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1.
2.
This work describes the evolution of NO2 and O3 levels from January to December of 2007, covering the four seasonal periods in the urban air of Ciudad Real in the central-southern Spain. The measurements were carried out by means of passive samplers (Radiello® samplers). Eleven samples were collected weekly, placed at different monitoring site locations. The data indicate that the mean levels obtained during this period for O3 and NO2 were 38.5?±?3.5 and 20.8?±?3.8 μg/m3, respectively. These measurements were compared with other studies in Ciudad Real. Meteorological conditions (temperature, pressure, humidity relative, wind speed and direction) were also investigated.  相似文献   

3.
The correlation of particulate PAHs, sulfur dioxide, nitrogen dioxide and ozone were examined. The pollution scenario of particulate PAHs, sulfur dioxide, nitrogen dioxide and ozone is also briefly presented as supplementary information. Both sulfur dioxide and nitrogen dioxide were found to have significant positive correlations with total particulate PAHs as well as with most individual PAH species studied, suggesting they mostly share the same common emission source and transportation pattern. On the other hand, ozone was observed to selectively have a strong negative correlation with several PAH species, namely BgP, BaP, BaA, Pyr and Ace, probably due to the ozonolysis reaction of these species.  相似文献   

4.
为研究城市功能分区对绿地土壤活性碳氮的影响,选择合肥市不同功能区(老商业区、老工业区、居民服务区、近郊森林公园)绿地土壤为研究对象,分析了土壤微生物量碳氮(MBC、MBN)、溶解性碳氮(DOC、DON)、有机碳(SOC)、全氮(TN)以及土壤基本理化性质的差异及其相互关系。结果表明,功能区类型对土壤微生物量碳氮及溶解性碳氮影响显著(P0.05),且0~30 cm土层含量均为近郊森林公园高于城区内各功能区。土层厚度对MBC、DOC、DON含量影响显著,MBC、DON在各功能区中均随土层深度增加而递减,森林公园MBN、DOC均为10~20 cm含量最高。不同功能区MBC/MBN在6~14间波动,以此预测本研究范围内土壤微生物可能以真菌和放线菌为主,细菌较少。本研究未证实DOC与MBC、MBC与DON、DON与MBN间的相关性,MBC+DOC、MBN+DON比MBC、DOC、DON、MBN更能反应土壤活性碳氮库与土壤微生物量。总体来说,相比城区内各功能区,近郊森林公园更利于土壤生物量碳氮及溶解性有机碳氮的积累。  相似文献   

5.
ABSTRACT

Spinach (Spinacia oleracea L.) has one of the highest United States per capita consumption rates among leafy vegetable crops, and also ranks second for lutein and β-carotene carotenoid concentration. The objectives of this study were to determine the effects of nitrogen (N) concentration on elemental and pigment accumulation in spinach. Two spinach cultivars (‘Melody’ and ‘Springer F1’) were greenhouse grown in nutrient solution culture under N treatments of 13, 26, 52, and 105 mg L? 1. Leaf tissue biomass increased from 45.6 to 273.2 g plant? 1 and from 127.0 to 438.6 g plant? 1 as N increased from 13 to 105 mg L? 1 for ‘Springer F1’ and ‘Melody’, respectively. Leaf tissue N, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) responded to N treatments. Lutein accumulations, expressed on a fresh weight basis, responded quadratically to increasing N treatments for ‘Springer F1’. Maximum lutein values were 110 and 76 μ g g? 1 on a fresh weight basis, and maximum β-carotene values were 85 and 57 μ g g? 1 on a fresh weight basis for ‘Springer F1’ and ‘Melody’, respectively. Interestingly, N levels had a significant effect on carotenoid accumulation in both ‘Springer F1’ and ‘Melody’ when the pigments were expressed on a dry weight basis. Leaf tissue lutein increased from 0.59 to 1.06 mg g? 1 and from 0.59 to 0.90 mg g? 1 on a dry weight basis with increasing N treatments for ‘Springer F1’ and ‘Melody’, respectively. Reporting lutein and β-carotene on both a fresh and dry weight basis may be the most accurate way to express the carotenoid values of spinach.  相似文献   

6.
不同氮水平对甘蔗氮素利用及土壤氮素残留的影响   总被引:2,自引:1,他引:2  
以新台糖22号(ROC22)为试材,设施用15N标记的尿素2.5 g pot-1、5.0 g pot-1及7.5 g pot-13个处理,研究施氮水平对甘蔗氮素利用效率及土壤氮素的影响。结果表明,随氮肥施用水平的提高,甘蔗干物质积累、氮素积累、来源于肥料氮素的比率不同程度增加,同时土壤碱解氮含量、硝态氮含量、肥料氮素残留量及肥料氮素残留率显著增加,但甘蔗氮肥利用率显著下降;施氮水平还明显影响甘蔗各器官的干物质分配、氮素分配、氮肥利用率及氮素在不同土层的分布。本试验条件下,甘蔗氮肥施用土层深度为20 cm、尿素施用量为5.0 g pot-1较为适宜。  相似文献   

