The release of cyanatryn from a controlled-release formulation into flowing water

The problem of maintaining a sufficient concentration of the herbicide cyanatryn in flowing water for a sufficient time to control aquatic weeds has been solved by using a controlled-release pellet formulation. The rate of release of the herbicide depends primarily on the rate of diffusion within the clay matrix and is a function of the formulation ingredients and the degree of compaction achieved during manufacture. Release appears to be independent of water velocity but the concentration produced downstream of the application point depends on the volume of water flowing in unit time and the mass of herbicide used.     

自流式注射法中苹果树体吸收量回归方程的建立

为确定苹果树体的有效吸收期并建立初始流速v0与有效吸收期内树体吸收量的回归方程,以纯水为注射液,研究了输液流速与树体吸收量的关系,通过统计软件分析相邻观测时间与对应流速间的函数关系,建立了初始流速v0与树体有效吸收期内吸收量的回归方程。结果表明:树体的有效吸收期为注射开始后0~48 h;相邻观测时间与对应的流速间存在极显著的一元线性关系和幂函数曲线关系,同时注射期间温度对流速具有一定影响,温度上升时流速上升,温度下降则流速亦下降;v0与48 h内树体的吸收量呈显著回归关系。建立回归方程时,若不区分9:00 am开始注射时的初始流速v0与注射开始后3 h (12:00 am)时流速v3的比值(流速比,v0/v3)关系,且v0在0~1 mL/min时,采用一元回归方程时的差异率显著高于幂函数方程,而当v0在2~4 mL/min时,采用幂函数方程的差异率显著高于一元回归方程;若区分流速比,且流速比为0.6~1,v0为1~4 mL/min时,采用一元函数方程估测的差异率显著低于幂函数方程,流速比为1~1.6,v0为0~4 mL/min时,一元函数与幂函数方程估测的差异率无显著性差异。在不区分流速比的情况下,两类方程的差异率均在20%~30%之间。因此,当v 0在0~1 mL/min之间时,建议采用幂函数方程;当v0为1~2 mL/min时,采用一元函数或幂函数方程均可;当v0在2~4 mL/min之间时,建议采用一元函数方程。区分流速比时,两类方程的差异率均小于15%。因此,当流速比为0.6~1,v0在0~1 mL/min之间时,采用一元函数或幂函数方程均可,当v0为1~4 mL/min时,建议采用一元函数方程;当流速比为1~1.6, v0在0~4 mL/min之间时,采用一元函数或幂函数方程均可。     

Loss of acrolein from water by volatilization and degradation

The loss of acrolein by volatilization and degradation from a large tank of water is described. The standard analytical method for carbonyl compounds, a colorimetric reaction with dinitrophenylhydrazine did not distinguish acrolein from a relatively non-volatile and non-toxic reaction product. In a modification of the method to correct the error, acrolein was separated from reaction products by scrubbing with air. Although acrolein is sufficiently volatile to use air-scrubbing to separate it from reaction products, its loss by evaporation from an open tank was much less than its loss by reaction in the local irrigation water. In other waters differences in chemical properties could affect the loss of acrolein by reaction, and greater turbulence is expected to increase loss by volatilization. Perte d'acroléine à partir de l'eau par volatilisation et dégradation. Les auteurs décrivent la perte d'acroléine par volatilisation et degradation k partir d'un grand reservoir d'eau. La methode analytique standard pour les composes carbonyl. une reaction colorimétrique avec la dinitrophenylhydrazine. n'a pas permis de distinguer l'acroléine d'autres produits relativement non volatils et non toxiques, apparaissant au cours de la reaction. Dans une modification de la méthode en vue de corriger l'erreur. l'acroléinc a été séparée des autres products de la reaction au moyen d'un entrainement par fair. Bien que l'acroléne soit suffisamment volatile pour que Ton puisse utiliser l'air pour la séparer des autres produits de la reaction, la perte par évaporation à partir d'un réservoir ouvert s'est avérée beaucoup moindre que la perte par reaction dans l'eau d'irrigation apportée localement. Dans d'autres CAS, des differences dans les proprióteschimiques peuvent affecter la perte d'acroléine au cours de la reaction de la faut s'attendre à un accroissement de la perte par volatilisation dans le cas d'une turbulence plus grande. Verlust von Acrolein durch Verfükhtigung und Abbau in Wasser Es wird der Verlust an Acrotein aus einem grossen Wassertank durch Verdampfung und Abbau beschrieben. Die analytische Standardmethode für Carbonylverbindungen mit Dinitrophenylhydrazin, lässt keine Unterscheidung zwischen Acrolein und einem verhältnismässig wenig flüchtigen und un-giftigen Reaktionsprodukt zu. Um die Fehlermöglichkeit Zu eliminieren. wurde die Methode abgeándert, indem das Acrolein von den Reaktionsprodukten durch “Auswaschen” mit Luft abgetrennt wurde, Obgleich die Flüchugkeit von Acrolein genúgend gross ist. um es durch “Auswaschen” mit Luft von Umsetzungsprodukten abzutrennen. ist der durch seine Verdampfung aus einem offenen Tank verursachte Verlusl viel geringer als der durch Umsetzung im lokalw Beregnun-swasser bedingte. In anderen Wassern könnten Unterschiede in den chemischen Eigenschaften den Verlust von Acrolein durch Umsetzung beeinflussen und es ist zu erwarten. dass grössere Turbulenz die Abnahmc durch Verflüchligung erhöht.     

苗木地除草剂的筛选

通过对苗木地不同除草剂的除草效果及安全性试验,表明土壤处理剂24%乙氧氟草醚EC是适合于湖州地区苗木地除草的较佳除草剂。     

Herbicides and plant hormesis

Herbicide hormesis is commonly observed at subtoxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon are influenced by plant growth stage and physiological status, environmental factors, the endpoint measured and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugar cane ‘ripeners’ to enhance sucrose accumulation. The many factors that can influence the occurrence, the magnitude and the dose range of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g. in adjacent fields, when shielded by crop vegetation). Some weeds that have evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production. © 2014 Society of Chemical Industry     

The uptake of the molluscicide, 4′-chloronicotinanilide into Biomphalaria glabrata (Say) in a flowing water system

A system is described for the exposure of freshwater snails to pesticides in flowing water. The method allows groups of seven snails to be confined in about 20 ml of water under constant conditions of pesticide concentration, oxygen tension and temperature for up to 5 days. The uptake rate of 4′-chloronicotinanilide into the planorbid snail, Biomphalaria glabrata (Say), has been measured using this method with liquid scintillation counting techniques. The necessity for an acclimatisation period prior to exposure and the possible influence of activity on uptake is demonstrated. The advantages of the flowing system over exposure in static solutions are discussed and the use of the apparatus in deciding whether relative uptake rates can account for interspecific differences in susceptibility or contribute to the improvement of molluscicide specificity, is indicated.