数字滤波法在点源和非点源污染负荷分割中的应用

以分辨流域点源和非点源污染负荷为研究目标,在傅立叶分析的基础上,提出了从污染负荷时间序列中分辨点源和非点源污染负荷的新方法——数字滤波法,探讨了数字滤波方程的参数与滤波次数的关系,并将该方法应用到东江流域COD_Mn负荷的分割上. 应用实例表明,分割的点源和非点源负荷系列曲线符合点源和非点源负荷的产生特点,使用者能够在污染负荷分割过程中通过滤波参数的选取比较方便地加入自己的经验. 一般取较大滤波参数时,只需要3次滤波就能得出较满意的结果.      

Different proxies for the reactivity of aquatic sediments towards oxygen: A model assessment

Information on benthic carbon mineralization rates is often derived from the analysis of oxygen microprofiles in sediments. To enable a direct comparison of different sediment environments, it is often desirable to characterize sediments by a single proxy that expresses their “reactivity” towards oxygen. For this, there are three commonly used proxies: the oxygen penetration depth (OPD), the oxygen flux at the sediment-water interface (DOU), and the maximum volumetric oxygen consumption rate (R_max). The OPD can be directly determined from the oxygen depth profile, while the DOU is usually obtained by a linear fit to the oxygen gradient either in diffusive boundary layer. The oxygen consumption rate R_max requires the fitting of a reactive-transport model to the data profile. This article shows that the OPD alone is a suboptimal proxy, because it shows a strong dependence on the half-saturation constant K_s, and secondly, because it is sensitive to the particular re-oxidation conditions right above the oxic-anoxic interface. Similarly, the volumetric oxygen consumption rate R_max is rather strongly dependent on the kinetic model formulation employed. To show this we fitted three different (Bouldin, Blackman and Monod) kinetics to the same oxygen data profiles. When fitting these models, the R_max values obtained differed by 20% for exactly the same oxygen profile. Accordingly, if one reports R_max values, it is crucial to specify the kinetic model alongside. Overall, DOU emerges as sediment reactivity proxy which is the least model dependent.     

密云水库流域植被覆盖度变化对输沙量的影响

封闭流域中,泥沙的产生是多种因素相互作用,相互制约的结果,而在这些众多的环境影响因素中,植被是土壤侵蚀中最重要的环境控制因子,目前,植被覆盖度变化对输沙量的影响一直是区域生态环境研究中比较热门的话题。文章使用遥感（Remote Sensing（RS））、地理信息系统（Geographic In formmionSystem（GIS））与统计分析相结合的方法评价了密云水库流域内2个子流域出口处2002年至2005年植被覆盖度变化对输沙量的影响。密云水库流域多为山地,其降雨具有明显的季节性。本文的主要目的在于分析2002年至2005年植被覆盖度变化对流域输沙量的影响,并分析了植被覆盖度变化对气候改变及人类活动的综合影响,结果表明：在密云水库流域内,输沙量是降雨情况和人为因素引起的地表植被覆盖度变化情况的综合反映,人口增长、经济发展和城市化是密云水库流域内引起土地利用变化和地表植被覆盖度变化的主要驱动力。并且,输沙量可以被看作是一个很好的指标来定量分离出生物生理和人为的影响,并从中能够找出在流域生态系统中获得显著结果关键的临界点。研究结果对制定流域的合理开发和管理计划将有所帮助。     

Sediment and nutrient dynamics during snowmelt runoff generation in a southern Taiga catchment of Russia

