高氯酸盐和铬复合污染对土壤酶活性及微生物数量的影响

通过室内模拟控制试验,研究了高氯酸盐和铬单一及复合污染在不同时间对农田土壤酶活性和微生物数量的影响。结果发现:在处理前期,随着高氯酸盐、铬及其复合污染浓度的增加,土壤多酚氧化酶活性显著增加;单一高氯酸盐处理对土壤过氧化氢酶活性无显著性影响,中、高浓度的六价铬单一处理及其复合处理显著降低了土壤过氧化氢酶活性;土壤脲酶活性与污染物浓度表现出明显的低促高抑的关系;单一高氯酸盐处理在第2 d显著促进了土壤蔗糖酶活性,单一铬、高氯酸盐与铬复合处理在第8 d对土壤蔗糖酶活性有显著的抑制效应;随着处理时间的延长,四种土壤酶活性逐渐恢复,到第30 d基本都趋于对照组水平。在整个试验过程中,高氯酸盐与铬的单一及其复合处理显著降低了土壤中真菌的数量。高浓度处理组在实验前期显著降低了土壤中放线菌和细菌的数量,但到第30 d时,其数量基本已恢复至对照水平。研究表明,高氯酸盐和铬污染在初期对土壤酶活性以及土壤微生物数量有显著的影响,随着土壤中耐性菌群的富集生长,土壤酶活性会逐渐恢复到正常,其中细菌和放线菌在这两种污染物的修复中起着主要作用。     

原子吸收光谱法测定大白菜中铬含量的不确定度分析

依据《食品中铬的测定(GB/T5009.123-2003)》标准测量大白菜中铬含量,对整个测量过程中不确定度的来源进行了分析,并对不确定度各个分量进行了评定、合成,最后得出合成不确定度。     

几种厨余垃圾施用对盆花吊兰（Chlorophytum comosum）生长的影响

通过盆栽试验研究4种家庭常见厨余垃圾（过期牛奶、沤制茶渣、新鲜茶渣、鸡蛋壳）在盆栽观叶植物（吊兰）的施用效果。结果表明,过期牛奶能促进吊兰叶长生长,使其叶绿素含量提高,并增加了土壤有效养分含量如有效氮、有效磷和速效钾等。茶渣和鸡蛋壳虽能使吊兰叶长生长有一定促进效果,但后期效果不明显。茶渣能使吊兰叶绿素含量下降,建议观叶植物不宜施用茶渣。厨余垃圾当作肥料用于家庭盆栽花卉是一条厨余垃圾循环利用新途径。     

水分、磷肥耦合对小麦各生育期土壤中氮磷养分的影响

通过田间试验,研究了施磷量、施磷深度和不同水分条件对冬小麦不同生育期土壤中氮、磷养分含量的影响。结果表明,在3种处理条件下,土壤中NO3-_N随小麦各生育期对氮素需求量而变化,在返青期和灌浆期,其在土壤中的含量均出现最低谷;土壤中的NH4 _N的含量在孕穗期出现高峰,其他生育期含量变化无明显影响;同样,土壤中有效磷含量在返青期和灌浆期出现低谷,而拔节或孕穗期达到高峰。根据土壤中氮磷养分的动态变化,推荐整个生育期灌水2次,施磷量及施磷深度分别为225 kg/hm2和30 cm。     

Phosphate-rich soils in the European Union: estimating total plant-available phosphorus

The estimation of plant-available phosphorus (P) has become important for farmers and environmental agencies, because it can help them: (i) use existing soil P reserves more efficiently, and (ii) establish criteria for reducing or stopping application of P fertilizers, which can cause water eutrophication. In this study, total plant-available P (TPAP) in 12 P-rich soils from major agricultural areas of the European Union was estimated by successive cropping in pots, and compared to the amount of P extracted by different methods. Plant desorption curves generally conformed to a Temkin equation (P uptake = A+B log(P concentration in soil solution)). P uptake was also linearly related to the change in Olsen P of soil. Of the various laboratory methods used to estimate TPAP, extraction by goethite (viz., a ‘near-infinite’ Fe oxide sink) proved the most efficient, followed by repeated extraction with an anion-exchange resin in chloride form. Isotopically exchangeable P (IEP) was found to be useless for estimating TPAP, particularly in acid soils. However, IEP at 14 days, combined with the P concentration in the soil solution, provided a good estimate for TPAP. In practice, TPAP can also be predicted from Olsen P, provided the varying efficiency of bicarbonate in extracting P from soils in different pH ranges is considered.     

