Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

Testing antimicrobial cleaner efficacy on gypsum wallboard contaminated with <Emphasis Type="Italic">Stachybotrys chartarum</Emphasis>

Goal, Scope and Background Reducing occupant exposure to indoor mold is the goal of this research, through the efficacy testing of antimicrobial cleaners. Often mold contaminated building materials are not properly removed, but instead surface cleaners are applied in an attempt to alleviate the problem. The efficacy of antimicrobial cleaners to remove, eliminate or control mold growth on surfaces can easily be tested on non-porous surfaces. However, the testing of antimicrobial cleaner efficacy on porous surfaces, such as those found in the indoor environment such as gypsum board can be more complicated and prone to incorrect conclusions regarding residual organisms. The mold Stachybotrys chartarum has been found to be associated with idiopathic pulmonary hemorrhage in infants and has been studied for toxin production and its occurrence in water damaged buildings. Growth of S. chartarum on building materials such as gypsum wallboard has been frequently documented. Methods Research to control S. chartarum growth using 13 separate antimicrobial cleaners on contaminated gypsum wallboard has been performed in laboratory testing. Popular brands of cleaning products were tested by following directions printed on the product packaging. Results A variety of gypsum wallboard surfaces were used to test these cleaning products at high relative humidity. The results indicate differences in antimicrobial efficacy for the six month period of testing. Discussion Results for the six types of GWB surfaces varied extensively. However, three cleaning products exhibited significantly better results than others. Lysol All-Purpose Cleaner-Orange Breeze (full strength) demonstrated results which ranked among the best in five of the six surfaces tested. Both Borax and Orange Glo Multipurpose Degreaser demonstrated results which ranked among the best in four of the six surfaces tested. Conclusions The best antimicrobial cleaner to choose is often dependent on the type of surface to be cleaned of S. chartarum contamination. For Plain GWB, no paint, the best cleaners were Borax, Lysol All-Purpose Cleaner-Orange Breeze (full strength), Orange Glo Multipurpose Degreaser, and Fantastik Orange Action. Recommendations and Perspectives These results are not meant to endorse the incomplete removal of mold contaminated building materials. However, it is recognized that complete removal may not always be possible and solutions to control mold regrowth may contribute to reduced occupant exposure. Current recommendations of removal and replacement of porous building materials should be followed. It is not the intension of this discussion to endorse any product. Reporting on the performance of these products under the stated conditions was and remains the only purpose. ESS-Submission Editor: Dr. Lee Young (youngrisk@bresnan.net)     

Experimental evidence for a dual pathway model analysis of coping with the climate crisis

Two experiments examined the psychological power of fear and group efficacy beliefs to increase environmental action intentions against the climate crisis. Extending a dual pathway model of coping with collective disadvantage, results showed evidence for emotion-focused approach coping: Environmental action intentions were increased by individuals' manipulated fear of the negative future consequences of the climate crisis (Experiments 1–2). Additionally, results showed evidence for problem-focused approach coping: Individuals' measured (Experiment 1) and manipulated group efficacy beliefs (Experiment 2) increased environmental action intentions. The results thus suggest that the dual pathway model can be successfully applied to a psychological analysis of emotion- and problem-focused approach coping with the climate crisis. We discuss the theoretical and practical implications of these results.     

Safety Attitudes and Their Relationship to Safety Training and Generalised Self-Efficacy

This paper studies safety attitudes, their relationship with safety training behaviour, and generalised self-efficacy. From a sociotechnical perspective, training programs might be used as a mechanism for enhancing attitudes, especially to improve safety and occupational health. Also, self-efficacy allows to enhance training effectiveness. The aim of this paper is to validate a safety attitude scale and to examine its relationship to safety training behaviour and self-efficacy in organisational settings. With data from 140 employees, results show a conceptually meaningful 3-factor solution. Hier-archical multiple regression analysis shows a main effect of safety training behaviour and levels of self-efficacy on safety attitude. Study limitations and its implications on safety training design are also discussed.     

Herbicide Transport in Goodwater Creek Experimental Watershed: II. Long‐Term Research on Acetochlor,Alachlor, Metolachlor,and Metribuzin1

Lerch, R.N., E.J. Sadler, C. Baffaut, N.R. Kitchen, and K.A. Sudduth, 2010. Herbicide Transport in Goodwater Creek Experimental Watershed: II. Long‐Term Research on Acetochlor, Alachlor, Metolachlor, and Metribuzin. Journal of the American Water Resources Association (JAWRA) 1‐15. DOI: 10.1111/j.1752‐1688.2010.00504.x Abstract: Farmers in the Midwestern United States continue to be reliant on soil‐applied herbicides for weed control in crop production, and herbicide contamination of streams remains an environmental problem. The main objective of this study was to analyze trends in concentration and load of acetochlor, alachlor, metolachlor, and metribuzin in Goodwater Creek Experimental Watershed (GCEW) from 1992 to 2006. A secondary objective was to document the effects of best management practices (BMPs) implemented within GCEW on herbicide transport trends. Median relative herbicide loads, as a percent of applied, were 3.7% for metolachlor, 1.3% for metribuzin, 0.36% for acetochlor, and 0.18% for alachlor. The major decrease in alachlor use and increase in acetochlor use caused shifts in flow‐weighted concentrations that were observed over the entire concentration range. The smaller decrease in metolachlor use led to a consistent decreasing time trend only for the upper end of the concentration distribution. Metribuzin also showed moderate decreases in concentration with time since 1998. Annual loads were generally correlated to second quarter discharge. Despite extensive education efforts in the watershed, conservation BMPs within GCEW were mainly implemented to control erosion, and therefore had no discernable impact on reducing herbicide transport. Overall, changes in herbicide use and second quarter discharge had the greatest effect on trends in flow‐weighted concentration and annual load.     

