Dry deposition and particle-size distribution of phosphorus in the marine atmosphere over the northeastern coast of Taiwan     

Hung-Yu Chen  Chin-Chang Hung  Tien-Hsi Fang  Gwo-Ching Gong 《Continental Shelf Research》2008

This study is the first to measure the particulate phosphorus, including total inorganic phosphorus (TIP) and organic phosphorus (OP), in size-fractionated atmospheric particles. The results indicate that continental and marine sources are the key controls on the particle-size distribution of phosphorus species. For continental and local anthropogenic sources, both TIP and OP are associated with fine-mode aerosols during the winter and spring, and both are also associated with coarse particles during the summer and autumn. The coarse/fine ratios are low during periods with a non-oceanic source but high at other times, probably because of the biological growing season in the surface waters of the study area. The calculated annual fluxes based on estimates of dual-mode particles are 532±185, 435±172, and 96.8±48.8 μmol m⁻² yr⁻¹ for TP, TIP, and OP, respectively. Based on previously published solubility data for particulate phosphorus (34%), we calculated an annual flux of 180±63 μmol m⁻² yr⁻¹ for readily soluble particulate phosphorus.  相似文献   

Spatial and temporal dynamics of stream water particulate and dissolved N, P and C forms along a catchment transect, NE Scotland   总被引：1，自引：0，他引：1  

M.I. Stutter  S.J. Langan  R.J. Cooper 《Journal of Hydrology》2008,350(3-4):187-202

The dynamics of dissolved and particulate N, P and organic C were examined for field drains, through a headwater (4 km²), into a mesoscale stream (51 km²) and river (1844 km²) catchment. Distributions of N and P forms were similar in the agricultural headwater and field drains; annual P fluxes of particulate and dissolved forms were of equal magnitude, whilst N was dominated by NO₃–N. Across all scales organic P was an important, often dominant, component of the dissolved P. Temporal variation in nutrient concentrations and proportions was greatest in the headwater, where storms resulted in the generation of large concentrations of suspended particulate matter, particulate and dissolved P, particularly following dry periods. The data suggest that groundwater and minor point source inputs to the mesoscale catchment buffered the temporal variability in hydrochemistry relative to the headwater. Summer low flows were associated with large PO₄–P concentrations in the mesoscale catchment at a critical time of biological sensitivity. At the largest river catchment scale, organic forms of C, N and P dominated. Inorganic nutrient concentrations were kept small through dilution by runoff from upland areas and biological processes converted dissolved N and P to particulate forms. The different processes operating between the drain/headwater to the large river scale have implications for river basin management. Given the prevalence of organic and particulate P forms in our catchment transect, the bioavailability of these fractions needs to be better understood.  相似文献   

Dynamics of a Prorocentrum minimum bloom along the northern coast of Sinaloa,Mexico     

Aída Martínez-López  Diana Cecilia Escobedo-Urías  Ana Elsi Ulloa-Pérez  Raul Aguirre 《Continental Shelf Research》2008

To investigate the relative importance of mesoscale physical events, such as upwellings and physical and chemical variables during an algae bloom of Prorocentrum minimum, 25 sampling sites were established offshore of the Navachiste Lagoon Complex on the east side of the Gulf of California. Samples were analyzed for phytoplankton concentration, water chemistry, and temperature during November 1999, January, March, April, May, and August 2000. Satellite imagery of sea surface temperature (SST) for April 2000 was processed to obtain a synoptic view of the area during the extraordinary bloom of P. minimum in the open waters of the Gulf of California. The bloom was associated with change of oceanographic conditions from moderate winds to calm period, temperature increase and high nitrate (NO₃⁻-N) and ammonia (NH₄⁺-N) content in the offshore waters. Depletion of these nutrients during the bloom suggests that this species uses both types of nitrogen substrates. Cysts in the northernmost sampling stations in January and March indicate that upwelling water, rich in nitrates, also carried a seed stock population of P. minimum. SST patterns in the satellite imagery suggest wind-forcing as the responsible mechanisms triggering the algal bloom offshore of the Navachiste Lagoon Complex.  相似文献   

