阻抗长廊式调压室围岩稳定与支护结构优化

阻抗长廊式调压室一般规模较大,其作为一种典型的水电站地下建筑物,受地质条件及人工开挖支护方式的影响很大。以黄金坪水电站调压室为例,利用FLAC3D软件对洞室开挖和支护过程中的围岩稳定性进行研究,根据应力和应变的变化情况,提出相应的支护方案并进行模拟分析。结果表明,所提方案合理,可为工程支护设计提供理论依据。     

土壤污染及其防治研究

通过分析和了解污染物进入土壤的途径、土壤污染物的种类、危害及土壤污染防治的特点,提出土壤污染的防治措施与对策。     

土壤高温储热热湿迁移过程的初步研究

初步建立了土壤高温储热热湿迁移过程的数学模型,并进行了数值求解.结果表明,土壤热湿迁移过程中的湿度场稳定时间明显滞后于温度场,且与土壤类型和水力传导特性等有关.对于水力传导性较差的土壤,在高温储热初期,靠近热源的地方容易产生湿份聚集,使得湿度曲线出现一个短期峰值.与低温储热相比,土壤高温储热时湿度迁移对温度场的影响较大,温度场呈整体降低趋势,降低幅度顺序为:砂土>壤土>粘土.在该文模拟条件下,粘土的热湿迁移过程对于初始湿度的变化不敏感,而砂土的热湿迁移过程则依赖于初始湿度,且影响程度随着初始湿度的增加而增大.     

环境因子对土壤水分蒸散的影响

在有作物生长的条件下，土壤散失到大气中的水分主要通过土壤表面蒸发和作物叶面蒸腾两种方式进行，二者之和称为土壤水分蒸散。由于作物冠层的遮荫作用，作物覆盖下土壤水分的蒸发强度与裸土情况下显然不同。本文建立了土壤水分蒸散率的计算公式，并对几个环境因子的影响进行了讨论。计算结果表明，冠层净辐射强度和空气饱和差对蒸散率影响较大，而气温和风速的影响相对较小。当冠层净辐射强度和空气饱和差增大时，蒸散率和日蒸散总量的增加均较为明显。另外，作物的叶面积指数对蒸散也有较大的影响，同时它对蒸发和蒸腾在蒸散中所占的比重影响很大，叶面积指数增大时，叶面蒸腾所占的份额增大，而蒸发所占的份额相应地减小。     

小方坯帘线钢末搅参数的优化研究

以小方坯帘线钢的连铸生产为研究对象,采用ProCast商业软件根据实际生产的工艺参数建立铸坯的凝固传热模型,并利用射钉试验对模型进行校正以提高模型的准确性。结果表明,该凝固传热模型可以模拟帘线钢的连铸生产过程。根据射钉试验和数值模拟结果,对末搅位置进行改进,可发现铸坯中心缩孔等级下降,等轴晶率增大。     

The current and residual value of superphosphate,Christmas Island C-grade ore,and Calciphos as fertilizers for a subterranean clover pasture

The effectiveness in the year of application of three phosphorus fertilizers, superphosphate, Christmas Island C-grade ore, and 500°C calcined Christmas Island C-grade ore (Calciphos), was measured for 5 consecutive years in a field experiment on a lateritic soil. The residual value of the phosphorus fertilizers was also measured for 6 years. Dry matter production of subterranean clover-based pasture and bicarbonate extractable soil phosphorus were used as indicators of fertilizer effectiveness.Despite the use of very large amounts of C-grade ore and Calciphos, the plateau of the pasture yield versus fertilizer applied curve for these fertilizers did not reach the yield plateau achieved with superphosphate in either the short or long term.C-grade ore and Calciphos were 3% and 8% as effective as superphosphate for dry matter production in the year of application. Relative to superphosphate applied in the current year the effectiveness of superphosphate decreased by about 70% between the first and second year after application and decreased by a further 14% from year 3 to year 6. C-grade ore and Calciphos remained about 2% and 9% as effective as currently applied superphosphate each year.The residual value of superphosphate as measured by bicarbonate-extracted soil phosphorus decreased by about 60% from year 2 to year 7. The residual value of Calciphos was very low for year 2, doubled from year 2–4 and thereafter decreased gradually to its original value by year 7. The residual value of C-grade ore was extremely low throughout the experiment. Thus after year 2, compared to pasture yield, bicarbonate extracted soil phosphorus overestimated the residual value of superphosphate and calciphos.It follows that neither C-grade ore or Calciphos are suitable replacement fertilizers for superphosphate for use on pastures growing on lateritic soils in south-western Australia.     