“百草枯”生产的环境风险评价

结合河北省桃园农药厂开发的百草枯新工艺(低温钠法),对百草枯生产过程中的环境风险进行评价。首先介绍了百草枯生产的工艺流程,然后系统分析了金属钠、吡啶、氯甲烷以及百草枯等危险物的性质及其危害性,并在上述分析的基础上,采用相应的评价模型对钠化釜及合成釜中吡啶可能造成的爆炸与扩散进行了评价。最后,就百草枯生产的环境风险提出了相应的对策和防范措施。     

Weekly work–school conflict,sleep quality,and fatigue: Recovery self‐efficacy as a cross‐level moderator

This study employed a weekly diary method among a sample of 74 Midwestern college student workers in order to examine the within‐person relationships between work–school conflict, sleep quality, and fatigue over five weeks. Further, recovery self‐efficacy was proposed as a cross‐level moderator of the relation between sleep quality and fatigue. Results from multilevel analyses demonstrated that weekly work–school conflict was negatively related to weekly sleep quality and positively related to end‐of‐week fatigue, with sleep quality partially mediating the relation between work–school conflict and fatigue. These findings enhance understanding of the process by which work–school conflict contributes to college student workers' strain on a weekly basis. Additionally, student workers with low recovery self‐efficacy demonstrated a negative relation between sleep quality and fatigue; however, this relation did not exist for student workers with high recovery self‐efficacy. This finding suggests recovery self‐efficacy as an important resource that may reduce the association between poor sleep quality (as a result of work–school conflict) and fatigue. The current findings provide important theoretical and practical implications for researchers, organizations, and college institutions as a whole. Copyright © 2014 John Wiley & Sons, Ltd.     

多重环境因子对氟胺磺隆在土壤中降解的影响

氟胺磺隆作为普遍使用的一种磺酰脲类除草剂,已经对土壤和作物造成了危害,其环境行为受很多物理化学或生物因素的影响.为探明不同环境因素对氟胺磺隆在土壤中降解程度的影响,通过实验室内模拟培养的方法,研究了土壤微生物、不同土壤类型、水溶性有机物（dissolved organic matter,DOM）、温度、土壤含水量等因素对氟胺磺隆在土壤中降解的影响.结果表明,各种环境因子：温度、湿度、土壤微生物和土壤类型等均在不同程度上影响了氟胺磺隆的土壤降解速率.土壤微生物量、土壤有机质和DOM的增加均有利于氟胺磺隆在土壤中的降解,并且土壤pH的降低,也会促进氟胺磺隆在土壤中的降解.其中,土壤微生物是影响氟胺磺隆土壤降解的主要因素.该研究结果将为一些生物和物理化学因子调节氟胺磺隆在土壤中消散提供初步数据.     

Absorption and translocation of sulfometuron-methyl in sugarcane (Saccharum officinarum L.) at different growth stages

ABSTRACT

In Brazil, weed management in sugarcane fields is mainly done with the use of selective herbicide formulations. For many years, diuron+hexazinone was one of the main herbicide mixture formulations used in sugarcane. Later, sulfometuron-methyl was included in the same mixture, which was marketed as a new herbicide formulation for residual in-season weed control in sugarcane. The mixture diuron+hexazinone+sulfometuron-methyl has been widely used in commercial sugarcane fields in Brazil. However, recent field observations have shown that sugarcane plants at different growth stages varied in their phytotoxicity levels after treatment with diuron+hexazinone+sulfometuron-methyl. Greenhouse and laboratory studies were conducted to determine ¹⁴Csulfometuron-methyl absorption and translocation, as well as ¹⁴C distribution in sugarcane at two growth stages, 2 to 3 leaves and 5 to 6 leaves. ¹⁴Csulfometuron-methyl absorption by sugarcane did not differ between the two growth stages. Different patterns of ¹⁴C accumulation were observed, which may explain variations in sulfometuron-methyl phytotoxic responses observed in the field.     

Inhibition kinetics of acid and alkaline phosphatases by atrazine and methomyl pesticides

The main objective of this work was to investigate the kinetic characteristics of acid and alkaline phosphatases isolated from different sources and to study the effects of the herbicide atrazine and insecticide methomyl on the activity and kinetic properties of the enzymes. Acid phosphatase (ACP) was isolated from the tomato plant (Solanum lycopersicum L. var. lycopersicum); alkaline phosphatase (ALP) was isolated from two sources, including mature earthworms (Aporrectodea caliginosa) and larvae of the Egyptian cotton leafworm (Spodoptera littoralis). The specific activities of the enzymes were 33.31, 5.56 and 0.72 mmol substrate hydrolyzed per minute per milligram protein for plant ACP, earthworms ALP and cotton leafworm ALP, respectively. The inhibition kinetics indicated that atrazine and methomyl caused competitive–non-competitive inhibition of the enzymes. The relationships between estimates of K_m and V_max calculated from the Michaelis–Menten equation have been explored. The extent of the inhibition was different, as estimated by the values of the inhibition constant K_i that were found to be 3.34 × 10^?3, 1.12 × 10^?2 and 1.07 × 10^?2 mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively, with methomyl. In the case of atrazine, K_i were found to be 8.99 × 10^?3, 3.55 × 10^?2 and 1.36 × 10^?2 mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively.