Laboratory analyses of nutrient release processes from Haihe River sediment   总被引：2，自引：0，他引：2  

Min WU  Xue-ming SUN  Sui-liang HUANG  Xian-qiang TANG  Miklas SCHOLZ 《国际泥沙研究》2012,27(1):61-72

Sediment samples were collected from the heavily contaminated Haihe River to conduct static nutrient release experiments with tap water,and to evaluate the effect of dredging depths,salinity and light ...  相似文献   

Phosphorus retention and release by sediments in the eutrophic Mai Po Marshes, Hong Kong   总被引：5，自引：0，他引：5  

Lai DY  Lam KC 《Marine pollution bulletin》2008,57(6-12):349-356

This study examined the phosphorus retention and release characteristics of sediments in the eutrophic Mai Po Marshes in Hong Kong. Results of chemical fractionation show that the sum of inorganic P pools exceeded 50% of the total sediment P content, with the redox-sensitive iron-bound P (Fe(OOH) approximately P) being the dominant P fraction. Given the considerable average Fe(OOH) approximately P concentration of 912 microg g(-1), Mai Po sediments demonstrated a great potential to release bioavailable P under low sediment redox potentials. This was further supported by the high mean anaerobic P flux of 31.8 mg m(-2)d(-1) recorded in Mai Po sediment cores, indicating the role of bottom sediments as a net P source. Although sediments in Mai Po had appreciable Langmuir adsorption maxima (1642-3582 mg kg(-1)), the high zero equilibrium P concentrations (0.02-0.51 mg L(-1)) obtained suggest that sediment sorption processes would contribute to sustaining the eutrophic conditions in overlying water column even with a further reduction in external P load. Concerted efforts should be made to reduce internal loading of P, especially under reducing conditions, to complement the implementation of zero discharge policy for Deep Bay for effective eutrophication abatement and long-term water quality improvement in the Mai Po Marshes.  相似文献   

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   

Variation in riverine phosphorus between 1994 and 2003 as affected by land-use and loading reductions in six medium-sized to large German rivers   总被引：1，自引：0，他引：1  

Marcus Schulz  Maik Bischoff 《Limnologica》2008,38(2):126-138

Land use and in-stream transformation exert great influence on concentrations and loads of phosphorus (P) in rivers. We aimed to display differences in the courses of total P (TP) and soluble reactive P (SRP) concentrations and loads in six medium-sized to large rivers in the central region of Germany, and to identify the reasons for different long-term trends. Therefore, we applied multivariate statistics to 10-year-time series (1994–2003) of TP, SRP, discharge (Q), water temperature (T), pH, dissolved organic carbon (DOC), total organic carbon (TOC), dissolved oxygen (DO), total iron (Fe), and total manganese (Mn). Statistical results were related to land use in the catchments of the rivers. TP concentrations ranged between 0.02 and 0.78 mg l⁻¹, and SRP concentrations ranged between 0.01 and 0.44 mg l⁻¹. Q correlated negatively with TP and SRP concentrations over the entire year. Furthermore, Fe correlated significantly and positively to TP and SRP and therefore, ferric hydroxides likely were the major P sorption sites. DOC showed significant positive correlation to SRP particularly in spring, indicating manure exposure in early spring as a major source of both, DOC and SRP. Significant negative correlations between DO and SRP in summer hint at internal P loading in rivers or in flushed lakes. Different forms of land use were the reasons of enhanced or retarded recovering from previous increases in P concentrations. High portions of arable land within some of the catchments impeded the process of decreases since 1996 because of remaining high-diffuse emissions from fertilized soils. Agricultural practices, exposing fertilizer to soils within the river catchments and high Q in early spring caused high TP and SRP loads to downstream systems, and evoked risks for downstream river reaches.  相似文献   

Transport and delivery of suspended solids, nitrogen and phosphorus from various sources to freshwaters in the UK   总被引：8，自引：0，他引：8  

A.C. Edwards  P.J.A. Withers   《Journal of Hydrology》2008,350(3-4):144-153

Sources of nutrients and suspended solids (SS) are diverse in origin and dynamic with respect to their transport pathways and delivery to surface and groundwaters. Three broad source groups can be identified based on their hydrological and compositional characteristics. Consented discharges from point sources are generally continuous and highly concentrated relative to receiving waters while non-point (diffuse) sources are generally more dilute with SS and phosphorus in particular tending to have a high transport dependence upon hydrological (storm) events. A third group with properties that are intermediate include overflows from septic systems, seepages from farmyards or road/track runoff. This grouping automatically introduces a strong temporal and spatial variability in the relative contribution individual group sources make to the total quantity of nutrients and SS delivered to freshwaters. This spatial or temporal variability in either effluent volumes or composition is generally not considered when predicting impacts, which can be highly significant in headwater streams. Complete compositional data for individual sources (especially the intermediary group) are also often lacking when apportioning source contributions in catchments, being simply lumped into average export coefficients. Better definition of intermediary sources would help to more accurately define the relative contribution of different sources and enable cost-effective river basin management planning as required under the Water Framework Directive.  相似文献   

Influence of rural land use on streamwater nutrients and their ecological significance   总被引：1，自引：0，他引：1  

