陕北无定河流域土壤侵蚀与植被覆盖和降雨关系研究

基于2000—2014年陕北无定河流域日降水、DEM、土壤类型、MODIS NDVI等数据,利用修正通用土壤流失方程(RUSLE)估算了流域土壤侵蚀情况,定量分析了植被覆盖和降雨在土壤侵蚀中的作用,结果表明:(1)无定河流域土壤侵蚀以微度侵蚀为主,平均占流域面积的88.35%,各土壤侵蚀等级面积比例随等级的升高而降低。2000—2014年微度侵蚀面积比例为下降趋势,轻度及以上等级面积比例均为上升趋势。(2)不考虑降雨因子影响时,无定河流域仍以微度侵蚀为主,且为增加趋势,而其他土壤侵蚀等级均为下降趋势。不考虑植被覆盖因子时,流域土壤侵蚀与模型计算结果的变化趋势基本一致。(3)植被覆盖对土壤侵蚀面积比例和变化速率的贡献率分别为13.67%和24.55%,而降雨作用达到86.33%和75.44%,表明降雨是流域土壤侵蚀的主要动力和控制因子,降雨变化主导着流域土壤侵蚀变化过程。     

水工隧洞地震作用计算模型的适用性研究

针对水工隧洞在地震作用下的计算问题,对水工隧洞地震作用计算模型进行了计算对比和适用性研究。分析常用的4种计算模型用于计算水工隧洞地震作用的可行性,通过理论和数值计算确定"径向和切向反力弹簧模型"的计算参数,研究了地震作用下隧洞上方计算土体对隧洞衬砌的作用方式。结合试验验证,该方法和数值计算对比的结果表明:围岩的法向和切向弹性抗力系数受隧洞埋深、围岩类型和衬砌不同部位的影响,随埋深的增加先增大,然后趋于一个定值,围岩条件越好,数值越大,在隧洞两侧部位的数值较大;在地震作用下,隧洞上方计算土体以切向力的方式作用在隧洞衬砌的上半部分,可以通过将隧洞上部计算土体分条后进行计算。该方法可充分考虑地震对隧洞的动力和约束作用,适用于水工隧洞抗震计算。     

土坝溃决跌坎水流水动力特性数值模拟

黏性土坝漫顶溃决涉及多学科交叉,过程极其复杂,尽管国内外大量物理模型试验成果表明其溃决多以“跌坎式”溯源冲蚀为主要特征,然而对该冲蚀发展形式下的水流-坝体微观作用机制尚不清晰。水流作为漫顶溃决的冲刷主动力,对坝体溃决发展起着主导性作用,采用RNG k-ε紊流模型和VOF自由液面捕捉技术针对黏性土坝漫顶溃决代表性水流结构——溃决跌坎水流开展了三维数值模拟研究,对跌坎水流的水流结构、流态、水力特性指标等进行了细致分析,揭示了不同工况下坝体跌坎上的剪切应力、流速分布规律,进而从水动力学的角度对坝面进行受力分析,初步推断了黏性土坝漫顶溃决过程中各级跌坎的主要合并方式为“台阶水平面刷深下切”。研究成果为进一步掌握黏性土坝漫顶溃决发展演变机理提供了理论基础。     

粤北某市"土法炼砷"土壤中化学砷污染的研究

粤北某市“土法炼砷”造成的砷污染,严重破坏了当地生态环境,而且砷还会进入河流或地下水,严重威胁了当地及北江下游的饮用水安全和生态安全。本文对“土法炼砷”遗址现场进行调查取样,并对砷污染的特点进行了分析。     

不同品种磷肥在土壤中的退化研究

对钙镁磷肥（FMP）、过磷酸钙（SSP）和部分酸化磷肥（PAPR）在河南郑州西岗沙土和河南西华县潮土中的退化情况进行了研究。     

Scientific basis for establishing country greenhouse gas estimates for rice-based agriculture: An Indian case study

A comprehensive scientific assessment of CH₄ budget estimation for Indian rice paddies, based on a decade of measurements in India, is presented. Indian paddy cultivation areas contain soils that have low to medium levels of soil organic carbon. The average seasonally integrated CH₄ flux (E _sif) values calculated from these measurements were 15.3 ± 2.6 g m^–2 for continuously flooded (CF), 6.9 ± 4.3 g m^–2 for intermittently flooded (IF) single aeration (SA) and 2.2 ± 1.5 g m^–2 for IF multiple aeration (MA) rice ecosystems. For CF and IF (MA) rice ecosystems having high soil organic carbon, without organic amendments, the CH₄ flux (E _sif) may be increased by 1.7 times relative to low soil organic carbon, whereas it may enhance by 5.3 for CF if amended organically. Organic amendment and high soil organic carbon paddy areas do not alter the methane budget estimates for India (3.6±1.4 TgY^–1) much, due to their small paddy harvested area. Methane estimated using average emission factors (E _sif) for all paddy water regimes, which include harvested areas having soils with high organic carbon and organic amendments, may give a budget of 5 TgY^–1 for India.     