Seasonal and spatial variation in suspended matter,organic carbon,nitrogen, and nutrient concentrations of the Senegal River in West Africa     

《Limnologica》2016

The Senegal River is of intermediate size accommodating at present about 3.5 million inhabitants in its catchment. Its upstream tributaries flow through different climatic zones from the wet tropics in the source area in Guinea to the dry Sahel region at the border between Senegal and Mauritania. Total suspended matter, particulate and dissolved organic carbon and nitrogen as well as nutrient concentrations were determined during the dry and wet seasons at 19 locations from the up- to downstream river basin. The aims of the study were to evaluate the degree of human interference, to determine the dissolved and particulate river discharges into the coastal sea and to supply data to validate model results. Statistical analyses showed that samples from the wet and dry season are significantly different in composition and that the upstream tributaries differ mainly in their silicate and suspended matter contents. Nutrient concentrations are relatively low in the river basin, indicating low human impact. Increasing nitrate concentrations, however, show the growing agriculture in the irrigated downstream areas. Particulate organic matter is dominated by C4 plants during the wet season and by aquatic plankton during the dry season. The total suspended matter (TSM) discharge at the main gauging station Bakel was about 1.93 Tg yr⁻¹ which is in the range of the only available literature data from the 1980s. The calculated annual discharges of particulate organic carbon (POC), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are 55.8 Gg yr⁻¹, 54.1 Gg yr⁻¹, and 5.3 Gg yr⁻¹, respectively. These first estimates from the Senegal River need to be verified by further studies.  相似文献   

Soil Carbon and Nutrient Accumulation under Forest Plantations in Jharkhand State of India     

Pankaj Kumar Roy  Nihar Ranjan Samal  Malabika Biswas Roy  Asis Mazumdar 《洁净——土壤、空气、水》2010,38(8):706-712

The decrease and degradation of the tropical forests affect not only the production of timber but also the global environment in a large scale. The ability of soil to sustain and its supply of nutrients to a growing forest are controlled by a complex of biogeochemical processes. The purpose of the present study aims to assess the degraded forest fringe areas, to promote plantations of various types and to evaluate their impacts on the soil nutrients and carbon content accumulation. The soil organic carbon (SOC) and nutrient content were evaluated and compared between plantations of mixed native species (MNS), some native tree species as Shorea robusta, Dalbergia sissoo, Dendrocalamus spp., certain agro‐forestry species and some exotic varieties. The impacts of the plantations on the SOC and the nutrients were firstly analyzed through comprehensive chemical analyses and the results were compared with the soil samples collected prior to plantation forestry. Significant changes were observed in SOC content, in nutrients, and in amounts of exchangeable cations. Soil carbon levels were highest under the MNS, Dendrocalamus and Tectona grandis stands and lowest under D. sissoo and Terminalia arjuna. Total N showed highest levels under Dendrocalamus and Pongamia pinnata and significantly higher in stands of native species; lowest total N level was observed in D. sissoo plantations. The C/N ratios of the soil varied between 9.2 and 13.5 among the exchangeable cations. Ca²⁺ recorded the maximum levels and Na⁺ showed the lowest levels.  相似文献   

Sewage impacts coral reefs at multiple levels of ecological organization     

Pasinee Reopanichkul  Thomas A. Schlacher  R.W. Carter  Suchai Worachananant 《Marine pollution bulletin》2009,58(9):1356-1362

Against a backdrop of rising sea temperatures and ocean acidification which pose global threats to coral reefs, excess nutrients and turbidity continue to be significant stressors at regional and local scales. Because interventions usually require local data on pollution impacts, we measured ecological responses to sewage discharges in Surin Marine Park, Thailand. Wastewater disposal significantly increased inorganic nutrients and turbidity levels, and this degradation in water quality resulted in substantial ecological shifts in the form of (i) increased macroalgal density and species richness, (ii) lower cover of hard corals, and (iii) significant declines in fish abundance. Thus, the effects of nutrient pollution and turbidity can cascade across several levels of ecological organization to change key properties of the benthos and fish on coral reefs. Maintenance or restoration of ecological reef health requires improved wastewater management and run-off control for reefs to deliver their valuable ecosystems services.  相似文献   

