密云水库小流域土地利用方式与氮磷流失规律

在密云水库石匣小流域对农田、林果地、荒草坡、村庄等4种不同类型的非点源污染发生区,进行降雨、径流量、径流水质同步监测,分析不同土地利用类型小区地表径流和泥沙中氮磷污染物的流失情况.结果表明,径流中总磷的浓度以村庄最高,其次为坡耕地、林果地和荒草坡.村庄径流的溶解态磷浓度为荒草坡径流的10倍.不同地表径流中的溶解态氮浓度的差别较大,村庄最高,其次是耕地、荒草坡、林果地.在降雨初期,随着径流量的增大,径流中总氮的浓度迅速降低,呈线性递减;此后随着径流的减少,总氮的浓度下降速度极其缓慢.不同土地利用类型中吸附态磷占总磷的比重都在90%以上,与泥沙结合的吸附态磷的浓度远大于溶解态磷的浓度,吸附态磷是磷流失的主要形态.      

事故损失预估方法的探讨

应用模糊数学的方法来评估企业的安全状况 ,在此基础上预估企业事故发生的概率及其可能产生的损失 ,为可靠地评价安全投资项目效益创造条件     

Valuing health effects from the industrial air pollution in rural Tianjin, China

IntroductionAirpollutioninTianjinisveryserious ,andismainlycausedbycoalconsumption .Theaverageconcentrationoftotalsuspendedparticulates (TSP)hasreached 0 3 5mg m3from 1990to 1998,exceedingChina’slevelⅡEnvironmentalCriterion ,whichis 0 2 0mg m3 Townshi…     

The role of radial oxygen loss and root anatomy on zinc uptake and tolerance in mangrove seedlings

Root anatomy, radial oxygen loss (ROL) and zinc (Zn) uptake and tolerance in mangrove plants were investigated using seedlings of Aegiceras corniculatum, Bruguiera gymnorrhiza and Rhizophora stylosa. The results revealed that B. gymnorrhiza, which possessed the ‘tightest barrier’ in ROL spatial patterns among the three species studied, took up the least Zn and showed the highest Zn tolerance. Furthermore, zinc significantly decreased the ROL of all three plants by inhibition of root permeability, which included an obvious thickening of outer cortex and significant increases of lignification in cell walls. The results of SEM X-ray microanalysis further confirmed that such an inducible, low permeability of roots was likely an adaptive strategy to metal stress by direct prevention of excessive Zn entering into the root. The present study proposes new evidence of structural adaptive strategy on metal tolerance by mangrove seedlings.     

Gene expression responses of paper birch (Betula papyrifera) to elevated CO2 and O3 during leaf maturation and senescence

Gene expression responses of paper birch (Betula papyrifera) leaves to elevated concentrations of CO₂ and O₃ were studied with microarray analyses from three time points during the summer of 2004 at Aspen FACE. Microarray data were analyzed with clustering techniques, self-organizing maps, K-means clustering and Sammon's mappings, to detect similar gene expression patterns within sampling times and treatments. Most of the alterations in gene expression were caused by O₃, alone or in combination with CO₂. O₃ induced defensive reactions to oxidative stress and earlier leaf senescence, seen as decreased expression of photosynthesis- and carbon fixation-related genes, and increased expression of senescence-associated genes. The effects of elevated CO₂ reflected surplus of carbon that was directed to synthesis of secondary compounds. The combined CO₂ + O₃ treatment resulted in differential gene expression than with individual gas treatments or in changes similar to O₃ treatment, indicating that CO₂ cannot totally alleviate the harmful effects of O₃.     

不锈钢在两种腐蚀试验方法的结果比较

通过标准GM 9540P和GMW 14872两种方法的试验,评价了不锈钢SUH409L、B409和409DG的耐蚀性,两种方法的结果表明三种不锈钢的耐蚀性能由强至弱依次为SUH409L〉B409〉409DG。     

Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants

The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6 mg As L⁻¹) and a soil pot trail (control, 60 mg As kg⁻¹). The results revealed that wetland plants showed great differences in root porosity (9-64%), rates of ROL (55-1750 mmo1 O₂ kg⁻¹ root d.w. d⁻¹), As uptake (e.g., 8.8-151 mg kg⁻¹ in shoots in 0.8 mg As L⁻¹ treatment), translocation factor (2.1-47% in 0.8 mg As L⁻¹) and tolerance (29-106% in 0.8 mg As L⁻¹). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity.     

