套种不同牧草的果园土壤对铵的吸附特性研究

以套种不同牧草的果园土壤为研究对象,通过室内等温吸附实验,分析比较了各个处理对氨态氮的吸附特性,并将结果用不同的数学模型拟合进行分析.结果表明:当土壤的氨浓度超过一临界值时,其对氨离子的吸附量会出现明显上升,而在此临界值以下则变化不明显；套种不同牧草可不同程度地提高土壤的铵吸附能力,具体表现为圆叶决明＞百喜草＞平托花生＞宽叶雀稗＞CK(自然生日本草)；各处理土壤铵等温吸附与多项式拟合效果最佳,与Freundlich、Temkin方程拟合达显著水平,Langmuir方程的拟合结果较差.     

花生壳残渣制备活性炭及吸附性能测定

用提取黄酮后废弃的花生壳做原料,选择不同的活化剂在一定温度下制备活性炭,并且测定其吸附性能。结果表明：磷酸作为活化剂时活性炭产率最高,达39.5%;当炭化温度为500℃、活化剂为氢氧化钾或磷酸、活化剂浓度为10%时,碘吸附值最高,为966.7mg/g;当炭化温度为500℃、活化剂浓度为10%时,几种活化剂制备出来的活性炭亚甲基蓝脱色力均达到40mL/g左右;与几种市售活性炭比较,花生壳活性炭碘吸附值能够满足市场需要,但是亚甲基蓝脱色力偏低;相同条件下,盐作为活化剂所制备出的活性炭对镍离子的吸附能力比较稳定。     

活性炭对柴油机尾气吸附机理及其行为研究

柴油车排放尾气严重污染环境并危害人类健康，其净化技术一直是人们研究的热点问题。基于各种活性炭的尘埃吸附性及气体通透性．研究了不同量活性炭在非催化条件下对尾气的吸附机理及行为。试验结果表明：各种活性炭对柴油机尾气排放物吸附作用较为明显：煤质活性炭对于尾气排放物吸附作用要强于椰壳活性炭碳，且对尾气排放降低程度最大、经济性最好用量在400g左右。     

The Magnesium Status of Some Fiji Soils

Abstract

Magnesium (Mg) is an essential macronutrient element for all living organisms, but literature reports of Mg deficiency in agriculture and forestry appear regularly. In many tropical areas, Mg is added to soils by using dolomitic limestone and as minor additions through impurities in some fertilizers. Minimal information is available on the Mg status of Fiji soils, and deficiencies have been observed in some crops. This study investigated the Mg status of a range of Fiji soils and found that major agricultural soils of Fiji contain variable amounts of Mg, both in the total concentrations and in the different forms of the element present. The variations can be related to the soil parent materials, degree of weathering, clay content, and mineralogy. Low plant‐available Mg concentrations are present in many of the highly weathered soils with limited reserves present. Development of intensive agriculture should consider Mg when developing fertilizer programs.     

Long-Term Effect of Fertilizer and Rice Straw on Mineral Composition and Potassium Adsorption in a Reddish Paddy Soil

Increasing K⁺ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K⁺ adsorption because of changes in the chemical and mineralogical properties of a rice (Oryza sativa L.). The aims of this study were (i) to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagram-decomposition method; (ii) to measure K⁺ adsorption isotherms before and after H₂O₂ oxidation of organic matter, and (iii) to investigate whether K⁺ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr long-term fertilization treatments caused little change in soil organic C (SOC) but a large variation in soil mineral composition. The whole-clay fraction (<5 μm) corresponded more to the fertilization treatment than the fine-clay fraction (<1 μm) in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage of illite peak area in the <5 μm soil particles (R=-0.946, P<0.0006). Different fertilization treatments gave significantly different results in K⁺ adsorption. The SOC oxidation test showed positive effects of SOC on K⁺ adsorption at lower K⁺ concentration (?120 mg L^?1) and negative effects at higher K⁺ concentration (240 mg L^?1). The K⁺ adsorption by soil clay minerals after SOC oxidization accounted for 60–158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K⁺ adsorption. The K⁺ adsorption potential was significantly correlated to the amount of poorly crystallized illite present (R=0.879, P=0.012). The availability of adsorbed K⁺ for plant growth needs further study.     

