用稀悬液Wien效应测量法来研究重金属离子与水稻土的相互作用

Interactions of three heavy metal ions, Cu²⁺, Cd²⁺, and Pb²⁺, and, for comparison, Na⁺ with electrodialytic clay fractions (less than 2 μm in diameter) of four paddy soils as well as a yellow-brown soil as a control soil were evaluated based on measurements of the Wien effect in dilute suspensions with a clay concentration of 10 g kg^?1 in four nitrate solutions of 2 × 10^?4/z mol L^?1, where z is the cation valence, and a nitric acid solution of 3 × 10^?5 mol L^?1. Field strengths ranging from 15 to 230 kV cm^?1 were applied for measuring the electrical conductivities (ECs) of the suspensions. The mean free binding energies between the various cations and all of the soils determined from exchange equilibrium increased in the order: Na⁺ < Cd²⁺ < Cu²⁺ < Pb²⁺. In general, the ECs of the suspensions in the sodium nitrate solution were smaller than those of the suspensions in the heavy metal solutions because of the lower electrophoretic mobility of sodium compared to the divalent cations. In terms of relative electrical conductivity-field strength relationships, relative electrical conductivity (REC) of suspensions containing various cations at field strengths larger than about 50 kV cm^?1 were in the descending order: Na⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺ for all tested soils. A characteristic parameter of the REC-field strength curves, ΔREC₂₀₀, REC at a field strength of 200 kV cm^?1 minus that at the local minimum of the concave segment of the REC-field strength curves, characterized the strength of adsorption of the cations stripped off by the applied strong electrical field, and for all soils the values of ΔREC₂₀₀ were generally in the order: Na⁺ < Cu²⁺ ≤ Cd²⁺ ≤ Pb²⁺.     

影响麦田杂草种类变化的因素分析及其防治对策--以定州市为例

以定州市为例,介绍了麦田杂草的主要种类,明确了长期单一使用麦田除草剂、小麦种子频繁调运、机械跨区作业等原因是影响麦田杂草种类和优劣势变化的主要因素,并针对杂草防治工作中出现的主要问题提出了防治对策。     

露地栽培番茄斑萎病毒病发生流行规律调查及TSWV重要寄主植物监测

为明确云南省昆明市露地栽培条件下番茄斑萎病毒病的发生流行特征,于2014—2015年采用病害系统调查法结合病毒ELISA及RT-PCR检测方法研究露地栽培条件下由番茄斑萎病毒(tomato spotted wilt virus,TSWV)引起的病毒病发生规律及其重要寄主种类,并研究利用防虫网隔离蓟马对番茄斑萎病毒病的防控效果。结果表明:番茄斑萎病毒病在露地番茄主要种植期3—10月普遍发生,番茄苗期和移栽初期是该病毒病防控的关键期,带毒种苗调运是该病毒病的主要传播途径;田间多种茄科和菊科植物是TSWV的重要中间寄主。在田间,菊科寄主植物油麦菜、莴苣、鬼针草、牛膝菊上TSWV的检出率均较高,在42.53%～81.63%之间;茄科寄主植物中辣椒上TSWV的检出率最高,为41.99%,其次为马铃薯,TSWV检出率为27.78%,在番茄上TSWV的检出率为19.02%,因此生产中应对这些TSWV重要中间寄主给予更多关注和防控。应用防虫网能有效隔离蓟马,使番茄斑萎病毒病发病率和病情指数较对照分别降低了6.44个百分点和5.31,可有效降低番茄苗期及定植期斑萎病毒病的发生。     

氟虫腈饵剂防控红火蚁的田间药效试验

以含0.05％氟虫腈为有效成分与多种天然物质配制饵剂,撒于红火蚁(SolenopsisinvatBuren)蚁巢上,药剂中的引诱剂吸引红火蚁取食,将饵剂带入巢内,并通过红火蚁在巢内交哺喂食行为将药剂传递给其它各品级个体,引起全巢红火蚁中毒死亡.结果表明,0.05％氟虫腈杀蚁饵剂对红火蚁具有良好的控制效果,药后15d开始进入防效高峰期,25～30d防效达到最佳.0.05％氟虫腈杀蚁饵剂药后30d对工蚁的防治效果达93.39％～100.00％;灭巢效果达95.84％～100.00％;药后50d,蚁群级别降低率达83.33％～100.00％,显著优于对照药剂.     

五种芽苗菜提取物抗氧化活性的比较

芽苗菜是普遍食用的保健型蔬菜,通过比较5种芽苗菜提取液对超氧阴离子自由基(O2-·)和羟基自由基(·OH)的清除率来研究5种芽苗菜的抗氧化活性。结果表明:5种芽苗菜不同浓度和不同部位取材提取液对超氧阴离子自由基(O2-·)和羟基自由基(·OH)清除率比较结果一致,香椿芽黑豆芽萝卜苗绿豆芽豌豆苗;5种芽苗菜叶对超氧阴离子自由基(O2-·)和羟基自由基(·OH)的清除率高于茎,但不同芽苗菜茎叶对自由基的清除率有差别;5种芽苗菜叶绿素、VC、类黄酮3种活性物质含量不同反映了抗氧化物质和抗氧化机制不同;叶绿素是影响抗氧化活性的因素,但其作用有限。     

