Assessment for Salinized Wasteland Expansion and Land Use Change Using GIS and Remote Sensing in the West Part of Northeast China

Due to human impact under climatic variations, western part of Northeast China has suffered substantial land degradation during past decades. This paper presents an integrated study of expansion process of salinized wasteland in Da’an County, a typical salt-affected area in Northeast China, by using Geographic Information Systems (GIS) and remote sensing. The study explores the temporal and spatial characteristics of salinized wasteland expansion from 1954 to 2004, and land use/cover changes during this period. During the past 50 years, the salinized wasteland in study area have increased by 135,995 ha, and in 2004 covers 32.31% of the total area, in the meantime grassland has decreased by 104,697 ha and in 2004 covers only 13.15% of the study area. Grasslands, croplands and swamplands were found the three main land use types converted into salinized wasteland. Land use/cover changes shows that between 1954 and 2004, 48.6% of grasslands, 42.5% of swamplands, and 14.1% of croplands were transformed into salinized wasteland, respectively. Lastly, the major factors influencing salinized wasteland expansion and land use/cover changes were also explored. In general, climatic factors supplied a potential environment for soil salinization. Human-related factors, such as policy, population, overgrazing, and intensified and unreasonable utilization of land and water resources are the main causes of salinized wasteland expansion.     

Cysteine-enhanced reductive degradation of nitrobenzene using nano-sized zero-valent iron by accelerated electron transfer

As an aliphatic amino acid, cysteine (CYS) is diffuse in the living cells of plants and animals. However, little is known of its role in the reactivity of nano-sized zero-valent iron (NZVI) in the degradation of pollutants. This study shows that the introduction of CYS to the NZVI system can help improve the efficiency of reduction, with 30% more efficient degradation and a reaction rate constant nine times higher when nitrobenzene (NB) is used as probe compound. The rates of degradation of NB were positively correlated with the range of concentrations of CYS from 0 to 10 mmol/L. The introduction of CYS increased the maximum concentration of Fe(III) by 12 times and that of Fe(II) by four times in this system. A comparison of systems featuring only CYS or Fe(II) showed that the direct reduction of NB was not the main factor influencing its CYS-stimulated removal. The reduction in the concentration of CYS was accompanied by the generation of cystine (CY, the oxidized form of cysteine), and both eventually became stable. The introduction of CY also enhanced NB degradation due to NZVI, accompanied by the regeneration of CYS. This supports the claim that CYS can accelerate electron transfer from NZVI to NB, thus enhancing the efficiency of degradation of NB.     

发酵-渗透汽化膜技术制无水乙醇研究进展

渗透汽化膜技术作为一种新型的膜分离技术和清洁生产技术,与发酵法相耦合生产燃料乙醇,具有高效、节能和环保的优势。综述了发酵-渗透汽化膜技术的研究进展,介绍了该工艺动力学模型的研究成果,与传统的发酵法进行了经济性对比,阐述了渗透汽化膜技术应用于无水乙醇工业化生产的现状和存在的问题,展望了发酵-渗透汽化膜技术的研究方向。     

泳动床/好氧颗粒污泥新技术处理生活污水的特性研究

基于生物膜法和活性污泥法的联合工艺技术,开发了泳动床/好氧颗粒污泥污水处理新技术.试验阶段,泳动床/好氧颗粒污泥技术表现出高效处理生活污水和实现污泥减量的显著特性.在水力停留时间HRT为3.2 h, COD负荷与NH⁺₄-Ｎ负荷分别为2.03 　kg/(m^３·d) 和0.52 　kg/(m^３·d)时,分别获得COD 90.9%和NH⁺₄-Ｎ 98.3%的平均去除效果.系统运行16 d开始出现好氧颗粒污泥,颗粒呈球形、椭球形和棒形,试验阶段混合液悬浮固体浓度MLSS最高达5 640 mg/L, MLVSS/MLSS平均高达0.87.此外,镜检表明好氧颗粒污泥与生物膜均聚集大量的原生动物和后生动物,形成较长和较稳定的食物链,有利于污泥减量,运行过程中污泥产率（MLSS/COD_removed）为0.175 5,仅为普通好氧工艺的50%左右.     

湿式双氧水氧化处理染料中间体H-酸钠盐溶液的研究

在0.5 L压力反应器内,对染料中间体H-酸钠盐溶液进行湿式双氧水氧化(WPO)及湿式双氧水催化氧化(CWPO)降解处理.分别考察反应时间、双氧水用量、温度、进水pH值和催化剂等对反应过程与对象污染物降解的影响规律.结果表明,WPO能在温和的条件下降解难于生物降解的有机物,在温度为110℃、压力为0.5 MPa、双氧水用量为理论需用量、进水pH=5的条件下,处理含10 g/L H-酸钠盐的H-酸盐溶液的COD和色度去除率分别为62.0%和98.7%;采用非均相Cu/Ni复合催化剂,在同样操作条件下,CWPO对同一废水的COD和色度去除率分别可达到92.0%和99.9%.表明催化剂的存在大大提高了WPO的氧化效果.     

