows in the Red Sea through the strait of Bab El-Mandab, biological consumption, organic matter decomposition and the partial dissolution of quartz particle transported to the sea from the surrounding desert during sand storms. Concentrations of ammonia, phosphorus, total nitrogen, and total phosphorus were significantly higher in summer compared to their corresponding values in winter. In general, the majority of TN and TP in winter were in the form of organic-N (91.3%) and organic P (96.8%). The mean DIN/DIP ratio revealed high nitrogen concentrations in comparison with that of phosphorous and the surface coastal waters of the Red Sea are principally, P-limited for phytoplankton growth with higher values in winter season compared to summer season. Concentrations of heavy metals were quite low most probably due the absence of major local impacts of any land-based sources and/or any major negative impacts of coastal tourism. Regional variations were almost negligible and except for Mn, Cd, and Hg insignificant seasonal variations were observed. The present study revealed concentrations for metals in the acceptable levels. Furthermore, concentrations of petroleum hydrocarbons were significantly higher in winter than in summer which is mainly attributed to the increase in the rate of evaporation for petroleum hydrocarbons in summer. In general, the maximum concentration was much lower than the harmful concentrations reported for seawater. Correlation coefficients as well as principle component analysis (PCA) were applied.

Assessment of the Hydrochemical Characteristics of the Suez Gulf Coastal Waters during 2011-2013

The coastal region of the Suez Gulf, is one of the most densely industrialized zones in Egypt. In order to assess the quality of Suez Gulf coastal waters for the sustainable use and development, and consequently for the national income, 12 field campaigns were carried out in 3 years (2011-2013). The results of beach litter cleared out that the shoreline of the Suez Gulf, especially Ras Gharib area was subjected to many factors which undoubtedly affected the rate of man-made litter accumulation. The most abundant visible items were general litter as they represented 30.64% of the total items encountered. Oil, seaweeds as well as old and new tar constituted 15.41%, 14.85% and 11.84%, respectively. The increase on the levels of water temperature, Chl-a, TSM, DO, BOD, DOM, COD, ammonium ion, nitrite, nitrate, total phosphorus, silicate and total nitrogen developed a eutrophic region. In general, dissolved inorganic nitrogen (DIN) species were almost 9 times higher in the northern parts compared to the south-ern ones revealing that the northern parts of the Gulf were more affected by human impacts compared to the southern area. Moreover, concentrations of most studied metals such as Zn, Mn, Ni, Cu, Cr, Cd, Pb, and Hg were higher in Northern parts com-pared to southern parts of the Gulf. The concentrations of dissolved metals in the northern and southern Suez Gulf followed the following order: Fe ≥ Zn ≥ Cu > Pb > Mn > Ni > Cr > Cd ≥ Hg. Except for Hg, concentrations of metals were in the accepta-ble ranges recommended internationally. Hg concentrations especially in the northern Suez Gulf were slightly higher than the permissible levels. As the northern parts of the Gulf were more suffered from oil pollution, total petroleum hydrocarbons revealed higher concentrations in the northern parts compared to the southern parts of the Gulf. Seasonal variations, on the other hand, indicated higher levels of DO, BOD, DOM and COD, chloropyll-a, TSM, ammonia, nitrate, total nitrogen in winter compared to their corresponding values in summer. In general, the majority of TN and TP in winter were in the form of organic-N (87.2%) and organic P (94.1%). These percentages were 77.8% and 37.3%, respectively in summer. The surface coastal water of the Suez Gulf was principally, P-limited for phytoplankton growth in different investigated regions. Furthermore, the DIN/DIP ratio was higher (94.2:1) in winter season compared to summer season (6.3:1). Concentrations of Fe, Zn, Cd, and Hg in winter exhibited sig-nificantly higher values compared to their corresponding values in summer. On con-trast, Mn, Ni, Cu, Cr, and Pb exhibited significantly higher values in summer compared to their corresponding values in winter. Furthermore, concentrations of petroleum hy-drocarbons were significantly higher in winter than in summer which is mainly at-tributed to the increase in the rate of evaporation for petroleum hydrocarbons in summer due to the increase in water temperature and water salinity. In general, the maximum concentration was much lower than the harmful concentrations reported for seawater. A stepwise multiple linear regression, analysis of variance (ANOVA), and principle component analysis (PCA) were applied.