施用生物质炭后稻田土壤性质、水稻产量和 痕量温室气体排放的变化

【目的】研究生物质炭对连续两年稻田土壤性质、水稻产量和痕量温室气体排放的影响,为合理施用生物质炭而促进水稻生产可持续的低碳发展提供科学依据。【方法】选择成都平原稻田,2010年布设了施氮与否（0与240 kg N•hm-2）下生物质炭土壤施用（0、20、40 t•hm-2）试验,连续两年观测土壤性质、水稻产量、土壤CH4和N2O排放的变化。【结果】施氮肥条件下,生物质炭连续两年对主要土壤肥力性质表现出改善效应,提高了土壤有机碳、全氮含量和pH,同时降低土壤容重,但对水稻产量影响不显著。生物质炭对CH4排放的影响依氮肥施用而异。不施氮肥下,施用生物质炭提高当季土壤CH4排放（20 t•hm-2用量时）,但次年无影响。施用氮肥下,不同用量生物质炭对土壤CH4排放无显著影响,仅40 t•hm-2用量时次年CH4排放有所增加;生物质炭对不施氮肥土壤当季N2O排放无显著影响,并降低次年的排放。然而,施氮肥下,生物质炭连续两年显著降低了土壤N2O的排放,其降幅高达66%。施氮肥条件下,连续两年生物质炭处理降低稻田痕量温室气体的综合温室效应及其水稻生产的碳强度,特别是40 t•hm-2的高用量下。【结论】在连续两年内,稻田采用生物质炭配施氮肥的管理措施对改善土壤性质和稳定水稻产量具有持续效应,高用量生物质炭(40 t•hm-2)显著降低稻田CH4和N2O痕量温室气体排放的综合温室效应和水稻生产的碳强度,且在连续两年内具有稳定的持续性。因此,在当前稻田管理措施下,生物质炭施用量为40 t•hm-2可实现稻田稳产和固碳减排的目标。     

设施菜地土壤镉钝化剂筛选及应用效果研究

针对设施农田土壤重金属污染与农产品累积风险日趋严重的问题,以设施农田镉污染土壤(0.4~0.8 mg·kg-1)为研究对象,在室内钝化剂筛选实验的基础上,通过田间效果验证,重点探究炭基、磷基、硅酸盐、黏土矿物等钝化材料施加浓度和磷基-炭基钝化材料复合配施对土壤镉修复效果及对植物生长的影响。结果表明:施加生物质炭、羟基磷灰石、蒙脱石等钝化剂可明显降低土壤有效态镉含量,其中羟基磷灰石+生物质炭配施效果最好,土壤有效态镉含量降低46.52%~58.11%。与对照相比,施加钝化剂均能抑制油菜对镉的吸收和根部向地上可食部分转移,使油菜地上部镉的含量较CK降低3.9%~51.2%,全部低于《食品安全国家标准》(GB 2762—2016)食品中污染物限量。考虑生产成本、材料来源等因素,推荐羟基磷灰石(225 kg·hm-2)与0.6%生物炭复合添加配施为优选钝化剂组合。田间效果分析也表明,土壤EC与土壤有效态镉含量呈显著正相关,进一步证明污染设施菜地中施加钝化剂降低土壤镉的生物有效性,是实现设施菜地安全生产的可行措施。     

Experimental comparison of aerial larvicides and habitat modification for controlling disease-carrying Aedes vigilax mosquitoes

BACKGROUND: Microbial and insect‐growth‐regulator larvicides dominate current vector control programmes because they reduce larval abundance and are relatively environmentally benign. However, their short persistence makes them expensive, and environmental manipulation of larval habitat might be an alternative control measure. Aedes vigilax is a major vector species in northern Australia. A field experiment was implemented in Darwin, Australia, to test the hypotheses that (1) aerial microbial larvicide application effectively decreases Ae. vigilax larval presence, and therefore adult emergence, and (2) environmental manipulation is an effective alternative control measure. Generalised linear and mixed‐effects modelling and information‐theoretic comparisons were used to test these hypotheses. RESULTS: It is shown that the current aerial larvicide application campaign is effective at suppressing the emergence of Ae. vigilax, whereas vegetation removal is not as effective in this context. In addition, the results indicate that current larval sampling procedures are inadequate for quantifying larval abundance or adult emergence. CONCLUSIONS: This field‐based comparison has shown that the existing larviciding campaign is more effective than a simple environmental management strategy for mosquito control. It has also identified an important knowledge gap in the use of larval sampling to evaluate the effectiveness of vector control strategies. Copyright © 2011 Society of Chemical Industry     

不同施肥方式下稻田氮磷流失特征

采用大田小区试验,研究3种不同施肥方式下稻田系统氮(N)、磷(P)流失特征。实验结果表明,施用尿素和缓释肥的混施处理(MT)田面水中总氮(TN)和总磷(TP)平均浓度均为最高,分别为24.01和3.78mg/L,降雨产生径流时的N、P流失风险最大。整个水稻季,MT处理的N、P径流流失负荷分别为23.91和2.67kg/hm2,均为3种施肥处理中最高;MT处理的N、P渗漏流失负荷也为最高,分别为9.19和1.79kg/hm2。相对于MT处理,施用尿素和BB肥的无机处理(CT)及施用有机肥的有机处理(OT)能分别减少14.69%和29.18%的N总流失负荷及61.85%和68.97%的P总流失负荷。N、P的径流流失是稻田N、P流失的主要途径。     

扬州市麦田草相特点及杂草防除对策

为了摸清扬州地区麦田杂草种类、分布状况,通过倒“W”形九点取样法调查,结果表明麦田杂草有26科81种,其中里下河地区优势种为日本看麦娘、牛繁缕、菵草等;沿江地区优势种为菵草、日本看麦娘、牛繁缕等;丘陵山区优势种为日本看麦娘、猪秧秧、野老鹳等;同时发现当前存在着杂草抗药性增强、防治技术不到位等方面问题,提出了强抓土壤封闭处理、合理选用除草剂及开展技术宣传培训等对策。