Modeling of Vertical Solute Dispersion in a Sediment Bed Enhanced by Wave‐Induced Interstitial Flow1

Abstract: Mass (solute) transport in a stream or lake sediment bed has a significant effect on chemical mass balances and microbial activities in the sediment. A “1D vertical dispersion model” is a useful tool to analyze or model solute transfer between river or lake water and a sediment bed. Under a motionless water column, solute transfer into and within the sediment bed is by molecular diffusion. However, surface waves or bed forms create periodic pressure waves along the sediment/water interface, which in turn induce flows in the pores of the sediment bed. The enhancement of solute transport by these interstitial periodic flows in the pores has been incorporated in a 1D depth‐dependent “enhanced dispersion coefficient (D_E).” Typically, D_E diminishes exponentially with depth in the sediment bed. Relationships have been developed to estimate D_E as a function of the characteristics of sediment (particle size, hydraulic conductivity, and porosity) and pressure waves (wave length and height). In this paper, we outline and illustrate the calculation of D_E as well as the penetration depth (d_p) of the flow effect. Sample applications to illustrate the computational procedure are provided for dissolved oxygen transfer into a stream gravel bed and release of phosphorus from a lake bed. The sensitivity of the results to input parameter values is illustrated, and compared with the errors obtained when interstitial flow is ignored. Maximum values of D_E near the sediment surface can be on the order of 1 cm²/s in a stream gravel bed with standing waves, and 0.001 cm²/s in a fine sand lake bed under progressive surface waves, much larger than molecular diffusion coefficients.     

矿产弃地的生态恢复研究

尾矿废弃地是一种典型的退化生态系统。本文通过对其生态恢复所面临问题的研究,讨论了尾矿废弃地生态恢复的理论,运用矿区废弃地生态恢复的土壤改良和先锋物种的选择方法,对包钢尾矿库的复垦进行了分析,说明矿产废弃地的生态恢复是与区域社会发展紧密联系的生态-经济工程。     

Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State1

Mulvihill, Christiane I. and Barry P. Baldigo, 2012. Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State. Journal of the American Water Resources Association (JAWRA) 48(3): 449-463. DOI: 10.1111/j.1752-1688.2011.00623.x Abstract: This study analyzes how various data stratification schemes can be used to optimize the accuracy and utility of regional hydraulic geometry (HG) models of bankfull discharge, width, depth, and cross-sectional area for streams in New York. Topographic surveys and discharge records from 281 cross sections at 82 gaging stations with drainage areas of 0.52-396 square miles were used to create log-log regressions of region-based relations between bankfull HG metrics and drainage area. The success with which regional models distinguished unique bankfull discharge and HG patterns was assessed by comparing each regional model to those for all other regions and a pooled statewide model. Gages were also stratified (grouped) by mean annual runoff (MAR), Rosgen stream type, and water-surface slope to test if these models were better predictors of HG to drainage area relations. Bankfull discharge models for Regions 4 and 7 were outside the 95% confidence interval bands of the statewide model, and bankfull width, depth, and cross-sectional area models for Region 3 differed significantly (p < 0.05) from those of other regions. This study found that statewide relations between drainage area and HG were strongest when data were stratified by hydrologic region, but that co-variable models could yield more accurate HG estimates in some local regional curve applications.     

本源微生物菌剂修复城市污染河流

通过丰湖河投菌过程中和总投菌后两周的各水质指标分析,对本源微生物菌剂作用城市重污染河流过程进行了探讨和研究。结果表明,在2010年11月20日全河布菌后,以COD下降后上升的情况作为补菌时间的判断依据,实现菌种效力最大化。继2010年11月25日、27日和30日3次补菌后上游至下游硐桥、久泰桥和益民水闸处COD的去除率分别达到52.7%、68.8%和61.6%,氨氮和总磷有所去除。水色由深灰绿色转变为深绿色,浮油减少,臭味明显消除。表明此法在冬季水温较低的天然河流条件下,不需大型设备便可较快修复水质,具有较好的经济环境效益。     