Water quality in the Dickinson Bayou watershed (Texas, Gulf of Mexico) and health issues     

Antonietta Quigg  Linda Broach  Winston Denton  Roger Miranda 《Marine pollution bulletin》2009,58(6):896-904

The Dickinson Bayou watershed (near Houston, Texas, Gulf of Mexico) provides habitat for numerous coastally influenced communities of wildlife, including scores of birds and fish. Encroaching development and impervious surfaces are altering the habitat and degrading water quality. Herein we have defined the current health of the bayou using water quality data collected between 2000 and 2006. Elevated bacteria (fecal coliform, Escherichia coli and Enterococcus) and depressed dissolved oxygen concentrations (often <3 mg l⁻¹) are the two major impairments to this ecosystem. While nutrient ratios indicate primary productivity may be nitrogen limited, concerns of eutrophication persist because the bayou has a low intrinsic flushing rate. Consistent with this is the magnitude of algal blooms (ca. 100 μg chl l⁻¹) which often occur in spring/summer. The findings of this study will assist with the understanding of the influence of urban development on small watersheds.  相似文献   

Assessing land use and land cover influence on surface water quality using a parametric weighted distance function     

《Limnologica》2019

Stream water quality is directly influenced by land use and human practices in the surrounding environment. Understanding such effects and the spatial extent of impacts is essential to generate reliable information for ecosystem-based management of water resources. We identified sources of impact on water quality and characterized indicator-specific landscape influence on samples collected during base flow along the Chubut River (43 °S, 69 °W). We modeled Total Nitrogen (TN), Total Phosphorous (TP), Soluble Reactive Phosphorous (SRP) concentrations and δ¹⁵N of particulate organic matter along the river, as a function of effective contribution areas (A_EC) of Land Use/Land Cover (LULC). A_ECs were calculated by assuming that landscape influence decays exponentially with the Euclidean distance between a given LULC parcel and the sampling point. We calibrated the model to the observations by estimating an indicator-specific decay rate. Agriculture and barren lands were the main sources of phosphate nutrients whereas urban areas were the main source of TN. Radius of landscape influence for SRP (100–180 km) was larger than for TP (10–25 km), reflecting different patterns of mobilization and delivery in the catchment. δ¹⁵N variation was explained by vegetation cover but the influence rapidly decreased (1–4 km) reflecting a mostly autochthonous source of organic matter.  相似文献   

春季长江口崇明东滩沉积物-水界面营养盐交换过程研究   总被引：4，自引：2，他引：2       下载免费PDF全文

高磊  李道季  余立华  孔定江  王延明 《海洋与湖沼》2009,40(2):109-116

2005年3-5月,选取位于长江口崇明东滩的3个典型站点,对沉积物间隙水中营养盐剖面进行了观测;同时,通过模拟现场环境培养的方法测定了营养盐在沉积物-上覆水界面的交换通量.结果表明,间隙水中NH4+和SiO32-浓度比PO43-和NO2-+NO3-一般要高2-3个数量级.沉积物-水界面交换过程在春季表现为对NO3-和SiO32-的吸收,吸收的量在很大程度上取决于上覆水中这两种营养盐的浓度;由上覆水和表层间隙水浓度梯度所决定的分子扩散通量对实际交换通量的控制有限.对NO3-,分子扩散通量占交换通量的比例为到21%;对SiO32-,前者和后者的方向相反;对NH3+,较大的浓度梯度支持显著的释放通量,而在培养过程中并没有发现上覆水中NH4+浓度持续的增长.以上结果都说明其它因素,如浮游植物吸收、颗粒物吸附以及底栖动物扰动在更大程度上决定着崇明东滩沉积物-水界面营养盐的交换过程.  相似文献