Bi2WO6催化剂的合成和表征及其光催化活性

以Bi（NO3）3和Na2WO4为原料，采用水热法合成了可见光催化剂Bi2WO6，并采用X射线衍射仪和BET法对其进行了表征。考察了合成温度、Bi2WO6加入量、邻氯苯酚（2-CP）浓度、溶液pH等对2-CP光催化降解效果的影响。实验结果表明：在加入140℃下合成的Bi2WO6催化剂1g／L、原始pH（pH=5．85）、可见光光照210min的条件下，对质量浓度为20mg／L的2-CP溶液进行处理，2-CP去除率最高为97．2％；添加少量H2O2对2-CP的降解有促进作用。     

掺杂过渡金属离子的纳米二氧化钛光催化氧化对氯苯酚的研究

以掺杂过渡金属离子Fe^ 的纳米Ti02为光催化剂，以高压汞灯为光源，研究了对氯苯酚在水悬浮溶液中的降解，考察了对氯苯酚的初始浓度、气相氧浓度、催化剂投加量、光强对对氯苯酚光解速率的影响。通过试验发现，光强、气相氧浓度以及催化剂投加量是影响光催化氧化反应的关键因素。采用掺杂过渡金属粒子Fe^3 的纳米TiO2为光催化剂比采用纯纳米TiO2为光催化剂对氯苯酚降解率提高了近1．4倍。     

含碳纳米TiO2光催化降解甲醇

采用管式光催化反应器，在石英玻璃管壁上涂镀含碳纳米TiO2薄膜，研究含碳纳米TiO2对甲醇气体的光催化降解性能。实验结果表明：随气体流量增加，甲醇降解率呈线性降低；在气体流量为200mL／min、相对湿度为40％、甲醇初始质量浓度为90～170mg／m^3的较佳条件下，甲醇降解率维持在80％以上，最高达85％；在甲醇初始质量浓度为150mg／m^3、气体流餐为200mL／min、相对湿度为40％的条件下，德国Degusa—P25光催化剂对甲醇的平均降解率为89％，含碳纳米TiO2对甲醇的平均降解率为82％，最人降解率为85％。     

仿酶型磁性Fe~0-Fe_3O_4复合催化剂的制备及其催化性能

采用原位氧化沉淀法制备出仿酶型磁性Fe0-Fe_3O_4复合催化剂,并将其作为非均相类Fenton催化剂用于溶液中对硝基苯酚的降解;采用SEM和XRD等技术对催化剂进行了表征。表征结果显示,Fe_3O_4与Fe0结合牢固,有利于Fe0的分散。实验结果表明:Fe0-Fe_3O_4对对硝基苯酚的降解为拟一级反应;在Fe0与Fe_3O_4的质量比为0.75、Fe0-Fe_3O_4投加量为1.2 g/L、初始H_2O_2浓度为10 mmol/L、初始溶液p H为3、反应温度为30℃的条件下反应90min,反应速率常数为0.067 min-1,COD去除率为77.28%,Fe溶出量为2.12 mg/L;在对硝基苯酚的降解过程中,pH先增大后减小,Fe溶出量先降低后升高;Fe0-Fe_3O_4是一种稳定的催化剂,可再生使用。     

TiO2-SiO2纳米复合粉体的制备、改性及其光催化性能

采用超声辅助水解法制备了TiO2-SiO2纳米复合粉体。通过XRD和紫外-可见漫反射光谱分析发现,复合粉体TiO2-SiO2-2(n(Si)∶n(Ti)=10%)的光吸收带边发生明显蓝移。光催化降解甲基橙的实验结果表明:加入SiO2可明显提高复合粉体的光催化活性,且随着SiO2含量的增加,复合粉体的光催化活性逐渐提高;但SiO2含量过高会使光催化剂中TiO2光催化活性组分的质量分数减少,使光催化剂的活性下降;TiO2-SiO2-2光催化活性最高。采用浸渍法对复合粉体进行酸化改性得到的SO42-/TiO2-SiO2催化剂具有超强酸结构。酸化后催化剂的光催化活性提高,SO42-/TiO2-SiO2-2催化剂的光催化活性最高。     