Adsorption-desorption behaviour of flufenacet in five different soils of India

Adsorption-desorption of the herbicide flufenacet (FOE 5043) has been studied in five soils from different locations in India (Delhi, Ranchi, Nagpur, Kerala and Assam) varying in their physicochemical properties. The organic matter (OM) content varied from 0.072 to 0.864%, clay content from 2.5 to 43.7% and pH from 4.45 to 8.35. The adsorption studies were carried out using a batch equilibration technique. Ten grams of soil were equilibrated with 20 ml of aqueous 0.01 M CaCl2 solution containing different concentrations (0-30 mg litre-1) of flufenacet. After equilibration, an aliquot of supernatant was taken out for analysis. During desorption, the amount withdrawn for analysis was replenished with fresh 0.01 M CaCl2 solution and further equilibrated. Desorption studies were carried out with the 30 mg litre-1 concentration of flufenacet only. The adsorption studies revealed that there was moderate to high adsorption of flufenacet considering the comparatively low organic carbon content in the five test soils. Average Kd values ranged from 0.77 to 4.52 and Freundlich KF values from 0.76 to 4.39. The highest adsorption was observed in Kerala soil (OM 0.786%; clay 25%; pH 4.45) followed by Ranchi, Nagpur and Delhi soils, and the lowest in Assam soil (OM 0.553%; clay 2.5%; pH 6.87). The trend in adsorption could be attributed to the chemical nature of flufenacet and the physicochemical properties of the soil such as pH, OM and clay contents. OM and clay contents were positively correlated whereas pH was negatively correlated. Soils having low pH, high OM and high clay contents showed higher adsorption. Desorption studies revealed that there was a hysteresis effect in all the soils. Hysteresis coefficient values (ratio of n(ad) and n(des)) varied from 0.09 to 0.45. The study implies that, because of its moderate to high adsorption, flufenacet is likely to persist in soil for some time. However, the possibility of its movement by leaching or surface run off is less.     

Variation of pesticide sorption isotherm in soil at the catchment scale

The variation of the sorption isotherm of pesticides has seldom been explored at the catchment scale. Such a study was conducted at the scale of a 187-ha agricultural catchment for three herbicides: atrazine, isoproturon and metamitron. Partition coefficient (Kd) values were measured in batch experiments on 51 topsoil samples, and showed moderate variability at the catchment scale (coefficient of variation CV approximately 30%). Values of Kd ranged from 0.47 to 1.70 litre kg(-1) for atrazine, 0.47 to 1.81 for isoproturon, and 0.55 to 2.21 for metamitron. A clustering method was used to reduce the number of samples on which to measure sorption isotherms to 14. Sorption isotherms agreed with the Freundlich rather than the linear model. Kf parameters had CV values similar to those for Kd, with values ranging from 0.78 to 2.13 mg(1 - Nf) litre(Nf) kg(-1) for atrazine, 0.61 to 1.82 for isoproturon, and 0.69 and 2.58 for metamitron. Nf exponents showed little variation (CV < 5%). Nf values were between 0.86 and 0.98 for atrazine, 0.85 and 0.90 for isoproturon, and 0.82 and 0.87 for metamitron. More than 97% of the Kf catchment-scale variations could be explained by the variations of the soil organic carbon content.     

分散、乳化条件及成囊工艺对二甲戊灵微 胶囊形成状态的影响

研究了分散、乳化条件及成囊工艺对以脲醛树脂为壁材采用原位聚合法制备二甲戊灵微胶囊状态的影响。讨论了不同乳化剂及其配比、不同分散乳化时间、搅拌速度、酸化时间和固化温度对微胶囊包封率、粒径大小及分布情况的影响,最终确定以聚丙烯酸钠(PAAS)和苯乙烯-马来酸酐(SMA)按4∶ 1(质量比)混合作乳化剂,1 500 r/min搅拌,分散乳化60 min,酸化90 min,50℃固化90 min作为制备二甲戊灵微胶囊的优化工艺条件。在此条件下可以得到平均粒径10 μm左右、粒度分布均匀的球形微胶囊,包封率在99％以上。     

人工清除流脂防治萧氏松茎象试验研究

研究了人工清除萧氏松茎象寄主流脂对其种群密度的影响,结果表明:该方法对萧氏松茎象的种群密度有明显的影响,试验区的有虫株率平均下降了37.2%,平均相对防治效果达49.1%。防治后试验区和对照区有虫株率差异极显著。     

Improvement of wood properties by composite of diatomite and “phenol-melamine-formaldehyde” co-condensed resin

We improved the overall performance of fast-growing poplar by utilizing a low-cost, effective and simple method. The fast-growing poplar was modified by a vacuum-pressure impregnation method with three...