基于电阻率的硫酸污染水泥土检测方法的探讨

电阻率法作为一种简单有效的测试方法,已在岩土工程检测中得到了一定程度的应用.通过室内试验模拟了水泥土试块受不同浓度硫酸溶液污染的反应,采用电阻率法研究了孔隙水电阻率、水泥土电阻率、结构因子与溶液浓度和龄期之间的关系.结果表明,孔隙水和水泥土电阻率随溶液浓度增大而减小、随龄期的增大而增大,结构因子随着溶液浓度和龄期的增加而增加,它们之间具有较高的相关性.这充分说明,电阻率法可应用于硫酸污染水泥土的检测和评价.     

沈阳市辽中县生态环境质量评价

采用中国环境监测总站《生态环境质量评价技术规定》中的生态环境评价指标和计算方法对辽中县生态环境质量进行定量评价。并分析了导致出现制约性因子的因素。     

Estimation of chlorophyll-a concentration using field spectral data: a case study in inland Case-II waters, North China

In the remote sensing of chlorophyll-a (Chla) in inland Case-II waters, the assumption that the optical parameter of Chla specific absorption coefficient a*ph remains constant usually restrains application of many models. In this paper, we presented a newly developed model [Rrs(-1)(lambda1) - Rrs(-1)(lambda2)] x Rrs(lambda3) x a*ph(-1)(lambda1) which was improved on a previous three-band model to isolate interferences from a*ph. In terms of the importance of water optical properties in the model development, spectral and absorption characteristics were analyzed for Shitoukoumen Reservoir and Songhua Lake in Northeast China, as typical examples of inland Case-II waters. Both waters showed overwhelming absorption sum of tripton and chromophoric dissolved organic matter (CDOM) owing to their relatively low Chla contents (1.53 to 19.35 microgl(-1)). According to the optical characteristics of waters studied, optimal positions for lambda (1), lambda (2) and lambda (3) were spectrally tuned to be at 664, 684 and 705 nm, respectively. The model allowed accurate Chla estimation with a determination coefficient (R (2)) close to 0.98 and a root mean square error (RMSE) of 0.87 microgl(-1). Comparison of different models further showed the stability of the improved model, implying its potential use in water color remote sensing. Although the findings underline the rationale behind the improved model, an extensive database containing data in different water conditions and water types is required to generalize its application.     

Research on the relationship between the fractional coverage of the submerged plant Vallisneria spiralis and observed spectral parameters

The present paper discusses the relationship between the coverage fraction of submerged plants and the observed spectral characteristics. The purpose of this paper is to validate a remote sensing technology to monitor the change in the plant composition of a water body. In the current study, the reflectance spectra of the submerged plant Vallisneria spiralis at different fraction coverages of the wetland in Hangzhou Bay were measured. The relationships between the fraction coverage of V. spiralis and simulated Quickbird normalized difference vegetation index (NDVI), red edge, and other spectral characteristic parameters were established. The results showed that the spectral reflectance characteristics of submerged plant V. spiralis were mainly in the visible light (490–650 nm) and near infrared (700–900 nm). The rate of change of the blue band curve and simulated Quickbird NDVI showed a higher correlation with the V. spiralis coverage, so estimation models of the fraction coverage were constructed using these parameters. The estimated fraction coverage of V. spiralis with different models were validated with ground data, and the accuracy of estimation models was assessed. The most suitable estimated fraction coverage of V. spiralis was obtained using the rate of change of the blue band curve and simulated Quickbird NDVI. The present work demonstrated a method to monitor the distribution and dynamical variation of submerged plants at the large scale.     

Heavy metal in surface sediments of the Liaodong Bay, Bohai Sea: distribution, contamination, and sources

In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, the surface sediments in Liaodong Bay, northeast China, were systematically sampled and analyzed for the concentrations of Cu, Pb, Zn, Cr, Ni, As, and Hg. The metal enrichment factor (EF) and geoaccumulation index (I _geo) were calculated to assess the anthropogenic contamination in the region. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality (GB18668-2002); however, both EF and I _geo values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cu, Pb, Ni, and As were likely to pose environment risks, and the toxic units decreased in the order: Ni?>?Pb?>?Cr?>?Zn?>?As?>?Cu?>?Hg. The spatial distribution of ecotoxicological index (mean-ERM-quotient) suggested that most of the surface sediments were “low–medium” priority zone. Multivariate analysis indicated that the sources of Cr, Ni, Zn, Cu, and Hg resulted primarily from parent rocks, and Pb or As were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region.