共查询到20条相似文献,搜索用时 0 毫秒
1.
The properties of stable oxygen isotopes make them useful for studying processes involved in the atmospheric oxidation of sulphur compounds. Experimental work in the 1980s reported that the formation of primary combustion sulphates by high temperature oxidation of SO2(g) to SO4 leads to δ18OSO4 values between +40 and +45‰. This study reports sulphate oxygen isotopic compositions from precipitation events collected at two sites in eastern Newfoundland. Values as high as +41.7‰ were measured in natural precipitation samples collected near a small oil-fired power plant located on the campus of Memorial University of Newfoundland in St. John's. These values are higher by 16‰ than any previously reported for precipitation in the literature and in conjunction with other chemical data implicate the power plant as the pollution source. Values from the second site (Seal Cove) were similar to previously reported ranges for precipitation, despite its proximity to a much larger oil-fired, thermal generating station, suggesting that different oxidation mechanisms were dominant there. Oxygen isotopic compositions of precipitation sulphates can be an important complementary tool to other isotopic, trace metal and meteorological analysis in the tracing of sources of atmospheric sulphur compounds. 相似文献
2.
Aerosol samples were collected in Tel-Aviv, Israel, during two different atmospheric situations, clear days and dust storms, and were analyzed for shape, size distribution, elemental composition, and presence of sulfate in individual particles. Results of two cases are presented in this paper. In both cases about 80% of the 0.2 to 2.0 µm particles contained sulfate. On the clear day over 50% of the total were pure sulfates while 27% were mixed sulfates; on the dusty day 63% were mixed sulfates — desert particles coated with sulfate — and only 20% were pure sulfates. The sulfate content of the desert particles was fairly high, on the order of 0.1 g sulfate g?1 of desert particles. A possible explanation of this phenomenon may be heterogeneous nucleation of SO2 on the surfaces of insoluble desert particles during their passage over the Mediterranean. 相似文献
3.
灌溉与降水对土壤NO^—3—N累积的影响 总被引:22,自引:0,他引:22
在粉砂粘壤土上,降水对休闲地和旱地土壤NO^-3-N累积的影响主要在0~2m的深度范围;以当地生产中习惯使用的灌水量进行灌溉,在小麦-玉米轮作8年之后,土壤中累积的NO^-3-N会逐渐被淋溶至400cm以下的层次;一次性过量灌水则可将土壤上层施入的NO^-3-N淋至500~600cm的深度范围,不合理的灌溉会引起NO^-3-N的大量淋失。 相似文献
4.
Douglas A. Burns James N. Galloway George R. Hendrey 《Water, air, and soil pollution》1981,16(3):277-285
Acidification by precipitation of undisturbed, upland surface waters was examined in the White Mountains of New Hampshire and the Blue Ridge Mountains of North Carolina. The pH and alkalinity of samples taken in the summer of 1979 were compared to those taken in North Carolina in the early 1960s and in New Hampshire in the late 1930s. These parameters had declined significantly over the sampling intervals. Results were confirmed by comparing recent measurements of Ca, Mg, Na, and K to those of bicarbonate alkalinity. This comparison confirmed the hypothesis that some acidification has occurred in both areas and that acidification was more pronounced in the New Hampshire waters. 相似文献
5.
Serra-Majem L Ribas L Ngo J Ortega RM García A Pérez-Rodrigo C Aranceta J 《Public health nutrition》2004,7(7):931-935
OBJECTIVE: To evaluate dietary habits in Spanish children and adolescents based on a Mediterranean Diet Quality Index tool, which considers certain principles sustaining and challenging traditional healthy Mediterranean dietary patterns. DESIGN: Observational population-based cross-sectional study. A 16-item Mediterranean Diet Quality Index was included in data gathered for the EnKid study (in which two 24-hour recalls, a quantitative 169-item food-frequency questionnaire and a general questionnaire about socio-economic, demographic and lifestyle items were administered). SETTING: Spain. SUBJECTS: In total, 3850 children and youths aged 2-24 years residing in Spain. RESULTS: Of the sample, 4.2% showed very low KIDMED index results, 49.4% had intermediate values and 46.4% had high index results. Important geographical differences were seen, with subjects from the Northeast showing the most favourable outcomes (52% with elevated scores vs. 37.5% of those from the North). Lower percentages of high diet quality were observed in low socio-economic groups, compared with middle and upper income cohorts (42.8%, 47.6% and 54.9%, respectively). Large cities had more positive results and only slight variations were seen for gender and age. CONCLUSIONS: The KIDMED index, the first to evaluate the adequacy of Mediterranean dietary patterns in children and youth, confirms that this collective is undergoing important changes, which makes them a priority target for nutrition interventions. Results challenge certain commonly perceived notions tied to income level, population size and diet quality. 相似文献
6.
