冻融对土壤分离能力及侵蚀阻力的影响

冻融后坡面为水力侵蚀产沙提供了大量有效物质源,是河道泥沙的主要策源地。该研究利用室内模拟冻融和径流冲刷试验,设置不同冻融循环次数、坡度和流量梯度,分析冻融对土壤分离能力及侵蚀阻力的影响机制。结果表明,冻融条件下,坡度、流量和冻融循环次数均对土壤分离能力有显著影响(P0.05),贡献率分别为17.94%、19.96%和18.43%。冻融前后,土壤分离能力基本均随坡度和流量的增加而增大,冻融后的均值(5.28±2.48g/(cm~2·min))显著大于冻融前(2.39±1.71 g/(cm~2·min)),但冻融后的增幅明显小于冻融前。不同坡度和流量条件下,冻融1次后,土壤分离能力均显著增大(P0.05),但其随冻融循环次数增加的变化趋势差异较大,只有在坡度与流量同时较小(10°和≤18L/min)或较大(15°和≥18L/min)时,呈显著增大趋势。冻融循环1、5、10次后,土壤细沟可蚀性分别增大1.25、1.66和1.72倍,随冻融次数的增加逐渐趋于稳定;土壤临界剪切力冻融后显著降低,与冻融次数无明显关系。冻融后土壤平均容重、水稳性团聚体和抗剪强度分别降低了6.61%、24.77%和21.35%,土壤孔隙度和三相结构指数变化与之相反。冻融条件下,土壤细沟可蚀性与水稳性团聚体和抗剪强度呈显著负相关关系,而与孔隙度呈显著正相关关系。     

添加秸秆对不同有机含量土壤酸度及缓冲性能的影响

通过向低（LSOM）、中（MSOM）、高（HSOM）及去除（RSOM）有机质土壤中添加玉米秸秆进行室内培养试验,研究秸秆添加量对不同有机质含量土壤酸度及缓冲性能的影响。结果表明,在15℃恒温培养150天后,土壤pH、交换性盐基离子、CEC和盐基饱和度的含量均随着秸秆添加量的增加而上升,交换性H⁺、交换性Al³⁺含量均随着秸秆添加量的增加而降低;其中,秸秆添加量为10~15 g/kg时,LSOM处理中土壤pH增幅、交换性Al³⁺及交换性H⁺含量减幅最大;秸秆添加量为15~20 g/kg时,在MSOM和HSOM处理中土壤pH增幅及土壤交换性Al³⁺、交换性H⁺含量减幅最大;且HSOM处理添加秸秆后对降低土壤酸度效果最好。土壤中添加秸秆后可明显提高土壤酸碱缓冲能力,且土壤对加碱侧表现出的缓冲区间比酸侧明显;土壤的缓冲容量随秸秆添加量增加而升高,且HSOM处理对酸碱缓冲能力 > MSOM处理 > LSOM处理 > RSOM处理。     

多层二次风配风对玉米秸秆颗粒燃烧降低NOx产率及结渣的影响

秸秆类生物质具有碱金属及灰分含量高的特性,燃烧时灰分容易团聚结块而影响燃烧室内的配风及燃料的燃烧。本文设计了一种具有多层二次风配风的生物质燃烧试验装置,以玉米秸秆颗粒为燃料,研究了不同一二次风分级配比、多层二次风配比对烟气中CO、NOx等污染物浓度、燃烧效率及灰分结渣率的影响规律。结果表明：当采用一二次风分级配风时,能够显著降低烟气中NOx的浓度,烟气中CO和NOx的浓度变化趋势相反,呈现一种竞争关系。二次风位置较高或下层二次风量的减少,都易导致玉米秸秆颗粒燃烧不完全,CO浓度显著提升。与对照组相比,二次风多层配风下,燃烧室内各测点的温度和烟气中NOx浓度均有所降低,最低NOx浓度排放放生在W1工况（空气系数为1.2,一、二次风配比为60%：40%时,下、中、上二次风按（1/2,0,1/2））,约150 mg/m3。当采用二次风多层配风时,结渣率大幅度下降,最低为4.5%。W1工况的NOx浓度和结渣率均较低,综合评价为最优工况。常用的硅比指数G、碱酸比、Na含量指数、碱性指数Alc等4种结渣指数,均不能正确预测因燃料燃烧区温度T1变化而造成的结渣倾向变化,为此在硅比指数G中引入燃料燃烧区温度T1作为变量,修正后的硅比指数Gt可以很好地对玉米秸秆颗粒因燃料燃烧区温度T1引起的结渣倾向变化进行预测。     

Characterizing Spatial Variability of Soil Textural Fractions and Fractal Parameters Derived from Particle Size Distributions

