卧龙巴郎山高山灌丛降雨和穿透水稳定性氢氧同位素特征研究

论文对巴郎山区夏季降雨和不同海拔样地穿透水的H、O同位素特征进行了研究。由于8月底9月初冷气团的到来较大地改变了降雨的同位素特征,该地区夏季大气降水线为δD=9.93δ^{18,/sup>O+26.07,偏离全球降水线(GMWL)较多。降雨的温度效应和雨量效应表现出相互交叉的现象,表明该地区温度和雨量是交替起主导作用而引起降雨同位素组成变化的。H的同位素效应比O明显,其原因是H同位素分馏比O剧烈,从而对环境因子的响应比O灵敏,因此H同位素在森林水文研究中比O更有用。H同位素值在不同样地穿透水间存在差异,这是由它们不同的植被结构及周边微环境因子引起的水分蒸发状况和对雾水截获能力差异导致的。穿透水和降雨同位素值间存在较强线性关系。穿透水的同位素值不一定大于降雨,表明影响穿透水同位素值的因素不仅仅是水分蒸发和植被对雾水的截获,而应是多种因素的综合效应,对这些因素的全面了解将对同位素技术在森林水文研究中的进一步应用有重要意义。}     

Enhanced methane hydrate storage using sodium dodecyl sulfate and coal

A potential solution to reduce global warming is to store greenhouse gases. Greenhouse gas storage has been recently improved using several materials and techniques. However, the actual storage capacity is slow, limited, and costly. Here, we tested the use of an accelerating agent, sodium dodecyl sulfate, and coal to produce methane hydrate for methane storage. Experiments of storing methane gas in coal samples have been carried out under high pressures, 4 or 6 MPa, and low temperature of 273.15 K. Results reveal that sodium dodecyl sulfate improved the rate up to 58.26 cm³/min and the capacity up to 179.97 volume at standard temperature and pressure per unit volume of coal. This finding shows that sodium dodecyl sulfate is efficient to accelerate the formation of methane hydrate. We also found that storage capacity increased with pressure. We conclude that our method allows a gas storage capacity higher than any other medium materials reported previously.     

基于景观指数和马尔科夫模型的铜梁县土地利用分析

以重庆市铜梁县为研究区域,以三期TM/ETM+遥感影像为主要数据来源,在获取大量数据的基础上,结合景观生态学理论研究了1993~2007年铜梁县土地利用的景观格局,运用马尔科夫模型对土地利用/覆被变化过程及数量转化情况进行分析并对其未来变化趋势进行预测。结果表明：1993~2007年铜梁县景观形状趋于复杂,斑块破碎度降低,景观异质程度下降,景观类型有向单一化或非均衡化发展的趋势;林地减少较快而建设用地增加较快,减少的林地主要转化为园地和耕地,增加的建设用地主要来自于园地和耕地。研究表明,将景观指数、马尔科夫模型结合进行土地利用/覆被变化的研究,能更有效地分析土地利用的格局和过程,取得较好的效果.     

Health risk assessment of heavy metals for edible parts of vegetables grown in sewage-irrigated soils in suburbs of Baoding City,China

With the long-term application of wastewater to vegetable production fields, there is concern about potential health risks of heavy metals contaminating the edible parts of vegetables grown in contaminated soils in the suburban areas of Baoding City, China. The average concentration of elemental Zn in sewage-irrigated soil was the highest (153.77 mg kg⁻¹), followed by Pb (38.35 mg kg⁻¹), Cu (35.06 mg kg⁻¹), Ni (29.81 mg kg⁻¹), and Cd (0.22 mg kg⁻¹) which were significantly higher (P < 0.05) than those in the reference soil. The results showed that long-term sewage irrigation had led to a growing accumulation of heavy metals in the soils, especially for Cd, Zn, and Pb. Furthermore, the concentrations of elemental Cd, Zn, and Ni in vegetables (e.g., Beassica pekinensis L., Allium fistulosum L., Spinacia oleracea L.) collected from the wastewater-irrigated soils exceeded the maximum permissible limits, and this also increased the daily intake of metals by food. However, compared with the health risk index of <1 for heavy metals, the ingestion of vegetables from the soils irrigated with sewage effluent posed a low health risk. Nevertheless, heavy metal concentrations should be periodically monitored in vegetables grown in these soils together with the implementation effective remediation technologies to minimize possible impacts on human health.     

Polycyclic aromatic hydrocarbons and ecotoxicological characterization of sediments from the Huaihe River, China

The distribution, source, ecological risk and ecotoxicity of polycyclic aromatic hydrocarbons (PAHs) of sediments from 7 sampling sites, named as Xinyang (XY), Huainan (HN), Bengbu (BB), Xuyi (XuY), Fuyang (FY), Mengcheng (MC) and Zhengzhou (ZZ), in the Huaihe River basin, China, have been investigated. The total concentrations of 16 USEPA priority PAHs ranged from 62.9 to 2232.4 ng g?1 dry weight (d.w.) with a mean concentration of 1056.8 ng g?1 d.w. Through the assessment of ecological risk, we found that the levels of PAHs in the Huaihe River should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent (TEQ) values calculated for samples varied from 0.01 to 194.1 ng g?1 d.w., with an average of 65.9 ng g?1. The toxicity data were accordant with the chemical analysis results in this study. HN, BB and ZZ showed the greatest pollution extent both in the chemical analysis and the study of ecotoxicological effects.     

Re-examining log law velocity profile in smooth open channel flows

Environmental Fluid Mechanics - A comprehensive investigation of velocity distribution is presented, and the log law is re-examined using experimental data from a smooth uniform open channel flow....     

Treatment of simulated wastewater containing Reactive Red 195 by zero-valent iron/activated carbon combined with microwave discharge electrodeless lamp/sodium hypochlorite

A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaClO) and the combination of ZVI/ACMDEL/ NaClO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaClO had much higher degradation e ciency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The e ects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic e ect between ZVI/AC and MEDL/NaClO, we found that in the ZVI/AC-MEDL/NaClO process, ZVI/AC could break the azo bond firstly and then MEDL/NaClO degraded the aromatic amine products e ectively. Reversing the order would reduce the degradation e ciency.     

河北坝上高原错季无公害蔬菜生产的环境标准与技术

着重论述了河北坝上高原错季无公害蔬菜生产的环境标准与技术问题。针对人们对农产品安全质量与环境标准的要求,简要介绍了无公害蔬菜生产绿色食品、有机食品的基本概念;明确了河北省坝上地区无公害蔬菜生产的地理区位优势:气候冷凉,光照充足,雨热同季,昼夜温差大等,并指出该区存在的干旱多风少雨等主要问题;进而提出坝上错季无公害蔬菜生产的环境标准与技术:限量施用纯氮≤225kg·hm-2和有机肥≤75000kg·hm-2等措施。这些对我国入世后加强农产品安全质量与环境质量管理,推行无公害绿色食品生产体系与技术指标,确保农业可持续发展均具有重要指导意义。