7.
Trace Elements in Soils of Urban Areas   总被引:2,自引:0,他引:2  
Urban soils are an essential element of the city environment. However, studies on urban soils are scattered in terms of geographical distribution, sampling pattern, analytical dataset, etc. One of the major issues arising from the studies on this ecosystem is the diffusion of its contamination. In cities, in fact, the proximity to humans may cause a serious danger for citizens. In the present study, results from the literature about trace elements in urban soils are presented to compare methodologies and results and to offer a basis for the harmonization of investigation approaches and establishment of remediation thresholds. A total of 153 studies on the urban ecosystem published in the last 10 years were collected and data on trace elements in soils of 94 world cities were compared and discussed. Data highlights the discrepancies among different studies (sampling strategies, analytical procedures) and the extreme variability of urban soils. Most cities are contaminated by one or more trace elements, revealing the environmental relevance of the urban soil system. While Pb is still one of the major concerns in many locations, new contaminants are on the rise and would deserve more attention from the researchers. While in fact some contaminants are almost ubiquitous in world cities and could be used as tracers for urban contamination, some traffic-related elements such as platinum, rhodium, and palladium, whose reactivity and toxicity is still unknown, are becoming of concern. Collation of literature data highlights the need for the harmonization of sampling, analytical, and rendering procedures for regulatory purposes and provides a useful dataset for environmental scientists dealing with the urban ecosystem and for city planners. A sampling design adapted to local urban patterns, a prescribed sampling depth, and a minimum set of elements that deserve to be measured could be the core of a common methodology.  相似文献   

8.
不同施氮水平下油菜地土壤氮素径流流失特征研究   总被引:6,自引:4,他引:2  
采用野外阳问试验,研究了浙北平原不同施氮水平对油菜地土壤氮素流失形态与含量的影响.结果表明,施肥的时间与降雨间隔对氮素的流失形态和浓度有明显影响,硝态氮是氮索流失的主要形态,占流失无机氮的比例为0.56~0.95;但若施肥后短期内降雨,铵态氮流失占有量增加,占流失无机氮的比例为0.37~0.42;氮素的流失量与施肥水平...  相似文献   

9.
Nitrogen (N) loss by ammonia (NH3) volatilization is the main factor for poor efficiency of urea fertilizer applied to the soil surface. Losses can be suppressed by addition of zeolite minerals to urea fertilizer. The objective of this study was to evaluate ammonia volatilization from soil and dry-matter yield and nitrogen levels of Italian ryegrass. A greenhouse experiment was carried out with the treatments of urea, urea incorporated into soil, urea + urease inhibitor, urea + zeolite, ammonium nitrate, and unfertilized treatment. Ammonia was captured by a foam absorber with a polytetrafluoroethylene tape. There were few differences between zeolite and urease inhibitor amendments concerning NH3 volatilization from urea. Results indicate that zeolite minerals have the potential to improve the N-use efficiency and contributed to increasing N uptake. Zeolite and urea mixture reduced 50% the losses by volatilization observed with urea.  相似文献   

10.
Limited research has been conducted on how atmospheric carbon dioxide (CO2) affects water and soil nitrogen (N) transformation in wetland ecosystems. A stable isotope technique is suitable for conducting a detailed investigation of mechanistic nutrient transformations. Nutrient ammonium sulfate (NH4)2SO4 input in culture water under elevated CO2 (700 μL L?1) and ambient CO2 (380 μL L?1) was studied to analyze N transformations with N blanks for both water and soil. It was measured by 15N pool dilution using analytical equations in a riparian wetland during a 3-month period. Soil gross ammonium (NH4 +) mineralization and consumption rates increased significantly by 22% and 404%, Whereas those of water decreased greatly by??57% and??57% respectively in enriched CO2. In contrast, gross nitrate (NO3 ?) consumption and nitrification rates of soil decreased by??11% and??14% and those of water increased by 29% and 27% respectively in enrichment CO2. These may be due to the extremely high soil microbial biomass nitrogen (MBN), which increased by 94% in elevated soil. The results can show when CO2 concentrations are going to rise in the future. Consequently soil microbial activity initiates the decreased N concentration in sediment and increased N concentration in overlying water in riparian wetland ecosystems.  相似文献   