《Communications in Soil Science and Plant Analysis》2012,43(1-2):47-59
As nitrogen (N) fertilizer-use efficiency rarely exceeds 50% in most agricultural systems, the potential leaching of N to the groundwater, particularly under irrigated conditions, has economic, health, and environmental implications. Research in the Akarsu irrigation district in the Lower Seyhan Plain in southern Turkey sought to determine spatial and temporal variability of groundwater (GW) nitrate (NO3) concentrations in 2007–2008. Shallow groundwater observation wells 3 m deep were installed at different locations to represent the whole irrigation district. Groundwater samples were collected (February, April, July, October) and analyzed for ammonium (NH4) and NO3 concentrations. Because NH4 values were negligible, only NO3 data were processed to determine spatial and temporal variability and then used to develop regional NO3 maps using geographic information systems. Groundwater NO3 concentrations ranged between 0.17 and 55.96 mg L–1 during the 2 years, only exceeding the critical 50 mg L–1 concentration in 1% of the area sampled. The areal mean of NO3 concentration was greatest in February, indicating a potential N leaching of unused N from the early season with intensive rainfall, especially in wheat-growing areas. Groundwater NO3 concentrations decreased after February; however, during the peak irrigation season in July, NO3 was relatively low because of crop uptake during spring and summer. In about half the area, groundwater NO3 concentrations ranged between 20 and 50 mg L–1 and were thus marginal relative to the critical pollution level. As N fertilizer use will continue to increase, especially with the expanded irrigation that is now occurring in the Mediterranean region, regular monitoring of groundwater NO3 is advisable under such conditions. 相似文献
7.
Kang Gongunn Collett Jeffrey L. Shin Dae-Ywen Fujita Shin-Ichi Kim Hui-Kang 《Water, air, and soil pollution》2004,151(1-4):11-34
Precipitation samples were collected at two coastal sites on the Korean Peninsula, Kangwha on the western coast and Yangyang on the eastern coast, from September 1991 to February 1997. The samples were analyzed for concentrations of major ions, in addition to pH and electrical conductivity. The annual volume-weighted mean pH values were 4.89 and 5.05 at Kangwha and Yangyang, respectively. The pH was generally lower at Kangwha than that at Yangyang, especially during the winter, because of reduced neutralizing inputs and greater acid inputs in winter. Dominant ions were different with NH4 + and SO4 2- most important at Kangwha and Na+ and Cl- at Yangyang. Neglecting sea salt components, nss-SO4 2- and NO3 - were important anions and nss-Ca2+ and NH4 + were important cations at both sites. Concentrations of these ions were 1.2–1.6 times higher at Kangwha than at Yangyang. Annual mean concentrations of these ions varied little during the study, while larger seasonal variations were observed. Annual mean nss-SO4 2-/NO3 - ratios at Kangwha and Yangyang were 2.8 and 2.6. The 5 yr annual mean values of nss-SO4 2-/NO3 - showed no trend at Kangwha but a decreasing tendency at Yangyang. The decreasing trend is similar to the decreasing trend in emissions of SO2/NOx in South Korea. Regional differences in chemical composition between Kangwha and Yangyang appear to be associated with long-range transport of acidic gases and alkaline dust originated from other regions. 相似文献
8.
1960-2013年中国东南沿海地区年内降水集中度和集中期的时空变化特征 总被引:2,自引:0,他引:2
[目的]揭示中国东南沿海地区降水集中度(PCD)和集中期(PCP)时空变化特征,为科学应对旱涝灾害和水资源利用等提供依据.[方法]基于东南沿海地区46个气象台站的逐日降水量资料,采用Morlet小波分析、EOF等气候分析方法对1960-2013年东南沿海降水集中度和集中期时空变化特征进行分析.[结果]在时间变化上,PCD波动幅度介于0.10~0.25,存在13~16 a,19~23 a和33~35 a的周期变化;PCP波动幅度介于139.5~208.2,存在13~16 a和25~30 a的周期变化.在空间变化上,PCD具有明显的地域分异特征,PCP空间差异性大.[结论]1960-2013年中国东南沿海地区降水集中度在增强,且沿海地区值大于内陆地区;降水集中期稳定波动,空间上变化具有一致性. 相似文献
9.