Soil particle size distribution (PSD) is a fundamental physical property affecting other soil properties. Characterizing spatial variability of soil texture is very important in environmental research. The objectives of this work were: 1) to partition PSD of 75 soil samples, collected from a flat field in the University of Guilan, Iran, into two scaling domains using a piecewise fractal model to evaluate the relationships between fractal dimensions of scaling domains and soil clay, silt, and sand fractions and 2) to assess the potential of fractal parameters as an index used in a geostatistical approach reflecting the spatial variability of soil texture. Features of PSD of soil samples were studied using fractal geometry, and geostatistical techniques were used to characterize the spatial variability of fractal and soil textural parameters. There were two scaling domains for the PSD of soil samples. The fractal dimensions of these two scaling domains (D₁ and D₂) were then used to characterize different ranges of soil particle sizes and their relationships to the soil textural parameters. There was a positive correlation between D₁ and clay content (R² = 0.924), a negative correlation between D₁ and silt content (R² = 0.801), and a negative correlation between D₂ and sand content (R² = 0.913). The geometric mean diameter of soil particles had a negative correlation with D₁ (R² = 0.569) and D₂ (R² = 0.682). Semivariograms of fractal dimensions and soil textural parameters were calculated and the maps of spatial variation of D₁ and D₂ and soil PSD parameters were provided using ordinary kriging. The results showed that there were also spatial correlations between D₁ and D₂ and particle size fractions. According to the semivariogram models and validation parameters, the fractal parameters had powerful spatial structure and could better describe the spatial variability of soil texture.     

骆马湖滨岸缓冲带土壤性质的空间异质性分析

通过野外调查、采样以及地统计学的方法,研究了骆马湖东南岸有草和无草两块滨岸缓冲区土壤的氮、磷、有机质含量的异质性特征,探讨植物带对污染物的富集、截留作用.结果表明:有草区土壤的TN、TP及有机质的平均含量均大于无草区;在骆马湖滨岸缓冲带,不同的植物群落对氮、磷元素的截留、富集效率差异不大;植物群落对有机质的截留作用不明显,有草区和无草区的有机质含量的性质较为接近.滨岸缓冲带植物能够通过吸收、截留、吸附、分解等作用减少湖泊水体中的碳、氮、磷的含量.研究结果可为骆马湖非点源的治理提供理论参考,为湖泊滨岸缓冲带的研究和构建提供借鉴.     

玉米秸秆与污泥的腐解物对盐碱地化学指标的影响

为探索发酵后的玉米秸秆对内蒙古地区盐碱化土壤化学性质(有机质、ESP,pH值、EC、土壤代换性Na~+)的影响,在实验室条件下以污泥作为接种物,将玉米秸秆在不同发酵的条件下以不同梯度的秸秆还田量施加到盐碱化土壤中,以施加未发酵的玉米秸秆为对照。结果显示:(1)施加玉米秸秆对土壤的部分化学性质有着一定的改善,且发酵后的玉米秸秆比未发酵的玉米秸秆效果要好;(2)当玉米秸秆与污泥的配比为2∶1且秸秆还田量为75%时,土壤的有机质含量上升幅度最大,土壤的ESP、pH值、土壤代换性Na~+降低幅度最大;(3)施加玉米秸秆对土壤的EC作用不明显,反而使EC的含量有所上升,施用发酵后的玉米秸秆尤为明显。综合考虑,在本试验条件下针对该土壤最佳参数为:玉米秸秆与污泥配比为2∶1,发酵后的玉米秸秆还田量为75%。     

不同母质发育土壤的中红外吸收光谱特征

选取湘东丘陵区四种典型母质发育土壤(酸性紫色土、花岗岩红壤、板岩红壤和第四纪红土红壤),采集剖面(深至母岩/母质层)样品,应用傅里叶变换红外光谱仪研究灼烧去除有机质处理、土层深度和母质类型对土壤中红外吸收光谱特征的影响,分析吸收光谱与土壤理化性质的关系。结果表明,去除有机质后,特征区的中红外吸收值升高,反映矿物质对红外吸收谱线的强烈影响。在剖面上,底土(60~80 cm或100~120 cm)的中红外吸收值高于表土(0~20 cm),与土壤有机质含量的剖面分布相反。四种土壤的中红外光谱均属典型的高岭石图谱。砂粒、粘粒含量与红外吸收值的相关性最好,砂粒含量的最大相关系数(0.51)出现在3700、913和720~540 cm~(-1)附近,粘粒含量的最大相关系数(0.54)出现在1100~694 cm~(-1);本研究表明,原土的中红外吸收光谱特征主要受矿物质的支配,可以很好地反映土壤质地的状况,指示土壤质量变化。     