THE MONSOON IN THE ARABIAN SEA:IMPLICATIONS FROM RADIOLARIAN FLUXES TO THE DEEP SEA

Evolution of Monsoon climate can be attributed to high altitude topography of the Himalaya—Tibetan Plateau. It is important to decipher the modern Monsoon processes in the Indian Ocean so that we will have a better understanding of global evolution of paleoclimate. An international collaborative effort has been expended since 1986 to collect marine particle fluxes in the Arabian Sea where significant amount of organic carbon is fixed annually. Such high biological productivity is mainly due to monsoonal upwelling that occurs twice a year in the region. The southwest (SW) Monsoon occurs in June to September and the northeastern (NE) Monsoon occurs in November to February with a varying degree depending on the regions. PARFLUX sediment traps were deployed in the bathypelagic zone (2800～3000m) at three locations (Western[16°20′N, 60°30′E], Central[14°31′N, 64°46′E], and Eastern[15°31′N, 68 43′E] Stations) representing different patterns and degrees of the Arabian Sea particle fluxes.

The Influence of Large-Scale Phenomena on La Paz Bay Hydrographic Variability

We analyzed the hydrographic variability of La Paz Bay, the largest coastal water body in the Gulf of California, and its relationship with Pacific large-scale phenomena, including the El Ni?o-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Pacific-North America pattern (PNA), and North Pacific pattern (NP). We used several indices related to these phenomena and the hydrographic variability data of La Paz Bay, consisting of the annual sea surface temperature patterns from satellite imagery from 2000 to 2010 and the mixed layer depths measured with?in situ?data from 1994 to 2009. The results indicate the sea surface temperature fluctuated during the study period, with 2007 as the coldest year and 2009 as the warmest. Two periods were identified in the annual thermal cycle of the bay, one period of warmth from June to November, and one of cold from December to May. The sea surface temperature is primarily influenced by the ENSO. The mixed layer depth analysis showed its absence during August-September, while the deepest ones were in November-March. The unusual 100 m mixed layer depth noted during February 2002 and its absence in March 1996 and 2009 were related to uncommon atmospheric conditions in the annual patterns of the ENSO, PNA, and NP. The variability of the mixed layer depth is primarily related to the variability of the NP. We concluded that the hydrographic conditions of La Paz Bay are most influenced by the NP during the cold phase of its annual cycle, and by the ENSO during the warm phase.

Contribution of Gulf of Aqaba Water(GAW)to Red Sea waters

Data obtained on hydrography and currents in meridional sections in the Gulf of Aqaba and the Red Sea in November 2013 and March 2015 were used to determine the extent of contribution of Gulf of Aqaba Water(GAW)to the formation of Red Sea waters.The southward flow across the Strait of Tiran was^0.02 Sv in both periods which is direct evidence of significant contribution of GAW to Red Sea waters in autumn-winter.A multiple tracer analysis using temperature,salinity,and dissolved oxygen showed that the GAW,on entry into Red Sea,bifurcates into two branches.The upper branch exiting the Strait in the depth range 150-220 m has densities between 28.3 and 28.5,continues to flow at the same depths,and feeds the Red Sea Overflow Water(RSOW).The lower branch that exits between 220 and 250 m above the sill cascades down its southern face,mixes with northward recirculating branch of Red Sea Deep Water(RSDW)and sinks to the bottom and forms part of southward-flowing RSDW.Contribution of GAW to northern Red Sea waters below 100 m depth was 36±0.4%in November 2013 and 42.1±5.4%in March 2015.GAW is traceable down to 17-19°N in RSDW and RSOW.Volume contribution of GAW to RSOW was 9.6*1012 m3,about 50%higher than that for RSDW(6*1012 m3).Analyses of the data from R.V.Maurice Ewing cruise in 2001 gave similar results and lend support for these deductions.

Roles of Geospatial Technologies in Hydrographic Practice

Any seafarer or mariner that uses the sea knows that navigation without correct charts is impossible and hazardous because nautical charts are the most essential and indispensable tools for vessels to sail safely at sea.For vessels to safely sail at sea,the seas and the oceans ought to be charted and this falls within the domain of hydrography.However,the seas cannot be charted effectively in the absence of the deployment of human resources and adequate tools like satellite and aerial imagery,survey boats and other equipment that will facilitate the hydrographic operations.The acquisition of data and information about the sea depths,nature of sea bed,waterways,navigational hazards and navigational objects among others,basically falls within the sphere of hydrography which is primarily known as survey at sea.The paper offers a review of geospatial technologies in hydrographic practice for enhanced safety of navigation at sea.The review is important to both the mariners,shipping industry and the government in order to explore the potentials provided by Geographic Information System,Remote Sensing,cloud GIS,big data GIS and Global Positioning System to enhance the practice of hydrography.The data and materials used for the review were obtained from literature in the internet and other published works.The paper looked at hydrography as a profession,roles of geospatial technologies in hydrographic practice,benefits of hydrography to national development and finally,the weaknesses of geospatial technologies in hydrographic practice were equally examined.

