Characterizing the Spatial Pattern of Soil Carbon and Nitrogen Pools in the Turkey Lakes Watershed: A Comparison of Regression Techniques

There is considerable spatial heterogeneity in organic carbon (C), total nitrogen (N), and potentially mineralizable nitrogen (PMN) pools in the soils of the Turkey Lakes Watershed. We hypothesized that topography regulates the spatial pattern of these pools through a combination of static factors (slope, aspect and elevation), which influence radiation, temperature andmoisture conditions, and dynamic factors (catenary position,profile and planar curvature), which influence the transport ofmaterials downslope. We used multiple linear regression (MLR)and tree regression (TR) models as exploratory techniques todetermine if there was a topographic basis for the spatialpattern of the C, N and PMN pools. The MLR and TR modelspredicted similar integrated totals (i.e., within 5% of eachother) but dissimilar spatial patterns of the pools. For thecombined litter, fibric and hemic layer, the MLR models explaineda significant portion of the variance (R² = 0.38, 0.23 and0.28 for C, N and PMN, respectively), however, the residuals werelarge and biased (the smallest contents were over-predicted andthe largest contents were under-predicted). The TR models (9-branch), in contrast, explained a greater portion of the variance (R² = 0.75, 0.67 and 0.62 for C, N and PMN, respectively) and the residuals were smaller and unbiased. Based on our sampling strategy, the models suggested that static factors were most important in predicting the spatial pattern of the nutrient pools. However, a nested sampling strategy that included scales where both static (among hillslopes) and dynamic (within hillslope) factors result in a systematic variation in soil nutrient pools may have improvedthe predictive ability of the models.     

Evaluation on abundance or deficiency of avai- lable trace elements in soil of middle area in China and the effect of applying trace element fertilizer

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Modelling the motion of an internal solitary wave over a bottom ridge in a stratified fluid

A series of laboratory experiments has been carried out to investigate the passage of an internal solitary wave of depression over a bottom ridge, in a two-layer fluid system for which the upper and lower layer is linearly-stratified and homogeneous respectively. Density, velocity and vorticity fields induced by the wave propagation over the ridge have been measured simultaneously at three locations, namely upstream, downstream and over the ridge crest, for a wide range of model parameters. Results are presented to show that wave breaking may occur for a sufficiently large wave amplitude and a strong ridge blockage factor, with accompanying mixing and overturning. Density field data are presented (i) to illustrate the overturning and mixing processes that accompany the wave breaking and (ii) to quantify the degree of mixing in terms of the wave and ridge parameters. For weak encounters, good agreement is obtained between the laboratory experimental results (velocity and vorticity fields induced by the wave propagation) and the predictions of a recently-developed fully nonlinear theory. Discrepancies between theory and experiment are discussed for cases in which breaking and mixing occur.     

区域尺度地形因素对奇台绿洲土壤盐渍化空间分布的影响

在对土壤盐分实测分析的基础上,研究新疆天山北坡奇台绿洲盐碱土的分布特征同SRTM数据提取的地形信息的相关性,探讨了区域尺度基于地形因子的土壤盐碱化分异规律. 结果表明:研究区土壤盐化与碱化并存,主要盐分类型为硫酸钠盐和氯化钠盐. 盐分在垂直剖面上呈V型分布,硫酸盐具有明显的表聚性. 在区域尺度上,地形对当前盐碱土分布的空间格局起主要作用,低于680 m高程的缓坡区为积盐区,高于740 m高程的陡坡区为碱化区. 研究区的碱化是典型的脱盐碱化,盐化和碱化的演化趋势表现为明显的逆向特征,即盐分随着海拔高度的降低而增高,pH则随着海拔高度的降低而减少. 地形因素对表层(0～20 cm)和中层(＞20～60 cm)土壤盐分分布格局影响较大,随着深度的增加,相关性下降. 高程与大部分盐分指标呈极显著相关,其对盐渍化程度、各盐分离子空间分布格局的影响作用大于坡度.      