土层置换对草甸土理化性状及作物产量的影响

研究旨在探讨土层置换对土壤物理性质和化学性质的变化及对作物产量的影响,这对作物高产具有重要意义。试验地点选在黑龙江省宝清县草甸土上,以玉米绥玉7、马铃薯克新13和甜菜德国KWS3418为材料,设置土层置换和浅翻深松2个处理,分析不同处理对土壤含水率、硬度、土壤三相、速效养分及产量的影响。结果表明:与浅翻深松处理相比,土层置换处理后2年内,明显改善土壤物理性质,0~40 cm土层土壤含水率分别提高3.7%和3.0%;土壤硬度分别下降17.6%和21.6%。20~40 cm土壤固相分别降低0.3%和0.7%;液相分别提高3.7%和1.1%;气相分别提高2.0%和4.2%。进而容重降低,提高土壤通透性。土层置换处理改善20~40 cm土层土壤化学性质,提高土壤速效养分。20~40 cm土层平均养分变化为:碱解氮分别提高48.4%和46.0%;速效钾分别提高12.9%和38.9%;速效磷分别提高11.9%和15.6%。土壤不同层次物理和化学性质的改变能够提高作物产量,与浅翻深松处理相比,2011年、2012年玉米分别增产31.6%、17.9%,马铃薯分别增产70.5%、25.0%,甜菜分别增产12.4%和38.9%,差异达到显著水平。综合以上分析表明,土层置换处理后土壤2个作物生育期内能够改善心土层土壤物理性状、化学性状,从而提高作物产量。因此土层置换技术可为低产土壤改良及作物高产提供理论依据和技术支持。     

不同含水率高易溶盐含量的伊犁黄土流变特性

流变学研究方法可以揭示黏弹性物质的流动和变形规律,常被应用于土体结构的力学稳定性及长期变形参数研究。为了深入探究伊犁黄土类土的黏弹性和结构稳定性,该研究采用流变仪对不同含水率和易溶盐(Na₂SO₄)含量的伊犁黄土类土进行了稳态和动态流变试验,引入Bingham模型对小剪切速率下的流变曲线进行了拟合,并分析解释了稳态和动态流变试验的演化过程。同时,讨论了含水率及易溶盐含量对稳态和动态流变参数的影响规律,定量分析了流变参数与各变量之间的关系。结果表明：稳态剪切过程中土体由固态向类固态转化,并最后趋于流态,具有剪切变稀行为;随着含水率及易溶盐含量增大,屈服应力和黏度均减小,且屈服应力在300～1 100 Pa之间。随着含水率和易溶盐含量增大,动剪切强度参数和黏弹性参数均线性减小,土体的结构稳定性降低。当剪切应变小于0.1%时,土体处于线性黏弹区,损耗因子变化不大;剪切应变大于0.1%时,损耗因子逐渐增大。高含水率及高易溶盐含量的土壤最先到达屈服点,说明高含水率和高易溶盐含量不利于土体结构的稳定性。随着含水率的增大,易溶盐含量对流变参数的影响程度变小...     

协助自然修复微量元素污染酸性土壤研究：8年田间试验

There are many remediation techniques for organic contaminated soils,but relatively few of them are applicable to trace elementcontaminated soils.A field experiment was carried out to investigate assisted natural remediation（ANR） of an acid soil contaminated by As,Cd,Cu,Zn and Pb using one inorganic amendment,sugar beet lime（SL）,and two organic amendments,biosolid compost（BC）and leonardeite（LE）.The experiment was arranged in a completely randomized block design with four treatments in three replicates:1) a non-amended control（NA）;2) SL amended at 30 Mg ha^-1 year^-1;3) BC amended at 30 Mg ha^-1 year^-1 and 4) LE amended at 20 Mg ha^-1 year^-1 plus SL amended at 10 Mg ha^-1 year^-1（LESL）.The amended plots received two doses of each amendment（DO2）:one in October 2002 and another in October 2003.The plots were then divided in half into two subpolts and one subplot received another two doses of the same amendments（DO4） in October 2005 and October 2006.In 2011,the pH values of the amended soils were greater than that of the NA soil,with the SL-amended soil showing the highest pH.Total organic carbon（TOC） was also greater in the amended soil,and greater with DO4 than with DO2.Amendments reduced the concentrations of 0.01 mol L^-1 CaCl₂-extractable Cd,Cu and Zn,especially in the SL-amended soil.Plant cover of colonizing vegetation was enhanced by amendments,but was independent of amendment doses.Changes in soil properties from 2003 to 2011 showed that the first amendment application of DO2 caused a high differentiation between all the amendment treatments and the NA treatment.After the second application of DO2,soil pH and TOC continued increasing slowly.Further two applications of amendments（DO4） caused differences only in the organic treatments.Plant cover increased over time in all the treatments including NA.It could be concluded that the slow and steady natural remediation of this soil could be enhanced by amendment application（ANR）.