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1.
The discharge of nutrients is investigated in relation to their sources and effects in two case studies. The reduction of 47% in the phosphorus load from Denmark to marine areas between 1989 and 1993 has resulted in significantly lower phosphorus concentrations in most Danish coastal waters, and tendency to decrease can be seen in the Belt Sea and Kattegat as well. No general changes in nitrogen concentrations have been observed. This is due to the fact that more than 80% of the nitrogen load in Danish waters originate from diffuse agricultural sources.In the Pomeranian Bight strong nutrient gradients are generated by the mixing of Odra river water and coastal water. The spreading of the river plume could be exactly observed especially in winter, when biological activity is low. In general, different types of distribution, transport and modification patterns can be described.The annual input of nutrients from the catchment area to the Baltic Sea was estimated to be around 1000 kt N and 46 kt P. As a result, winter concentrations of phosphate and nitrate are characterized by positive overall trends in the surface layer in all subregions of the Baltic Proper for the period 1969 to 1993. These trends stem mainly from the strong increase in the 1970ies and early 1980ies. Thereafter, the concentrations of both nutrients fluctuate strongly around a high level. The drastic decrease in fertilizer consumption since the late 1980ies mainly caused by the great economic changes in the countries of the former East Bloc is not yet significantly reflected in decreasing winter concentrations, but first signs already have been found in the decrease in averaged phosphate concentrations in winter, especially in the Arkona and Bornholm Seas.  相似文献   

2.
蔡梅  钱旭  王元元  陆志华  张玮 《湖泊科学》2022,34(5):1493-1504
为进一步了解人类活动及环境因子对太湖磷污染的贡献,揭示磷在太湖不同介质中的迁移转化规律,本文以太湖主要入湖湖区竺山湖、西部沿岸区、南部沿岸区和主要出湖湖区东太湖为对象,调查了表层水、上覆水、间隙水和沉积物中总磷(TP)分布的概况,分析了不同介质中磷的交换特征及其影响因素. 结果表明,表层水和上覆水TP浓度基本相当,平均值均为0.10 mg/L,上覆水和间隙水TP差异较大,间隙水平均浓度约为上覆水的7倍,表层沉积物TP含量为474~2160 mg/kg. 在本研究水域中,TP具有较强的沉积物吸附特性,沉积物作为“汇”的特征明显强于其“源”的特征,且磷的留存能力高度依赖于铁浓度. 空间分布上,入湖湖区磷污染程度明显高于出湖湖区,竺山湖和西部沿岸区存在较大的底泥污染释放风险,但竺山湖外源污染影响较内源污染更加突出,应列为当前太湖磷治理重点关注的区域,建议以控源截污作为竺山湖周边区域的治理重点. 西部沿岸区需注重外源和内源污染同步控制. 南部沿岸区周边区域需妥善处理好未来经济发展与废水排放负荷的关系.  相似文献   

3.
In July 1978, total phosphorus and organic carbon were determined in the sediments of Tolo Harbour, a sewage-polluted estuary in north-east Hong Kong. Concentrations were correlated with % silt-clay in each of three areas. Phosphorus concentrations were highest in central Tolo Harbour, lower by about 1.5μg at. P g?1 in the outer estuary, Tolo Channel, and lowest in the polluted inner reaches near large coastal reclamations. The latter values, about 3.0 μg at. P g?1 lower than in central Tolo Harbour, might reflect a selective adsorption of phosphate by reclamation sediments. Organic carbon concentrations were high in the inner reaches and decreased towards the outer channel. Correlations between phosphorus and organic carbon were compared with a published correlation for the east coast of England: in Hong Kong, phosphorus concentrations showed a smaller increase as organic carbon increased, and reached only one-third of the English values as organic carbon approached 2.0%.  相似文献   

4.
The Orbetello lagoon (Tyrrhenian coast, Italy) receives treated urban and land based fishfarms wastewater. The development of severe eutrophication imposed the three main activity adoption focuses on (1) macroalgae harvesting; (2) pumping of water from the sea; (3) confining wastewater to phytotreatment ponds. The responses to these interventions were rapid and macroalgal reduction growth and seagrass return were recorded. Since 1999, a new macroalgal development was recorded. The aim of this research was to discover whether the recent macroalgal growth can be attributed to the continuing wastewater influx from the remaining persistent anthropic sources (PAS) or from the sediment nutrient release. A monitoring programme was carried out between August 1999 and July 2000 in order to measure dissolved inorganic nitrogen and phosphorus in the wastewaters entering into the lagoon and in central lagoon areas, seaweed and seagrass distribution and lagoon N, P annual budgets. The results showed higher N and P values close to PAS. The distribution of the macroalgal species confirms that the available P comes almost entirely from these remaining PAS. In conclusion, the environmental measures adopted produced a significant reduction in algal biomass development in the lagoon; the macroalgal harvesting activities produced a sediment disturbance with following oxidize conditions, which make P unavailable in the lagoon water, excepting close the PAS.  相似文献   

