Degradation of 3,4-dichloro- and 3,4-difluoroaniline by Pseudomonas fluorescens 26-K

3,4-Dichloro- and 3,4-difluoroanilines were degraded by Pseudomonas fluorescens 26-K under aerobic conditions. In the presence of glucose strain degraded 170 mg/L of 3,4-dichloroaniline (3,4-DCA) during 2-3 days. Increasing of toxicant concentration up to 250 mg/L led to degradation of 3,4-DCA during 4 days and its intermediates during 5-7 days. Without cosubstrate and nitrogen source degradation of 3,4-DCA took place too, but more slowly--about 40% of toxicant at initial concentration 75 mg/L was degraded during 15 days. 3,4-Difluoroaniline (3,4-DFA) (initial concentration 170 mg/L) was degraded by Pseudomonas fluorescens 26-K during 5-7 days. The strain was able to completely degrade up to 90 mg/L of 3,4-DFA, without addition of cosubstrate and nitrogen during 15 days. Degradation of fluorinated aniline was accompanied by intensive defluorination. Activity of catechol 2,3-dioxygenase (C2,3DO) (0.230 micromol/min/mg of protein) was found in the culture liquid of the strain, grown with 3,4-DCA and glucose. This fact, as well as, the presence of 3-chloro-4-hydroxyaniline as a metabolite suggested that 3,4-DCA degradation pathway includes dehalogenation and hydroxylation of aromatic ring followed by its subsequent cleaving by C2,3DO. On the contrary, activity of catechol 1,2-dioxygenase (C1,2DO) (0.08 micromol/min/mg of protein) was found in the cell-free extract of biomass grown on 3,4-DFA. 3-Fluoro-4-hydroxyaniline as intermediate was found in this cell-free extract.     

Hydrochemical Buffer Assessment in Agricultural Landscapes: From Local to Catchment Scale

Non-point-source pollution of surface and groundwater is a prominent environmental issue in rural catchments, with major consequences on water supply and aquatic ecosystem quality. Among surface-water protection measures, environmental or landscape management policies support the implementation and the management of buffer zones. Although a great number of studies have focused on buffer zones, quantification of the buffer effect is still a recurring question.The purpose of this article is a critical review of the assessment of buffer-zone functioning. Our objective is to provide land planners and managers with a set of variables to assess the limits and possibilities for quantifying buffer impact at the catchment scale. We first consider the scale of the local landscape feature. The most commonly used empirical method for assessing buffers is to calculate water/nutrient budgets from inflow–outflow monitoring at the level of landscape structures. We show that several other parameters apart from mean depletion of flux can be used to describe buffer functions. Such parameters include variability, with major implication for water management. We develop a theoretical framework to clarify the assessment of the buffer effect and propose a systematic analysis taking account of temporal variability. Second, we review the current assessment of buffer effects at the catchment scale according to the theoretical framework established at the local scale. Finally, we stress the limits of direct empirical assessment at the catchment scale and, in particular, we emphasize the hierarchy in hydrological processes involved at the catchment scale: The landscape feature function is constrained by other factors (climate and geology) that are of importance at a broader spatial and temporal scale.Published on line     

对加拿大东南部湖泊从酸沉降效应中恢复的评价

北美洲SO2排放量的减少激起了人们对加拿大东南部的水生态系统能迅速摆脱酸化的状态的期待.但是只有那些明显减少了排放量的冶炼厂附近的湖泊达到了这种期望值.在临近大西洋的省份魁北克和安大略,受远程污染源影响的湖泊的硫酸根离子(SO2- 4)浓度都有一定降低,但pH和碱度则仅有较少量的提高.对于这种延迟的酸度响应,有如下几种因素可以解释:碱基阳离子含量的下降,干旱加速SO2- 4的迁移,水体内部碱性物质生成机制遭到破坏;同时硝酸盐和有机阴离子含量的提高也可能是其中的原因.对加拿大东南部生物恢复的监测资料非常有限,即使有的话,在萨德伯里(Sudbury)和基拉尼(Killarney)地区以外也很难找到恢复的证据.比如,尽管除了酸化作用外其他因素也对上述现象有一定影响,新思科舍河中的大西洋鲑鱼出现率和安大略湖潜鸟的繁殖成功率实际上正在下降.化学和生物学模型预测,只有比目前法规要求严格的多的SO2排放削减额才能促进广泛的化学恢复和其后的生物恢复,而在加拿大东南部的众多湖泊中重建工业化前的化学与生物学条件或许很难实现.     

Prenatal diagnosis of the pterygium syndrome

We report two second trimester pregnancy terminations in the same woman following intrauterine ultrasonic findings of hydrops fetalis, polyhydramnios, lack of fetal movements, and short, fixed malformed limbs. One fetus also showed a cystic mass at the back of the head. Radiographic and anatomic studies of the fetuses demonstrated multiple pterygia, flexion contracture of multiple joints, abnormal facial appearance, cleft palate, pulmonary hypoplasia, and gracile bones. The cystic mass of the back of the head was found to be a cystic hygroma. These findings are consistent with the lethal variant of multiple pterygium syndrome. Early prenatal diagnosis of this condition is possible using ultrasonography.