二氰蒽醌在几种典型土壤中的降解吸附和移动特性

采用室内模拟试验方法,研究了二氰蒽醌在国内3种典型土壤江西红壤、东北黑土和太湖水稻土中的降解、吸附和移动特性。结果表明,25℃下二氰蒽醌在江西红壤、东北黑土与太湖水稻土中的降解半衰期分别为5.614、1.939、4.767d,其在土壤中化学稳定性较弱,易于降解,且pH越高,降解越快。二氰蒽醌在江西红壤的吸附等温线可以Freundlich方程很好地拟合,在东北黑土和太湖水稻土中的则可用线性方程拟合,吸附系数Kd值分别为36.4、114.6和51.9,Koc值分别为3 661.9、6 741.1、4 119.0,二氰蒽醌在土壤中具有中等或较强的吸附性能,在环境中迁移扩散的能力较弱。采用土壤薄层试验得到二氰蒽醌在这三种土壤中的移动分配系数Rf均<0.1,属于难于淋溶的农药,对地下水影响较小。二氰蒽醌在我国的几种典型土壤中均表现出了易降解性,难迁移以及难淋溶的特性,在目前的使用情况下,二氰蒽醌的环境风险较低。     

双唑草腈在3种典型土壤中的降解

为明确双唑草腈在环境中的降解行为特性，采用室内模拟试验方法，分别研究了积水厌气、好氧和灭菌条件下，双唑草腈在紫色土、水稻土及红壤3种典型土壤中的降解特性。结果表明:双唑草腈在3种土壤中的降解均符合一级反应动力学方程，好氧条件下，其在紫色土、水稻土及红壤中的降解半衰期分别为13.4、10.1和31.1 d，且降解速率与土壤中有机质和黏粒含量呈正相关；不同条件下的降解速率依次为积水厌气 > 好氧 > 灭菌，说明双唑草腈在土壤中的降解一定程度上受水解和微生物活性的影响；在一定的土壤持水量范围内，双唑草腈在土壤中的降解速率随土壤含水量增加而加快。研究表明，双唑草腈在稻田淹水条件下施用降解较快，残留期较短。所得结果可为双唑草腈的合理使用及其环境安全性评价提供科学依据。     

咪唑乙烟酸降解菌的分离、鉴定及降解特性研究

采用高压富集方法,从生产咪唑乙烟酸农药厂排污口污泥中分离得到1株咪唑乙烟酸高效降解菌P14,根据菌株形态、生理生化特性及16S rDNA分析,鉴定该菌株为哈夫尼希瓦氏菌Shewanella hafniensis。初步研究了其在不同条件下对咪唑乙烟酸的降解性能。结果表明:在以咪唑乙烟酸为唯一碳源的无机盐培养基中,当咪唑乙烟酸初始质量浓度为100 mg/L、培养温度为30 ℃、pH值6.0、接种量7%时,菌株P14对咪唑乙烟酸的降解效果最佳,3 d内的降解率可达92%,因而可以此作为菌株P14降解咪唑乙烟酸的最佳条件。外加不同碳源时,P14菌株对咪唑乙烟酸的降解率呈现不同程度下降,其中柠檬酸钠对P14菌株降解效果影响较小。     

典型咪唑啉酮类除草剂的微生物降解研究进展

咪唑啉酮类除草剂是中国广泛应用的除草剂,具有杀草谱广、活性高、选择性强等优点,但其在土壤中残留期长,影响后茬作物。本文综述了典型的咪唑啉酮类除草剂甲氧咪草烟、咪唑乙烟酸和甲咪唑烟酸残留对后茬作物的影响,探究了降解部分咪唑啉酮类除草剂(甲氧咪草烟、咪唑乙烟酸和咪唑烟酸)的微生物所属类群及降解途径,分析了影响微生物降解咪唑啉酮类除草剂的因素,对目前除草剂污染修复存在的问题进行了讨论,并对未来发展进行了展望。该文对研究咪唑啉酮类除草剂的微生物降解有一定的参考作用。     

科尔沁沙地不同环境条件下植物叶凋落物CO2释放研究

采用可以有效控制环境因子的室内土壤培养试验,对不同生境土壤、土壤水分及温度作用下叶凋落物释放CO2的情况进行了初步研究。结果表明:①在培养的前4 d,土壤水分含量越高,叶凋落物释放CO2的速率越快;而从整个培养期来看,沙地中较低的含水量对叶凋落物释放CO2的速率无显著的影响。②在流动沙地和半流动沙地的生境中,凋落物释放CO2的总量高于丘间低地和固定沙地。③叶凋落物释放CO2速率与环境温度呈显著的正相关(F=0.7316,P<0.01)。在10℃,20℃以及30℃条件下,CO2的释放速率均较为平稳,而在40℃时0~16 d呈现出明显逐步加快的趋势,在17~24 d则缓缓下降并趋于平稳。     