5.
The aim of the present study was to evaluate the mixed function oxidase (MFO) system and the forms of supposed cytochrome P-450 in the liver of black-headed gulls (Larus ridibundus) feeding in a lagoon and on a garbage dump. Tissue levels of polychlorinated biphenyls (PCBs) were also determined. Ethoxyresorufin 10-deethylase (EROD) and aldrin epoxidase activities were higher in the dump gulls than in the lagoon gulls. A marked thickening of the proteins in the cytochrome P-450 area, particularly of P-450c and P-450d, was also found in the dump gulls. No relationship was found between MFO activity and tissue chlorinated hydrocarbon levels.  相似文献   

6.
Phosphorus (P) concentrations in sediments and in surface and interstitial water from three gravel bars in a large river (Garonne River, southern France) were measured daily, downstream of a wastewater treatment plant for a city of 740 000 inhabitants (Toulouse). Measurements were made of vertical hydraulic gradient (VHG), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP) and total phosphorus (TP) in water and of three extractable forms of phosphorus (water extractable, NaOH extractable and H2SO4 extractable) in hyporheic sediments from the gravel bars. Dissolved phosphorus was the major contributor to TP (74–79%) in both interstitial and surface waters on all sampling dates, and in most cases surface water P concentrations were significantly higher than interstitial concentrations. Hyporheic sediment TP concentrations ranged between 269 and 465 µg g?1 and were highest in fine sediment fractions. Acid‐extractable P, a non‐bioavailable form, represented at least 95% of sediment TP. A positive relationship was observed between VHG and TP in two of the gravel bars, with wells that were strongly downwelling having lower TP concentrations. These results suggest that in downwelling zones, hyporheic sediments can trap surface‐derived dissolved P, and that much of this P becomes stored in refractory particulate forms. Bioavailable P is mainly present in dissolved form and only occupies a small fraction of total P, with particulate P comprising the majority of total P. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

7.
两淮采煤沉陷区水域水体富营养化及氮、磷限制模拟实验   总被引：9，自引：5，他引：4  
选取两淮采煤沉陷区内3个不同营养水平的水域为研究站点,即淮北南湖站(HBNH)、淮南潘谢顾桥站(PXGQ)和潘谢谢桥站(PXXQ),首先分析了水体营养盐含量、比例结构和营养状态指数,3个站点TP浓度的年均值分别为0.056、0.064和0.092 mg/L,TN浓度年均值则为1.00、0.94和2.67 mg/L,3个站点水体呈现"中营养-轻度富营养"和"中度富营养"2种营养状态,总体上表现出P相对N缺乏的特征.设置对照组、加氮组、加磷组和加氮磷组开展秋季氮、磷限制模拟实验研究.结果表明:HBNH、PXXQ两个站点为P限制,而PXGQ站点则为N限制.尽管水体正磷酸盐浓度较低,但由于藻类具有利用有机磷或储备P库的能力,3个研究站点依然保持了较高的初级生产力,HBNH、PXGQ和PXXQ 3个站点的叶绿素a浓度年均值分别为13.07、26.95和46.25 mg/m3,与各水体的营养水平保持一致.两淮采煤沉陷区水体富营养化控制关键可能在于调控磷元素的水平.  相似文献   

8.
Human activities in coastal areas have increased the occurrence of eutrophication events, especially in vulnerable ecosystems such as coastal lagoons. Although we have a general knowledge of the consequences of eutrophication in these ecosystems, some efforts need to be made to understand biotic feedbacks that could modify the response of the environment to nutrient enrichment. The plant-mediated 'coastal filter' is one of the main factors that determine lagoonal efficiency in processing excess nutrients. In this context, the present paper examined the relative contribution of benthic macrofauna to the 'coastal filter' of a Mediterranean lagoon. The analysis of macrofaunal assemblages in the Mar Menor lagoon led to a clear differentiation between shallow areas of net nutrient recycling and exportation and deeper areas of net retention. These differences enhance nutrient removal from the water column, thus increasing the ecosystem's resistance to eutrophication.  相似文献   

9.
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10.
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11.
Puerto Galera Bay is a coastal lagoon with a variety of marine habitats and high species diversity. It is an area in the Phillippines where the growing influence of human activities is affecting the quality of its marine resources. This study examined the distribution and behaviour of nutrients and the physical hydrography of Puerto Galera Bay and determined how its physico-chemical nature affected the condition of biotic components in the bay. The relative importance of the nitrogen and phosphorus signals were used as indicators to implicate the influence of sewage and run-off into the bay. A nutrient pool accumulated in the bay as a result of low flushing rates. The interaction of hydrodynamic forcing with the biota have implications on the phytoplankton production and coral communities in the area.  相似文献   

