Forms of Nitrogen (NO 3 - -N; NO 2 - -N and NH 2 CONH 2 -N) and their relations to A.O.U. in the Indian coastal waters of Arabian Sea

The distribution of three important dissolved forms of nitrogen, viz. nitrate, nitrite and urea in the surface and bottom water samples collected from 27 selected hydrographic profiles, in the Arabian Sea, along the west coast of India is described. Of the three forms, nitrate concentrations were the highest and comparatively higher concentrations were observed in the bottom water. Decomposition of organic matter resulting in the release of the thermodynamically stable nitrogen species, i.e. nitrate, may be the major factor resulting in higher nitrate concentrations at these depths, where the water is also characterized by low values of dissolved oxygen and temperature. The significant positive correlation between A.O.U. and nitrate of the bottom water samples emphasizes the role of oxidative decomposition of organic matter which plays an active role in reducing the oxygen concentrations below the theoretical values since at this depth ( , 200 m) the net production is taken to be zero. This is also evidenced by the negative correlation of nitrate with dissolved oxygen and temperature, for the bottom samples.     

Nutrient distribution in locations of the Gulf of Trieste (northern Adriatic sea) suspected of pollution

Nutrients (ammonium‐nitrogen, nitrite, nitrate, orthophosphate and dissolved silica) as well as some chemical‐physical parameters (temperature, pH, salinity, dissolved oxygen and total suspended matter) were determined in filtered seawater samples taken at the surface, at middle depth and at the bottom, in 6 open‐sea locations of the Gulf of Trieste (northern Adriatic Sea) close to pipeline exits that discharge wastewaters from treatment plants. The collected data allow a comparison of the quality of these open‐sea waters with coastal waters and constitute a reference for successive monitoring in these locations suspected of pollution. A multivariate statistical analysis by the principal component method shows that the considered ecosystem can be modeled with two factors: the first one is referenced to the marine environment, in particular to the decomposition of the organic debris in deep water; whereas the second factor is referenced to the input of freshwaters in the Gulf, driving nitrates from agricultural lands.     

Examining the coupling of carbon and nitrogen cycles in Appalachian streams: the role of dissolved organic nitrogen

Although regional and global models of nitrogen (N) cycling typically focus on nitrate, dissolved organic nitrogen (DON) is the dominant form of nitrogen export from many watersheds and thus the dominant form of dissolved N in many streams. Our understanding of the processes controlling DON export from temperate forests is poor. In pristine systems, where biological N limitation is common, N contained in recalcitrant organic matter (OM) can dominate watershed N losses. This recalcitrant OM often has moderately constrained carbon:nitrogen (C:N) molar ratios (approximately 25-55) and therefore, greater DON losses should be observed in sites where there is greater total dissolved organic carbon (DOC) loss. In regions where anthropogenic N pollution is high, it has been suggested that increased inorganic N availability can reduce biological demand for organic N and therefore increase watershed DON losses. This would result in a positive correlation between inorganic and organic N concentrations across sites with varying N availability. In four repeated synoptic surveys of stream water chemistry from forested watersheds along an N loading gradient in the southern Appalachians, we found surprisingly little correlation between DON and DOC concentrations. Further, we found that DON concentrations were always significantly correlated with watershed N loading and stream water [NO3-] but that the direction of this relationship was negative in three of the four surveys. The C:N molar ratio of dissolved organic matter (DOM) in streams draining watersheds with high N deposition was very high relative to other freshwaters. This finding, together with results from bioavailability assays in which we directly manipulated C and N availabilities, suggests that heterotrophic demand for labile C can increase as a result of dissolved inorganic N (DIN) loading, and that heterotrophs can preferentially remove N-rich molecules from DOM. These results are inconsistent with the two prevailing hypotheses that dominate interpretations of watershed DON loss. Therefore, we propose a new hypothesis, the indirect carbon control hypothesis, which recognizes that heterotrophic demand for N-rich DOM can keep stream water DON concentrations low when N is not limiting and heterotrophic demand for labile C is high.     

WATER QUALITY IN A MEDITERRANEAN MARINE PROTECTED AREA (NORTH SPORADES ISLANDS, GREECE)

Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits.     

Water quality in a mediterranean marine protected area (North Sporades Islands,Greece)

Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits.     