Size distribution of trace elements is measured at the Mediterranean coast of Turkey, by analyzing hi-vol impactor samples collected between August 1993 and May 1994. Mass median diameters of marine elements are between 4.6 and 5.3 μm, and those of crustal elements are between 3.0 and 3.5 μm. Mass median diameters of crustal elements are 30% smaller in samples impacted by Saharan Dust. Pollution derived elements, As, Cd, Mo, Pb, Se, and Zn have MMD's between 1.25 and 1.01 μm. Although 70–90% of the masses of these elements were associated with particles smaller than 2.1 μm, 10–30% of their mass was associated with coarse particles. Coarse component in concentrations of Cd, Pb, Sb and particulate Hg are due to adsorption of fine anthropogenic particles on coarse crustal aerosol, whereas coarse fraction Zn, As, Se, In, Mo and Au are crustal at Al concentrations > 100 ng m?3. Bromine, Cr, Ni, and V have bimodal distributions. The fine component, which account for approximately 30–40% of their masses are due to anthropogenic sources, whereas the coarse component, which accounts for 30–50% of their masses are due to sea salt for Br, and crustal particles for Cr, Ni, and V. 相似文献
10.
Monthly fluxes of sulphate (SO4 2-) and base cations(Ca2+, Mg2+, K+) were studied from 1993 to 1996 as precipitation passed through forest vegetation and surfacesoil layers in an area receiving low and declining levels of atmospheric sulphate pollution. The canopy was dominated by mature Norway spruce (Picea abies Karsten) and the soilwas a podzol developed on glacial till material. The mean annual bulk deposition of SO4 2- collected in the open was 136 molc ha-1 and that of Ca2+, Mg2+ and K+ was 44, 11 and 25 molc ha-1, respectively. The annual total throughfall deposition of SO4 2- was 318 molc ha-1 and that of Ca2+, Mg2+ and K+ was 151, 64 and 181 molcha-1, respectively. Sulphate was the dominant anion accompanying the base cations leached from the canopy. More than half (58%) of the annual total throughfall deposition ofSO4 2- was retained by the O-horizon and only 15% leached from below the B-horizon. The annual leaching of Ca2+, Mg2+ and K+ from below the B-horizon was14, 25 and 9% of the annual total throughfall deposition, respectively. The transport of base cations through the soil was predominantely countered by SO4 2- anions. 相似文献
11.
We applied trend analyses to data from the International Cooperative Programme forAcidification of Rivers and Lakes in an attempt to discover regional patterns of long-term changesin surface water chemistry both in Europe and North America, and to relate these changes totrends in deposition. Decreases in surface water SO 3 - concentrations predominated at European sites in theFederal Republic of Germany, The Netherlands, and in Norway, and at the North American sitesin Ontario, Canada, the Adirondacks and Catskill Mountains of New York, U.S.A. Otherpredominating trends in the European sites were decreasing Ca2+ concentrations at many of thesites in The Netherlands, Norway, and Sweden. Increases in NO 3 - were observed at several sites in southern Norway, and in theAdirondack and Catskill regions of eastern New York. This, combined with an increasedoccurrence of declining base cation concentrations may well be responsible for the lack ofdocumented surface water recovery from acidification. Despite region-wide trends in severalvariables of importance in acidification, no correlations between surface water trends and changesin deposition were found using these data. 相似文献
12.
G. Ruecker P. Schad M. M. Alcubilla C. Ferrer 《Land Degradation \u0026amp; Development》1998,9(2):179-188
Abandonment of degraded and marginal agricultural land is a widespread phenomenon in Spain and other Mediterranean countries. To study soil development and site dynamics, a comparative investigation of field groups representing different ages of abandonment was realized in the Meastrazgo region of the Mediterranean province of Castellón. Analysis of soil samples for organic carbon and total nitrogen content and pH showed that a sufficient regeneration of organic matter is accomplished after 20 years of fallow. Contrary to this there is no build-up of ‘available’ phosphorus after abandonment. A fixation of phosphorus in unavailable forms in the first fallow years seems evident, and there is no re-enrichment through solution or mineralization of organically bound P thereafter. The vegetation of the fallow fields develops after passing through a low-cover therophyte stage within 10–20 years to nanophanerophyte-dominated \underline matorral (shrubs), in the best case within 40–50 years to a stone oak juniper association. Under intensive cattle grazing, grasslands rich in hemicryptophytes evolved. Rates of soil erosion estimated through application of the Universal Soil Loss Equation are of medium to low intensity and range between 2·2 t ha−1 year−1 in the first fallow years and 0·6 t ha−1 year−1 after establishment of vegetation cover. Under grassland erosion is negligible unless vegetative cover is destroyed through treading. © 1998 John Wiley & Sons, Ltd. 相似文献
13.