12.
In recent years, eutrophic phenomena have frequently been reported in the Italian coastal waters of the northern Adriatic Sea. The aim of the present study was to determine that the phytoplankton blooms occurring along the Italian coastline in the area of Pesaro are caused by the Po River waters. In fact between October and December 2000 the nutrient load flushed into the sea from local rivers is not significant (phosphorus 10 tons and nitrogen 110 tons), instead N and P load from the Po River are: 650 and 8969 tons. The bloom episodes occurred during this period, at which time hypoxia developed on the sea bottom. The phytoplankton cell concentrations were 40.0 x 10(6) cells L(-1), and a significant presence of diatoms was observed. This issue is important in analysing the anthropogenic disturbances and environmental changes. The eutrophic seawater conditions were also analysed using the eutrophic index.  相似文献   

13.
Degradation of coastal ecosystems in the Great Barrier Reef (GBR) lagoon, Australia, has been linked with increased land-based runoff of suspended solids, nutrients and pesticides since European settlement. This study estimated the increase in river loads for all 35 GBR basins, using the best available estimates of pre-European and current loads derived from catchment modelling and monitoring. The mean-annual load to the GBR lagoon for (i) total suspended solids has increased by 5.5 times to 17,000ktonnes/year, (ii) total nitrogen by 5.7 times to 80,000tonnes/year, (iii) total phosphorus by 8.9 times to 16,000tonnes/year, and (iv) PSII herbicides is 30,000kg/year. The increases in river loads differ across the 10 pollutants and 35 basins examined, reflecting differences in surface runoff, urbanisation, deforestation, agricultural practices, mining and retention by reservoirs. These estimates will facilitate target setting for water quality and desired ecosystem states, and enable prioritisation of critical sources for management.  相似文献   

14.
Coastal lagoons are significant wetland environments found on coastlines throughout the world. Groundwater seepage may be a key component of lagoon water balances, though only a few studies have investigated large (>100 km2) coastal lagoons. In this study, we combined airborne thermal infrared imagery with continuous measurements of radon (222Rn—a natural groundwater tracer), conductivity, water temperature and dissolved oxygen to map groundwater seepage to a large coastal lagoon in New Zealand. We found evidence of seepage along the margins of the lagoon but not away from the margins. Our findings confirmed previously known seepage zones and identified new potential locations of groundwater inflow. Both point source and diffuse seepage occurred on the western and northwestern margins of the lagoon and parallel to the barrier between the lagoon and sea. These observations imply geologic controls on seepage. The combination of remote sensing and in-situ radon measurements allowed us to effectively map groundwater discharge areas across the entire lagoon. Combined, broad-scale qualitative methods built confidence in our interpretation of groundwater discharge locations in a large, dynamic coastal lagoon.  相似文献   

15.
Segara Anakan, a mangrove-fringed coastal lagoon in Indonesia, has a high diversity of macrobenthic invertebrates and is increasingly affected by human activities. We found >50 organic contaminants in water, sediment and macrobenthic invertebrates from the lagoon most of which were polycyclic aromatic compounds (PACs). Composition of PACs pointed to petrogenic contamination in the eastern lagoon. PACs mainly consisted of alkylated PAHs, which are more abundant in crude oil than parent PAHs. Highest total PAC concentration in sediment was above reported toxicity thresholds for aquatic invertebrates. Other identified compounds derived from municipal sewage and also included novel contaminants like triphenylphosphine oxide. Numbers of stored contaminants varied between species which is probably related to differences in microhabitat and feeding mode. Most contaminants were detected in Telescopium telescopium and Polymesoda erosa. Our findings suggest that more attention should be paid to the risk potential of alkylated PAHs, which has hardly been addressed previously.  相似文献   

16.
A new method has been developed that predicts the natural background concentrations of microelements of interest in sediments using the concentrations of various components present in the sample. This is done by developing multiple linear regressions using a dataset which has been selected, using radiochronological dating and statistical methods, to reflect the concentration distributions of natural levels of a large number of sediment constituents. This method is demonstrated in Venice Lagoon, using data generated in a lagoon-wide sampling effort. A quantitative assessment is carried out of the variability of natural background levels at the lagoon scale for the main inorganic microelements, and distribution maps of the background and anthropogenic concentrations of a selected metal (Ni) in sediments at the lagoon scale are presented. With sufficient data, this method can be applied in other areas, allowing for a site-specific separation of natural background and anthropogenic levels of microconstituents in sediments, providing insights into regional geochemistry and aiding in the risk-based management of coastal sediments.  相似文献   