The water quality of the Volga catchment, Russia, is diminished and major nutrients reach critical levels. Proper management strategies depend on process knowledge about nutrient sources and pathways as well as appropriate models. For the 18.8 km² experimental catchment Lubazhinkha, 100 km south of Moscow, a monitoring scheme was conducted to identify runoff generation and nutrient source areas. The grey forest soils of the catchment are utilized with arable land and pasture (54%) and forest areas. The received results show a high intra-annual and inter-annual dynamic of the snowmelt runoff generation as major hydrological process. Overall sediment export rates during the 3 years of snowmelt investigation from 2003 to 2005 are low with a maximum of 0.33 t ha⁻¹ during snowmelt period 2005 and effectively reduced by a dam at the catchment outlet. Also, the total phosphorus loss from the catchment is low reaching from 0.03 to 0.35 kg ha⁻¹ during the snowmelt periods. However, sediment and total phosphorus concentrations vary within one snowmelt event and can reach high concentrations. Detailed analysis of element concentrations during snowmelt events allows an identification of different flow components and runoff generating mechanisms. During low flow situations phosphorus and dissolved organic carbon are transferred from the arable soils with slow flow components to the channel. In contrast to this situation, the sources of sediment and nutrients split up temporarily and spatially during high flow situations. Aside arable fields that are source of sediment and phosphorus during snowmelt episodes, the forested areas were detected as major source for the export of dissolved organic carbon with surface runoff. In particular these areas are characterized by a late thawing of the topsoil which causes a delayed peak of dissolved organic carbon concentration. The awareness of the dynamic and complex catchment reaction during snowmelt events is of importance for the development of proper management strategies.     

An integrated approach to the toxicity assessment of Irish marine sediments: validation of established marine bioassays for the monitoring of Irish marine sediments

This paper describes the ecotoxicological evaluation of marine sediments from three sites around Ireland representative of a range of contaminant burdens. A comprehensive assessment of potential sediment toxicity requires the consideration of multiple exposure phases. In addition to the evaluation of multi-exposure phases the use of a battery of multi-trophic test species has been advocated by a number of researchers as testing of single or few organisms may not detect toxicants with a specific mode of action. The Microtox(R) solid phase test (SPT) and the 10-d acute amphipod test with Corophium volutator were used to assess whole sediment toxicity. Porewater and elutriates were assessed with the Microtox(R) acute test, the marine prasinophyte Tetraselmis suecica, and the marine copepod Tisbe battagliai. Solvent extracts were assayed with the Microtox(R) and T. battagliai acute tests. Alexandra Basin was identified as the most toxic site according to all tests, except the Microtox(R) SPT which identified the Dunmore East site as being more toxic. However, it was not possible to correlate the observed ecotoxicological effects with a specific and/or class of contaminants based on sediment chemistry alone. Therefore porewaters found to elicit significant toxicity (Dunmore East and Alexandra Basin) with the test battery were selected for further TIE assessment with T. battalgiai and the Microtox(R) system. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.     

Evaluation of compost blankets for erosion control from disturbed lands

Soil erosion due to water and wind results in the loss of valuable top soil and causes land degradation and environmental quality problems. Site specific best management practices (BMP) are needed to curb erosion and sediment control and in turn, increase productivity of lands and sustain environmental quality. The aim of this study was to investigate the effectiveness of three different types of biodegradable erosion control blankets- fine compost, mulch, and 50-50 mixture of compost and mulch, for soil erosion control under field and laboratory-scale experiments. Quantitative analysis was conducted by comparing the sediment load in the runoff collected from sloped and tilled plots in the field and in the laboratory with the erosion control blankets. The field plots had an average slope of 3.5% and experiments were conducted under natural rainfall conditions, while the laboratory experiments were conducted at 4, 8 and 16% slopes under simulated rainfall conditions. Results obtained from the field experiments indicated that the 50-50 mixture of compost and mulch provides the best erosion control measures as compared to using either the compost or the mulch blanket alone. Laboratory results under simulated rains indicated that both mulch cover and the 50-50 mixture of mulch and compost cover provided better erosion control measures compared to using the compost alone. Although these results indicate that the 50-50 mixtures and the mulch in laboratory experiments are the best measures among the three erosion control blankets, all three types of blankets provide very effective erosion control measures from bare-soil surface. Results of this study can be used in controlling erosion and sediment from disturbed lands with compost mulch application. Testing different mixture ratios and types of mulch and composts, and their efficiencies in retaining various soil nutrients may provide more quantitative data for developing erosion control plans.     

