The Role of Soil Organic Carbon in Maintaining Surface Elevation in Rapidly Subsiding U.S. Gulf of Mexico Coastal Marshes

Subsidence is a primary factor governing marsh deterioration in Mississippi River deltaic plain coastal marshes. Marsh surface-water level relationships are maintained primarily through soil organic matter accumulation and inorganic sediment input. In this study we examined the role of soil organic matter accumulation in maintaining marsh elevation in a brackish Spartina patens marsh. Measured rates of soil organic accumulation were compared to plant biomass production and soil respiration (carbon dioxide and methane emission) at the study sites. The study demonstrated the importance of plant biomass production to soil organic carbon accumulation in maintaining viable Spartina patens marshes in sediment-deficient coastal environments. The role of Mississippi River freshwater reintroduction in maintaining conditions for organic accretion is discussed.     

Chemical Composition and Acidity of Rain at the Gulf of Iskenderun,North-East Mediterranean

The purpose of the present work was to investigate the chemistry of rain in the Gulf of Iskenderun, North East Mediterranean, Turkey. The Gulf region has a large number of industries. Main industries existing in the region are iron and steel works, fertilizer plants, a cement plant, and several medium and mini size steel mills in addition to the international pipe line terminals. This study aims to apportion the local sources contributing to the overall pollution of the region. To this end a precipitation sampling program was started in January 2000, and over 48 precipitation samples were collected from each of 5 stations located at Iskenderun city center, Iskenderun industrial zone, Payas city center, the campus of Iskenderun Technical College and the campus of Mustafa Kemal University. Samples were analysed for pH, NO₃ ⁺, Cl^-. Ca, Al, Ba, Na, Cd, Co, Cr, Cu, Pb, Li, Mg, Mn, Ni, Zn, Fe, K. Concentrations of metal ions were determined by ICP-AES. NO₃ ^- ions and pH were determined by using NO₃ ^- selective electrode and pH meter, respectively.pH values of the collected samples at the industrial zone and at Payas city center, ranged between 5.02 and 7.38, respectively. NO₃ ^- and metal ions concentrations were highly variable. Concentrations of Ca and Fe ions were higher in the industrial zone and Payas city center. In the other three stations, concentrations of metal ions and NO₃ ^- ion were lower than that of industrial zone and the values of pH ranged between 6 and 7.4. The average pH values at Iskenderun Gulf showed that the precipitation was not acidic, because of the high concentration of Ca. The highest concentrations of Na and Cl ions were recorded in the University campus because the campus is located by the Mediterranean Sea.     

GROUND WATER NITRATE REDUCTION IN GIANT CANE AND FOREST RIPARIAN BUFFER ZONES1

ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone.     

三峡库区降雨径流水体中铜、锰、镍、锌、铅含量及分布特征

本文按时段和随机采集了三峡库区降雨径流水体样品，测定了水体中Ｃｕ、Ｍｎ、Ｎｉ、Ｚｎ、Ｐｂ含量，统计结果表明：Ｍｎ、Ｚｎ、Ｐｂ在径流水体中的含量趋于平均，变异系数较小。随产流时间的变化，水体中５种元素的变化规律不明显     

我国燃煤电厂脱硫技术应用现状及展望

介绍了我国二氧化硫排放及污染现状，分别从燃烧前、燃烧中、燃烧后三个阶段，阐述了我国脱硫煤生产、低硫污染燃烧技术及燃煤烟气脱硫的污染控制技术现状和发展方向，提出我国控制燃煤硫污染的对策及建议。     

超滤膜处理火电厂废水的工业性试验研究

结合现场中试探讨了超滤作为反渗透预处理工艺的可行性，确定了超滤工艺处理某火电厂废水的基本参数，研究了超滤膜的恢复及效果，并且提出了系统设计的相关建议，对工业系统设计具有指导意义。     

火电厂石灰石湿法烟气脱硫废水处理方法

阐述了石灰石湿法烟气脱硫（FGD）废水的水质特征，介绍了国内外普遍应用的化学沉淀去除脱硫废水中重金属、悬浮物等物质的工艺特点及其不足，并着重介绍了最新发展的流化床法、沉淀一微滤法等FCD废水处理新型工艺。     

水环境中重金属的生物积累研究及应用

本文综述了水环境中重金属在水生生物体内（包括鱼类的鳃、软体动物及贝类的肾、肝和肌肉等组织器官）蓄积研究现状及蓄积规律。利用生物积累的特性，为重金属污染的防治及生物监测提供参考。     

四川彭州铜尾矿库植被特征分析与植物群落演替初探

本文分析了四川彭州铜矿尾矿库的植被特征、群落特征与演替。在该尾矿库上自然定居的高等植物共91种，隶属38科79属，以菊科（Compositae）和禾本科（Gramineae）植物为主。形成6种相对稳定的群落类型；在2003年弃耕后形成的地段分布有史蒿＋小飞蓬群落（Artemisia argyi＋Conyza conadensis Comm．）、艾蒿＋打破碗花花群落（Artemisia argyi＋Anemone hupehensis Comm．）、艾蒿群落（Artemisia argyi Comm．）和白车轴苹群落（Trifolium repens Comm．）；在经过30～40年自然演替的地段分布有芭茅＋羊耳菊群落（Miscanthus sinensis＋Inula cappa Comm．）和羊耳菊＋千里光＋密蒙花群落（Inula cappa＋Senecio scandens＋Buddleja officinalis Comm．）；在近十年内新形成的地段现主要覆盖地衣和葫芦藓（Funaria hygrometrica）。通过对群落结构和不同地段植被特征的对比，对本铜尾矿库的演替现状和规律进行了分析，井讨论了人为影响对演替进程的影响，提出了人工恢复措施的建议。