家禽饲用玉米可利用氨基酸营养价值评价

以凯氏定氮法测定“9409”饲用玉米的粗蛋白质为91.9g/kg。用Beckman121型氨基酸分析仪测定其18种氨基酸含量(88.3252g/kg)占粗蛋白质含量的96.11%,13种必需氨基酸含量为4.3731g/kg。以90日龄未取盲肠公鸡测定中的氨基酸真可利用率在84.65%-96.21%。以蛋鸡和肉仔鸡理想蛋白质为模型,计算氨基酸平衡性指数,表明饲用玉米是家禽的良好蛋白源。     

不同抗性小麦品种与蚕豆间作对小麦根际速效养分含量的影响

通过田间试验研究了3个对白粉病抗性不同的小麦品种93-124(低抗)、云麦-47(高抗)和云麦-42(中抗)分别与蚕豆间作对小麦不同生育期根际速效氮、磷、钾养分的影响差异。结果表明,在单作条件下,不同抗性小麦品种间根际速效氮含量和根际速效钾含量在各生育期均无显著差异,根际有效磷含量在分蘖、拔节、抽穗期无显著差异,灌浆期93-124根际有效磷含量显著高于云麦-42。小麦蚕豆间作显著提高了分蘖、拔节和抽穗期小麦根际土壤速效氮、磷、钾含量,降低了成熟期根际速效氮、有效磷含量。在分蘖至抽穗期,与单作相比,93-124、云麦-47和云麦-42的根际碱解氮含量分别提高了23.16%~46.90%、23.74%~31.78%和11.23%~22.44%间作93-124的根际有效磷含量提高了35.26%~59.63%;间作云麦-47根际速效钾提高了10.87%~57.59%。间作提高根际速效氮、磷养分的效应以93-124最高,间作提高根际速效钾的效应以云麦-47最高。小麦蚕豆间作具有显著的产量优势,93-124、云麦-47和云麦-42的LER(土地当量比)分别为1.01,1.20和1.14。     

旱作水稻西瓜间丛枝菌根菌丝桥诱导水稻磷转运蛋白的表达及对磷吸收的影响

采用中间隔网的土培根箱试验,对旱作水稻或/和西瓜接种丛枝菌根真菌(简称AM真菌)幼套球囊霉(Glomus etunicatum Becker&Gerdemann),研究了旱作水稻/西瓜间形成菌丝桥并诱导水稻磷酸盐转运蛋白OsPT11的表达和对磷吸收的影响。结果表明:(1)根箱两侧均未接种AM真菌时,旱作水稻和西瓜根系均不形成菌根,水稻根系的磷酸盐转运蛋白OsPT11也不表达。(2)西瓜侧接种AM真菌时,西瓜与水稻间形成的菌丝桥引起水稻菌根的形成,并诱导水稻根系磷酸盐转运蛋白OsPT11表达。(3)菌丝桥侵染和直接接种侵染对旱作水稻和西瓜形成丛枝菌根能达到相同的效果,旱作水稻和西瓜的菌根侵染率分别为80%以上和70%以上。(4)在旱作水稻/西瓜间作系统中,当接种AM真菌时,水稻和西瓜根际有效磷含量显著高于对照处理,水稻地上部全磷含量降低,而西瓜地上部全磷含量升高。     

动态条件下壳聚糖稳定纳米铁去除水体中Cr（Ⅵ）的研究

以重金属Cr（Ⅵ）为目标污染物,在两种实验条件下（实验柱Ⅰ为模拟污染水样,实验柱Ⅱ为实际污染水样）考察了壳聚糖稳定纳米铁对Cr（Ⅵ）的去除能力。实验柱Ⅰ和实验柱Ⅱ分别在第160PV和127PV时发生了击穿效应。与实验柱Ⅰ相比,实验柱Ⅱ中壳聚糖稳定纳米铁对Cr（VI）的去除能力降低了25％。SEM表征显示,实验柱Ⅱ中壳聚糖稳定纳米铁的表面形成了许多葡萄状晶体,它们的存在导致实验柱Ⅱ中纳米铁的去除能力明显低于实验柱Ⅰ。XPS表征显示,由于Ca和Mg的氢氧化物替代了部分铁氢氧化物,导致实验柱Ⅱ中壳聚糖稳定纳米铁表面Fe原子的相对含量低于实验柱Ⅰ。Cr元素高分辨率XPS能谱分析显示,在实验柱Ⅰ的条件下CKVI）被还原得更充分,而且在两种实验条件下都有部分Cr（VI）被吸附在纳米铁表面最终没有被零价铁所还原。     

Evaluation of P sorption capacity and P extractants for assessing P requirements of maize in Western Nigeria savannah soils.

Abstract

Most of the P extractants developed for soils in temperate countries have not been able to successfully predict P requirements of crops in the tropics. Some workers have, however, suggested the use of sorption capacity at standard equilibrium P concentration to estimate fertilizer P requirements. Phosphorus sorption capacity (psc), determined at 0.2 and 2.0 ug/ml equilibrium P concentrations, were evaluated by greenhouse and field fertilizer experiments on savannah soils of western Nigeria. Correlation coefficients between psc at 0.2 and 2.0 ug/ml P and yield attributes were very low and not statistically significant. The sorption values were also not able to predict P requirement in these soils because psc, and therefore, buffer capacity were low, difficult to measure accurately and did not approximate values required for maximum crop yields.

Field P rates usually exceeded P requirements obtained from psc measurements. However, extractants which were able to indicate P status and availability in the soils correlated significantly with yield. It is suggested, therefore, that soil tests with suitable P extractants in addition to fixation studies which would evaluate P needed to increase soil F to a given level would have to be investigated for meaningful fertilizer recommendations.