华北地区冬小麦干旱风险评估的初步研究

作者在本文中探讨了利用风险分析进行气象灾害影响评估的方法。根据华北地区冬小麦干旱的特点，确定了小麦各发育阶段在有限灌溉条件下的干旱指标及发生概率。利用ＦＡＯ产量与水分关系模型，计算出干旱引起的减产率，并综合考虑当地抗灾性能和承灾体密度，得到冬小麦各发育阶段及全生育期的干旱风险度，进行分级定量评估。为小麦持续高产稳产决策提供科学依据。     

Patterns of Pollen Dispersal in an Invasive Population of Solanum rostratum (Solanaceae) in China

Russian Journal of Ecology - Paternity analysis, carried out on 13 microsatellite loci, was used to investigate pollen dispersal and mating patterns in an invasive population of Solanum rostratum...     

重金属在水体中的化学状态、危害及其 防治对策

本文对目前研究最多的汞、铬、镉、铅和砷等重金属,详细分析了它们在水体中的迁移转化、价态变化、吸附与解吸附作用、吸附和共沉淀作用等动态过程;简要地阐述五种重金属对水体的污染给人体带来的危害;重点讨论了对水体重金属污染采取控制与消除土壤污染源、含重金属工业废水的排放和生物修复技术等防治对策。     

Nocturnal atmospheric chemistry of NO3 and N2O5 over Changzhou in the Yangtze River Delta in China

Comprehensive observations of the nocturnal atmospheric oxidation of NO₃ and N₂O₅ were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy (CRDS) from 27 May to 24 June, 2019. High concentrations of NO₃ precursors were observed, and the nocturnal production rate of NO₃ was determined to be 1.7 ± 1.2 ppbv/hr. However, the nighttime NO₃ and N₂O₅ concentrations were relatively low, with maximum values of 17.7 and 304.7 pptv, respectively, illustrating the rapid loss of NO₃ and N₂O₅. It was found that NO₃ dominated the nighttime atmospheric oxidation, accounting for 50.7%, while O₃ and OH only contributed 34.1% and 15.2%, respectively. For the reactions of NO₃ with volatile organic compounds (VOCs), styrene was found to account for 60.3%, highlighting its dominant role in the NO₃ reactivity. In general, the contributions of the reactions between NO₃ and VOCs and the N₂O₅ uptake to NO₃ loss were found to be about 39.5% and 60.5%, respectively, indicating that N₂O₅ uptake also played an important role in the loss of NO₃ and N₂O₅, especially under the high humidity conditions in China. The formation of nitrate at night mainly originated from N₂O₅ uptake, and the maximum production rate of NO₃⁻ reached 6.5 ppbv/hr. The average NO_x consumption rate via NO₃ and N₂O₅ chemistry was found to be 0.4 ppbv/h, accounting for 47.9% of the total NO_x removal. The predominant roles of NO₃ and N₂O₅ in nitrate formation and NOx removal in the YRD region was highlighted in this study.     

Freeze-thaw effects on phosphorus loss in runoff from manured and catch-cropped soils

Concern over nonpoint source P losses from agricultural lands to surface waters in frigid climates has focused attention on the role of freezing and thawing on P loss from catch crops (cover crops). This study evaluated the effect of freezing and thawing on the fate of P in bare soils, soils mixed with dairy manure, and soils with an established catch crop of annual ryegrass (Lolium multiflorum L.). Experiments were conducted to evaluate changes in P runoff from packed soil boxes (100 by 20 by 5 cm) and P leaching from intact soil columns (30 cm deep). Before freezing and thawing, total P (TP) in runoff from catch-cropped soils was lower than from manured and bare soils due to lower erosion. Repeated freezing and thawing significantly increased water-extractable P (WEP) from catch crop biomass and resulted in significantly elevated concentrations of dissolved P in runoff (9.7 mg L(-1)) compared with manured (0.18 mg L(-1)) and bare soils (0.14 mg L(-1)). Catch crop WEP was strongly correlated with the number of freeze-thaw cycles. Freezing and thawing did not change the WEP of soils mixed with manures, nor were differences observed in subsurface losses of P between catch-cropped and bare soils before or after manure application. This study illustrates the trade-offs of establishing catch crops in frigid climates, which can enhance P uptake by biomass and reduce erosion potential but increase dissolved P runoff.     