Isabel Díaz María Carmen del Campillo Vidal Barrón José Torrent Antonio Delgado 《Journal of Soils and Sediments》2013,13(8):1369-1377
Purpose
Information about phosphorus (P) losses from agricultural catchments in Mediterranean environments is scarce. In this work, P losses in overland flow from two representative small Mediterranean catchments, one dominated by Alfisols and the other by Vertisols, were studied.Materials and methods
At the lowest level of each catchment, overland flow was measured and several runoff samples taken in each runoff event during two growing seasons (2001–2002 and 2002–2003). After centrifugation, total P in sediments and total and molybdate reactive P in supernatant were determined. Different chemical extraction methods were used to quantify the forms of P in soils and sediments.Results and discussion
Total P losses in the studied catchments ranged between 0.5 and 3.2 kg ha?1 year?1, losses higher than 2 kg P ha?1 being observed in one event. Phosphorus was mainly lost in the sediments, the ratio of total dissolved P to particulate P being higher in the Alfisol than in the Vertisol catchment. Phosphorus concentration in sediments from the Vertisol catchment was similar to that in the source soils, whereas sediments in the Alfisol catchment had 2.1 times more inorganic P and 9 times more organic P (OP) than the source soils. In the latter catchment, there was an enrichment in the more labile inorganic P forms in the sediments relative to the source soils, which corresponds to a relative enrichment in iron (Fe) oxides by a factor of 2.4. Alfisols had lower TP contents and exhibited lower erosion rates than Vertisols in the studied period but they posed a greater environmental risk than the latter soils because their sediments were richer in P and had a higher proportion of P in forms bound to the Fe oxides compared to the source soils—these P forms can be easily released with the onset of reducing conditions at the bottom of waterbodies.Conclusions
A study of the P enrichment ratios and the dominant P forms in eroded sediments is therefore necessary to predict the impact of P losses from soils on the ecological quality of waterbodies. 相似文献14.
J. S. Swanston R. P. Ellis A. Perez-Vendrell J. Voltas J.-L. Molina-Cano 《Cereal Chemistry》1997,74(4):456-461
To determine whether patterns of grain filling were consistent between seasons and different between sites in northern and southern Europe, the cultivar Troubadour and TR49, a mutant derived from it, were grown, over two seasons, at sites in Scotland and northern Spain. Differences in sowing date and climate were reflected in different patterns of grain filling. Ear emergence in Scottish grown barley occurred around the time when daylight hours were maximal; optimal photosynthesis was the likely explanation for the rapid increase in grain size observed at the Scottish site. Differences between the sites in temperature and rainfall were most evident during the last month of the growing season. In Scotland, where ripening occurred in cooler, more humid conditions, synthesis of hordein and β-glucan followed the pattern of grain filling, reaching a peak at ~600 degree days after anthesis (the product of days after anthesis and average temperature). Levels then remained fairly constant until harvest ripeness was reached. In Spain, levels of hordein and β-glucan rose virtually throughout the growing season. Differences observed at maturity, between Scottish and Spanish grown grain, in total nitrogen and β-glucan levels were due to this accumulation in the later stages of growth. This was accompanied by a major change in the ratio of the constituent polypeptides of the storage protein and differences in the relative proportions of soluble and insoluble β-glucan. 相似文献
15.
Curt M. D. Aguado P. Sánchez G. Bigeriego M. Fernández J. 《Water, air, and soil pollution》2004,151(1-4):135-142
This work aims to identify the sources of nitrogencontamination in nitrate vulnerable zones (NVZs) of Spain by means of the nitrogen isotope method. Three categories of nitrogen sources (synthetic fertilisers, animal wastes, and sludges and effluents from waste-water treatment plants) from three NVZs were analysed for their nitrogen isotopic composition (δ15N) in order to assess the applicability of the method to the identification of these N sources. The mean δ15N values were: +1.48‰ for synthetic fertilisers, +15.98‰ for animal wastes and +11.52‰ for sludges and effluents. The synthetic fertiliser sources were significantly different from the organic sources and so, the method can be used for their identification. The highest variability was found within the animal waste category. The range of values found for the different kinds of animal wastes (+5.86 to +36.74) was very wide and overlappedthe range found for sludges and effluents from waste-water treatmentplants (+4.57 to +20.18). Accordingly, these two nitrogen sources areisotopically indistinguishable. 相似文献
16.
