共查询到20条相似文献，搜索用时 185 毫秒
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石油污染是南海北部近岸海域最严重的污染问题之一．为了掌握该海域海洋鱼类石油污染现状及特点，在近岸6个水域采集了蓝圆鲹(Decopterus mareausi)、金线鱼(Nemipterus virgatus)、斑鰶(Clupanodom punctatus)和花鲆(Tephrinectes sinensis)等4种鱼类样品，采用毛细管气相色谱法分析了鱼类样品的脂肪烃组分(f1)。其正构烷烃相对分子质量分布范围(nC12～nC30)、f1UCN(12．9～35．1mg/kd)、nC16指数(3.27-140)和CPI(0．73～2．61)等特征参数表明，鱼类样品体中的脂肪烃类组丹主要来源于石油烃类，而其某些奇碳数正构烷烃优势组分的出现，表明少量的脂肪烃类组分来自海洋生源烃类。ΣnC14-30/f1UNC(0．0002—0．00231)、nC12／C19:0(0．06～1．90)和nC18／C20:0(0．03～1.93)比值分析表明，鱼类样品体内的石油烃已经经历了一定程度的降解和代解，反映出该海域低浓度持续性石油污染的特点。 相似文献
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为探讨TiO2光催化法处理微污染水中腐殖酸的规律,利用悬浮状的TiO2颗粒在紫外光的照射下催化降解含有腐殖酸污染物的水样,设计正交试验研究pH值、TiO2的投加量、腐殖酸溶液初始浓度、曝气量和温度等对腐殖酸降解效果的影响及规律。结果表明:pH=3.5时,TiO2的投加量为1.0 g/L、曝气量为0.12 m3/h、温度为18℃时,最佳有机物降解效果为96.83%;TiO2光催化法对微污染水中的腐殖酸能够有效降解。 相似文献
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利用2种植物带(芦苇、香蒲与芦苇)对受非点源污染河水进行植物带处理污染物的降解效果模拟试验研究。结果表明,植物带处理污染物的降解效果明显优于无植物带,且以混合植物带效果最好。香蒲与芦苇植物带对COD、TN、TP和NH3-N去除率的周平均值分别为31.62%、37.84%、30.65%和34.31%。植物带能够截留地表径流中的颗粒物,提高水域中的溶解氧含量,对防止水土流失与改善流域水质均有显著作用。 相似文献
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盘锦芦苇湿地土壤微生物初步研究 总被引：7，自引：0，他引：7
基于盘锦湿地生态系统野外观测站芦苇群落生长季的定位观测资料,分析了芦苇湿地土壤微生物不同层次上的比率变化。结果表明:在0—10,10—20 cm和20—30 cm的3个层次上及微生物总数中土壤的细菌所占比率最大,而且在3个层次上的比率自上至下逐渐增大;其次是放线菌,且在3个层次上的比率逐渐减少;最少的是真菌,在3个层次上相差不大接近为零,在整个微生物中所占比率为最少的。这是由于盘锦芦苇湿地的土壤偏盐碱性,有利于细菌和放线菌繁殖,抑制了真菌的繁殖;而且季节性积水导致通气状况不良也抑制了真菌的生存。在盘锦芦苇湿地土壤微生物垂直梯度的比率中,细菌垂直梯度变化比较明显,基本上是下面2个层次所占比率比表层大一些;放线菌垂直梯度变化明显,一般表层比率最大,下面2层比率较小;真菌垂直梯度上所占的比率没有明显变化,接近为零。 相似文献
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利用自行组装的烟气采集装置,研究了TiO2对香烟烟气中多环芳烃(PAHs)光催化降解的效果.运用气质联用仪,对烟气中的多环芳烃进行分析,结果表明TiO2和光对多环芳烃光降解效果随环数变化有不同的变化趋势,TiO2的量是决定低环多环芳烃降解效率的主要因素;紫外辐射强度是决定高环多环芳烃降解效果的主要因素.在弱紫外辐射条件下,TiO2的量由3g增加到6g时,低环多环芳烃降解效率提高38.7%;在固定TiO2为3g时,紫外辐射强度增强1倍使高环多环芳烃降解效率提高87.2%;在强紫外辐射条件下,TiO2的使用会降低低环多环芳烃的光催化降解效率,TiO2分别为3g和6g时,低环多环芳烃降解效率分别下降76.9%和72.4%;在3gTiO2条件下,苯并[a]芘的催化降解效果最好,效率提高83.5%. 相似文献
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黄土高原芨芨草土壤水分特征及水分利用效率研究 总被引：3，自引：0，他引：3
通过对芨芨草草地土壤水分状况及芨芨草水分利用情况进行初步分析，结果表明：芨芨草地土壤贮水量呈明显的季节变化；土壤剖面可依含水量变化分为3层，即速变层、活跃层和稳定层。芨芨草群体水分利用效率以6月份为最高，而单叶水分利用效率7月份最高，具有较强的抗旱性。 相似文献
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在南京市浦口和大厂的五大主要功能区（工业区、交通干线、居民区、蔬菜生产基地和风景区）分别布置采样点,共采集了75个菜地耕层土壤样品,以Cd、Cu、Pb和Zn等典型污染重金属元素的全量数据为基础,运用经典统计分析、综合污染指数和地统计分析相结合的方法对土壤重金属污染进行评价。结果表明,Cd、Cu和Zn分别超出其南京地区土壤背景值的5．42、1．84和1．14倍,Pb未超出。不同功能区菜地土壤的重金属全量水平存在明显差异,其中工业区菜地土壤的重金属污染较为严重。对于Cd和Cu,单因子污染指数大于1的样点数达100％,Zn为52％,Pb为2．67％。研究区内菜地土壤重金属的综合污染指数为4．12,属于中度污染。Cu的空间相关性很弱,Cd、Pb和Zn具有中等的空间结构性;四种重金属的空间相关尺度较为接近。Cd、Cu和Zn的单因子污染指数具有相似的空间分布,总体呈现出南高北低的带状递减趋势,且高峰值具有空间分布的趋同性,而Pb的单因子污染指数分布呈现西北和东南两端高,中间较低的趋势。综合污染指数的空间分布显示,研究区大部分菜地土壤处于中度重金属污染水平,钢铁生产厂周边的斑块状区域重金属污染更加严重。 相似文献
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Allessandro Piccolo Riccardo Spaccini Rolf Nieder Joerg Richter 《Climatic change》2004,67(2-3):329-343
In a long-term (one year) experiment, a sandy Podzol and a silty-loamy Loess soil were treated with labile (polysaccharides, AG) and stable (mature compost, CMP, and two humic acids from compost, HAC, and lignite, HAL) organic matter and the organic carbon (OC) lost by mineralization was periodically evaluated. The stable materials alone induced a significant reduction of OC losses in Podzol CMP <, HAL, <, HAC, Control), whereas the same treatments, except for CMP, produced an OC loss larger than control in Loess. This was attributed to the diverse textural and physical status of the two soils. The