Comparison and Evaluation of Gridded Precipitation Datasets in a Kansas Agricultural Watershed Using SWAT

Gridded precipitation datasets are becoming a convenient substitute for gauge measurements in hydrological modeling; however, these data have not been fully evaluated across a range of conditions. We compared four gridded datasets (Daily Surface Weather and Climatological Summaries [DAYMET], North American Land Data Assimilation System [NLDAS], Global Land Data Assimilation System [GLDAS], and Parameter‐elevation Regressions on Independent Slopes Model [PRISM]) as precipitation data sources and evaluated how they affected hydrologic model performance when compared with a gauged dataset, Global Historical Climatology Network‐Daily (GHCN‐D). Analyses were performed for the Delaware Watershed at Perry Lake in eastern Kansas. Precipitation indices for DAYMET and PRISM precipitation closely matched GHCN‐D, whereas NLDAS and GLDAS showed weaker correlations. We also used these precipitation data as input to the Soil and Water Assessment Tool (SWAT) model that confirmed similar trends in streamflow simulation. For stations with complete data, GHCN‐D based SWAT‐simulated streamflow variability better than gridded precipitation data. During low flow periods we found PRISM performed better, whereas both DAYMET and NLDAS performed better in high flow years. Our results demonstrate that combining gridded precipitation sources with gauge‐based measurements can improve hydrologic model performance, especially for extreme events.     

碳酸镁与镉离子的吸附和沉淀作用研究

以碳酸镁为吸附剂,在镉离子初始浓度为0~6 mmol/L,初始pH值为4和7的条件下,研究了碳酸镁与镉离子的吸附与沉淀作用。结果表明,由于碳酸镁的溶解及与体系中氢离子的中和,碳酸镁—镉体系的最终pH值为10.4左右;体系的平衡pH值随着镉离子初始浓度的增加而减小;体系中镉的平衡浓度随着初始镉离子浓度的增加缓慢上升;碳酸镁对镉的吸附等温线为折线型,不符合Freundlich和Langmuir模型,符合伪二阶吸附动力学模型。结合碳酸镁吸附镉前后固相表征的结果,说明碳酸镁与镉离子的作用机制随着镉离子浓度的增加,从离子交换发展为离子交换和表面配位反应并存,最后表现为表面沉淀。     

pH对煤泥水絮凝沉降的影响

选择聚合氯化铝(PAC)/阴离子型聚丙烯酰胺(PHP)、氯化钙(CaCl2)/非离子型聚丙烯酰胺(NPAM)组合与NPAM、PHP、两性离子型聚丙烯酰胺(ZPAM)作为絮凝剂,在对道清选煤厂水采筛下原生煤泥和浮选尾矿的煤泥水进行组合药剂絮凝实验的基础上,考察了pH对煤泥水絮凝沉降的影响。实验结果表明,在不同的pH下,煤泥水的絮凝效果不同:在酸性条件下,宜单独使用有机高分子絮凝剂;在中性至碱性条件下,无机凝聚剂和有机絮凝剂联合使用效果较好。     

混凝-Fenton试剂氧化工艺处理机械厂洗涤废水

对某厂机械洗涤废水,采用混凝-Fenton试剂进行处理。结果表明,用聚铝（w（PAC）=5%）对废水进行絮凝沉淀,PAC最佳投加量为1.5 mL/L（废水）,絮凝后的COD去除率为29.6%;芬顿试剂最佳操作条件为：n（H2O2）∶n（Fe2＋）=5∶1,m（H2O2）∶m（COD）=2.5∶1,废水pH=5,温度为30℃,反应时间为2 h,经氧化后,COD的去除率为78.5%;经过混凝沉淀-芬顿氧化处理,COD的总去除率为84.9%,去除效果良好。     

生活垃圾渗滤液处理工艺探讨

分析了国内生活垃圾（以下简称垃圾）渗滤液的特点,探讨了一种比较科学的垃圾渗滤液处理工艺：沉淀-厌氧处理-MBR-纳滤处理,并且分析了各段工艺的原理、特点以及其作用。     