Nutrient Loadings to Streams of the Continental United States from Municipal and Industrial Effluent1

Maupin, Molly A. and Tamara Ivahnenko, 2011. Nutrient Loadings to Streams of the Continental United States From Municipal and Industrial Effluent. Journal of the American Water Resources Association (JAWRA) 47(5):950‐964. DOI: 10.1111/j.1752‐1688.2011.00576.x Abstract: Data from the United States Environmental Protection Agency Permit Compliance System national database were used to calculate annual total nitrogen (TN) and total phosphorus (TP) loads to surface waters from municipal and industrial facilities in six major regions of the United States for 1992, 1997, and 2002. Concentration and effluent flow data were examined for approximately 118,250 facilities in 45 states and the District of Columbia. Inconsistent and incomplete discharge locations, effluent flows, and effluent nutrient concentrations limited the use of these data for calculating nutrient loads. More concentrations were reported for major facilities, those discharging more than 1 million gallons per day, than for minor facilities, and more concentrations were reported for TP than for TN. Analytical methods to check and improve the quality of the Permit Compliance System data were used. Annual loads were calculated using “typical pollutant concentrations” to supplement missing concentrations based on the type and size of facilities. Annual nutrient loads for over 26,600 facilities were calculated for at least one of the three years. Sewage systems represented 74% of all TN loads and 58% of all TP loads. This work represents an initial set of data to develop a comprehensive and consistent national database of point‐source nutrient loads. These loads can be used to inform a wide range of water‐quality management, watershed modeling, and research efforts at multiple scales.     

阳宗海表层沉积物磷、氟、硫的分布与污染状况

对阳宗海表层沉积物中磷、氟、硫的含量进行了调查,并用单指标标准指数法对污染水平进行了评价.结果表明,阳宗海表层沉积物磷、氟、硫含量的平均值依次为1 041 mg/kg、1 075 mg/kg、2 743 mg/kg.生活、生产污水、工业废气,以及机动船只、网箱养鱼等活动是阳宗海表层沉积物中磷、氟、硫的主要来源.磷、氟、...     

Four kinds of capping materials for controlling phosphorus and nitrogen release from contaminated sediment using a static simulation experiment

• Lanthanum modified bentonite (LMB) can effectively absorb phosphorus (P). • Water treatment plant sludge (WTPS) capping is effective for controlling P release. •Aluminum-based P-inactivation agent (Al-PIA) is an efficient P control material. •The P adsorbed by WTPS and Al-PIA is mainly in the form of NAIP. We determined the effects of quartz sand (QS), water treatment plant sludge (WTPS), aluminum-based P-inactivation agent (Al-PIA), and lanthanum-modified bentonite (LMB) thin-layer capping on controlling phosphorus and nitrogen release from the sediment, using a static simulation experiment. The sediment in the experiment was sampled from Yundang Lagoon (Xiamen, Fujian Province, China), which is a eutrophic waterbody. The total phosphorus (TP), ammonium nitrogen (NH₄⁺-N), and total organic carbon (TOC) levels in the overlying water were measured at regular intervals, and the changes of different P forms in WTPS, Al-PIA, and sediment of each system were analyzed before and after the test. The average TP reduction rates of LMB, Al-PIA, WTPS, and QS were 94.82, 92.14, 86.88, and 10.68%, respectively, when the release strength of sediment TP was 2.26–9.19 mg/(m²·d) and the capping strength of the materials was 2 kg/m². Thin-layer capping of LMB, WTPS, and Al-PIA could effectively control P release from the sediment (P<0.05). However, thin-layer capping of LMB, Al-PIA, and QS did not significantly reduce the release of ammonium N and organic matter (P > 0.05). Based on our results, LMB, Al-PIA, and WTPS thin-layer capping promoted the migration and transformation of easily released P in sediment. The P adsorbed by WTPS and Al-PIA mainly occurred in the form of NAIP.     

建筑结构活荷载标准与灾害荷载设防水平 --使用年限的影响

旨在提供不同使用年限建筑结构对应的活荷载水平.分析了结构可靠度理论的特点,揭示了设计使用年限是结构可靠度的时间特征.应根据不同设计使用年限活荷载的超越概率等于常规设计荷载超越概率的原则确定活荷的载标准;通过建立不同设计使用期、不同设计基准期与活荷载取值的关系,给出了不同使用年限对应活荷载与灾害荷载设防水平.