环境条件和微生物对灭线磷降解的影响

环境条件和微生物影响灭线磷在土壤中的降解。随着土壤含水量和温度的增加,灭线磷的降解速度加快;微生物对灭线磷的降解有显著影响,30℃、含水量为40%条件下,未灭菌土中灭线磷的半衰期为16.6 d,灭菌土中灭线磷的半衰期为31.6 d;有机质对灭线磷的降解也有显著影响,有机质含量高,有利于灭线磷的降解;灭线磷在碱性土壤中的降解快于在酸性土壤中;30℃、含水量为40%条件下,灭线磷在3种土壤中的降解速度为:东北黑土＞广东红土＞山东砂壤土。     

稻丰散在土壤和水中的降解及其在土壤中的吸附

在室内模拟条件下,研究了稻丰散在土壤和水中的降解及其在土壤中的吸附行为。结果表明:稻丰散的降解速率随土壤温度的升高和土壤含水量的增加而加快;微生物的存在有利于其在土壤中的降解;在20 ℃时,稻丰散在pH为5、7、9的水溶液中的降解半衰期分别为10.66、11.65和6.53 d。3种供试土壤对稻丰散的吸附均符合Freundich方程,且有机质含量越高,土壤对稻丰散的吸附越强。     

咪唑乙烟酸高效降解菌降解性能的研究

研究了丙酸杆菌属（Propionibacterium）、海球菌属（Marinococcus）和酸单胞杆菌属（Acidomonas）单一菌株和混合菌株对咪唑烟酸的降解能力及环境条件对降解活性的影响。结果表明,混合菌株处理的咪唑乙烟酸,在第90天时的降解率高达87.20％,明显优于单一菌株。此外,外界环境条件对降解菌的活性也有显著的影响,在培养温度为25～30 ℃,土壤湿度为田间最大持水量的50%,咪唑乙烟酸残留浓度为100 μg/kg,最佳接菌量为5 mL/kg时,3株降解菌的降解活性最强,对咪唑乙烟酸的降解率最高。     

实验室条件下威百亩及异硫氰酸甲酯在土壤中的降解特性

在实验室条件下,利用高效液相色谱研究了威百亩及其降解产物异硫氰酸甲酯在土壤中的降解特性及影响因素。结果表明:威百亩在土壤中的降解与土壤绝对含水量、环境温度和土壤有机质含量均密切相关。25 ℃下,威百亩在绝对含水量为0、20%、40%、60%的土壤中的半衰期分别为5.0、1.2、4.1和4.3 d,绝对含水量约为20%的土壤最有利于其降解。威百亩的降解速率还随温度的升高和土壤有机质含量的增加而加快。异硫氰酸甲酯的降解趋势与威百亩基本相同。研究结果可为威百亩的田间安全、合理施用提供参考。     

七种农药在3种不同类型土壤中的吸附及淋溶特性

采用振荡平衡法和土柱淋溶法研究了2,4-滴酸、丁噻隆、毒草胺、炔草酸、氟环唑、甲基磺草酮和烯啶虫胺7种农药在江西红壤、太湖水稻土及东北黑土3种不同理化性质土壤中的吸附及淋溶特性,探讨了农药性质及土壤理化性质对供试农药在土壤中吸附、淋溶行为的影响。结果表明:农药的水溶性越大,其在土壤中的吸附性越弱,淋溶性越强;农药在土壤中的吸附性与土壤pH值、有机质含量以及阳离子交换量之间有较好的相关性。土壤pH值、有机质含量以及农药性质是影响农药在土壤中淋溶及迁移的主要因素。     

Dissipation of imazapyr, flumetsulam and thifensulfuron in soil

The degradation of imazapyr, flumetsulam and thifensulfuron applied at 500.40 and 30 g active ingredient (a.i.) ha^-1, respectively, to silt loam soil was studied under laboratory and field conditions. Herbicide residues were analysed by a lentil ( Lens culinarits L.) bioassay. Results showed that temperature had a significant effect on herbicide degradation, whereas the impact of soil organic matter ami pH were less well defined. Half-lives for imazapyr, flumetsulam and thifensulfuron in soil samples from the 0-5 cm layer (6.4% organic carbon) at 15 °C were 125, 88 and 5.4 days, respectively, and 69, 30 and 3.9 days at 30°C. In soil sampled from the 15-20 cm layer (3.5% organic carbon) half-lives were 155. 70 and 6.4 days, respectively, at 15 °C and 77, 24 and 4.8 days at 30 °C, A field experiment investigated the degradation and teaching of each herbicide under two precipitation regimes [natural precipitation (208 mm), and natural precipitation plus 75 mm irrigation (283 mm) over 4 months to a soil depth of 25 cm. Thifensulfuron degraded rapidly, whereas residues of flumetsulam and imazapyr leached below 25 cm in both the low-and high-precipitasion treatments after 4 months. Significant imazapyr residues were still present in the soil to 25 cm depth after 3 months, A multi-component model for herbicide dissipation was developed and evaluated using data from the laboratory and field experiments.     