Invasion of Danish and Adjacent Waters by the Comb Jelly Mnemiopsis leidyi—10 Years After

The invasive ctenophore Mnemiopsis leidyi, which comes from North America’s east coast, was observed in Danish waters for the first time in 2007. Since then, the new invader has every summer spread in Danish and adjacent waters (i.e. North Sea, Limfjorden, Skagerrak, Kattegat, Belt Sea, Baltic Sea). The invasive comb jelly has apparently come to stay, as it has no effective enemies. Possible harmful effects of M. leidyi which feeds voraciously on zooplankton, fish eggs and larvae, have so far not been thoroughly studied in Danish waters, although dedicated attempts have been made in Limfjorden and in the central Baltic Sea. Over the last 10 years, the Danish national environmental monitoring program did not include gelatinous zooplankton, but new initiatives have been recently taken. A brief overview of our current knowledge on the impact of M. leidyi in Danish waters is given here.

The Conceptual Model and Its Empirical Studies of Sustainable Carrying Capacity of Water Resources: A Case Study of China Mainland

Based on the interactive development of new industrialization, rapid urbanization and agricultural modernization(IUAM), and from the viewpoint of interactive responses and supply-demand relationships between regional water resources carrying capacity and economic-social development, this paper puts forward the concepts and characterization methods of water resources relative intensity(WRI), water resources carrying rate(WCR) and sustainable index of water resources system(WSI). Considering the catastrophic trait of water resources carrying capacity and its contradictory relationship with WRI, a modified Catastrophe Model, which combines Catastrophe Theory and Fuzzy Mathematic Theory, was introduced to perform a multi-objective and multi-criterion comprehensive assessment of the sustainability of water resources carrying capacity(WSCC) based on benchmarking. According to these concepts and models, land WSCC for the China mainland was set as an example for empirical analysis. The results showed that at the scale of first-grade water regions, Liaohe River, Yangtze River and Pearl River regions had high WRI of domestic water, while Northwestern Rivers, Southeastern Rivers regions and Yangtze River region in some years had high WRI of eco-environment water. However, they were all in a downtrend, while the other four northern regions had low WRI in an uptrend. The agricultural WRI in Songhua River, Yellow River and Northwestern Rivers regions were relatively high and industrial WRI in Songhua River, Yangtze River and Pearl River regions were also relatively high. At the provincial scale, WSCC of urban domestic water was relatively stable, WSCC of eco-environment was obviously fluctuating, and WSCC of agriculture and industry were constantly rising. Overall, WRI in the China mainland generally decreased. The convergence of provinces with high consumption intensity of water resources and spatial spillover of WUE in high WCR provinces promotes water resources development and utilization, progressing toward doubly sustainable development. In the future, China should try to find new ideas and methods of dynamic management of regional water resources and unified management of basin water resources, building on the foundation of traditional water resources planning. Meanwhile, water resources should be considered in regional PRED(population, resources, ecology and development) systems for integrated dispatching and optimizing configuration so that the improvements of WSCC and harmonious development of water resources and regional populations, eco-environment, economy and society can be achieved.

Review of near-shore satellite derived bathymetry: Classification and account of five decades of coastal bathymetry research

The number of civilian,commercial and military applications are dependant on accurate knowledge of bathymetry of coastal regions.Conventionally,hydrographic surveying methods are used for bathymetric surveys carried by ship-based acoustic systems,but needs highcost resources.Space technology has provided a cost-effective alternate means for charting near shore and inaccessible waters.The optical satellite data have capabilities to offer alternate solution in near-shore region,which has been researched for past 50 years,using evolving algorithms to estimate Satellite Derived Bathymetry(SDB).However,there is no agreement on use of terms like approach,model,method and techniques,which have been used varyingly and interchangeably as per context of SDB research.This paper suggests a classification scheme for SDB algorithms which is also applicable to other Marine Remote Sensing studies.In this paper,based on literature available on SDB for the past five decades,an insight on SDB classification has been offered grounded in research philosophy.The SDB approaches,models,methods and techniques have been elaborated with chronological development,along with SDB studies based on them,their accuracy and errors in SDB retrieval.We have suggested a matrix of prerequisite satellite data,in-situ data resolution,methods and algorithms of SDB based on level of accuracy needs to be achieved,which will guide future researchers to select one as per their context of research.