地形对中国气温季节分布格局的差异影响

利用中国气象中心160台站的长期观测资料,分析发现中圜气温的空间分布格局的存在着巨大的季节差异:在冬季,等温线基本上与纬线平行;在夏季,等温线形成一个个闭合高温或低温中心.同时,这些高温中心都足以负地形地区为中心分布,而低温分布是以正地形地区为中心.可见,我国冬夏季节的气温分布格局是由不同的控制机制决定的:冬季气温分布格局主要由纬度控制,夏季气温分布格局主要南地形控制.     

中国半个世纪以来夏季降水量变化总趋势

全球气候变化已经影响到人类生存环境的方方面面.全球升温及其幅度的区域差异,必然引起降水在区域分布的变化.文章利用160站点的夏季降水资料,分别计算出各个站点1951-2002年的变化斜率,以展示我国各地在这半个世纪中的降水总趋势变化的区域差异.通过分析发现,降水量总的变化趋势存在着随纬度而变化的规律:31°N以北区域近半个世纪降水量总的变化趋势是减少,31°N以南地区降水量以增加为主.40°N以北地区的降水变化幅度相对要小得多.区域上,中国西北和东南存在一个降水增多的趋势.中国降水的区域变化,在季风区受季风强弱变化影响;在非季风区,受西风强弱变化影响.     

牧草植物篱对紫色土坡耕地水土流失及土壤肥力空间分布的影响

植物篱的水土保持效果已得到广泛的认可,并在世界很多地方推广.随着经济植物篱概念的提出,牧草已作为经济植物篱植物得到广泛应用.然而,到日前为止,牧草植物篱对坡耕地土壤肥力的影响规律研究却很少.利用长期定位小区试验,研究了苜蓿(Medicago saliva Linn.)和蓑草(Eulaliopsis lsinata(Retz.)C.E.Hubb.)植物篱对坡耕地土壤肥力的影响规律,旨在弄清牧草植物篱提高土壤肥力的作用与效果,不断完善植物篱技术.研究发现,坡耕地在建立牧草植物篱后,土壤粘粒在篱前富积,篱下加剧侵蚀,粘粒的富积与侵蚀沿等高线成水平带状分布;土壤有机质、N、P等主要营养元素出现与土壤颗粒相同的分布规律;对K来说,其分布不受植物篱的影响.表现出从坡上向坡下逐渐减少的分布特点.从土壤养分的绝对数量来看,P呈高度富积,而有机质和K则足高度耗竭.因此,坡耕地施肥时可以适当减少P的施用量,增加有机物和K的施用量.针对植物篱带对坡耕地肥力影响的特点,即篱前肥力升高,篱下肥力下降,在坡耕地管理上应特别加强篱下土壤带的培肥,以提高坡而整体生产能力.     

Impact of data quality and model complexity on prediction of pesticide leaching

Accurate input data for leaching models are expensive and difficult to obtain which may lead to the use of "general" non-site-specific input data. This study investigated the effect of using different quality data on model outputs. Three models of varying complexity, GLEAMS, LEACHM, and HYDRUS-2D, were used to simulate pesticide leaching at a field trial near Hamilton, New Zealand, on an allophanic silt loam using input data of varying quality. Each model was run for four different pesticides (hexazinone, procymidone, picloram and triclopyr); three different sets of pesticide sorption and degradation parameters (i.e., site optimized, laboratory derived, and sourced from the USDA Pesticide Properties Database); and three different sets of soil physical data of varying quality (i.e., site specific, regional database, and particle size distribution data). We found that the selection of site-optimized pesticide sorption (Koc) and degradation parameters (half-life), compared to the use of more general database derived values, had significantly more impact than the quality of the soil input data used, but interestingly also more impact than the choice of the models. Models run with pesticide sorption and degradation parameters derived from observed solute concentrations data provided simulation outputs with goodness-of-fit values closest to optimum, followed by laboratory-derived parameters, with the USDA parameters providing the least accurate simulations. In general, when using pesticide sorption and degradation parameters optimized from site solute concentrations, the more complex models (LEACHM and HYDRUS-2D) were more accurate. However, when using USDA database derived parameters, all models performed about equally.     

基于区分权的水质综合评价方法

论证"隶属度"作为相似性度量是水质评价的最佳选择,定义指标区分权重,规范隶属函数的拓扑空间结构、代数性质和标准化方法,建立基于区分权的水质评价模型。     

垃圾渗滤液中溶解性有机物对土壤中重金属迁移的影响

垃圾渗滤液主要组分中含有重金属和大量的溶解性有机物(DOM).实验选用北方最具代表性的褐土为供试样品,通过室内土柱淋滤实验研究了垃圾渗滤液溶解性有机物对重金属Cu、Cd、Pb和Zn在土壤中的迁移行为的影响.结果显示,DOM对土壤中Cd、Zn的垂直迁移起着促进作用,而对Cu、Pb迁移起着一定的抑制作用;不同浓度的垃圾淋洗...     

Comparison of initial hydrolysis of the three dimethyl phthalate esters (DMPEs) by a basidiomycetous yeast,Trichosporon DMI-5-1, from coastal sediment

Purpose  

Dimethyl phthalate esters (DMPEs) are a group of plasticizers commonly detected in the environment with potential adverse human health impact. The degradation of DMPEs by fungal systems has been studied to a limited extent, particularly by yeasts. In this study, a basidiomycetous yeast Trichosporon DMI-5-1 capable of degrading DMPEs was obtained and the degradation pathways were investigated.     

Contribution of isoprene to formaldehyde and ozone formation based on its oxidation products measurement in Beijing,China

The atmospheric mixing ratios of methacrolein (MACR) and methyl vinyl ketone (MVK), the two specific products from isoprene oxidation in the atmosphere, were measured in Beijing from March to November, 2006. Distinct amounts of MACR and MVK were detected during vegetable growing seasons from April to October with ambient levels of 0.11–0.67 ppbv and 0.19–1.36 ppbv, respectively. The reacted isoprene and its ozone formation potentials (OFPs) in Beijing were evaluated in the range of 0.49–3.46 ppbv and 6.4–44.7 ppbv, respectively, from April to October. OFP of the reacted isoprene accounted for 10.6–23.6% of the total OFPs of VOCs (including carbonyls and isoprene) and 6.38–29.9% of the photo-chemically produced ozone. The maximum OFP of the original emitted isoprene prior to its photo-oxidation was calculated as 56.0 ppbv in August. The contribution from the reacted isoprene in Beijing to HCHO formation was also estimated to be in the range of 0.35–2.45 ppbv from April to October, which accounted for 4.6–11.5% of ambient HCHO.     

卡鲁塞尔氧化沟流速与水质组分分布的现场测试

通过实测卡鲁塞尔氧化沟不同位置处流速与水质组分,分析了流速对沟内污泥、溶解氧浓度的影响以及溶解性组分的微生物转化规律。结果表明,溶解氧与流速呈正相关、污泥浓度（MLSS）与流速呈负相关;水质组分在沟中不同区段呈现出各自特点,反映了COD、氨和磷酸盐的生物转化历程;流速也是影响溶解性组分混合的重要因素,改善进水口附近混合液的流场,提高局部流速有利于缩短进水组分均布的距离。