Effect of Monosodium Methanarsonate Application on Cuticle Wax Content of Cocklebur and Cotton Plants

Leaf cuticle waxes were extracted from monosodium methanearsonate (MSMA)-resistant (R) and -susceptible (S) common cocklebur (Xanthium strumarium L.) and cotton (Gossypium hirsutum L.) plants at 0, 3, 5, and 7 days after treatment (DAT) following 1× and 2× MSMA applications. Wax constituents were analyzed by gas chromatography (GC) with flame ionization detection and compared to alkane and alcohol standards of carbon lengths varying from C21 to C30. Differences in waxes were calculated and reported as change per ng mm^2–1. Tricosane (C23) was found to increase following MSMA applications. All other alkanes decreased by 7 DAT, with some showing a linear effect over time in the R-cocklebur. Alcohol constituents were also observed to decrease by 7 DAT. Total arsenic in the extracted wax fraction was determined, with greatest quantities detected in the R-cocklebur. Wax changes are not believed to play a role in cotton tolerance, since changes in cuticle concentrations were minimal. Cocklebur resistance to MSMA is not due to cuticle constituents; the wax changes are a secondary effect in response to herbicide application.     

2,4-D mineralization in unsaturated and near-saturated surface soils of an undulating,cultivated Canadian prairie landscape

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is one of the most widely used pesticides in the Canadian prairies and is frequently detected as a ground and surface water contaminant. The objective of this paper was to determine the magnitude and extent of variation of 2,4-D mineralization in a cultivated undulating prairie landscape. Microcosm incubation experiments, using a 4 × 3 × 2 factorial experimental design (soil moisture, 4 levels: 60, 85, 110, 135% of field capacity; slope position, 3 levels: upper-, mid- and lower-slopes; soil depth, 2 levels: 0–5 and 5–15 cm), were used to assess 2,4-D mineralization. The first-order mineralization rate constant (k₁) varied from 0.03 to 0.22 day^{? 1}, while total 2,4-D mineralization varied from 31 to 52%. At near-saturated conditions (110 and 135% of field capacity), the onset of 2,4-D degradation was delayed in soil obtained from the upper- and mid-slopes but not in soils obtained from the lower-slope position. The k₁ and total 2,4-D mineralizationwas significantly influenced by all three factors and their interactions. The Freundlich sorption coefficient of 2,4-D ranged from 0.83 to 2.46 ug ^1–1/ng^{? 1} mL^1/n and was significantly influenced by variations in soil organic carbon content across slope positions. The infield variability of 2,4-D sorption and mineralization observed across slope positions in this undulating field was comparable in magnitude and extent to the regional variability of 2,4-D sorption and mineralization observed in surface soils across Manitoba. The large variability of 2,4-D mineralization and sorption at different slope positions in this cultivated undulating field suggests that landform segmentation models, which are used to delineate slope positions, are important considerations in pesticide fate studies.     

气相色谱法测定气田产出水中的甲醇含量

文章建立了使用气相色谱仪分析气田产出水中甲醇含量的方法。通过实验在设定不同分流比的情况下,能有效监测出气田产出水中不同浓度的甲醇含量,此方法灵敏度高,最低检出限为0.02%,测定气田产出水中甲醇加标回收率达到93%～94%。     

电改袋技术在回转窑窑头烟气净化中的应用

在对水泥生产线篦冷机尾气除尘进行分析的基础上,提出了电除尘改袋式除尘的必要性,可有效控制新型干法窑烟尘和粉尘的排放浓度;针对具体案例的使用结果进行了阐述。     

高硬度富锶地下水的软化沉淀-超滤膜联用工艺

针对一种高硬度富锶地下水,分别采用石灰和石灰-碳酸钠两种方法,利用药剂软化/超滤膜工艺对其进行软化处理,同时考察了药剂投量对出水锶含量的影响。结果表明,采用石灰软化/超滤膜法,Ca(OH)2最佳投加量为270 mg/L时,出水总硬度(以CaCO3计)由287.12 mg/L降低到96.44 mg/L,硬度去除率为66.41%,出水锶含量也由原水中的0.37 mg/L下降为0.21 mg/L;而采用石灰-碳酸钠软化/超滤膜法,Ca(OH)2和Na2CO3最佳投加量分别为270 mg/L、160mg/L时,出水总硬度降低到60.34 mg/L,硬度去除率达78.98%,锶含量仅为0.02 mg/L。2种处理方法出水总硬度均达到预期目标,石灰软化/超滤膜法可使出水锶含量满足富锶水的要求,而石灰-碳酸钠软化/超滤膜法则造成了对人体有益微量元素锶的大量损失。     