微波-改性活性炭-Fenton试剂氧化法降解水中2,4-二氯酚

以经Fe2（SO4）3溶液浸渍改性的活性炭作催化剂、Fenton试剂作氧化剂，采用微波-改性活性炭-Fenton试剂氧化法降解水中的2，4-二氯酚。考察了改性活性炭加入量、H2O2与Fe^2＋摩尔比、Fenton试剂加入量、微波功率和2，4-二氯酚溶液初始pH对2，4-二氯酚降解效果的影响。在改性活性炭加入量1．0g／L、n（H2O2）：n（Fe^2＋）=16．7（H2O2加入量6．0mmol／L、Fe^2＋加入量0．36mmol／L）、Fenton试剂加入量为6．36mmol／L、微波功率600W、微波辐射时间10min、2，4-二氯酚溶液初始pH为6．0的条件下，2，4-二氯酚降解率和TOC去除率分别可达98．7％和84．0％。     

超声光催化降解酸性粒子元青染料的研究

对超声波作用下的纳米TiO2光催化氧化法降角酸性粒子元青染料进行了研究。结果表明，超声波的引入提高了纳米TiO2光催化降解酸性粒子元青染料的降解率；降解率受反应时间、坡声波功率、空气流量的影响；添加少量的H2O2能够明显地提高酸性粒子元青染料的降解率。     

太阳光催化降解阿特拉津的研究

利用太阳光作光源,用含在颗粒活性炭中的TiO2(TiO2／GAC)作光催化剂,在流动循环系统中考察了阿特拉津的光催化降解效果。在阿特拉津初始质量浓度27．18mg／L、液体循环流量6L／h、液体总体积400mL、平均辐照度2．64mW／cm^2、液体温度40℃、TiO2／GAC质量浓度7g／L、3％H2o2用量240μL,光催化反应时间1．65h的条件下,阿特拉津去除率达92．8％,TOC去除率接近70％。通过测定光催化降解过程中TOC的变化、紫外吸收光谱吸收峰的变化和质谱图对阿特拉津的降解途径和降解程度进行了分析。     

光催化氧化法降解废气中苯系物的研究

采用溶胶-凝胶工艺制备以多孔泡沫镍为载体的TiO2薄膜，并用其光催化氧化降解挥发性苯系物(苯、甲苯和二甲苯)。考察了催化剂粒径、反应时间、苯系物的初始浓度、体系的相对湿度和反应温度等因素对苯系物去除率的影响。结果表明，以粒径20．7nm的TiO2为催化剂、甲苯初始质量浓度为200mg/m^3、体系的相对湿度为5％、反应温度为20—50℃、反应时间为60min条件下，甲苯的去除率达76％以上。     

TiO2-xNx光催化氧化苯甲酸的研究

采用悬浮态光催化反应体系，以氙灯为光源，自制纳米TiO2-xNx为催化剂，考察了苯甲酸光催化氧化过程中TiO2-xNx质量浓度、反应体系初始pH和苯甲酸初始质量浓度对苯甲酸溶液中TOC去除率的影响。实验结果表明：最佳催化剂质量浓度为0．30g／L；TiO2-xNx的等电点为pH=5．3，在酸性条件下（pH=2．0）更有利于苯甲酸在催化剂表面的吸附，以及光生电子与O2反应生成·OH的进行；随苯甲酸初始质量浓度增加，TOC去除率降低，反应速率也相应地降低。TiO2-xNx比P25型TiO2表现出更强的浓度适应能力。     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Programs assessing implementation and effectiveness of state forest practice rules and BMPs in the West

The major forest nonpoint source control programs in the West are largely regulatory, either under forest practices acts (California, Idaho, New Mexico, Nevada, Oregon, and Washington) or a streamside management act (Montana). These programs and the specific rules they enforce continue to undergo intensive scrutiny. Still, the questions are the same for these regulatory programs as for states that base nonpoint source control on voluntary BMPs (Arizona, Colorado, Utah, Wyoming). Are the rules or BMPs being applied, and are they effective in reducing nonpoint source pollution to levels that protect beneficial uses of water? The level of debate about forestry in the West has resulted in detailed monitoring and research to answer these questions. In the past, state agencies have assumed levels of BMP compliance based on the percent of operations without enforcement actions. These estimates are being replaced by statistically valid and reproducible monitoring of forest practices rules and BMP compliance levels. BMP effectiveness is being assessed using both qualitative and quantitative methods. This can involve field assessments, process-based research, and control watershed studies. Some trend monitoring is also beginning. With the regional implementation rate for forestry BMPs at about 94% and rising, it is likely that effectiveness testing will continue to be a priority and consume the majority of assessment resources for this region.     