粒径对膨胀土无荷膨胀率的影响研究

为了研究粒径大小对重塑土无荷膨胀率试验结果的影响,在符合现有规范的试验条件下,将某地基泥岩碾碎成1~2 mm、0.1~1 mm、0.1 mm的三种不同粒径,进行不同比例组合搭配的重塑土无荷膨胀率试验。试验结果表明:不同粒径大小的膨胀土样的无荷膨胀率试验结果有很大差异,并且不同粒径组合下的无荷膨胀率试验结果呈正态分布趋势,且峰值处的无荷膨胀率值为该重塑土稳定、可靠的无荷膨胀率值,无荷膨胀率试验结果接近峰值处无荷膨胀率值的粒径级配为该重塑土的最佳级配。经过分析得到使重塑土无荷膨胀率结果稳定、可靠的粒径级配是1~2 mm、0.1~1 mm、0.1 mm的土粒质量比为0∶100∶0,即使重塑土无荷膨胀率试验结果稳定可靠的粒径范围为0.1~1 mm。在该粒径范围内的重塑土无荷膨胀率试验结果最为真实、准确。     

修复土壤,腐植酸能做些什么

我国土壤污染形势严峻,已成为农产品安全和农业可持续发展的一大障碍."十一五"期间已将防治土壤污染列入重要议事日程,"全国土壤污染状况调查和防治项目"业已启动,2006年11月<农产品质量安全法>也开始实施.腐植酸学术界及行业又面临新的机遇和挑战.介绍了我国土壤污染的现状及其治理技术,阐述了腐植酸类物质(HS)修复污染土壤的研究进展、存在问题及应用的可行性,并对今后的研究开发及应用方向提出若干建议.     

Reactive rock phosphate fertilizers and soil testing for phosphorus: The effect of particle size of the rock phosphate

North Carolina rock phosphate (NCRP) (highly carbonate—substituted apatite) was ground to produce three samples with different particle size distributions. The effectiveness of these fertilizers was compared with the effectiveness of superphosphate in a field experiment and three glasshouse experiments using lateritic soils from south-western Australia. Non-reactive Queensland rock phosphate (low carbonate-substituted apatite from the Duchess deposit) was also used in the pot experiments. Bicarbonate-soluble phosphorus extracted from the soil is widely used in Western Australia to predict plant yields from previously-applied fertilizer dressings. For both field and pot experiments bicarbonate-extractable phosphorus (soil test value) was measured and related to subsequent plant yields.As calculated from the initial slope of the relationship between yield and the level of P applied, finely powdered NCRP was about 5–32% as effective as freshly-applied superphosphate in the year of application and also for two years after application in the field experiment, and for two successive crops in the three pot experiments. For both field and pot experiments, finely powdered NCRP, was at best, 1.5–2.0 times as effective as granular NCRP. Relative to freshly-applied superphosphate, the effectiveness of rock phosphates usually decreased with increasing level of application.For each of the crops in the field experiment, the relationships between yield and phosphorus content of plants (i.e. internal efficiency curves) were similar for all fertilizers. Thus the low effectiveness of the rock phosphates relative to superphosphate was solely due to much less phosphorus being taken up by plants. By contrast, in the pot experiments internal efficiency curves differed for different fertilizers. This is attributed to differences in the rate of phosphorus uptake by plant roots during the early stages of plant growth.For both field and pot experiments, soil test calibrations (the relationship between yield and soil test value) differed for rock phosphates and superphosphate. For superphosphate, soil test calibrations also differed for the three different years after the initial application of this fertilizer in the field experiment. For the second crop in the pot experiment, soil test calibrations differed for superphosphate applied at different times (before the first and the second crop). These results point out the difficulty of applying soil testing procedures to soils that have experienced different histories of fertilizer application.     

利谷隆在玉米及土壤中的残留动态

采用高效液相色谱分析技术测定了利谷隆在玉米及土壤中的残留动态和最终残留量。喷施50％利谷隆可湿性粉剂（2812.5g a．i.／hm^2）测出在玉米植株上的残留量较低，施药后14d的残留量仅为0．08mg／kg；土壤中的原始沉积量为7．02mg／kg，半衰期为2．1d，据施药后第14d采样，消解率为72％。利谷隆属于易降解农药。