Distributions, cycling and recovery of amino acids in estuarine waters and sediments

Acid hydrolysis of estuarine water samples for the determination of amino acids (AAs) was tested and found to be effective at high (250 μM) nitrate concentrations when the anti-oxidant, ascorbic acid, was added to the samples. Hydrolysable AA concentrations were then determined in surface sediments collected from low and high salinity regions of the Tamar Estuary (UK) during winter 2003 and 2004, and in overlying water when simulated resuspension of sediment particles was performed. Concentrations of AAs in sediment samples comprised <50% of particulate nitrogen, fitting the paradigm that most sedimentary nitrogen is preserved within an organic matrix. When sediment samples were resuspended in overlying water (salinity 17.5), the rapid, measured increase in dissolved AA concentrations almost equalled the reported nitrate concentration in the lower estuary, with the subsequent decrease in the total dissolved AA levels suggested that bacterial uptake was occurring. Our data concur with previous studies on nitrogen desorption from sediments and suggest that an understanding of organic nitrogen cycling will be an important aspect of future effective estuarine management.     

Variability of dissolved reactive phosphate and apparent oxygen utilization along the west coast of India

This work focuses on the spatial variability of dissolved reactive phosphate along the west coast of India. In this study, samples of surface and bottom water was collected from each of the 27 sites during a single pre-monsoon transect along the west coast of India to study the variation of dissolved reactive phosphate. Phosphate showed an enrichment pattern with increase in depth of the water column. In addition to this, an offshore increase in phosphate concentrations was noticed for both surface and bottom stations. Almost all the surface stations of this study area were found to be characterized by negative apparent oxygen utilization (AOU) values, and bottom stations of the deeper offshore zone (200 m depth) displayed large positive AOU values. The bottom stations of shallow near coastal waters and the deeper offshore zone are characterized by an inverse relationship between phosphate and dissolved oxygen, whereas at these depths, a direct relation was observed between phosphate and AOU. AOU is calculated as the difference between oxygen saturation value at the in situ temperature and salinity and the actual measured concentration. This oxidative re-mineralization mechanism decreases the observed dissolved oxygen well below the expected theoretical values, which is concordant with the higher concentration of phosphate and high positive AOU values.     

海洋沉积物-水界面营养盐交换过程的研究1

对胶州湾和渤海沉积物分别进行室内培养实验.结果表明,在沉积物中加入营养盐后,铵氮、硅酸盐由沉积物向水体的迁移增大,铵氮的迁移在总溶解态氮的交换中起主要作用,其交换量约占总溶解态氮扩散量的76%,硝酸盐及磷酸盐由水体向沉积物的迁移减弱.在上覆水中加入营养盐后,硝酸盐、磷酸盐由水体向沉积物的迁移增大,硝酸氮的迁移占总溶解态氮交换的主要部分,约为62%.铵由沉积物向水体的迁移减弱,硅酸盐变成由水体向沉积物迁移.沉积物对于上覆水中营养盐的浓度具有一定的调节作用.无论在充空气或充氮气条件下,磷及硅的交换速率变化不明显,铵氮的迁移占总溶解态氮扩散量的98%以上.充氧条件下硝酸盐由沉积物向上覆水的迁移通量较充氮气条件增加.比较两种不同的通量计算方法(积分和拟合),结果表明由两种计算方法计算的交换速率的变化趋势基本是一致的.     

Impact of domestic sewage on fresh water body

In the present study various (physico-chemical) factors were assessed over a period of two years (from February 2002 to January 2004) to note the chemistry and quality of tank water in Bhalki town of Bidar. Physico-chemical factors like pH, dissolved oxygen, magnesium, chlorine, nitrite, sulphates and chemical oxygen demand were found with maximum concentration during summer season. Similarly, during monsoon season free carbon dioxide, alkalinity hardness, calcium, phosphate, silicon, total solids and biological oxygen demand; and in winter season organic matter were recorded. The concentrations viz., pH, hardness and nitrite were more compared to the potable water standard of WHO. The correlation matrix and dendrogram of physico-chemical factors have been computed and analysed. The positive co-relation coefficient observed between pH and magnesium, dissolved oxygen and hardness, free carbondioxide and calcium, alkalinity and nitrite, alkalinityand phosphate, alkalinity and biological oxygen demand, hardness and calcium, hardness and magnesium, magnesium and chlorine, nitrate and phosphate, nitrite and biological oxygen demand, phosphate and organic matter; and silicon and chemical oxygen demand. The dendrogram confirms chlorine, pH, hardness, silicon, total solids and sulphates are the key factors of the change in the chemistry of water body     

Water quality monitoring in a slightly-polluted inland water body through remote sensing — Case study of the Guanting Reservoir in Beijing, China

This study focused on the water quality of the Guanting Reservoir, a possible auxiliary drinking water source for Beijing. Through a remote sensing (RS) approach and using Landsat 5 Thematic Mapper (TM) data, water quality retrieval models were established and analyzed for eight common water quality variables, including algae content, turbidity, and concentrations of chemical oxygen demand, total nitrogen, ammonia nitrogen, nitrate nitrogen, total phosphorus, and dissolved phosphorus. The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation. With an appropriate method of sampling pixel digital numbers and multiple regression algorithms, retrieval of the algae content, turbidity, and nitrate nitrogen concentration was achieved within 10% mean relative error, concentrations of total nitrogen and dissolved phosphorus within 20%, and concentrations of ammonia nitrogen and total phosphorus within 30%. On the other hand, no effective retrieval method for chemical oxygen demand was found. These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring. The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.     

