珠江三角洲降水化学成分的区域特征研究

通过对珠江三角洲地区降水（降雨）化学成分的分析表明，该区可能存在二条降水物质通道，一条是从陆到海通道，从肇庆和广州分别至佛山、顺德、江门、台山、中山，至珠海出海，基本与西江和江河谷走向一致，另一条是从海到陆通道，从深圳始，到东莞和惠州，珠江口水面成为此二条通道的天然分隔屏障。地面源污染是造成该区局部降水酸度差异的调节因素，而造成全区降水酸化的根本原因是存在于平流层的区域性酸化大气层。南海海洋对降水     

Effects of long-term nitrogen addition and precipitation changes on CH4 flux in an alpine steppe北大核心CSCD

土壤是甲烷(CH4)重要的源和汇.氮沉降和降水格局变化正在急剧改变土壤碳循环,进而可能对土壤CH4通量造成深刻影响.高寒生态系统是巨大的碳库,对氮沉降和降水变化十分敏感.然而,目前多数研究集中在短期实验上,缺乏对长期氮沉降和降水变化背景下CH4通量的响应及其调控因素的认识.以青藏高原高寒草原为研究对象,在2013年搭建模拟氮沉降和降水格局改变实验平台.基于静态箱–气相色谱法测定2020年生长季(5-10月)土壤CH4通量.结果显示,高寒草原土壤呈CH4的汇.氮添加没有显著改变生长季和植物生长高峰CH4通量.然而,降水变化显著改变了生长季和植物生长高峰CH4通量,其中降水增加(+50%降水)降低了CH4的吸收(分别为–16%和–45%),降水减少(–50%降水)增强了CH4的吸收(分别为+73%和+33%).进一步研究发现,与植物属性和功能基因丰度相比,土壤环境因子主导了CH4通量变化(解释率>90%).其中CH4通量与土壤含水量和温度显著正相关,与土壤pH显著负相关.综上所述,在未来全球变化情景下,降水格局改变更能调节青藏高原高寒草原CH4通量的变化.(图6表1参37)     

好氧颗粒污泥在生物强化除磷中的应用

结合近年来好氧颗粒污泥的最新研究成果,分析了好氧颗粒污泥的物理、化学、生物学、结构特征,并从生物除磷、反硝化除磷和沉淀作用三方面对好氧颗粒污泥除磷现象进行探讨。旨在为好氧颗粒污泥在生物强化除磷中的实际应用提供理论知识。     

Polycyclic aromatic hydrocarbons in the bulk precipitation and surface waters of Northern Greece

Bulk (wet and dry) precipitation and surface water sampling was undertaken in the main plain of central Macedonia in Northern Greece. Fourteen polycyclic aromatic hydrocarbons (PAHs) included in the US EPA's priority pollutant list were analysed. The concentrations determined in bulk precipitation were in general within the range of values worldwide reported. Concentrations were highest in the cold months. Deposition fluxes of PAHs were of the same order of magnitude as reported data. The greatest values were found when high concentrations of PAHs in precipitation coincided with large precipitation amounts. The concentrations of PAHs in surface waters (main rivers, tributaries, ditches, etc) were in general lower than those in bulk precipitation, and among the lowest reported for European rivers, excepting Np and Ph. Bulk deposition and domestic effluents are suggested as being the main PAH sources into surface waters.     

废水除磷技术的研究与发展

目前 ,人们越来越重视污水除磷技术。本文介绍与评述了化学和生物两种除磷方式及其除磷机理和工艺 ,并着重介绍了生物除磷的现状、发展和研究动向     

鸟粪石沉淀法预处理高氨氮废水的镁盐研究

药剂费用一直是限制鸟粪石法处理高氨氮废水实际应用的主要因素。实验采用鸟粪石沉淀法预处理高氨氮废水,以磷酸氢二钠作为磷盐,就不同镁盐对高氨氮废水的处理效果进行了分析比较。实验结果表明,将氯化镁与氧化镁联用作为新型镁盐时,有很大的优势。在n（N）：n（P）：n（Mg）=1：1：1．5,n（MgCl2）：n（MgO）=1：2,反应时间为30min条件下,氨氮的去除率可以达到90％以上,与常规单独采用氯化镁的处理方法相比,镁盐药剂费用可节约2／3以上。     

2001～2003年间北京大气降水的化学特征

为了了解北京大气降水的化学组成与时间变化特征,连续进行了2年的降雨采样与分析.在65个降雨样品中,12%的降水呈酸性;全年降水的酸度主要取决于夏季的降水.SO₄^2-、NH₄⁺与Ca²⁺是含量最丰富的组分,其平均浓度均接近或超过200礶q/L.比较分析表明,在近几年,SO₄^2-对降水酸度的贡献显著降低,降水的硫污染特征减弱,而No₃^-的贡献显著增加.人为污染元素和地壳元素的浓度均在冬春季较高,在夏季最低.     

辽宁省背景地区降水化学特征及其与大气传输的关系

为了解辽宁省背景地区降水化学特征及其与大气传输的关系,于2007年2月─2008年1月在辽中县水文监测站进行了降水化学特征观测,测量项目包括降水pH,电导率和离子浓度. 观测期间降水pH为3.4～7.3,降水量加权平均值为4.6,整体呈酸性. 降水中主要阴离子为SO₄2-和NO₃-,浓度分别为154.3和53.4 μeq/L,二者占阴离子总量的76.8%; 主要阳离子为NH₄+和Ca2+,浓度分别为124.6和89.2 μeq/L,占阳离子总量的70.6%. 利用后向气流轨迹分析了降水气团来源对降水化学的影响,结果表明:在辽宁省及周边地区的局地气团影响下,降水中离子浓度最高;而在起源于东亚地区,经朝鲜半岛到达的南-东南气团影响下,降水次数虽最多,但离子浓度最低.      

Chemical fluxes in time through forest ecosystems in the UK - Soil response to pollution recovery

Long term trend analysis of bulk precipitation, throughfall and soil solution elemental fluxes from 12 years monitoring at 10 ICP Level II forest sites in the UK reveal coherent national chemical trends indicating recovery from sulphur deposition and acidification. Soil solution pH increased and sulphate and aluminium decreased at most sites. Trends in nitrogen were variable and dependant on its form. Dissolved organic nitrogen increased in bulk precipitation, throughfall and soil solution at most sites. Nitrate in soil solution declined at sites receiving high nitrogen deposition. Increase in soil dissolved organic carbon was detected - a response to pollution recovery, changes in soil temperature and/or increased microbial activity. An increase of sodium and chloride was evident - a possible result of more frequent storm events at exposed sites. The intensive and integrated nature of monitoring enables the relationships between climate/pollutant exposure and chemical/biological response in forestry to be explored.     

IS IT REALISTIC TO DEFINE A 100-YEAR DROUGHT FOR WATER MANAGEMENT?1

ABSTRACT: The concept of recurrence interval has been used for years in engineering designs. Can the same concept be applied to the drought analysis? This paper uses the plotting position method to define drought of various recurrence intervals based on stream-flow data. The method of truncation level was applied to the same data to examine the defined drought. Based on the method of truncation level, drought duration and its corresponding flow deficit were investigated. Eighteen flow gage stations from the Scioto River Basin in Ohio were selected for the study. The results show that flows of 100-year droughts using the plotting position method are practically nil. On the other hand, flows of droughts using the truncation method are gradually decreasing with an increase in truncation level, where flows of 95 percent are approximately equal to those of two-year droughts defined by the plotting position. It is also shown that there is a strung correlation between drought duration and deficit.