Addition of a monovalent cationic pesticide to improve efficacy of bipyridyl herbicides in Hulah Valley soils

Bipyridyl herbicides are widely used in agriculture and gardening for non-selective weed control. Since they are toxic and relatively expensive, it is ecologically and economically desirable to reduce the amounts applied. A decrease in efficacy of these herbicides is caused by dust accumulated on leaves of weeds. This inactivation arises from the adsorption of the herbicides on dust particles, mainly made of clay minerals, lime and soil organic matter. In order to improve the efficacy and so lower the amounts applied, formulations were developed which include cationic pesticides approved for agricultural use, such as mepiquat or difenzoquat. Such addition restored the efficacy of the bipyridyl herbicides by reducing their binding to dust particles. The proposed formulations, which were tested on a number of different dust-covered plants, allowed the amounts of herbicide applied to be reduced to 50% of the minimum recommended rate. Neither mepiquat or difenzoquat had any herbicidal activity when sprayed alone at the added rates. The results suggest a procedure that may lower the required rates of contact herbicides, reducing costs and toxicity. This procedure, which can be applied immediately, may have broad implications in farming and gardening.     

松脂直接制备210树脂试验研究初报

在试验室条件下,以松脂为原料经熔解、过滤除杂后,直接与苯酚、甲醛进行缩合加成反应,再用甘油酯化,制得210松香改性酚醛树脂.并通过正交试验,选出了较好的工艺条件。     

Selenium adsorption in soils as influenced by different anions

Studies on selenium adsorption were conducted on seleniferous and non‐seleniferous soils of north‐west India. Soils were equilibrated with graded levels of Se ranging from 1 to 100 μg ml^—1 tagged with ⁷⁵Se in the presence of sulphate, nitrate and phosphate ions, generally being applied to soils as inorganic fertilizers. The adsorption of Se on different soils, both in the presence and absence of competing anions, increased with increase in the level of Se added. Adsorption of Se conformed to Langmuir equation. In the absence of any competing anions, adsorption maxima of Se for different soils ranged from 270 to 461 μg g^—1. The corresponding values decreased appreciably in the presence of competing anions; per cent decrease ranged from 3 to 21 at 10 μg SO₄‐S ml^—1, from 8 to 40 at 60 μg NO₃‐N ml^—1 and 32 to 56 at 15 μg H₂PO₄‐P ml^—1. The bonding energy of Se in different soils decreased by 33 to 66 per cent in the presence of only phosphate ions. The changes in bonding energy were inconsistent in the case of nitrate and sulphate ions. At equal concentration of added P and Se, the amount of P adsorbed was 2 to 3 times the amount of Se adsorbed. With increasing concentration of Se, greater amounts of S were released in the equilibrium solution. The distribution coefficients (K_d) decreased significantly in the presence of different anions; the effect was conspicuous in the case of phosphate ions.     

Application of gypsum and lime to increase cation adsorption of a Geric Ferralsol in the Brazilian Amazon region

A Brazil-nut plantation 140 km east of Manaus was the site of a 3-month field trial, in which a by-product gypsum and a lime were compared. The soil properties in the plantation, 23 years after slash-and-burn, are not basically different from the remaining primary forest. The comparison is impeded by a distinct spatial variability of the soil nutrient content within the plantation. A linkage between Effective Cation Exchange Capacity (ECEC) and sulfate content of the soil is presumed. Gypsum-application increases the exchangeable Ca considerably, which is not an effect of Al-exchange, but of newly created adsorption sites. The potential of gypsum to increase the ECEC corresponds on a 1:1 basis with the potential for sulfate adsorption in the soil. Mg and nitrate are strongly leached after gypsum application. The applied, extremely fine ground lime has almost no effects below 5—10 cm depth. Ca, Mg and, to a lesser extent, K exhibit a much enhanced adsorption when applied as sulfate instead of chloride. All three cations are preferentially adsorbed in the subsoil, where the ECEC is only half the value of the upper soil. For fertilization concepts of those soils, the subsoil deserves much greater attention. The infiltration pattern of an organic dye gives evidence of a strong influence of bypass water flow through macropores in the soil.     

