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排序方式: 共有4222条查询结果,搜索用时 15 毫秒
221.
Mona Akbar Muhammad Farooq Saleem Khan Ling Qian Hui Wang 《Frontiers of Environmental Science & Engineering》2020,14(6):98
222.
Mukdawan Sukhang Anongphan Junkuy Nicholas Buckley Fahim Mohamed 《Journal of environmental science and health. Part. B》2020,55(3):273-282
AbstractA sudden increase in serum creatinine after paraquat intoxication has been reported in several clinical studies. However, this dramatic change of creatinine may be possibly due to an interconversion of creatine-creatinine in relation to paraquat toxicity. In order to investigate the creatine-creatinine relationship, a liquid chromatography tandem mass spectrometry in combination with electrospray ionization was developed and validated for simultaneous determination of creatine and creatinine in the serum. The chromatographic separation was achieved on a Gemini® C6-Phenyl column with a gradient elution consisting of 0.1% formic acid in ultrapure water and methanol as the mobile phase. The method yielded suitable levels of specificity and selectivity, and calibration curves of creatine and creatinine in serum were linear over the concentration range of 0.5–200?µg mL?1. The limit of quantification of both compounds was 0.5?µg mL?1, and the method was accurate within the recovery range of 96.23–102.75%, indicating the robustness of the method. The method was successfully applied to toxicological samples from paraquat-intoxicated patients, and the concentrations of creatine and creatinine were quantified. High creatine concentrations in serum samples were observed which may lead to high serum creatinine despite normal kidney function as creatine is converted to creatinine in proportion to its concentration. 相似文献
223.
以国家重点生态功能区县域环境监测质量评价为目标,综合应用德尔菲法、层次分析法和模糊综合评价法,构建了国家重点生态功能区县域环境监测质量评价方法,并确定了评价因子、权重系数、计算方法。该方法评价指标共分为三层:第一层为目标层,即国家重点生态功能区县域环境监测质量;第二层为准则层,包括人员及资质、现场监测、实验室管理、报告编制及数据上报;第三层为方案层,包括人员操作、持证上岗、资质认定、人员培训、水质布点采样流转情况、空气自动站运维情况、现场质控实施情况、实验室环境条件、样品试剂的保存与管理、仪器检定与校准、实验室质量控制实施情况、数据填报软件运行情况、监测报告规范性等13个评价要素。经矩阵一致性检验确定了各评价要素的权重,将该权重与各要素得分运算后得到县域环境监测质量评价结果。在此基础上,选取广东、山西、陕西、四川和青海等5个省份的15个国家重点生态功能区县域作为典型区开展了实地调研,并应用评价体系对其进行了监测质量等级评价。结果表明,15个典型县域中,环境监测质量等级为优的县域占13.3%,一般、较差的县域分别占66.7%、20%。县域环境监测承担单位在资质、报告编制及数据上报方面表现较好,在现场监测、人员操作方面问题突出,在实验室管理方面有待提升。 相似文献
224.
主体功能区划通过主体功能划分的方式将开发和保护结合,自然资源开发利用复杂化过程中资源利用与目标实现之间亟需实现基本的定量核算关系。本文从自然资源可持续利用角度,试图探讨建立初步的主体功能核算关系,通过核算框架进行生产、生活、生态主体功能概算与比较。以京津冀主体功能区与水资源为例,对所设立的核算关系进行了验证与应用,并构造绝对与相对量指标量化京津冀主体功能量、功能水资源投入量与效率,进行了异空间尺度与异质性功能的比较,为以主体功能实现最大化为目标的资源优化配置提供量化工具。结果显示:①利用生态服务价值测算的当量因子法与水足迹测算的投入产出法,刻画了水资源对于地区主体功能的支撑作用。②利用功能总量与单位功能水资源投入量指标完成了异质性功能在异质性空间上规模、结构、相应水资源效率的比较。基于算例结果得到以下结论:①本文构建的自然资源-主体功能核算关系框架能够有效衔接主体功能规划,定量核算能有效反映与评价资源对区域功能目标、经济开发活动的支撑作用。②区域资源配置存在相对功能实现的效率差异,可根据资源投入与功能产出之间的关系引导实现功能最大化目标的资源配置。合理、有效的量化手段能够推进主体功能制度的落实,也有助于当前中国空间规划体系编制与落实的实际指导效果。 相似文献
225.
226.
