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71.
72.
There is a profound debate over how to assign greenhouse gas (GHG) responsibilities; therefore, we have decided to follow IPCC guidelines, as they offer the only standardized method. We have identified each type of greenhouse emission and its level of absorption. We have studied the province and its districts and municipalities. We have determined that the energy sector is that with the highest level of emissions, even if the per capita emissions of the Province of Siena are very low. This is caused by a very low level of industrialization and the presence of a local geothermal production of energy. In order to highlight this aspect, we have considered scenarios both with and without geothermal production. Our research was then focused on single districts (groups of homogenous municipalities) and municipalities, where we found great differences among the greenhouse emissions of the areas. We have constructed a map of the greenhouse emissions of the whole province. It has been interesting to note that there are 14 municipalities with net negative emissions, seven with low positive emissions, 12 with medium positive emissions and three with elevated positive emissions. These latter correspond to the main city and to two of the most industrialized municipalities.  相似文献   
73.
In Europe, the use of direct methods using lysimeters for measuring water and solute flow in soils increased in recent years. Large weighable lysimeters are best suitable for obtaining reliable data about seepage water quantity and quality. Field lysimeters – lysimeters built in directly in agriculturally used areas – of high technical standard allow a precise determination of the influence of different cropping systems on groundwater quality. They combine the advantages of true field conditions and laboratory possibilities of varying parameters, handling and maintenance. Due to the specific needs of each application the instrumentation varies. Based on general remarks on the advantages of precise weighing lysimeters four standardized lysimeter configurations are presented. Beside the specific needs of design and setup of lysimeter stations, there is need to define general requirements to enable comparable results based on standardized basic design and to reduce individual mistakes.  相似文献   
74.
污水处理是一个复杂的生物、物理及化学反应过程.污水水温直接影响到污染物生物处理效果,并对污水处理运行能耗产生重要影响.另一方面,污水中也蕴含着相当热能,是潜在可以回收的低品位能源,加以利用则有望实现污水处理碳中和运行.然而,现有研究很少涉及污水处理厂污水进、出水水温变化及其影响因素;工程中也只强调冬季保温,并无法从微观角度认识处理过程水温变化规律.为此,研究尝试构建污水处理过程水温变化热量衡算模型,涵盖污水生化反应、机械传热、环境热传递和水蒸发热损失等4个主要涉热过程.与此同时,收集北京某污水处理厂实际水温、气温数据,借助热量平衡图来模拟污水处理过程中水温变化,并对理论模型参数进行校验和修正.通过参数敏感性分析,可以评价不同参数对水温热量的影响程度.基于这些工作,一个污水温度变化模型被构建成功,可用于指导实际污水处理厂水温控制或余温热能回收过程,可助力污水处理厂节能降耗、甚至实现碳中和目标.  相似文献   
75.
李竹  王兆峰  吴卫  邵海琴 《自然资源学报》2022,37(12):3136-3152
厘清碳平衡能力与城镇化的关系对实现碳中和目标和推动新型城镇化发展具有重要的理论价值及实践意义。采用温室气体清单法、碳吸收清查法、碳平衡指标法和多元城镇化测量法分别测算1999—2018年中国省域碳平衡能力与各类城镇化指标,利用空间自然断点分级法和Granger因果检验法分别分析中国省域碳平衡能力与城镇化的时空演变特征及互动关系。主要结论如下:(1)中国碳排放不断增多,碳吸收不断减少,碳平衡能力呈上升、下降、先减后增和先增后减四种趋势,碳排放呈“东多西少”分布,碳吸收与碳平衡能力分别呈“西多东少”和“西强东弱”分布。(2)中国人口、经济、空间、生态城镇化和城镇化综合指标不断提升,其中空间城镇化大致呈“西高东低”分布,其余则呈“东高西低”分布。(3)除空间城镇化外,中国整体碳平衡能力与各类城镇化的关系均为反馈型,而各省域增长保护型数量最多,中立型数量最少。  相似文献   
76.
杭州市大气PM2.5和PM10污染特征及来源解析   总被引:36,自引:12,他引:24  
2006年在杭州市两个环境受体点位采集不同季节大气中PM2.5和PM10样品,同时采集了多种颗粒物源类样品,分析了其质量浓度和多种化学成分,包括21种无机元素、5种无机水溶性离子以及有机碳和元素碳等,并据此构建了杭州市PM2.5和PM10的源与受体化学成分谱;用化学质量平衡(CMB)受体模型解析其来源。结果表明,杭州市PM2.5和PM10污染较严重,其年均浓度分别为77.5μg/m3和111.0μg/m3;各主要源类对PM2.5的贡献率依次为机动车尾气尘21.6%、硫酸盐18.8%、煤烟尘16.7%、燃油尘10.2%、硝酸盐9.9%、土壤尘8.2%、建筑水泥尘4.0%、海盐粒子1.5%。各主要源类对PM10贡献率依次为土壤尘17.0%、机动车尾气尘16.9%、硫酸盐14.3%、煤烟尘13.9%、硝酸盐粒8.2%、建筑水泥尘8.0%、燃油尘5.5%、海盐粒子3.4%、冶金尘3.2%。  相似文献   
77.