南黄海不同粒度表层沉积物中可转化氮与环境因子的关系

南黄海不同粒度表层沉积物中可转化氮的形成与释放受环境因子的驱动作用各不相同,上覆水体的温度、盐度、pH值、DO的含量以及NH4^ 和NO3^-的含量都对其有一定的影响．其中DO是不同形态的氮形成与释放最显著的影响因素,这是因为上覆水体中DO的含量愈高,扩散进入表层沉积物中的O2就愈多,沉积物处于相对氧化的环境中,有机质的矿化作用较易进行,致使无机形态氮的含量相对较高,而有机形态氮的含量相对较低,所以其与可转化有机形态氮呈负相关,而与可转化无机形态氮呈正相关．温度与中、细粒度沉积物中的SOEF-N的含量呈显著正相关,可能是因为温度的升高加快了海洋底栖生物的生长发育,使生物排泄物和死亡残体增多,尽管温度的升高加快了沉积物中有机质的矿化分解,但由于中、细粒度沉积物堆积紧密,对温度的响应不明显,致使SOEF-N的含量随温度的升高而升高．上覆水体中的NH;和NO3^-分别与中、细粒度沉积物中的SAEF-N和SOEF-N的含量呈正相关,说明上覆水体中的NH4^ 和NO3^-主要来自于沉积物中SAEF-N和SOEF-N的形成与释放．另外,粗粒度沉积物中不同形态的氮对环境的响应较中、细粒度沉积物中的强．     

大鹏湾中溶解态总氮和总磷的多年调查结果分析

依据2000—2010年每月1次的调查资料,简要描述和讨论大鹏湾海水中溶解态总氮（DTN）和溶解态总磷（DTP）质量浓度的空间分布和时间变化。结果表明由于受到香港和深圳陆源排放的影响,DTN和DTP质量浓度在吐露港和沙头角附近水域1年4季都较高。DTN和DTP的平均质量浓度分别为0.21和0.03 mg.L-1,比溶解态无机氮（DIN）和溶解态无机磷（DIP）的高1倍以上,表明大鹏湾海水中溶解态有机氮（DON）和溶解态有机磷（DOP）分别是DTN和DTP的主要赋存形态。平均DTN/DTP原子比〉16,反映了大鹏湾海水中磷可能是海洋浮游生物生长繁殖的限制因素。夏季,由于南海北部陆架低温、高盐和高营养盐底层水潜入湾内,底层DTN和DTP质量浓度明显高于其他季节。11年调查期间,DTN质量浓度的年际变化趋势平稳,DTP质量浓度的年际变化呈较明显的下降趋势,而DTN/DTP原子比的年际变化呈较明显的上升趋势。     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.     

沉水植物对水-沉积物界面各形态氮含量的影响

在室内模拟条件下研究沉水植物对水-沉积物界面的上覆水、不同层次的间隙水和沉积物中不同形态氮含量的影响.结果表明:总体上,上覆水和间隙水中不同形态氮含量的顺序为有机氮＞氨氮＞硝态氮;沉积物中可交换态无机氮以氨氮为主,沉水植物的存在并没有改变这一格局.不同处理不同层次的间隙水中,各形态氮含量均为下层＞中层＞上层,但沉积物中氨氮和硝态氮含量变化规律不明显.水-沉积物界面氨氮和硝态氮含量呈现明显季节性变化.总之,水-沉积物界面氨氮是沉积物向上覆水扩散的主要氮组分,沉水植物降低了氨氮和硝态氮的扩散通量.     

Processes Influencing Dissolved Organic Nitrogen, Phosphorus and Sulphur in Soils

The influence of different plant and soil processes on the concentrations of soluble organic forms of carbon, nitrogen, phosphorus and sulphur in soil and drainage waters is reviewed. Current knowledge about soluble organic matter is restricted mainly to dissolved organic carbon. Comparable information about soluble organic nitrogen, phosphorus and sulphur in processes such as eutrophication, plant uptake and decomposition is limited. Data are presented to highlight the potential sources of soluble organic components together with a discussion of their likely fate within the soil profile. the implications of changes in land use and management practices on dissolved organic matter are discussed.     