Cypermethrin has the potential to induce hepatic oxidative stress, DNA damage and apoptosis in adult zebrafish (Danio rerio)

Cypermethrin (CYP), a widely used Type II pyrethroid pesticide, is one of the most common contaminants in the freshwater aquatic system. We studied the effects of CYP exposure on the induction of hepatic oxidative stress, DNA damage and the alteration of gene expression related to apoptosis in adult zebrafish. Hepatic mRNA levels for the genes encoding antioxidant proteins, such as Cu/Zn-Sod, Mn-Sod, Cat, and Gpx, were significantly upregulated when zebrafish were exposed to various concentrations of CYP for 4 or 8 days. In addition, the main genes related to fatty acid β-oxidation and the mitochondrial genes related to respiration and ATP synthesis were also significantly upregulated after exposure to high concentrations (1 and 3 μg L⁻¹) of CYP for 4 or 8 days. Moreover, in a comet assay of zebrafish hepatocytes, tail DNA, tail length, tail moment and Olive tail moment increased in a concentration-dependent manner. The significant induction (p < 0.01) of all four parameters observed with CYP concentrations of 0.3 μg L⁻¹ or higher suggests that heavy DNA damage was induced even at low levels. Furthermore, several apoptosis- related genes, such as p53, Apaf1 and Cas3, were significantly upregulated after CYP exposure, and Bcl2/Bax expression ratio decreased, especially in groups treated with 1 and 3 μg L⁻¹ CYP for 8 days. Taken together, our results suggested that CYP has the potential to induce hepatic oxidative stress, DNA damage and apoptosis in zebrafish. This information will be helpful in fully understanding the mechanism of aquatic toxicology induced by CYP in fish.     

SCR反应器内各关键部件对系统压力损失特性影响的研究

选择性催化还原(selective catalytic reduction,SCR)脱硝反应器的关键部件对系统压力损失特性的影响非常明显.针对某电厂1×300 MW锅炉机组的SCR脱硝反应器,采用数值模拟和实验研究的方法研究了各关键部件对系统压力损失特性影响.通过研究确定了SCR反应器的最优设计方案,即关键部件1设计为...     

Impacts of natural weathering on the transformation/neoformation processes in landfilled MSWI bottom ash: a geoenvironmental perspective

Natural weathering processes are significant mechanisms that noticeably affect the fundamental nature of incineration ash residues. To provide a greater understanding of these processes, a MSWI (mono)landfill site in the north east of the US was selected as the target for systematic investigation of the natural weathering of bottom ash residues. Samples of various ages were collected from locations A (1 yr), B (10 yrs), C (13-14 yrs) and D (20 yrs) of the landfill in 2009. We investigated the phase transformation of the collected bottom ash particles, neoformation processes as well as the behavior and distribution of certain heavy metals (Cu, Pb, Zn, Ni, and Cr) in the neoformed phases using optical microscopy, SEM-EDX, and bulk examinations. Key findings: at the preliminary stage, the waste metallic particles (Al, Fe, and Cu) and unstable minerals such as lime, portlandite, ettringite and hydrocalumite convert to oxide and hydroxide (hydrate) phases, calcite, alumina gel and gypsum. At the intermediate stage, the decomposition of melt products including magnetite spinels and metallic inclusions is triggered due to the partial dissolution of the melt glass. At the longer time horizon it is possible to track the breakdown of the glass phase, the extensive formation of calcite and anhydrite, Al-hydrates and more stable Fe-hydrates all through the older ash deposits. Among the dominant secondary phases, we propose the following order based on their direct metal uptake capacity: Fe-hydrates>Al-hydrates>calcite. Calcite was found to be the least effective phase for the direct sorption of heavy metals. Based on overall findings, a model is proposed that demonstrates the general trend of ash weathering in the landfill.