茶叶中多种有机氯与拟除虫菊酯类农药残留的测定方法

农残是衡量茶叶品质的重要指标之一。结合固相萃取和气相色谱技术,开发一种茶叶中多种有机氯与拟除虫菊酯类农药残留的检测方法。结果表明,采用该检测方法对13种农药在所测定的浓度范围内线性关系良好,相关系数大于0.996 7,最低检测限为0.007 mg/kg,加标回收率为84.7%~110.4%。可见,该检测方法能够满足茶叶中多种有机氯类和拟除虫菊酯类农药残留分析的要求。     

树冠喷钙对杨桃果实品质的影响

选用5种常用钙肥对杨桃(Averrhoa carambola)进行树冠喷施,研究喷钙后杨桃果实品质的变化情况。结果表明,5种钙肥均能提高杨桃的可溶性固形物含量和硬度,其中效果较好的是稀土氨基酸钙,该处理果实的可溶性固形物含量比对照提高13.0%,硬度提高19.6%,均达显著差异,但对果实VC、可滴定酸含量的影响不显著。喷钙后杨桃的总酚含量也显著提高,尤其是幼果期喷施能极显著提高杨桃的总酚含量。稀土氨基酸钙喷施时期以在果实生长发育期间每隔15 d喷施一次为佳。     

叶面喷施SOD液肥对小麦生长和产量构成因素的影响

为了进一步研究SOD液肥对小麦生长发育和产量构成因素的影响,试验利用不同浓度SOD液肥在小麦拔节期对其进行叶面喷施试验,稀释浓度分别为100、300、500倍液,以喷施等量清水作对照.结果显示:①喷施SOD液肥能促进小麦光合作用及干物质积累,达到增产效果;②在拔节期叶面喷施3种不同浓度的SOD液肥有不同的肥效,处理2比对照增产19.55％,处理1比对照增产13.13％,处理3比对照增产6.28％.表明叶面喷施SOD液肥是一项简单易行、回报率相对较高的增产措施,在小麦高产高效栽培方面属一项实用技术,有较高的推广应用价值.     

固相萃取-气相色谱法检测烟叶中18种有机氯类杀虫剂残留

[目的]建立固相萃取-气相色谱法检测烟草中18种有机氯类杀虫剂多残留检测分析方法。[方法]烟草样品经正己烷超声提取、Florisil固相萃取柱净化后,用气相色谱电子捕获检测器(ECD)进行有机氯类杀虫剂残留检测。[结果]在0.05～0.50μg/g浓度范围内,18种有机氯类杀虫剂的线性关系良好,回收率在81.82%～101.50%,相对标准偏差为1.95%～4.56%(n=6),检测限均为0.01μg/g。[结论]该方法灵敏、快速、简便,适用于烟叶中有机氯类杀虫剂多残留分析。     

Fenton试剂处理草甘膦废水试验

利用Fenton试剂氧化处理改性粉煤灰吸附后的草甘膦废水。通过试验确定的最佳条件pH为3,H2O2(30%)与FeSO4.7H2O的投加量分别为1.0 mL、0.25 g,反应时间为30 min,反应温度为60℃。最佳条件下草甘膦废水的CODCr去除率为91.98%。     

烯效唑浸种和秧苗喷施效果试验

进行5%烯效唑20 mg/kg、30 mg/kg、40 mg/kg、50 mg/kg浸种和喷施秧苗试验,研究烯效唑对水稻生长的影响,结果表明:5%烯效唑20 mg/kg、30 mg/kg、40 mg/kg、50 mg/kg浸种与对照药剂对比,发芽率提高0.4%～8.1%、出苗率提高2.7%～5.7%;烯效唑浸种和秧苗喷施处理后,水稻植株矮化,基茎宽、叶片宽、单株白根数增加,分蘖提早2～4 d,多蘖,田间有效穗增加,产量增加,效果优于目前常用的多效唑。生产上推荐使用浓度以30～40 mg/kg为宜。     

Susceptibility of Aphelinus certus to foliar‐applied insecticides currently or potentially registered for soybean aphid control