11.
关于深圳市城市水土流失问题的探讨   总被引:2,自引:1,他引:2  
深圳市在农村城市化进程中,由于管理滞后,开发单位盲目野蛮开发,造成了严重的水土流失.据统计,深圳市水土流失总面积为184.99km~2,其中人为开发造成的水土流失面积占总流失面积的93.43%.在分析深圳市水土流失现状、成因及危害程度的基础上,探讨了农村与城市水土流失的异同点,认为城市水土保持较农村水土保持的内涵更为广泛,城市水土保持主要体现为以城市建设服务为中心目标的水土资源保护.  相似文献   

12.
We measured formaldehyde concentrations in ambient air at urban (Isesaki) and rural (Annaka) sites in Gunma Prefecture, Japan from June 1998 to March 2003. Measurements were carried out once in a month to obtain daily mean formaldehyde concentrations. At both the sites, mean concentrations of formaldehyde were significantly higher from April to September (summer) than from October to March (winter). Formaldehyde concentrations in Annaka were essentially as high as those in Isesaki in summer, but were significantly lower in winter. At both the sites, concentrations of formaldehyde and oxidants correlated significantly with one another in the summer; correlation coefficients in Annaka and Isesaki were 0.82 and 0.64, respectively. The fraction of formaldehyde formed photochemically based on concentrations of benzene was calculated to be as high as 80% in both the sites in summer. The results suggested that formaldehyde concentrations were high even in rural air, reflecting photochemical reactions rather than automobile exhaust.  相似文献   

13.
The results of ambient sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentrations measured in ten cities of China and Korea by the improved passive samplers are reported. The property of this sampler is the utilization for the long-term exposure to the high level of SO2 and NO2. In this method, the conversion coefficients from the analytical data to the ambient concentrations were obtained from the comparison with the direct concentrations through the automatic analyzers for SO2 and for NO2, respectively. The interesting monthly variations were observed in the ambient SO2 and NO2 concentrations measured by this passive sampler method, which seems to give important information to the formation of acid rain in these countries.  相似文献   

14.
Abstract

Pollution of surface and groundwater by inorganic nitrogen (N) was assessed in farm villages of northern Vietnam. The pH and ammonium‐N and nitrate‐N concentrations were monitored at three communes near Ha Noi in the Red River Delta in March and September 2003, following monitoring in October 2002. In each monitoring time, ammonium‐N concentrations exceeded the Vietnamese water standards applicable to surface and groundwater, whereas the nitrate‐N concentrations were relatively low and below the corresponding standards. Neither spatial nor temporal variation was found in the ammonium‐N and nitrate‐N concentrations of the surface water. A temporal increase in the ammonium‐N concentration was statistically confirmed in the groundwater. Intensively applied fertilizer‐N and disposed animal/human wastes were thought to be sources of ammonium‐N. Ammonium‐N originating from those sources was seen to accumulate steadily in the groundwater through percolation from the surface water and surrounding land. A spatial variation of the nitrate‐N concentration was observed in the groundwater. The nitrate‐N concentration in the groundwater was particularly low in communes located in lowland areas with alluvial soils. The suppression of nitrification or promotion of denitrification was considered to be responsible for the low nitrate‐N concentration. A spatial variation was also found in the groundwater pH. Therefore, variation of the pH may be linked to variation of the nitrate‐N concentration in the groundwater.  相似文献   

15.
采用温室沙培试验,通过不同浓度氮处理,研究红桤木、喜马拉雅灰桤木、欧洲桤木和灰桤木4种国外引种的桤木属幼苗对不同氮水平的响应差异,分析了氮胁迫对桤木属幼苗根系形态和氮累积利用的影响.结果表明:随着氮水平(N0、N1/2、N1(标准E.G.Bollard营养液)、N2)的增加,各桤木属植物的生物量、氮累积量和根长、根体积、根表面积、须根数等生长参数均呈先增后降的趋势,且在N1/2水平中各参数值最大;细根比例及氮利用效率、氮利用率均呈持续下降趋势.参试的4种桤木中欧洲桤木、红桤木的生物量、氮累积量、根系形态参数均较高,且在N1/2时氮利用率较高,分别为44.57%、40.14%,具有在我国长江中下游地区作为生态防护和短周期工业用材树种推广应用潜力;灰桤木和喜马拉雅灰桤木各生长参数均较低,不宜推广.试验结果也表明尽管桤木属植物具有一定的固氮能力,但在低地力河滩沙地、丘陵等地区集约化经营中仍需采取一定施肥措施.  相似文献   

16.
The zeolite and urea mixture may be use to improve nitrogen (N)–use efficiency of silage corn. The objective of this study was to evaluate dry-matter yield and nutritional levels of N of silage corn fertilized with urea and zeolite mixture. The experimental design was a 2 × 4 × 4 factorial randomized block design with three replications. Treatments included two types of stilbite zeolite (natural and concentrated), four levels of nitrogen (0, 50, 100, and 200 kg ha?1), and four ratios of zeolite (25%, 50%, and 100% of N level). Treatments were applied 60 days after planting with the topdressing fertilization. The use of concentrated (650 g kg?1 of stilbite) or natural (470 g kg?1 of stilbite) zeolite with urea increased silage corn dry-matter production and leaf N concentrations.  相似文献   