Hysteresis in Reversal of Central European Mountain Lakes from Atmospheric Acidification

Extremely high emissions of S and N compounds in Central Europe (both 280 mmol m^-2 yr^-1) declined by 70and 35%, respectively, during the last decade. Decreaseddeposition rates of SO₄ ^-2, NO₃ ^-, and NH₄ ⁺ in the region paralleled emission declines. The reduction in atmospheric inputs of S and N to mountain ecosystemshas resulted in a pronounced reversal of acidification in the Tatra Mountains and Bohemian Forest lakes. Between the 1987–1990and 1997–1999 periods, concentrations of SO₄ ^-2 and NO₃ ^- decreased (average ± standard deviation) by 22±7 and 12±7 mol L^-1, respectively, in theTatra Mountains, and by 19±7 and 15±10 mol L^-1, respectively, in the Bohemian Forest. Their decrease was compensated in part (1) by a decrease in Ca²⁺ + Mg²⁺ (17±7 mol L^-1) and H⁺ (4±6 mol L^-1), and an increase in HCO₃ ^-(10±10 mol L^-1) in the Tatra Mountains lakes, and (2) by a decrease in Al (7±4 mol L^-1), Ca²⁺ + Mg²⁺ (9±6 mol L^-1), and H⁺ (6±5 mol L^-1), in Bohemian Forest lakes. Despite the rapid decline in lake water concentrations of SO₄ ^-2 and NO₃ ^- in response to reduced S and N emissions, their present concentrations in some lakes are higher than predictionsbased on observed concentrations at comparable emission rates during development of acidification. This hysteresis in chemical reversal from acidification has delayed biological recovery of the lakes. The only unequivocal sign of biological recovery hasbeen observed in erné Lake (Bohemian Forest) where a cladoceran species Ceriodaphnia quadrangular has recentlyreached its pre-acidification abundance.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

Heavy Metals Removal by Biosorption and Flotation

The removal of a mixture of heavy (toxic) metal cations (copper, nickeland zinc) from liquid effluents was investigated in this study at pilotscale, using counter-current contact mode. The innovative processinvolved the abstraction of metal ions onto fungal biosorbents, followedby the application of flotation for the subsequent solid/liquid separationof biomass particles. The ability of microorganisms to remove metal ionsfrom aqueous solutions is a well-known phenomenon. Nevertheless,engineering considerations are very important in decisions, concerningthe commercial future of biosorption and practical solutions are neededfor certain problems, such as the efficient post-separation ofmetal-loaded biomass. The two processes (flotation and biosorption) caneffectively operate in combination, in what it was termed biosorptiveflotation process. The sorbents may be recycled, after appropriate elutionof metals, as well as the treated (clean) water.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

Bioassessment of silvicultural impacts in streams and wetlands of the Eastern United States

Bioassessment is a useful tool to determine the impact of logging practices on the biological integrity of streams and wetlands. Measuring biota directly has an intuitive appeal for impact assessment, and biota can be superior indicators to physical or chemical characteristics because they can reflect cumulative impacts over time. Logging can affect stream and wetland biota by increasing sedimentation rates, altering hydrologic, thermal, and chemical regimes, and changing the base of food webs. Biotic impacts of logging on streams compared to wetlands probably differ, and in this paper we review some of those differences. In streams, invertebrates, fishes, amphibians, algae, and macrophytes have been used as indicators of logging impacts. In wetlands, bioassessment is just beginning to be used, and plants and birds are the most promising indicator taxa. Various best management practices (BMPs) have been developed to reduce the impacts of logging on stream and wetland biota, and we review quantitative studies that have evaluated the efficacy of some of these techniques in streams and wetlands in the eastern United States. Remarkably few studies that address the overall efficacy of BMPs in limiting biotic changes in streams and wetlands after BMP implementation have been published in scientific journals, although some work exists in reports or is unpublished. We review these works, and compile conclusions about BMP efficacy for biota from this body of research.     

Characterization of air emissions and residual ash from open burning of electronic wastes during simulated rudimentary recycling operations

Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.     

Selection of Autochthonous Plant Species from SE Spain for Soil Lead Phytoremediation Purposes

Mining activity in SE of Spain, in the west Mediterranean coast, originated more than two millenniums ago. It has generated huge areas affected by heavy metals contamination, especially of lead, which is possibly one of the most important. Investigations related to the selection of autochthonous plant taxa from a typical Spanish Mediterranean area, useful for phytoextraction and phytostabilization purposes in these polluted areas are shown. Under these edaphoclimatic conditions 12 interesting species were considered, from them six taxa were chosen for further studies. Some plant species have been proposed either for phytoextraction or phytostabilization purposes. Recommendations for further research have been discussed.