BACKGROUND: Soybean aphid, a serious economic pest of soybean in North America, is currently managed by applying non‐selective foliar insecticides during outbreaks according to decision thresholds and crop maturity. Natural enemies, such as the parasitoid Aphelinus certus Yasnosh, potentially play an important role in suppressing soybean aphid. Using selective insecticides that preserve A. certus may enhance the biological control service they provide and thus prevent or reduce the severity of soybean aphid outbreaks. The toxicity of five insecticides (λ‐cyhalothrin, dimethoate, flonicamid, mineral oil, spirotetramat) and the biopesticide Beauveria bassiana to A. certus was assessed. RESULTS: The LD₅₀ values of λ‐cyhalothrin and dimethoate were similar; however, the hazard quotient of dimethoate was greater than that of λ‐cyhalothrin. In a screening bioassay, the descending order of toxicity for the recommended rates 48 h after application was dimethoate > λ‐cyhalothrin > flonicamid > mineral oil > Beauveria bassiana > spirotetramat. CONCLUSIONS: Overall, λ‐cyhalothrin and dimethoate were both harmful to A. certus. The other insecticides tested were harmless to A. certus and are potential candidates for inclusion in soybean aphid management programs. Copyright © 2011 Society of Chemical Industry     

牛奶质量安全主要风险因子分析Ⅴ.激素类药物残留

牛奶中激素类药物残留对人体健康危害较大,各国家及国际组织制定了相关的标准和法规。作者对主要国家和国际组织牛奶中激素类药物残留的限量及禁用标准作了比较和分析,并对其所制定的检测方法和风险监测模式作了综述。     

Allocation of feed based on individual dairy cow live weight changes: II: Effect on milk production

Based on individual cow live weight gain, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems, and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH), and 93 Danish Jersey (DJ). The objective of the present paper was to examine the milk yield obtained in response to three feeding strategies. The interrelationship between feed intake and live weight changes is presented in a companion paper.Cows were stalled in a loose-housing system based on automatic milking, automatic recording of feed intake and automatic weighing of the cows. All cows had 3 kg of individually separately offered concentrate (ISC) in addition to a mixed ration (MR). Cows were either allowed a medium energy MR during whole lactation (strategy MR1) or a high energy MR during early lactation, which was reduced to a low energy MR either early or late (strategy MR2-E and MR2-L). The early and late changes were defined as a live weight gain after live weight minimum at 15 and 35 kg, respectively, for DR/DH and 11 and 25 kg, respectively, for DJ. When MR energy concentration was changed, cows on the MR2 strategies were offered 3 kg per day of extra concentrate. The total allowance of 6 kg ISC was stepwise reduced to 3 kg per day as live weight continued to increase until 50 and 35 kg for DR/DH and DJ, respectively.Compared to feeding the MR1 strategy, the analysis showed that feeding the MR2 strategies did not significantly affect milk yield within primiparous DR and DH or within any DJ, as total lactation feed energy intake within these groups of cows was not significantly affected by the feeding strategy. Results obtained for multiparous DH showed that it is possible to increase milk yield without reducing the milk:feed ratio, when MR2 strategies were applied compared to the MR1 strategy. Feeding high energy rations during early lactation caused a higher peak feed energy intake within multiparous cows of DH and DR, but only multiparous DH obtained higher peak ECM yield in response to higher feed energy intake in early lactation. Across breed the results suggested that cows offered the MR2-E strategy might obtain higher lactation ECM yield compared to cows offered the MR2-L strategy due to a higher ECM yield persistency obtained by cows offered the MR2-E strategy. Results on feed intake and live weight changes presented in a companion paper indicated, that cows offered the MR2 strategies obtained a lower extent of mobilization compared to cows offered the MR1 strategy, and feeding the MR2-E strategy significantly increased duration of the mobilization period, which might have increased MR2-E cows' ability to maintain a high milk production during mid lactation.     

放射性农药标记化合物的合成研究进展

放射性核素示踪技术在农药代谢降解、作用机理与环境行为等研究中得到了广泛应用。而利用放射性同位素标记示踪法研究农药的关键在于如何获得合适的农药标记化合物。放射性同位素农药标记化合物通常很难从国内外市场中直接获得,尤其是新的、结构较复杂的且合成路线较长的农药标记化合物。放射性农药标记化合物的合成对合成产率要求较常规有机合成高,合成路线也往往不同于非放射性农药合成。本文对放射性同位素标记农药的合成中如何选择放射性核素及正确的标记位置、主要的合成方法、合成过程中需要注意的问题等进行了综述。