17.
Sediment is commonly considered as a source of phosphine, which is a highly toxic and reactive atmospheric trace gas. This study aims to investigate the seasonal and spatial distribution of matrix-bound phosphine (MBP) and its relationship with the environment in the Changjiang River Estuary. A total of 43 surface sediments were collected in four seasons of 2006, and concentrations of MBP and relative environmental factors were analyzed. MBP ranged from 1.93 to 94.86ngkg(-1) dry weight (dw) with an average concentration of 17.14ngkg(-1)dw. The concentrations of MBP in the upper estuary were higher than those in the lower estuary, which could be attributed to greater pollutant inputs in the upper estuary. The concentrations of MBP also varied with season, with November>August>May>February. Significant correlations existed between MBP and total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), organic carbon (OC), total nitrogen (TN), the grain size, and redox potential (Eh), suggesting that these sedimentary environmental characteristics played an important role in controlling the MBP levels in the sediments. Notably, there were positive linear relationships between the concentrations of soluble reactive phosphorus (SRP), TP, and chlorophyll a (Chl a) in bottom water and MBP in sediments. These relationships might be very complicated and need further exploration. This work is the first comprehensive study of the seasonal and spatial distribution of MBP in sediments and its relationships with environmental factors in a typical estuary, and will lead to deeper understanding of the phosphorus (P) biogeochemical cycle.  相似文献   

18.
This study aims to investigate the effects of region and three regional dominated mangrove species(Avicennia marina, Aegiceras corniculatum and Kandelia candel) on the distribution of inorganic nitrogen and phosphorus. Measurement of the inorganic nitrogen and phosphorus and enzymatic activities was carried out in soils covered by three mangrove species in the Quanzhou Bay estuarine wetlands, a typical coastal wetland in China.Species with a higher biomass in upstream and midstream absorb more nitrogen from soils, and the retention of the available phosphorus in the soils of different regions causes the regional variation of phosphorus. In areas dominated by A. marina, nitrate nitrogen is lower while available phosphorus is higher. Meanwhile, nitrate nitrogen and available phosphorus are higher in the soils covered by K. candel.Moreover, all three species affect the elemental and enzymic stoichiometry. The mangrove species influences the diversity of the elemental and enzymic stoichiometric relationship through differential microenvironments, which induce the biodiversity of wetland ecosystems. Thus, this study may facilitate a better understanding of the transformation ability of mangroves to nitrogen and phosphorus and will therefore be beneficial for providing a basis for the ecological restoration of estuarine wetlands.  相似文献   

19.
Nutrient and suspended sediment concentrations were measured in the dry season and during the rising and falling stages of flood events in the Annan and Daintree rivers to estimate catchment exports. These flood events were also sampled along the salinity gradient in the estuary and nearshore shelf to quantify the modification of terrestrial sediment and nutrient loads as they pass through estuaries into the Great Barrier Reef lagoon. In the Daintree River TSS concentrations were found to increase between the catchment and the estuary plume. The source of TSS may have been scour of the estuarine channel or from land use in the catchment of the lower estuary. In the dry season nitrogen enters the Annan and Daintree estuaries predominantly in the form of PON and DON in roughly equal proportions. Nitrogen exports to the GBR are mostly in the form of DON. In the wet season the majority of nitrogen enters the estuaries as DON and leaves as PON. Nitrogen removal in the estuaries and plumes appears to be biologically mediated once suspended sediment concentrations decrease to a point where phytoplankton growth is not light limited. In the dry season phosphorus enters and leaves the estuaries primarily in organic form. PIP is the dominant form of phosphorus in river water, but leaves the estuary more evenly distributed between all forms. These estuarine processes result in less nitrogen and phosphorus being delivered to the GBR lagoon than is exported from the catchment. The differences between these estuaries highlights the need for further work to explore modifications in estuaries that drain into the Great Barrier Reef lagoon.  相似文献   

20.

Natural and human-induced disturbances challenge the resilience of coastal ecosystems. The relative impact of a projected increase in storm intensity versus a temporary sediment spill from the construction of the planned Fehmarnbelt Fixed Link on the suspended sediment concentrations was estimated in the shallow coastal embayment of Rødsand lagoon. The investigations were performed through a combination of field observations and numerical modeling. The numerical model was calibrated and validated with the field observations. The lagoonal response to a regional increase in wind speed showed temporarily amplified suspended particulate matter concentration (SPMC) levels (26–37%) and amplified exceedance duration above wash load (30–32%) in the entire lagoon, but especially in the shallow regions. The lagoonal response to a sediment spill outside Rødsand lagoon showed temporarily amplified SPMC levels (2–4%) and amplified exceedance duration above wash load (1–2%) in the entire lagoon, but especially in the regions in close proximity to the spill source. The regional response to increasing wind speed was thus 10-fold larger than the sediment spill where only advective sediment transport took place. This highlights the importance of the internal lagoonal processes as opposed to exterior disturbances. The study contributed to an improved understanding of the potential natural and human-induced stressors on the sediment dynamics in lagoonal ecosystems.

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