17.
ABSTRACT

Soil pH is one of the properties that mostly influences nitrification rates, and can be used as a tool for controlling this process, seen that depending on its extent it may lead to nitrogen (N) losses and subsequent contaminations. The aims of this study were to evaluate mineralization and nitrification of two soils at different pH levels. The experimental design was factorial with two factors and three replicates, with the first factor referring to two samples of red latosols, one eutrophic (LV1) and the other dystrophic (LV2), and the second factor was soil’s pH, at six levels: 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5. Samples were incubated for 70 days in laboratory conditions. Both nitrate (N-NO3) and mineral N contents were determined and adjusted to growth models. The eutrophic soil presented higher mineral N and N-NO3, and the increase of pH levels led to increases of both inorganic N and N-NO3contents. Increases in pH levels caused N-NO3levels to increase in both soils, however this occurrence happened because it increased the amount of mineralized N in the soil, seen that in all pH ranges in both soils practically all mineral N was in the form of N-NO3.  相似文献   

18.
An important component of monitoring pollution of urban road-deposited sediment (RDS) is an understanding of the temporal variability in its composition and physical characteristics. This study set out to determine what the monthly variability in metal concentrations, organic matter content, grain-size and grain-size fraction metal-loadings are in inner city sites in Manchester, northwest England. The results show that there is significant temporal variability in metal (Pb, Zn, Fe, Mn) concentration in RDS from inner city Manchester. There was no significant temporal variability in grain-size characteristics or organic matter content, indicting that these metal variations were the result of variation in sources and accumulation processes. Pb and Zn displayed local variability, suggesting local controls on variability, whereas Fe and Mn displayed consistent variability across all sites, suggesting a common, larger-scale control on variability. The finest grain-size fraction (<63 μm) contained the highest Pb, Cu and Zn concentrations, but for the case of Fe and Mn, the coarser fractions (>300 μm) commonly contained the highest concentrations, again suggesting differing controls. For all metals, due to the weight percent dominance of the coarser fractions, the dominant loading of metals is in the coarser fractions. This has implications on management strategies, via street sweeping and the subsequent waste disposal, and on the modelling of the input of RDS and associated metals into surface waterways. The recognition of significant temporal variability of metal concentrations in RDS, independent of grain-size changes, implies that the monitoring of urban road sediment pollution will require not just consideration of spatial variability, but the design of schemes that will capture temporal variability also.  相似文献   

19.
在高产条件下研究了施氮水平对强筋小麦济麦20氮素同化及籽粒蛋白质组分积累和品质的影响,结果表明,在0~195 kg/hm2施氮量范围内,增施氮肥显著提高旗叶硝酸还原酶和谷氨酰胺合成酶活性,提高各器官氮素含量和积累量,促进籽粒单体蛋白、可溶性和不溶性谷蛋白积累,提高籽粒蛋白质含量及可溶性和不溶性谷蛋白占总蛋白的比例,改善籽粒品质;285 kg/hm2施氮量处理与195 kg/hm2施氮量处理相比,旗叶硝酸还原酶和谷氨酰胺合成酶活性及籽粒蛋白质含量均无显著变化,但单体蛋白含量及占总蛋白质的比例升高,可溶性和不溶性谷蛋白含量及占总蛋白质的比例降低,籽粒品质下降,兼顾高产和优质的适宜施氮量为105~195 kg/hm2。  相似文献   

20.
研究不同氮用量对冷浸田水稻氮钾吸收利用和产量的影响,探求在冷浸田水稻氮肥适宜用量;以D优202水稻品种为材料,田间试验研究6个不同氮量(0、45、90、135、180、225 kg hm-2)下水稻含氮量、含钾量、氮和钾的积累量以及产量的差异及其相互关系。在冷浸田开沟降渍的条件下,在0225 kg hm-2纯氮范围内,随氮肥水平的增加,水稻含氮量在有效分蘖临界叶龄期、拔节期、抽穗期均显著增加,成熟期先增后减,含钾量除有效分蘖临界叶龄期外其他时期均显著降低,含氮量相应提高含钾量会有所降低;植株氮和钾的积累量基本具有相同的趋势,先增加后减少。分析表明:水稻各个生育阶段的氮、钾与稻谷产量均呈正相关,增施氮肥有利于水稻氮和钾吸收利用的提高,但氮肥过高时氮和钾吸收利用不再增加,甚至有所降低。在磷钾一定的条件下,冷浸田水稻最高产量施氮量为169.0 kg hm-2,经济施氮量为153.9 kg hm-2。  相似文献   

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