低温空气氧化生物炭吸附苯系污染物的作用机制

为进一步明晰低温空气氧化生物炭吸附苯系污染物的作用机制,以竹屑为原料、CaCl₂为活化剂,通过两步活化法制备低温空气氧化生物炭,并综合吸附试验、炭结构表征和密度泛函理论（density functional theory, DFT）计算,解析低温空气氧化生物炭吸附苯酚、苯胺、对苯二酚、对硝基苯酚等4种苯系污染物的过程与行为。结果表明：低温空气氧化生物炭对苯系污染物的吸附性能受生物炭孔隙结构和表面官能团的协同作用影响,生物炭通过微孔结构的孔隙填充作用在空间几何尺度调控苯系污染物的吸附存储过程。低温空气氧化生物炭后,氧原子以羟基、醛基和羧基的形式赋存于生物炭碳骨架表面,从电子尺度影响碳骨架的电子结构排布、改变碳骨架与苯系污染物间的吸附位置及作用类型,通过静电引力及氢键等作用,显著增强生物炭对苯系污染物的吸附能力,其中,羟基和羧基的氢原子作为氢键的供体,醛基的氧原子作为氢键的受体。     

利用数码相机获取水稻氮营养及其长势长相参数的初步研究

提出了通过交换树脂和数码相机来获取土壤肥力及作物长势、长相参数的方法。结果表明,树脂袋解吸出的速效N与土壤中的速效N间有较好的相关性;数码技术采集的作物生长发育信息(叶色指数)与土壤速效氮含量之间也有良好的相关性;结果还表明,水稻产量在一定范围内和生长发育信息成正相关。     

苹果渣高吸水树脂的合成及其溶胀性能研究

以苹果渣为主要材料,以过氧化氢为引发剂,采用微波辐射法制备出了苹果渣高吸水性树脂,研究了该树脂的溶胀性能,并通过FTIR对其官能团进行了表征。试验结果表明:在丙烯酸中和度70%,苹果渣为单体的50%,引发剂与单体的摩尔比为0.075∶1,交联剂为单体的0.5%的制备条件下,苹果渣树脂的吸水倍率最高,可达298 g/g。FTIR结果表明,苹果渣与丙烯酸单体实现了有效的接枝共聚。此外,在对树脂的性能研究中发现,树脂在0.9%氯化钠溶液中的吸水倍率明显低于蒸馏水中的吸水倍率;在温度4～30℃、pH值4～9的环境中树脂均具有较好的吸水效果;粒径越小的树脂溶胀速度越快,即达到饱和的时间越短,不同粒径的苹果渣树脂在蒸馏水中的溶胀均符合二级动力学过程。上述结果将为苹果渣树脂的应用提供有效依据。     

马来海松基环氧纳米复合材料的制备及性能研究

以松香为原料,通过Diels-Alder加成制备了马来海松酸酐(MPA),再经过酯化、闭环反应得到了马来海松基环氧树脂(MPA-ER),并用FT-IR和1 H NMR对MPA和MPA-ER的结构进行了表征.进一步将多壁碳纳米管(MWCNTs)与MPA-ER共混制备了一系列的MPA-ER/MWCNTs复合材料,对其力学性...     

玉米淀粉改性UF树脂胶合高含水率木材工艺研究

用二元酸与玉米淀粉进行酯化反应,制成半酯化玉米淀粉悬浮液,对ＵＦ树脂进行改性、胶合含水率１６％￣１８％的单板生产的胶合板物理力学性能符合ＧＢ９８４６．１￣１２－８８的标准要求,同时使树脂水和性良好。便于清洗涂胶设备。