中国夏季夜雨的空间分布特征

夜雨作为降水日变化中的特殊现象,是一种独特的气候资源。论文借助2 046 个经质量控制的自动气象站逐小时降水资料分析中国夏季夜雨空间分布特征,并比较分析不同典型夜雨区和非典型夜雨区的降水日变化特征。结果表明:中国夜雨现象站点多且分布较广。降水峰值时间多出现在下午和后半夜,其中东部多发生在下午,西部多发生在后半夜;夜雨现象最明显的区域是青藏高原、四川盆地、云贵高原,此外在山脉及附近区域也普遍存在,北方和西部最明显;而夜雨现象不明显的区域在长江中下游以南区域;中国大部分地区夜间的降水前半夜少于后半夜,而青藏高原东部、四川盆地大部分地区呈现前半夜多于后半夜。地形对降水日变化的主要影响为双日波特征,降水峰值不仅出现在下午,也出现在后半夜;其次,波动性更大。山区夜雨的成因与独特地形的热力差异引起的山谷风环流有关,而下午的峰值与太阳辐射加热大气引起的热对流有关;高原夜雨与山区不同,可能与夏季对流性的积状云比较多有关。     

Unsustainable urban development for Zonguldak metropolitan area (NW Turkey)

Since Turkey is located on a region that is prone to the risks of natural disasters like earthquake, flooding, and avalanche; a majority of the residential areas are facing these risks at various levels. Before determination of these risks, taking action in order to decrease the vulnerability levels of the residential areas will help keep the damage at the minimum level in case of a disaster. Urban planning decisions which are made in accordance with vulnerability studies aiming to determine natural disaster risks will not only help prevent loss of life but also help decrease negative social and economic effects of disasters. The Zonguldak city has been chosen as a case study area since Zonguldak metropolitan area has endured almost all kinds of threats that a city can face. In this study disaster-producing factors in the area are primarily considered which can be named as topography, destruction of forest lands, geological and karstic structure, mining activities, and misuse of the land, and later risk assessment is conducted with geographic information system (GIS). It has been assessed that more than half of the buildings within the study area were constructed in areas not suitable for housing. It is concluded that there is a need for urgent urban development plan for the city.     

东北典型林区土壤黑碳分布特征及影响因素

以长白山、小兴安岭和大兴安岭三大东北林区为研究对象,研究了各区域森林土壤的黑碳含量和密度等分布特征,并对比林型、地形和火烧强度等研究结果,探讨了上述因素对黑碳分布特征的影响.研究表明,东北森林土壤的黑碳分布在垂直方向上差异显著,表现为表层(A11层)亚表层(A1 2层)(p0.01),3个区域内表层土壤黑碳含量大小表现为:大兴安岭长白山小兴安岭,黑碳密度大小为:长白山大兴安岭小兴安岭.长白山林区不同林型的黑碳含量和密度存在明显差异,杨桦次生林显著高于原始阔叶红松林(p0.01);小兴安岭林区,同一土层不同坡位土壤黑碳含量和密度均表现为:下坡上坡(p0.01),不同坡向均表现为:阳坡阴坡(p0.05);不同火烧强度下大兴安岭森林土壤黑碳含量和密度也有差异:对照轻度火烧中度火烧重度火烧,且对照与中度、重度火烧强度间均差异显著(p0.01).综上可知,林型、坡位和火烧强度是影响东北森林土壤黑碳分布的重要因素,但各林区主控因素不同.     

复杂地形污染物扩散模式比较

对复杂地形污染物扩散模式的国内外的研究成果作了回顾性的展望,在此基础上对各模式的适用性做出比较,最后,对今后有待改进的方面提出了一些意见。     

辽河流域环境要素对水生态的影响

为了分析流域内气候、地形地貌和人类活动对水生态的影响,分别于2009年8月和2010年6月对辽河流域76个采样点的鱼类和底栖动物进行了调查采样。运用统计学的相关分析和典型相关分析,从流域尺度分别建立了气候、地形地貌、土地利用类型与鱼类和底栖动物生物多样性的关联。结果表明,鱼类多样性与年均日照时数、草地用地比例、耕地用地比例、城市用地呈显著负相关,与多年平均降水量、相对湿度和水域的用地比例呈显著正相关;底栖多样性与年均日照时数、林地、草地、耕地用地比例呈显著负相关,与坡度、NDVI、多年平均降水量、相对湿度和水域的用地比例呈显著正相关。典型相关分析表明对水生生生物影响最大的环境要素是多年平均温度、坡度和水域用地。     

内蒙古中西部地区沙尘暴日数分布的地貌特征

以内蒙古中西部地区的地貌格局为背景，探讨了该地区沙尘暴日数分布的地貌特征。通过比较地貌类型、地形剖面线与沙尘暴日数分布的关系，以及统计不同地貌类型区的沙尘暴日数特征，得出的结论为：在内蒙古中西部地区，沙漠边缘及沙地区沙尘暴日数最多，高平原区次之，山地丘陵区较少，平原区最少。