1961—2008年新疆阿克苏地区降水、温度变化特征

利用阿克苏地区5个气象站1961—2008年的降水和温度资料,对近50 a来该地区气候变化及其趋势进行了分析。各气象站年降水量变化趋势基本一致,总体上都呈增加趋势。除库车县气象站年平均温度呈降低趋势外,其余呈上升趋势。总体上,阿克苏地区年降水量和年平均温度均呈上升趋势。     

Reclaimed Mineland Curve Number Response to Temporal Distribution of Rainfall1

Warner, Richard C., Carmen T. Agouridis, Page T. Vingralek, and Alex W. Fogle, 2010. Reclaimed Mineland Curve Number Response to Temporal Distribution of Rainfall. Journal of the American Water Resources Association (JAWRA) 46(4): 724-732. DOI: 10.1111/j.1752-1688.2010.00444.x Abstract: The curve number (CN) method is a common technique to estimate runoff volume, and it is widely used in coal mining operations such as those in the Appalachian region of Kentucky. However, very little CN data are available for watersheds disturbed by surface mining and then reclaimed using traditional techniques. Furthermore, as the CN method does not readily account for variations in infiltration rates due to varying rainfall distributions, the selection of a single CN value to encompass all temporal rainfall distributions could lead engineers to substantially under- or over-size water detention structures used in mining operations or other land uses such as development. Using rainfall and runoff data from a surface coal mine located in the Cumberland Plateau of eastern Kentucky, CNs were computed for conventionally reclaimed lands. The effects of temporal rainfall distributions on CNs was also examined by classifying storms as intense, steady, multi-interval intense, or multi-interval steady. Results indicate that CNs for such reclaimed lands ranged from 62 to 94 with a mean value of 85. Temporal rainfall distributions were also shown to significantly affect CN values with intense storms having significantly higher CNs than multi-interval storms. These results indicate that a period of recovery is present between rainfall bursts of a multi-interval storm that allows depressional storage and infiltration rates to rebound.     

煤矿矿井水处理节能降耗实践

文章针对煤矿矿井水因含有油污和大量轻质悬浮物时存在处理能耗高、混凝刑消耗量大,导致处理成本高的情况,以华蓥山煤业股份公司龙滩煤矿水处理系统技改为例,探讨矿井水处理节能降耗的可行性和途径。本文介绍了根据矿井水特性及排放规律,以及混凝沉淀机理,通过优化设计矿井水处理工艺精减耗电设备,合理选择混凝药剂和投药方式等措施,达到提高沉淀效率,节能降耗的目的。     

烟气脱硫溶液中硫酸根的去除

分别采用石灰乳化学沉淀法和低温结晶法去除烟气脱硫溶液中的SO42-。实验结果表明：在室温、CaO溶液质量分数25%的条件下,石灰乳化学沉淀法对SO42-的去除率仅为59.51%,且向溶液中引入了Ca2+,产生的硫酸钙固体废物难以再生利用;采用低温结晶法处理烟气脱硫溶液,在结晶温度7 ℃、结晶时间3 h、NaOH加入量34.8 g/L的条件下,SO42-的去除率为82.04%、滤液中的ρ（Na+）为3.88 g/L。在现场工业应用试验中,采用低温结晶法去除烟气脱硫溶液中的SO42-,平均SO42-的去除率可达70.00%以上,滤液中的ρ（Na+）小于15.00 g/L。该法可有效抑制烟气脱硫溶液中SO42-含量的增加。     

基于DFA法的江苏省极端降水时空分布特征研究

为进一步掌握江苏省极端降水的时空分布特征,基于该省1961-2010年均一性较好的逐日降水数据,利用去趋势波动分析法确定了全省13个站点的极端降水阈值,并通过Morlet小波及Mann-Kendall法分析了江苏省极端降水频数的振荡周期及其突变。结果表明,江苏省极端降水年频数和夏季极端降水均呈现8～10 a的变化周期,且1998年和2006年分别为其突变增加年,而秋季极端降水主要呈2～3 a与5～7 a的变化周期;极端降水与降水总量的空间分布具有较好的一致性,均呈南部大、北部小的特征。