水工泄水建筑物高性能抗冲磨混凝土试验研究

针对水工泄水建筑物高性能混凝土高抗裂性和高抗冲磨性的要求,通过掺用具有梳型结构的聚羧酸减水剂实现水工泄水建筑物高性能混凝土,同时研究了聚丙烯纤维、粉煤灰和硅粉等因素对混凝土抗冲磨性能的影响。研究表明：聚羧酸减水剂掺量为1.0%,粉煤灰掺量为15%,硅粉掺量为10%,聚丙烯纤维掺量0.9 kg/m3时,混凝土的抗裂性和抗冲磨性能满足水工泄水建筑物高性能混凝土工程的使用要求。     

Foliar residue dynamics of azadirachtins following direct stem injection into white and green ash trees for control of emerald ash borer

BACKGROUND: Azadirachtins are natural insecticides derived from the neem tree. The emerald ash borer (EAB) is an exotic invasive insect pest that infests various ash tree species and has the potential for significant economic, aesthetic and ecological impacts throughout North America. The initial translocation and foliar residue dynamics of azadirachtins were examined following direct injection into white and green ash trees growing in urban scenarios as a potential control for EAB. RESULTS: Substantial concentrations of azadirachtins A and B [mean maxima > 0.98 mg kg^?1 fresh weight (f.w.)] were observed within 2 days of injecting a specifically designed formulation of azadirachtins. Foliar residues declined exponentially through time, with half‐life estimates ranging from 5.1 to 12.3 days. At the time of leaf senescence, foliar residue levels approximated 0.01 mg kg^?1 f.w., strongly mitigating the potential effects of non‐target biota in soil or aquatic compartments. CONCLUSION: The magnitude and duration of exposures observed in this field study were considered to be above the thresholds required for biological effectiveness against both larval and adult life stages of EAB. Results support the use of azadirachtins as an environmentally acceptable systemic insecticide for control of EAB and protection of high‐value ash trees in urban environments. Copyright © 2011 Society of Chemical Industry     

不同产地花椒主要营养成分的比较研究

对主产区花椒主要营养成分的测定结果表明,醇溶抽提物含量较高的有秦安、凤县、汉源、韩城和茂县,分别为276.9、253.8、252.7、250.2和247.1 g/kg;不挥发性乙醚抽提物含量较高的有韩城、芮城、凤县、武都和秦安,分别为131.5、130.2、123.5、122.2和115.5 g/kg;挥发油含量较高的有凤县、芮城、武都、太白和茂县,分别为52.0、48.0、40.0、37.0和37.0 g/kg;蛋白质含量较高的有韩城、芮城、凤县、秦安和汶川,分别为130.6、126.4、122.0、113.2和106.2 g/kg。在矿质元素中,钙含量以茂县、芮城、凤县、秦安、武都的较为丰富,磷以凤县、芮城、秦安、茂县、韩城的较为丰富,铁以茂县、芮城、凤县、陈仓的较高。     

水曲柳实生种群发生的初步研究

用野外生态试验的方法研究水曲柳(Fraxinus mandshurica Rupr.) 种群发生与环境条件的生态关系。通过定量分析,确定影响水曲柳种群天然发生的主要环境因子为林分郁闭度、林地表层土壤水分和林下地被物。林分郁闭度影响种群的发生进程、幼龄个体的生长发育及其与草本植物的种间竞争,水曲柳宜在郁闭度为0.4—0.8的林分内天然发生;表层土壤水分通过影响种子后熟和萌发限制种群的发生数量;林下地被物的存在阻隔了种子与地表的接触,从而影响种群的天然发生数量,清除这些地被物可促进种群的天然发生。     

粉煤灰中有害元素对土壤、粮食影响的初步评价

本文通过大量资料在每公颂施用不超过６０万公斤的粉煤灰改良石灰性粘质土壤时，采用污染指数法，污染起始值对壤与粮食中镉，铬，砷，汞及３．４Ｂ（ａ）Ｐ的含量进行了初步的评价，认为在上述施用量的基础上，不会造成土壤，粮食的污染。通过二年三作模拟储灰一种有害元素ｋｍ值测定进行初步分析表明：个别元素在表层或底层有弱度淋溶或富集，但层次间，年度间变化不大，总的趋势是比较稳定，同上述评价结果一致。     