The research was carried out in order to verify the influence that light, oxygen, and microbial activity have on the degradability of pyrimethanil (PYR) in soil. The products of degradation were also identified and their evolution in time evaluated. The results indicate that the molecule is more persistent in the absence of light, oxygen, and microbial activity. The order of importance of these three factors is as follows: light < microbial activity < oxygen. The following products of degradation were identified: (1) benzoic acid, (2) cis,cis-muconic acid, (3) hydroxyl-4,6-dimethyl-2-pirimidinamine, (4) N′-ethyl-N-hydroxyformamidine, and (5) 4,6-dimethyl-2-piridinamine, which appeared different from those reported in literature for the degradation of PYR in abiotic conditions. This result suggests that the degradation in soil is mainly biotic.  相似文献   
78.
Abstract

The urea herbicide buturon (N‐[p‐chlorophenyl] ‐N’ ‐methyl‐N’ ‐isobutinyl‐urea), 14C‐labeled, was sprayed on winter wheat as an aqueous formulation (2.98 kg/ha) under outdoor conditions. Upon harvest (three months after application), a total of 49. 2% of the applied radiocarbon was recovered: 2.0% in the plants, 46.9% in the soil, and 0.3% in the leaching water (depth > 50 cm); less than 0.1% was in the grains (0.464 ppm). Only about half of the radioactivity present in plants could be recovered under mild extraction conditions; about half of this was unchanged buturon. In straw and husk extracts, the following metabolites were identified by gaschromatography/mass spectrometry: N‐(p‐chlorophenyl)‐N‐methyl‐O‐methyl‐carbamate (metabolite I), N‐phenyl‐N’ ‐formyl‐urea (metabolite II), two unstable metabolites giving (p‐chlorophenyl)‐isocyanate upon purification (metabolites III and IV), N‐(p‐chlorophenyl)‐N’ ‐methyl‐N’ ‐isobutenylol‐urea (metabolite V), p‐chloroformanilide (metabolite VI) and biologically bound p‐chloroaniline (metabolite VII). In the root and basal stem extract, the following metabolites were identified by gas chromatography/mass spectrometry: N‐(p‐chlorophenyl)‐O‐methyl‐carbamate (metabolite VIII) and N‐(p‐chlorophenyl)‐N’ ‐methyl‐urea (metabolite IX).  相似文献   
79.
采用室内模拟实验方法,研究环境因子(温度、pH、扰动强度、供气量)对底泥释放COD的影响。结果表明,水温升高能加速底泥中有机质的释放;上覆水在弱酸至中性条件下底泥释放有机质最低;扰动上覆水体会加快有机质的释放。  相似文献   
80.
Moore, R.D. (Dan), J.W. Trubilowicz, and J.M. Buttle, 2011. Prediction of Streamflow Regime and Annual Runoff for Ungauged Basins Using a Distributed Monthly Water Balance Model. Journal of the American Water Resources Association (JAWRA) 48(1): 32‐42. DOI: 10.1111/j.1752‐1688.2011.00595.x Abstract: Prediction of streamflow in ungauged basins is a global challenge, but is particularly an issue in physiographically complex regions like British Columbia (BC), Canada. The objective of this study was to assess the accuracy of a simple water balance model that can be run using existing spatial datasets. The model was developed by modifying an existing monthly water balance model to account for interception loss from forest canopy, glacier melt, and evaporation from lakes. The model was run using monthly climate normals from the ClimateBC application, which have a horizontal resolution of 400 m. Each ClimateBC grid cell was classified as forest, open land, glacier or water surface based on provincial scale digital maps of biogeoclimatic zones, glaciers, and water. The output was monthly mean runoff from each grid cell. These values were integrated within the catchment boundaries for streams gauged by the Water Survey of Canada. Annual runoff was predicted with modest accuracy: after updating the predicted runoff by interpolating errors from neighboring gauged streams, the mean absolute error was 25.4% of the gauged value, and 52% of the streams had errors less than 20%. However, the model appears to be quite robust in distinguishing between pluvial, hybrid, and melt‐dominated hydroclimatic regimes, and therefore has promise as a tool for catchment classification.  相似文献   
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