Helen P. Jarvie  Paul J.A. Withers  Robin Hodgkinson  Adam Bates  Margaret Neal  Heather D. Wickham  Sarah A. Harman  Linda Armstrong 《Journal of Hydrology》2008,350(3-4):166-186

Concentrations and loads of N and P fractions were examined for lowland rivers, the Wye and Avon, draining a range of representative agricultural land-use types in two major UK river basins. Data collected over a 2-year period demonstrated important diffuse agricultural source contributions to N and P loads in these rivers. Ground water provided a major source of total dissolved nitrogen (TDN) loads, whereas near-surface sources provided a major contribution to total phosphorus (TP) loads. In terms of aquatic ecology, concentrations of nutrients, at times of eutrophication risk (spring and summer low flows) were of key environmental and management significance. Agricultural diffuse sources provided the major source of long-term P loads across the two basins. However, the results demonstrated the dominance of point-source contributions to TP and SRP concentrations at times of ecological risk. Point sources typically ‘tip the balance’ of dissolved inorganic P (soluble reactive P, SRP) above the 100 μg l⁻¹ guideline value indicative of eutrophication risk. The significance of point sources for TP and SRP concentrations was shown by (a) the strong correlations between TP, SRP and B concentrations, using B as a tracer of sewage effluent, (b) the dominant contribution of SRP to TP concentrations and (c) the predominant pattern of dilution of SRP and B with flow. The clean Chalk streams draining low intensity grassland in areas of the Avon with sparse human settlement were oligotrophic and P limited with low SRP concentrations under spring and summer baseflows attributable to groundwater sources. The data provide important insights into the ecological functioning of different lowland stream systems. There was evidence of greater SRP losses and N-limitation in a stream which drains a pond system, demonstrating the importance of longer water residence times for biological nutrient uptake.  相似文献   

PSYCHIC – A process-based model of phosphorus and sediment transfers within agricultural catchments. Part 2. A preliminary evaluation     

J. Strmqvist  A.L. Collins  P.S. Davison  E.I. Lord 《Journal of Hydrology》2008,350(3-4):303-316

This paper describes the preliminary evaluation of the PSYCHIC catchment scale (Tier 1) model for predicting the mobilisation and delivery of phosphorus (P) and suspended sediment (SS) in the Hampshire Avon (1715 km²) and Herefordshire Wye (4017 km²) drainage basins, in the UK, using empirical data. Phosphorus and SS transfers to watercourses in the Wye were predicted to be greater than corresponding delivery in the Avon; SS, 249 vs 33 kg ha⁻¹ yr⁻¹; DP, 2.57 vs 1.26 kg ha⁻¹ yr⁻¹; PP, 2.20 vs 0.56 kg ha⁻¹ yr⁻¹. The spatial pattern of the predicted transfers was relatively uniform across the Wye drainage basin, whilst in the Avon, delivery to watercourses was largely confined to the river corridors and small areas of drained land. Statistical performance in relation to predicted exports of P and SS, using criteria for relative error (RE) and root mean square error (RMSE), reflected the potential shortcomings associated with using longer-term climate data for predicting shorter-term (2002–2004) catchment response and the need to refine calculations of point source contributions and to incorporate additional river basin processes such as channel bank erosion and in-stream geochemical processing. PSYCHIC is therefore best suited to characterising longer-term catchment response.  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   

A Review of Seismicity in 2007     

Li Gang  Liu Jie  Yu Surong 《中国地震研究》2008,22(1):101-111

1 SURVEY OF GLOBE SEISMICITY IN 2007
A total of 22 strong earthquakes with Ms ≥ 7.0 occurred in the world according to the Chinese Seismic Station Network in 2007 （Table 1 ）.  相似文献   

华北型煤田矿井岩溶水涌(突)出机理与涌(突)水量预测方法探讨     

傅耀军 《中国煤炭地质》2019,(4):42-50

北方岩溶水系统的形成与相关河流的发育贯通相辅相成。不同的岩溶水系统模式表现出不同的地下水动力学特征,岩溶水径流带控制的岩溶水网络系统是北方岩溶水系统的基本特征。天然状态下,华北型煤田煤层顶板砂岩地下水系统与底板岩溶地下水系统有水力联系的区域,是矿井岩溶水涌(突)出的危险区。煤矿采掘工程打破了煤层顶、底板地下水系统水压力平衡,在压差作用下,承压岩溶水的"压裂"作用对构造煤系发育层段的疏通有着重要作用。承压岩溶水的释放或涌(突)出,是岩溶承压含水层弹性贮存量的释放,岩溶水运动属非稳定流。将断层等线形过水断面概化成环状井(孔)过水断面,则可用定降深非稳定流承压井流方程,预测可能的岩溶水涌(突)水流量及其变化规律。对流量函数Q(t)定积分,则可预测任意延续时间段的涌(突)水量。基于承压岩溶水弹性释放的非稳定流矿井岩溶水涌(突)水量预测方法,突破了岩溶水涌(突)水量无法预测的禁锢,对提升矿井岩溶水防治水平,解放华北型煤田下组煤有积极、重要意义。  相似文献