Dimitrakopoulos PG Siamantziouras AS Galanidis A Mprezetou I Troumbis AY 《Environmental management》2006,37(6):826-839
We conducted a field experiment using constructed communities to test whether species richness contributed to the maintenance
of ecosystem processes under fire disturbance. We studied the effects of diversity components (i.e., species richness and
species composition) upon productivity, structural traits of vegetation, decomposition rates, and soil nutrients between burnt
and unburnt experimental Mediterranean grassland communities. Our results demonstrated that fire and species richness had
interactive effects on aboveground biomass production and canopy structure components. Fire increased biomass production of
the highest-richness communities. The effects of fire on aboveground biomass production at different levels of species richness
were derived from changes in both vertical and horizontal canopy structure of the communities. The most species-rich communities
appeared to be more resistant to fire in relation to species-poor ones, due to both compositional and richness effects. Interactive
effects of fire and species richness were not important for belowground processes. Decomposition rates increased with species
richness, related in part to increased levels of canopy structure traits. Fire increased soil nutrients and long-term decomposition
rate. Our results provide evidence that composition within richness levels had often larger effects on the stability of aboveground
ecosystem processes in the face of fire disturbance than species richness per se. 相似文献
227.
228.
中温和高温厌氧生物产氢反应器连续运行的研究 总被引:4,自引:2,他引:2
采用2个厌氧生物产氢反应器分别在中温(37℃)和高温(55℃)下连续运行.以河底沉积物接种,葡萄糖为基质,在CSTR中成功实现了连续中温厌氧产氢,最高产氢量达8.6L/(L·d),基质产氢摩尔比(H2/葡萄糖)为1.98.以厌氧产甲烷颗粒污泥接种,蔗糖为基质,在UASB反应器中成功实现了连续高温厌氧产氢过程,最高产氢量达6.8L/(L·d),基质产氢摩尔比(H2/蔗糖)为3.6.在高温UASB反应器中培养获得了灰白色的产氢颗粒污泥,平均粒径为0.8~1.2mm,沉速为30~40m/h,电镜观察发现其表层生长大量杆状细菌.对2种产氢污泥的总DNA进行提取和纯化,通过PCR扩增和DGGE分析,发现高温和中温厌氧产氢污泥中的大部分真细菌种类相同,但各自的优势菌种明显不同. 相似文献
229.
Managing disposal of water produced with petroleum in Kuwait 总被引:1,自引:0,他引:1
Disposal of water produced with petroleum has been of great interest in Kuwait for the last 20 years. The current problem arose when the Burgan oil field, which is the second largest field in the world, experienced successive increases in the water content of the produced oil. This study introduces a decision-making analysis of the considered alternatives for the disposal of the produced water. Four alternative solutions exist for the industry as practical solutions for the disposal of water produced in Kuwait. The first method utilizes a large number of pits to discharge water. The second alternative depends on discharging water into sealed pits. The third approach to dispose water is by injecting the water underground. The last method is similar to the previous one, but takes into consideration the recovery of reservoir pressure to maintain the rate of oil production. A questionnaire was distributed to 48 experts at the top management level of the petroleum companies and the governmental authority. The data collected considered cost, efficiency, and environmental parameters. Based on the data, a statistical analysis was conducted using the factor analysis method to reduce the number of investigated variables. The analysis concluded that the optimal solution is to use the effluent injection method to discharge water produced with oil in Burgan and similar fields in Kuwait. 相似文献
230.
Decisions on soil remediation are one of the most difficult management issues of municipal and state agencies. The assessment of contamination is uncertain, the costs of remediation are high, and the impacts on the environment are multiple. This paper presents a general, transparent, and consistent method for decision making among the remediation alternatives. Soil washing, phytoremediation, and no remediation are exemplarily considered. Multi-criteria utility functions including (a) the cost of remediation (b) the impact on human health and agricultural productivity, and (c) the economic gain after remediation are constructed using probability density functions representing contamination for all site coordinates. Herewith, the probability of different types of (i) correct decisions such as a hit or a true rejection and (ii) erroneous decisions such as a false alarm or miss are examined. The decision theoretic model is applied to a case study on heavy metal contaminated soil. This case study reveals the non-linear structure of multi-criteria-decision making. The case study shows that the geostatistical uncertainties of the log-normal distributed soil contamination must be taken into account: When uncertainties are not considered and the utilities are assessed according to the estimated value for a spatial unit, only few (N=26) spatial units result where the utility score of the alternative soil washing are higher than the utility score to the no remediation alternative. However, when taking into account geostatistical uncertainties of the log-normal soil distribution this number is about ten times greater (N=237). Furthermore, the use of 'maximizing expected utility' as decision rule is critical in that it may lead to a high probability of misses. 相似文献