Biochemical studies on the terrestrial snail,Eubania vermiculata (müller)treated with some pesticides

Abstract

The in vivo effects of methomyl, thiodicarb and metaldehyde on total soluble proteins, total lipids and glycogen content, in addition, the activity of glutamic oxaloacetic transaminase, (GOT), (GPT) glutamic pyruvic transaminase and catalase (CAT) enzymes of terrestrial E. vermiculata snails was studied. The experimental snails were treated with low concentration of 0.2% bran bait w/w of the pesticides for a period of 1,3,5,7 and 10 days. The results showed that methomyl and thiodicarb lead to significant reduction in total soluble proteins, lipids, and glycogen content, while significant increases in the activity of all enzymes tested were noted. Metaldehyde treatment showed no significant effect on total soluble proteins, lipids and GOT level, whereas a significant increase in GPT and CAT enzymes was observed. Also, metaldehyde resulted a significant reduction in glycogen content of snails.     

EFFECT OF SOIL STERILIZATION BY MERCURIC CHLORIDE ON HERBICIDE SORPTION BY SOIL

Microbial inhibitors such as mercuric chloride are frequently used to sterilize soil or soil–water slurries in experimental studies on the fate of xenobiotics in the environment. This study examined the influence of mercuric chloride additions to soil–water slurries on the sorptive behaviour of a phenoxy herbicide (2,4-D) in soil. The results demonstrated that mercuric chloride strongly decreased the capacity of the soil to retain herbicides, and that the interference of mercuric chloride with herbicide sorption increased with increasing soil organic carbon contents. Because of the competitive sorption between mercuric chloride and the phenoxy herbicide, we conclude that mercuric chloride may not be a good soil sterilization procedure for use in xenobiotic fate studies.     

珠江三角洲蔬菜基地蔬菜中邻苯二甲酸酯的含量特征

邻苯二甲酸酯是一类重要的环境激素类污染物。本文以气相色谱/质谱(GC/MS)联用检测技术,对珠江三角洲地区典型蔬菜生产基地蔬菜中6种邻苯二甲酸酯化合物进行测试分析。结果发现:(1)珠江三角洲地区典型蔬菜生产基地的蔬菜样品中,多数样品检测出6种邻苯二甲酸酯,总含量为0.46～12.02mg/kg。(2)基地蔬菜中单个邻苯二甲酸酯化合物的种类和含量因蔬菜种类、品种、部位和生长环境等因素而异。(3)同种类蔬菜在不同基地或同一基地不同种类蔬菜中邻苯二甲酸酯的含量分布不同。(4)大部分蔬菜中以邻苯二甲酸正二丁酯(DnBP)和邻苯二甲酸双(2-乙基己基)酯(DEHP)为主。     

Impact of carbon,oxygen and sulfur content of microscale zerovalent iron particles on its reactivity towards chlorinated aliphatic hydrocarbons

Zerovalent iron (ZVI) abiotically degrades several chlorinated aliphatic hydrocarbons (CAHs) via reductive dechlorination, which offers perspectives for in situ groundwater remediation applications. The difference in reactivity between ZVI particles is often linked with their specific surface area. However, other parameters may influence the reactivity as well. Earlier, we reported for a set of microscale zerovalent iron (mZVI) particles the disappearance kinetic of different CAHs which were collected under consistent experimental conditions. In the present study, these kinetic data were correlated with the carbon, oxygen and sulfur content of mZVI particles. It was confirmed that not only the specific surface area affects the disappearance kinetic of CAHs, but also the chemical composition of the mZVI particles. The chemical composition, in addition, influences CAHs removal mechanism inducing sorption onto mZVI particles instead of dechlorination. Generally, high disappearance kinetic of CAHs was observed for particles containing less oxygen. A high carbon content, on the other hand, induced nonreactive sorption of the contaminants on the mZVI particles. To obtain efficient remediation of CAHs by mZVI particles, this study suggested that the carbon and oxygen content should not exceed 0.5% and 1% respectively. Finally, the efficiency of the mZVI particles may be improved to some extent by enriching them with sulfur. However, the impact of sulfur content on the reactivity of mZVI particles is less pronounced than that of the carbon and oxygen content.