Selective catalytic oxidation of ammonia over copper-cerium composite catalyst

This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a copper (Cu)-cerium (Ce) composite catalyst at temperatures between 150 and 400 degrees C. A Cu-Ce composite catalyst was prepared by coprecipitation of copper nitrate and cerium nitrate at various molar concentrations. This study also considers how the concentration of influent NH3 (500-1000 ppm), the space velocity (72,000-110,000 hr(-1)), the relative humidity (12-18%) and the concentration of oxygen (4-20%) affect the operational stability and the capacity for removing NH3. The effects of the O2 and NH3 content of the carrier gas on the catalyst's reaction rate also are considered. The experimental results show that the extent of conversion of NH3 by SCO in the presence of the Cu-Ce composite catalyst was a function of the molar ratio. The NH3 was removed by oxidation in the absence of Cu-Ce composite catalyst, and approximately 99.2% NH3 reduction was achieved during catalytic oxidation over the Cu-Ce (6:4, molar/molar) catalyst at 400 degrees C with an O2 content of 4%. Moreover, the effect of the initial concentration and reaction temperature on the removal of NH3 in the gaseous phase was also monitored at a gas hourly space velocity of less than 92,000 hr(-1).     

Development and application of a water pollution emergency response system for the Three Gorges Reservoir in the Yangtze River, China

There are many watercraft and production accidents in the Three Gorges Reservoir Area (TGRA) of the Yangtze River in China every year. Accidents threaten the water quality of the 1085 km2 surface area of the TGRA and millions of local people if oil and chemical leakage were to occur. A water pollution management system for emergency response (WPMS ER) was therefore designed for the management of pollution in this area. An integrated geographic information system (GIS)-based water pollution management information system for the TGRA, called WPMS ER TGRA, was developed in this study. ArcGIS engine was used as the system development platform, and Visual Basic as the programming language. The models for hydraulic and water quality simulation and the generation of body-fitted coordinates were developed and programmed as a dynamically linked library file using Visual Basic, and they can be launched by other computer programs. Subsequently, the GIS-based information system was applied to the emergency water pollution management of a shipwreck releasing 10 tons of phenol into the Yangtze River during two hours. The results showed that WPMS ER TGRA can assist with emergency water pollution management and simulate the transfer and di usion of accidental pollutants in the river. Furthermore, it can quickly identify the a ected area and how it will change over time within a few minutes of an accident occurring.     

硫化亚铁自燃温度影响研究

硫化亚铁自燃是引起石油化工行业火灾爆炸事故的重要原因之一。为了规避此类事故的发生,利用自燃温度测试仪测定了不同粒径硫化亚铁以及硫磺与硫化亚铁混合物的自燃温度。结果表明:随着硫化亚铁粒径比表面积的增大,其自燃温度先减小后增大,之后随着粒径的继续增大,自燃温度基本保持平稳状态;硫磺与硫化亚铁混合物自燃温度彼此具有协同作用,其自燃温度比硫化亚铁自燃温度降低了116.3℃,使硫化亚铁自燃失控危险性大大增加,为采取安防措施带来了极大的不便。     

Greenhouse gas emission and its potential mitigation process from the waste sector in a large-scale exhibition

As one of the largest human activities, World Expo is an important source of anthropogenic Greenhouse Gas emission (GHG), and the GHG emission and other environmental impacts of the Expo Shanghai 2010, where around 59,397 tons of waste was generated during 184 Expo running days, were assessed by life cycle assessment (LCA). Two scenarios, i.e., the actual and expected figures of the waste sector, were assessed and compared, and 124.01 kg CO₂-equivalent (CO₂-eq.), 4.43 kg SO₂-eq., 4.88 kg NO₃⁻-eq., and 3509 m³ water per ton tourist waste were found to be released in terms of global warming (GW), acidification (AC), nutrient enrichment (NE) and spoiled groundwater resources (SGWR), respectively. The total GHG emission was around 3499 ton CO₂-eq. from the waste sector in Expo Park, among which 86.47% was generated during the waste landfilling at the rate of 107.24 kg CO₂-eq., and CH₄, CO and other hydrocarbons (HC) were the main contributors. If the waste sorting process had been implemented according to the plan scenario, around 497 ton CO₂-eq. savings could have been attained. Unlike municipal solid waste, with more organic matter content, an incineration plant is more suitable for tourist waste disposal due to its high heating value, from the GHG reduction perspective.     

外置双U型静钻根植工法能源桩换热性能研究∗

为探究外置双U型静钻根植工法能源桩换热性能,通过现场热响应试验,利用热源理论初步分析其岩土综合导热系数,建立三维传热数值模型并进行验证。利用三维传热数值模型分析换热管间距及其导热系数、换热液流速和桩周水泥土导热系数等因素对该新型桩换热性能的影响。分析结果表明,试桩区域岩土综合导热系数为1.64W(m·K)-1。提高换热管间距、换热管导热系数、换热液流速和桩周水泥土导热系数均能提高能源桩的换热性能,但当换热管间距大于0.25 m,换热液流速达到紊流态,换热管和桩周水泥土导热系数高于岩土综合导热系数后,提高上述参数对能源桩换热性能的提高贡献不大。