原子吸收法测定土壤中铜的不确定度评定

根据GB/T17138-1997规定的测量步骤对土壤中的铜进行了测定,对影响测定结果的各不确定度来源进行了分析,并对一个样品进行了不确定度评定。     

Nutrient balance of shifting cultivation by burning or mulching in the Eastern Amazon – evidence for subsoil nutrient accumulation

For over a hundred years shifting cultivation with slash-and-burn land preparation has been the predominant type of land use by smallholders in the Bragantina region of the Brazilian Eastern Amazon. This study contrasts the nutrient balance of slash-and-burn agriculture with a fire-free cultivation. Therefore, one half of a 3.5-year-old (28.7 t DM ha^–1) and a 7-year-old woody fallow vegetation (46.5 t DM ha^–1) was burnt and the other half mulched, leaving the biomass as a surface residue. Subsequently, a sequence of maize, beans and cassava was cropped for 1.5 year. Burning the 3.5- and 7-year-old fallow removed 97 and 94% of the C, 98 and 96% of the N, 90 and 63% of the P-stocks, and between 45 and 70% of the cations K, Mg and Ca of the aboveground biomass by volatilization or ash-particle transfer. These losses were avoided with the slash-and-mulch land preparation. Mulching did not increase the losses of nutrients by leaching, despite the high amount of rapidly decomposing surface mulch. Also the length of preceding fallow had no significant influence on leaching losses. At a depth of 3 m, leached nutrients were quantitatively negligible in both treatments. Comparing the nutrient fluxes at soil depths of 0.9 m, 1.8 m and 3 m, the amounts of all mobile nutrients, and also of chloride and sodium were markedly reduced during percolation and must have been retained. It is likely that nutrient retention in the subsoil layer is only temporary, emphasizing the need for a rapid re-establishment of the naturally deep-rooting secondary vegetation after abandonment of sites to enable uptake of these nutrients. The overall nutrient balance was highly negative for slash-and-burn. 291 and 403 kg N ha^–1, 21 and 18 kg P ha^–1, and 70 and 132 kg K ha^–1 were removed from the burnt plots with a preceding fallow of 3.5 and 7 years, respectively. A reduced fallow period (3.5 years), which is a common trend in the region, resulted in a higher mean annual rate of nutrient loss averaged over the duration of the cycle than a fallow period of 7 years. Eliminating the burning losses by mulching brought the agricultural system back to an equilibrated or even slightly positive nutrient balance, even after a reduced fallow period. Thus, slash-and-mulch is a viable alternative to maintain agricultural productivity and ecosystem functioning.     

石油烃污染土壤微生物修复技术研究现状及进展

土壤石油烃污染已引起广泛关注,石油烃具有高毒性和持久性,对生态环境和人体健康会产生严重危害。本文综述了石油烃污染土壤修复技术的国内外研究进展,系统论述了微生物技术在石油烃污染土壤修复中的研究现状,重点探讨了微生物联合修复技术的过程机制和应用前景,包括植物-微生物联合修复、电动-微生物联合修复、表面活性剂强化微生物修复、化学氧化-微生物联合修复及动物-微生物联合修复等,并对未来石油烃污染土壤微生物修复技术的研究发展方向提出了展望。     

过碳酸钠修复石油污染土壤及其环境效应

化学氧化可快速高效修复石油污染土壤,但很少关注研究其对土壤质量的影响以及残留污染物的环境风险。本文以过碳酸钠（SPC）为氧化剂,以柠檬酸（CA）/硫酸亚铁[Fe(Ⅱ)]为催化剂,分析了其对柴油污染土壤的修复效率,分析了柴油中不同组分的降解特征,通过残留初始总石油烃（TPH）有效性和浸提液生物毒性变化提示不同处理的环境风险,通过有机碳和傅里叶变换红外光谱（FTIR）分析修复前后土壤特性变化。结果表明,SPC单独处理效率较低,CA/Fe(Ⅱ)显著提高了TPH去除率。FTIR光谱表明,处理后土壤样品的Si—O—Si、C—H和—OH振动增强。气相色谱-质谱联用（GC/MS）图谱表明,残留TPH组分主要为长链烷烃（C₁₆~C₂₁）。羟丙基-β-环糊精（HPCD）浸提液发光抑制率随着浸提液pH的增加而增加,表明SPC投加量过多产生的强碱性对土壤生物毒性具有显著影响。增加CA投加量对TPH去除率的促进幅度大于SPC和FeSO₄,且有助于降低残留TPH的生物有效性和提升土壤总有机碳（TOC）含量。采用化学氧化修复有机污染土壤应进行环境风险分析并对修复条件进行优化。