added stable organic matter became protected in the Podzol soil within the aggregates formed by the interaction with the coarse inorganic phase, while it was more easily decomposed in the Loess soils due to the strength of the native humic-clay complexes. In both soils, when the stable organic materials were mixed with polysaccharides (AG), the OC losses from this labile fraction were significantly reduced, being CMP more OC sequestering than HAC and HAL, in the order. These results confirmed that labile organic matter in soils can be protected from biodegradation by repartition into the hydrophobic domains of the stable, humified organic matter. This study suggests that mature compost and humic acids may usefully integrate management practices aimed to sequester organic carbon in soils. 相似文献
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S. V. Vasilenkov 《Russian Meteorology and Hydrology》2010,35(6):401-405
Experimental investigations under field and laboratory conditions of 137Cs washout from the periodically frozen and thawed soils were carried out. The experiments demonstrated that the amount of
cesium washed out from the soil after freezing was much larger than from the non-frozen soils and by its intensity it corresponds
to the washout under the influence of intensifiers. This fact allows recommending cheap and technologically simple measures
for the in-snow runoff control to rehabilitate the contaminated lands. 相似文献
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Soil salinization is a common phenomenon that affects both the environment and the socio-economy in arid and semi-arid regions; it is also an important aspect of land cover change. In this study, we integrated multi-sensor remote sensing data with a field survey to analyze processes of soil salinization in a semi-arid area in China from 1979 to 2009. Generally, the area of salt-affected soils increased by 0.28% per year with remarkable acceleration from 1999 to 2009 (0.42% increase per year). In contrast, the area of surface water bodies showed a decreasing trend (-0.08% per year) in the same period. Decreases in precipitation and increases in aridity due to annual (especially summer) warming provided a favorable condition for soil salinization. The relatively flat terrain favored waterlogging at the surface, and continuous drought facilitated upward movement of soil water and accumulation of surface saline and calcium. Meanwhile, land-use practices also played a crucial role in accelerating soil salinization. The conversion to cropland from natural vegetation greatly increased the demand for groundwater irrigation and aggravated the process of soil salinization. Furthermore, there are potential feedbacks of soil salinization to regional climate. The salinization of soils can limit the efficiency of plant water use as well as photosynthesis; therefore, it reduces the amount of carbon sequestrated by terrestrial ecosystem. Soil salinization also reduces the absorbed solar radiation by increasing land surface albedo. Such conversions of land cover significantly change the energy and water balance between land and atmosphere. 相似文献
