城市区域土体铁的化学行为与土体强度变异关系研究

统计了南宁市地下水中Fe的变化情况,实验研究了Fe的物理化学行为与土体强度之间的联系,并进一步研究了铁对土体强度影响的双向性.结果显示,城市区域将由于Fe的溶蚀、置换作用等使土体强度降低;城市区域CO2分压增高将促进土体中铁的溶蚀而使土体强度进一步恶化.在含水量相对较高时,铁质胶结物被溶解、迁移,土体强度降低;而在含水量相对较低时,铁质胶结物不易被溶解,而更趋向于发生沉淀反应,使土体对铁的吸附作用加强,从而使土体的强度增加.     

Bankfull Regional Curves for the Inner and Outer Bluegrass Regions of Kentucky1

Brockman, Ruth R., Carmen T. Agouridis, Stephen R. Workman, Lindell E. Ormsbee, and Alex W. Fogle, 2012. Bankfull Regional Curves for the Inner and Outer Bluegrass Regions of Kentucky. Journal of the American Water Resources Association (JAWRA) 48(2): 391‐406. DOI: 10.1111/j.1752‐1688.2011.00621.x Abstract: Bankfull regional curves that relate channel dimensions and discharge to watershed drainage area are useful tools for assisting in the correct identification of bankfull elevation and in stream restoration and reconstruction. This study assessed 28 stable streams located in two physiographic regions of Kentucky: the Inner Bluegrass and the Outer Bluegrass. Bankfull channel dimensions, discharge, and return period as well as average channel slope, median bed material size, sinuosity, Rosgen stream classification, and percent impervious area were determined. Significant relationships were found between drainage area and the bankfull characteristics of cross‐sectional area, width, mean depth, and discharge for both the Inner Bluegrass and Outer Bluegrass regions (α = 0.05). It was also found that the percent impervious area in a watershed had minimal effect on bankfull dimensions, which is attributed to the well‐vegetated nature of the streambanks, cohesive streambank materials, and bedrock control. No significant differences between any of the Inner Bluegrass and Outer Bluegrass regional curves were found (α = 0.05). Comparisons were made between the Inner Bluegrass and Outer Bluegrass curves and others developed in karst‐influenced areas in the Eastern United States. Although few significant differences were found between the regional curves for bankfull discharge and width, a number of the curves differed with regards to bankfull cross‐sectional area and mean depth.     

Climate change and village adaptation impact on reliability of irrigation wells in China

This paper builds a water supply reliability econometric model to analyze climate changes and adaptation impact factors on water supply reliability of irrigation wells by using 100 villages’ three-year (2010–2012) field survey data of five middle and eastern provinces of China. The results show that long-run climate change factors, adaptation measures, village-level organizations of irrigation management, as well as extreme climate factors affect the water supply reliability of irrigation wells significantly. Meanwhile, there are significant differences impacting different crops and provinces. This paper suggests that agriculture meteorological disaster monitoring and warning systems should be strengthened by increasing irrigation facilities construction and maintenance, promoting reform of agricultural irrigation water management system, and developing various forms of peasant cooperation organization in order to improve agricultural production capacity to adapt to climate change.     

灰色关联度分析在地下水污染源强定量评价中的应用

以氨氮为研究对象,利用HYDRUS-1D软件模拟多个污染场地氨氮质量浓度的折减系数,通过灰色关联度法分析折减系数与场地污染源、包气带特征指标之间的关联程度.依据关联度计算结果,建立了以主要特征指标为自变量、折减系数为因变量的多元线性回归方程,综合反映包气带对某一特征污染物的衰减能力.案例研究结果表明,在典型场地资料有限的前提下,该方法能快速有效地得到地下水中的氨氮质量浓度预测值,并保证计算误差在统计学标准范围内.     

Wind‐Powered Desalination: An Estimate of Saline Groundwater in the United States1

James Androwski, Abraham Springer, Thomas Acker, and Mark Manone, 2011. Wind‐Powered Desalination: An Estimate of Saline Groundwater in the United States. Journal of the American Water Resources Association (JAWRA) 47(1):93‐102. DOI: 10.1111/j.1752‐1688.2010.00493.x Abstract: Increasing scarcity of freshwater resources in many regions of the world is leading water resource managers to consider desalination as a potential alternative to traditional freshwater supplies. Desalination technologies are energy intensive and expensive to implement making desalination using renewable energy resources a potentially attractive option. Unfortunately, saline groundwater resources are not well characterized for many regions hindering consideration of such technologies. In this assessment, we estimate the saline groundwater resources of the principal aquifers of the United States using a geographic information system and correlate these resources to wind resources potentially sufficient to supply the energy demand of desalination equipment. We estimate that 3.1 × 10¹⁴ m³ saline groundwater, total volume, are contained in 28 of the country’s principal aquifers known to contain saline groundwater. Of this volume, 1.4 × 10¹⁴ m³ saline groundwater are co‐located with wind resources sufficient for electrical generation to desalinate groundwater.     