The cross-referencing of sedimentological, stratigraphic, geoarchaeological and radiocarbon data enables us to establish the geomorphologic evolution of the Late Holocene coastal flood plain of the Turia River. The Holocene marine transgression formed a coastal barrier lagoon environment in the coastal plain. During the Late Holocene, increased sediments supplied to the low reach of the river promoted: (a): the progradation of deltaic coastal sandy ridges on the coastline and (b): the aggradation of the floodplain on top of the sedimentary sequence. Four phases are clearly recognised in the geoarchaeological record of the flood plain. (1): High magnitude flooding events (2800 BP to 3rd century BC). (2): Slow riverbed aggradation and progressive levee formation (low energy flood regime) in Roman times (2nd century BC to 5th century AD). (3): Swampy environmental processes (6th to 9th centuries). (4): Second high-magnitude flooding phase (11th century). The navigable channel of the Roman and early Islamic periods became a wide and shallow braided channel in Medieval times. These phases are correlated with others detected by researchers in many areas of the Mediterranean region and with global Holocene climate events. 相似文献
17.
Cárceles Rodríguez B. Zuazo V. H. Durán Rodríguez M. Soriano Ruiz B. Gálvez García-Tejero I. F. 《Eurasian Soil Science》2021,54(5):792-806
Eurasian Soil Science - The rainfed mountain plantations in semiarid areas of the Mediterranean region with conventional practices register soil erosion values much higher than soil formation... 相似文献
18.
A study was conducted of the Mediterranean Red soils of a region in Central Western Spain with a goal of describing the relationship between their main characteristics and the age of the geomorphic surfaces over which they have developed. The main macromorphological characteristics of the soils were analyzed, with a statistical study of the analytical data on 70 samples of Mediterranean Red soils. The oldest surfaces contain Palexerults and Ultic Palexeralfs, Calcic Rhodoxeralfs, Calcic-vertic Palexeralfs, Typic Rhodoxeralfs, Typic Palexeralfs, Vertic Haploxeralfs and Typic Haploxeralfs have been observed in a chronosequence on terraces of the River Tormes. The soil typology changes with the age of the surfaces, from soils with a sharp textural contrast at the upper limit of the argillaceous horizon, with a dark red very clayey and very thick Bt horizon (on the oldest surface) to not very thick brown soils without a clear clay illuviation and with a lower content in clay (on the youngest surface).The effect of recent erosion on the morphology of the soils located on a single surface has caused new soils to form superimposed on pre-existing soils. 相似文献
19.
L. Negral S. Moreno-Grau J. Moreno X. Querol M. M. Viana A. Alastuey 《Water, air, and soil pollution》2008,192(1-4):227-238
Source apportionment analysis was used to identify the factors contributing to atmospheric pollution at a monitoring location in the Southeast of Spain, a well documented area with an arid climate and high insolation favouring two sources of particulate matter: secondary transformation in the atmosphere and resuspension of crustal dry soils to the air. These conditions are further complicated by numerous industrial facilities in the area of the historical city of Cartagena. This paper describes the air quality of an area which includes a zinc metallurgical industry, a petrochemical factory, an oil power station, a shipyard and natural phenomena including African dust transport and resuspension of regional and/or local crustal materials. Major and trace element concentrations in PM10 and PM2.5 were determined at two monitoring stations in Cartagena (one PM10 sampler located at a traffic hotspot and the PM2.5 sampler at a suburban station), during 2004 and 2005. Results showed that in the PM10 fraction, the zinc metallurgical activity was linked to high levels of Cd, Zn and Pb; shipyard emission was associated with high levels of Cr and Ni; and high Ni and V levels were associated with the secondary aerosol indicating the contribution from oil combustion (oil-fired power station or petrochemical facilities). In the PM2.5 size fraction, the zinc source is defined by Zn and Pb; V, Ni and As appear with the oil combustion emissions. In contrast to PM10, shipyard activity is not consistently defined. Consistent sources found in both size fractions include crustal materials and traffic emissions. 相似文献