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In mountain areas, radar observations are often contaminated （1） by echoes from high-speed moving vehicles and （2） by point-wise ground clutter under either normal propagation （NP） or anomalous propagation （AP） conditions. Level Ⅱ data are collected from KMTX （Salt Lake City, Utah） radar to analyze these two types of contamination in the mountain area around the Great Salt Lake. Human experts provide the ＂ground truth＂ for possible contamination of either type on each individual pixel. Common features are then extracted for contaminated pixels of each type. For example, pixels contaminated by echoes from high-speed moving vehicles are characterized by large radial velocity and spectrum width. Echoes from a moving train tend to have larger velocity and reflectivity but smaller spectrum width than those from moving vehicles on highways. These contaminated pixels are only seen in areas of large terrain gradient （in the radial direction along the radar beam）. The same is true for the second type of contamination - pointwise ground clutters. Six quality control （QC） parameters are selected to quantify the extracted features. Histograms are computed for each QC parameter and grouped for contaminated pixels of each type and also for non-contaminated pixels. Based on the computed histograms, a fuzzy logical algorithm is developed for automated detection of contaminated pixels. The algorithm is tested with KMTX radar data under different （clear and rainy） weather conditions. 相似文献
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Olivier Daillant David Boilley Martin Gerzabek Justin Porstendörfer Roland Tesch 《Journal of Atmospheric Chemistry》2004,49(1-3):329-341
Lichens are now well known for their potential as bio-indicators of environmental pollution, but less is known about their suitability as quantitative biomonitors for atmospheric emissions of tritium (mainly as tritiated water, HTO) and radiocarbon (as 14CO2) from nuclear facilities, although both radionuclides could result in non-trivial individual or collective radiation doses due to their high environmental mobility and their long half-lives. 3H and 14C are fixed in lichens mainly by the photosynthesis of the algal partner and then stored in the organic molecules of both alga and fungus. They have the advantage of allowing the monitoring of atmospheric water vapour without interference of soil water or soil organic substances as long as soil-inhabiting species are avoided. Lichens were collected in the surroundings of (military and civil) nuclear facilities, in areas away from any direct source of contamination and some were transplanted from a contaminated area to a non-contaminated one. The influence of the nuclear facilities can be clearly traced, sometimes in a spectacular way and the first results of analyses after transplants give a base for estimating the effective half-life of 3H in lichens. 相似文献
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以矮抗58为研究对象,在冬小麦拔节期设置灌溉与未灌溉两种水分处理,通过对无霜冻年份(2012年)和晚霜冻年份(2013年)的对比试验,分析晚霜冻害对冬小麦群体密度、干物质积累、产量及其构成要素的影响,探讨拔节期灌溉的防霜效果。研究结果表明:1)孕穗-抽穗期发生晚霜冻害可使冬小麦群体密度下降、产量显著降低。2012年的产量整体高于2013年的,且2012年未灌溉处理的产量显著高于2013年灌溉处理的(P0.05);受霜冻影响,2013年灌溉与未灌溉的成熟期密度分别比抽穗期下降11.8%和14.8%,地上部分总干物质重先显著下降而后逐渐恢复,和抽穗期相比其下降幅度分别为18.5%(灌溉)和33.7%(未灌溉)。2013年成熟期叶片干重占地上部分总干物质重比例为43.5%(灌溉)和41.0%(未灌溉),显著高于2012年的16.3%(灌溉)和4.1%(未灌溉)。2)无论是否有霜冻害发生,拔节期灌溉均可显著提高产量,灌溉处理产量分别比未灌溉处理的偏高16.3%(2012年)和24.5%(2013年)。霜冻年份拔节期灌溉处理可显著降低穗粒数损失和抽穗期以后叶面积指数的衰减速度。3)2013年灌溉处理较2012年灌溉处理减产23.6%,未灌溉处理较2012年未灌溉处理减产32.9%。拔节期灌溉能够有效减少霜冻造成的产量损失,但这主要是由水分增加所引起,抽穗期的冬小麦抗霜能力并没有提高。 相似文献
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Potential of Desertification Control to Sequester Carbon and Mitigate the Greenhouse Effect 总被引：16，自引：0，他引：16