The Role of Headwater Wetlands in Altering Streamflow and Chemistry in a Maine,USA Catchment1

Morley, Terry R., Andrew S. Reeve, and Aram J.K. Calhoun, 2011. The Role of Headwater Wetlands in Altering Streamflow and Chemistry in a Maine, USA Catchment. Journal of the American Water Resources Association (JAWRA) 1‐13. DOI: 10.1111/j.1752‐1688.2011.00519.x Abstract: Headwater wetlands, including hillside seeps, may contribute to downstream systems disproportionately to their relatively small size. We quantified the hydrology and chemistry of headwater wetlands in a central Maine, USA, catchment from 2003 to 2005 to determine their role in maintaining headwater streamflow and in affecting stream chemistry. A few of these headwater wetlands, commonly referred to as “seeps,” were characterized by relatively high groundwater discharge. During summer base flow, seeps were the primary source of surface water to the stream, contributing between 40 and 80% of stream water. Comparisons of groundwater and surface water dominant ion chemistry revealed only slight differences at the bedrock interface; however, significant changes occurred at the shallow groundwater‐surface water interface where we found decreases in total and individual cation concentrations with decreasing depth. Seep outflows significantly increased total cation and calcium concentrations in streams. Outflows at two seeps produced relatively high nitrate concentrations (88 ± 15 and 93 ± 15 μg/l respectively), yet did not correspond to higher nitrate in stream water below seep outflows (2 ± 1 μg/l). We demonstrate that small wetlands (< 1,335 m²) can contribute to headwater stream processes by linking groundwater and surface‐water systems, increasing the duration and magnitude of stream discharge, and by affecting stream chemistry, particularly during periods of base flow.     

Comparison of Aquifer Sustainability Under Groundwater Administrations in Oklahoma and Texas1

Mittelstet, Aaron R., Michael D. Smolen, Garey A. Fox, and Damian C. Adams, 2011. Comparison of Aquifer Sustainability Under Groundwater Administrations in Oklahoma and Texas. Journal of the American Water Resources Association (JAWRA) 1‐8. DOI: 10.1111/j.1752‐1688.2011.00524.x Abstract: We compared two approaches to administration of groundwater law on a hydrologic model of the North Canadian River, an alluvial aquifer in northwestern Oklahoma. Oklahoma limits pumping rates to retain 50% aquifer saturated thickness after 20 years of groundwater use. The Texas Panhandle Groundwater Conservation District’s (GCD) rules limit pumping to a rate that consumes no more than 50% of saturated thickness in 50 years, with reevaluation and readjustment of permits every 5 years. Using a hydrologic model (MODFLOW), we simulated river‐groundwater interaction and aquifer dynamics under increasing levels of “development” (i.e., increasing groundwater withdrawals). Oklahoma’s approach initially would limit groundwater extraction more than the GCD approach, but the GCD approach would be more protective in the long run. Under Oklahoma rules more than half of aquifer storage would be depleted when development reaches 65%. Reevaluation of permits under the Texas Panhandle GCD approach would severely limit pumping as the 50% level is approached. Both Oklahoma and Texas Panhandle GCD approaches would deplete alluvial base flow at approximately 10% development. Results suggest periodic review of permits could protect aquifer storage and river base flow. Modeling total aquifer storage is more sensitive to recharge rate and aquifer hydraulic conductivity than to specific yield, while river leakage is most sensitive to aquifer hydraulic conductivity followed by specific yield.     

甲基叔丁基醚在地下水系统中的自然衰减

地下水中的甲基叔丁基醚（MTBE）自然衰减是生物与非生物过程综合作用的结果。在厌氧条件下,MTBE的同位素方面的证据表明：挥发、吸附和稀释等非生物过程中MTBE自然衰减的主要作用。在实际工作中,应结合当地水文地质条件,从主要环境因子来分析MTBE的自然衰减,从而判定MTBE自然衰减的速率和程度。在进行地下水中MTBE自然衰减研究时,应加强对于能反映MTBE自然衰减的＂印迹＂的研究。对这些＂印迹＂的确定将为野外监测MTBE的自然衰减提供理论上的依据。     

塔里木河中游水盐梯度下的物种多样性研究

根据塔里木河中游5个断面30眼地下水监测井和30个植物样地2006—2008年调查监测的数据,分析了输水堤防修建后地下水埋深、地下水质以及物种多样性的变化及其相互关系。结果表明:地下水埋深的空间变化表现为沿河道方向先增加后减小的趋势,在时间上则表现为,从2006年到2008年埋深呈逐渐增加的特点;地下水化学类型的变化,在空间上表现出沿着河道方向有由Cl-—SO42-—Na+—Mg2+向Cl-—Na+类型转变的趋势,在时间上,地下水矿化度逐渐增加。物种多样性总体上呈现增加变化,地下水位和水质对塔里木河中游物种多样性变化有着密切的关系,地下水埋深2.8~3.7 m,矿化度1.8~2.4 g·L-1水平下的多样性较高,随着地下水埋深的增大和矿化度的升高,物种多样性水平降低。     

利用氮、氧稳定同位素识别地下水硝酸盐污染源研究进展

氮污染特别是地下水硝酸盐污染已成为一个相当普遍而重要的环境问题。地下水硝酸盐污染与人类健康和环境安全密切相关。为控制地下水硝酸盐污染,最根本的解决办法就是找到硝酸盐的来源,减少硝态氮向地下水的输送。由于不同来源的硝酸盐具有不同的氮、氧同位素组成,人们利用NO3-中δ15N和δ18O开展了硝酸盐污染源识别研究。本文综述了利用氮、氧同位素识别地下水硝酸盐污染源及定量硝酸盐污染源输入的研究进展及目前存在的问题,并提出几个值得重视的研究方向。