乌梁素海叶绿素a与理化因子的统计分析

利用2008年6月—10月乌梁素海水体叶绿素a浓度与环境理化因子的测定结果,分析了叶绿素a的时空分布特征.运用分层聚类分析法将乌梁素海现有的20个测点分成四类,找出各类测点及总测点中与叶绿素a显著相关的理化因子,建立了多元逐步回归方程.2008年乌梁素海各测点叶绿素a的平均值为6.31 mg.m-3,变幅1.54—26.87 mg.m-3;夏季最高,秋季居中,春季最低,整个区域呈现较明显的东北高西南低的分布趋势.应用SPSS统计分析软件进行相关分析的结果表明叶绿素a与BOD5、悬浮物、浊度、总磷都呈极显著相关,与透明度呈极显著负相关,与pH值和溶氧呈显著负相关.综合逐步回归方程表明,影响乌梁素海叶绿素a的理化因子因不同类型的测点各有所不同,但主要的影响因子有浊度、悬浮物、总磷、总氮、硝酸盐氮和亚硝酸盐氮.     

Dissolved organic substances during a Phaeocystis pouchetii bloom in the German Bight (North Sea)

Dissolved organic substances (carbohydrates, organic nitrogen, free amino acids) were measured in the German Bight (North Sea) in June, 1981. During and before this survey, sea foam was observed in the east Frisian coastal water and it accumulated on the nearby beaches to an unusually high extent. In this coastal water area, a large Phaeocystis pouchetii Lagerheim bloom and very high concentrations of dissolved organic matter were found. The above dissolved organic substances were all positively correlated to a highly significant degree with P. pouchetii cell numbers in the bloom area. An influence of salinity (or river water) on this correlation could be excluded. Thus, exudation or decomposition products of P. pouchetii were most likely the cause of the unusually high concentrations of dissolved organic matter in the bloom area off the east Frisian coast, where P. pouchetii blooms have been reported for many years. Ammonia concentrations were very low in the P. pouchetii bloom area; this and the accumulation of dissolved organic substances might lead to speculation that decomposition of dissolved organic matter by bacteria could have been reduced due to antibiotic activity of P. pouchetii.     

Environmental Impact on Coastal Waters off Rio De Janeiro Due to Sewage Discharge via Submarine Outfall

A survey was made in an area of 28 km² around the outlest of Ipanema's submarine outfall in order to evaluate the impact of the raw domestic sewage effluent on coastal waters. Nutrient concentrations, dissolved oxygen, particulate matter and other physico-chemical parameters were measured monthly for 15 months. Copper and lead concentrations were also determined for two of the samplings.

The outfall has been in operation for 18 years, and the parameters measured within the observation area appear to be in steady state. From the observed radial concentration gradients within the survey area, a real extension of the steady state distribution of particulate matter and of sewage-derived nitrogen was estimated. the stationary cloud of particulate organic matter was about 150 km². From its total inventory and the discharge rate, a mean residence time of the particles in the sea of 56 days is estimated, prior to their being decomposed by bacterial action or settling to the bottom. for sewage derived N (as ammonia or nitrate), the steady state amount (above background) covers an area of about 60 km² and leads to a mean residence time of 5 ± 1 days in the ocean. Phosphorus is readily absorbed by the phytoplankton.

The presence of temperature gradients established by cold upwelling waters controls the dispersion of the sewage material and the rising of the sewage plume to the surface waters.     

Analysis of water quality factors influencing the speciation of inorganic nitrogen using GRA

Based on the water quality data from 2006 to 2008, grey relational analysis (GRA) is used to analyze factors that may have influence on the speciation of inorganic nitrogen in the Chengdu section of middle Min river. The results show that water temperature, changing from 20.2 +/- 2.7, 13.4 +/- 5.7 and 16.8 +/- 5.6 degrees C, is the first restrictive factor for the speciation of inorganic nitrogen; it is negatively correlated with the ratio of total ammonia nitrogen to total inorganic nitrogen contents [m(AN)/m(TIN)] in three different periods of wet season, dry season and year-round. The average pH values for years, in wet and dry periods are 7.6 +/- 0.4, 7.3 +/- 0.3 and 7.8 +/- 0.2, respectively, and have different influences in different seasons. It is the second restrictive factor and positive correlation between pH and m(AN)/m(TIN) in wet season and through the year yet it is the fourth factor in dry seasons. The values of dissolved oxygen (DO), which are 4.6 +/- 1.4, 4.6 +/- 2.4, 4.6 +/- 2.0 respectively, is the third factor and negatively correlates with m(AN)/m(TIN) in third different periods. The chemical oxygen demand (COD) indirectly inhibits the nitrifying bacteria because the DO is depleted in the decomposition of organic matter by heterotrophic bacteria, showing the positive correlation.As the alkalinity can meet the requirement of nitrification in wet season and through the year, it is not restrictive factor. However, it is the second restrictive factor in dry season because of low content of alkalinity inhibiting the growth of nitrifying bacteria.