R. Lal 《Climatic change》2001,51(1):35-72
There is a strong link between desertification of the drylands and emission of CO2 from soil and vegetation to the atmosphere. Thus, there is a strong need to revisit the desertification process so that its reversal can lead to C sequestration and mitigation of the accelerated greenhouse effect. Drylands of the world occupy 6.31 billion ha (Bha) or 47% ofthe earth's land area distributed among four climates: hyper-arid (1.0 Bha), arid (1.62 Bha), semi-arid (2.37 Bha) and dry sub-humid (1.32 Bha). Principal soils of drylands are Aridisols (1.66 Bha), Entisols (1.92 Bha), Alfisols (0.38 Bha), Vertisols (0.21 Bha) and others (1.27 Bha). Drylands occur in all continents covering 2.01 Bha in Africa, 2.00 Bha in Asia, 0.68Bha in Australia, 1.32 Bha in the Americas and 0.30 Bha in Europe. Desertification, degradation of soil and vegetation in drylands resulting from climatic and anthropogenic factors, affects about 1.137 Bha of soils and an additional 2.576 Bha of rangeland vegetation. The rate of desertification is estimated at 5.8 million hectares (Mha) per year. Desertification is a biophysical process (soil, climate and vegetation) driven by socio-economic and political factors. The principal biophysical processes involved, accelerated soil erosion by water and wind and salinization, reduce soil quality and effective rooting depth, decrease vegetal cover, reduce biomass productivity, and accentuate vagaries of climateespecially low and variable rainfall. Major consequences of desertification include reduction in the total soil C pool and transfer of C from soil to the atmosphere. Total historic loss of C due to desertification may be 19 to 29 Pg. The rate of C emission from drylands due to accelerated soil erosion is estimated at 0.227 to 0.292 Pg C y–1. Therefore, desertification control and restoration of degraded soils and ecosystems would improve soil quality, increase the pool of C in soil and biomass, and induce formation of secondary carbonates leading to a reduction of C emissions to the atmosphere. Desertification control and soil restoration are affected by establishing vegetative cover with appropriate species, improving water use efficiency, using supplemental irrigation including water harvesting, developing a strategy of integrated nutrient management for soil fertility enhancement, and adopting improved farming systems. Adoption of these improved practices also have hidden carbon costs, especially those due to production and application of herbicides and nitrogen fertilizers, pumping irrigation water etc. Restoration of eroded and salt-affected soils is important to C sequestration. Total potential of C sequestration in drylands through adoption of these measures is 0.9 to 1.9Pg C y–1 for a 25- to 50-year period beyond which the rate of sequestration is often too low to be important. In addition to enhancing productivity and food security, C sequestration in soils and ecosystem has numerous ancillary benefits. Therefore, identification and implementation of policies is important to facilitate adoption of recommended practices and for commodification of carbon. 相似文献
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利用土壤水分平衡方程，结合河南省冬小麦和夏玉米的生长规律和1994～2000年冬小麦、夏玉米田实测土壤湿度资料，建立了河南省冬小麦、夏玉米土壤水分预报及优化灌溉的计算机模型。用1998～1999年郑州市麦田实测土壤湿度资料验证该模型模拟结果，未来10、20、30天土壤湿度相对误差分别为-7．3％～7．7％、-8．3％～6．8％、-7．6％～7．7％，表明利用该模型，可以较为准确地预报未来1个月的土壤水分变化，并可根据小麦、玉米不同发育期特点，给出以最高产量和最佳经济效益为目标的灌溉建议。 相似文献