生物质气化站玉米芯飞灰的特性及其综合利用

作为玉米生产加工过程的农业废弃物,玉米芯的产量巨大,生物质气化工业利用玉米芯原料制备生物质燃气的过程中将产生大量的玉米芯灰。为了全面认识这些废弃玉米芯灰的灰特性及可能的应用,通过激光粒度分析、X射线荧光(X-ray fluorescence,XRF)、X射线衍射(X-ray diffraction,XRD)、热重和差热分析(thermal gravimetric and differential thermal analysis,TG-DTA)、扫描电镜(scanning electron microscopy,SEM)、能谱分析(energy dispersive X-ray,EDX)等方法对其进行深入研究。结果表明:玉米芯灰的粒度较小且分布不均,平均粒径为12.96μm;灰的元素组成中K和Si所占的比重最大;富含K、Ca、S和Cl等元素使玉米芯灰可用作土壤改良剂,而且灰中大量的Si O2和Al2O3使其可以用来制备抗压强度较高的水泥混凝土;灰中存在多种含钾元素的KHCO3、KAl Si O4、KAl Si2O6、KCl和K2SO4等结晶相矿物成分;灰粒的形状极不规则,树枝状的团聚灰渣具有丰富的空隙,易逐级吸附小颗粒,灰粒表面存在大量弱粘结的絮状物,断面多为孔状结构;熔融灰粒表面存在富钾现象,且多以KCl形式存在;飞灰的热解具有分段机制,加热到1 200℃时,其总失重和最大失重速率均随着氧气浓度的升高而增加;氮气中620℃的吸热峰是由KCl熔融吸热所致,而有氧气氛中在630℃处的放热峰则是未燃尽的残碳继续燃烧或有机物分解放热所致。     

Evaluation of fly ash,apatite and rice straw derived-biochar in varying combinations for in situ remediation of soils contaminated with multiple heavy metals

ABSTRACT

In

-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.     

Mineralization and volatile loss of nitrogen from soils treated with coal combustion byproducts

There is an increasing need to find a suitable means for disposal of coal combustion byproducts because of the increasing world-wide production of these byproducts. This need has prompted interest in the use of land disposal, but there are concerns that this use may degrade the quality of soil. To determine the influence of coal combustion byproducts on the transformation and fate of soil N and assess the potential impact of land disposal on soil quality, we studied the effects of two combustion byproducts (fly ash and bed ash) applied at rates of 22.5, 45, 90, and 180 Mg ha^-1 on mineralization and volatile loss of N from soil. Studies comparing the influence of the byproducts on these processes showed that whereas fly ash had little influence on the fate of soil N, bed ash caused substantial mineralization of organic soil N and volatile loss of this N as NH₃. Studies monitoring the pH of soils treated with bed ash showed that soil pH increased immediately after this treatment, with values reaching as high as 12.8. These studies indicated that such extreme alkaline conditions caused chemical degradation and volatile loss of as much as 10% of the organic N in soil, and they provide strong evidence that the improper disposal of bed ash on land can have a substantial negative impact on soil quality.     

Dry farming with soils under natural tephra cover in Lanzarote, Spain

Abstract. The volcanic island of Lanzarote (Canary Islands, Spain) is one of the most arid parts of the European Union. During the eruptions of 1730–36, a third of the island was covered with lava and pyroclastic material. In areas under basaltic tephra, an agrosystem has been developed that allows a form of dry farming that has become a key component of the local economy. This article illustrates the effectiveness of the layer of natural tephra mulch in conserving soil and water.     

Determination of Plant-Available Nutrients in Two Wood Ashes: The Influence of Combustion Conditions

Wood ashes were traditionally used as a fertilizing agent from the very beginning of working land but the fertilizing quality varies according to the combusted biomass and also the industrial burning equipment. The differences between wood ash originated from fluid and classic boiler were investigated by X-ray powder diffraction (XRD), X-ray fluorescence spectrometry (XRF), differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and Mehlich 3 and deionized water extraction procedures in relation to extraction time. The results, especially of the SEM and chemical extractions, have demonstrated that the type of burning boiler determines the portions of the leachable nutrient elements. The silica and alumina ash content conducted by the elevated temperature transforms the main proportion of calcium and potassium into the insoluble feldspars. Due to this effect only a small amount of nutrients could be released and served as a fertilizing matter.