生态修复综合技术在杭州虾龙圩河的应用

杭州虾龙圩河由于多年污染,河道水质严重黑臭,自净能力遭到破坏。本研究通过综合利用底泥污染物削减、生物接触氧化水质净化、造流曝气及水生生态系统修复等技术对虾龙圩河进行治理。结果显示,此项综合技术对城市河流污水具有良好的污染物去除性能,COD、NH3-N和TP的去除率分别可达到73．3％、80．1％和81．7％。通过1年的运行与养护,虾龙圩河治理段的水质、生态环境等有了明显改善,没有发生过水华及黑臭现象,河道水体具备了较强的自净能力。     

贡湖湾退渔还湖区的基底稳定性的时空特征

2012年11月至2014年5月期间季度性对无锡贡湖湾退渔还湖生态修复工程进行跟踪调查与检测,就贡湖湾湿地土壤环境退渔还湖修复工程前后的理化性质进行了分析比较,用以评估修复工程实施后退渔还湖区基底的改善效果.结果表明:退渔还湖区内基底化学性质,有机质、总氮、总磷比退渔还湖初期分别提高241.59％、98.61％和162.86％.其中,有效氮和有效磷的均值为102.31 mg/kg和15.10 mg/kg,满足土壤养分分级标准Ⅲ级标准.有关基底稳定性物理性质与退渔还湖初期相比,土壤容重减少17.84％,pH值稳定在5.8 ～6.5之间,土壤缓冲能力明显提高,修复区南部(人为种植植物)的土壤团聚体稳定性恢复状况最好,西部(自然恢复)次之,北部(基底状况差,无植物种植)恢复状况低于前述两区.总之,贡湖退渔还湖修复区在经过17个月后,其基底的整体质量趋于良好,土壤各项养分及团聚体稳定性指标逐步达到合理水平,土壤环境已具有良好的生态功能.     

基于RS和GIS的汶川地震极重灾区生态恢复监测——以都江堰市为例

"5.12"汶川地震造成灾区尤其极重灾区严重的生态破坏。论文以都江堰市为例,利用遥感(RS)和地理信息系统(GIS)等手段对震害区土地利用/植被覆盖变化进行监测,对动态变化进行定量分析,得到都江堰市地震生态受损及灾后两年生态恢复信息,并结合DEM对变化信息进行空间分析,研究灾害发生、生态恢复与坡度的相关关系,从而为灾区生态环境的恢复重建和保障生态安全提供借鉴和依据。     

Traditional Farming Landscapes for Sustainable Living in Scandinavia and Japan: Global Revival Through the Satoyama Initiative

Traditional, pre-industrial farming was adapted to the natural environment—topography, geology, hydrology, climate, and biota. Traditional land use systems are still to be traced in Scandinavia as an “infield/outland landscape”, and in Japan as a “Satoyama landscape.” There are obvious similarities and differences in land use—the main difference being that pasturing of cattle and sheep has been less important in Japan. These land use systems can be traced back to early sedentary settlements 1500–2500 years ago. In both regions, traditional management almost ceased in the mid-twentieth century leading to afforestation and decreased biological diversity. Today, there is in Japan a growing movement for landscape restoration and promotion of a sustainable living countryside based on local agrarian and forestry production, local energy, tourism, etc. With this background, the so-called Satoyama Initiative has been organized and introduced as a global socio-ecological project with ecosystem services for human well-being.     

乌东德水库坝前段消落带生态类型划分及生态修复模式初探

采用GIS技术,根据高程、坡度、土壤类型等环境特征,将乌东德水库坝前段消落带分为18种生态类型,并完成了高程图、坡度图和土壤类型图,建立了环境特征和消落带类型的直观联系。然后根据不同的生态类型,提出了4种生态修复模式,并选择了10种植物作为生态修复物种。为其它水库消落带生态修复提供了参考依据。     

Spain's greatest and most recent mine disaster

On 25 April 1998, the mineral waste retaining wall at the Swedish-owned pyrite mine at Aznalcóllar (Seville, Spain) burst, causing the most harmful environmental and socio-economic disaster in the history of the River Guadiamar basin. The damage was so great that the regional government decided in May 1998 to finance a comprehensive, multidisciplinary research initiative with the objective of eradicating or at least minimising all of the negative social, economic and environmental impacts. This paper utilises a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis to identify eight strategic measures aimed at providing policymakers with key guidelines on implementing a sustainable development model, in a broad sense. Empirical evidence, though, reveals that, to date, major efforts to tackle the negative impacts have centred on environmental concerns and that the socio-economic consequences have not been completely mitigated.