Study on the behaviour of imazapyr in two Moroccan soils

Imazapyr owes its importance in Morocco to its success in controlling the perennial weed Solanumelaeagnifolium Cav., which infests the Tadla area. Persistence and mobility of imazapyr has been studied in two Moroccan soils from the Rabat area, with differing organic matter content (red and organic soils), under laboratory conditions at 75% of their field capacities and 25–28 °C. Residue analysis was performed on the basis of a bioassay test using lentil (Lens culinaris Medic.) as indicator species. The residual activity of imazapyr accounted for 69%, 25%, 50% and 62%, 46%, 66% of the initial activity for the red and organic soils at 1, 5 and 10 mg L^?1 respectively. The half-lives varied between 25 and 58 days for the red soil and 55 and 58 days for the organic soil. In the organic soil, imazapyr was highly mobile under the irrigation regime applied. Most of the activity was found in the first 3 × 75 mL of the effluents. A following biotest with the leached soil showed low remaining residual activity.     

烯酰吗啉顺反异构体在土壤中的降解动态研究

实验室条件下,研究了烯酰吗啉在土壤中的降解动态特性。结果表明,烯酰吗啉在供试吉林黑土、河南褐土和江西红土中的降解半衰期分别为69、69和462 d,在土壤中的降解性能为中等至难降解。其Z式异构体在吉林黑土、河南褐土和江西红土中的降解半衰期分别为89、126和533 d,E式异构体的降解半衰期分别为53、29和408 d,在3种土壤中Z式异构体的降解速率均低于E式异构体。河南褐土中E/Z的比值在降解过程中发生了明显变化。实验室条件下,烯酰吗啉在土壤中的降解速率明显低于其在田间土壤中的降解速率。     

异噁唑草酮在土壤表面光解及在土壤中的降解和淋溶特性

为合理评估除草剂异唑草酮的环境风险，在实验室模拟条件下，研究了异唑草酮在土壤 (红壤土)表面光解以及在不同质地土壤 (潮土、水稻土和红壤土) 中的降解和淋溶特性。结果表明:异唑草酮在土壤表面的光解遵循一级反应动力学方程c_t = 4.23e–0.008t (r = 0.937)，半衰期为82.5 h；其在潮土、水稻土和红壤土中的降解均符合一级动力学方程，好氧条件下，异唑草酮在3种土壤中的降解半衰期分别为10.5、43.3和139 h，厌氧条件下的降解半衰期分别为19.4、18.4和158 h；其在潮土、水稻土和红壤土中的淋溶系数 (R_f) 分别为0.417 0、0.083 3和0.083 3。研究表明:异唑草酮在土壤表面光解速率较慢，而在土壤中好氧及厌氧条件下降解速率均较快，残留期短；其在土壤中淋溶性较弱，不易对周围环境及地下水造成污染风险。     

氟虫腈在三种土壤中的降解特性研究

实验室条件下,研究了氟虫腈在东北黑土、江西红壤和太湖水稻土中的降解特性。结果表明,氟虫腈在土壤中降解较慢,其在好气条件下的东北黑土、江西红壤和太湖水稻土中的降解半衰期分别为165、267和42 d,在渍水条件下的3种土壤中的降解半衰期分别为31、173和32 d。氟虫腈在pH 偏中性的太湖水稻土中降解最快;微生物对氟虫腈在土壤中的降解起主要作用;渍水条件有利于氟虫腈的降解,推测降解氟虫腈的微生物主要是厌氧菌属。     

The fate of imazapyr in a Swedish railway embankment

The long-term fate of the herbicide imazapyr [2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid] applied to a Swedish railway embankment was studied. Imazapyr was applied at 750 and 1500 g ha(-1) by a spraying train used for full-scale herbicide treatment operations. Soil and groundwater were sampled twice a year for 8 years after application of the herbicide, and the dissipation of imazapyr was studied by HPLC analysis of the residues in soil and groundwater. A clean-up procedure including solid-phase extraction was performed prior to detection by HPLC. Recoveries of imazapyr from soil and water samples were 76-98% and 61-90%, respectively, and detection levels were 0.003 mg kg(-1) and 0.05 microg litre(-1), respectively. Sorption, desorption and microbial amount and activity were also measured at the two locations. The organic matter content correlated positively and the pH negatively to the adsorption of imazapyr on soil, and increasing organic matter contents decreased desorption. Apart from the 0-10-cm top layers of both sites, the microbial amount and activity were small. The main proportion of imazapyr was found in the upper 30 cm of the soil, and degraded with a half-life in the range 67-144 days. Small amounts were transported to lower soil layers and to the groundwater in proportion to the amounts applied. Traces of imazapyr were detected in the groundwater even 8years after application. It was concluded that environmental risks from the use of herbicides on railway embankments could be reduced by including adsorption layers in the embankment during their construction and by reducing the dose of the herbicide used.     

Modelling the leaching of imazapyr in a railway embankment

The use of herbicides on railway tracks is known to present a risk to groundwater, but little is known of the mechanisms influencing leaching through the coarse material used to construct railway embankments. Therefore, in the present study, four different models based on the convection-dispersion equation (CDE) were compared with previously reported field data on the leaching of imazapyr. In particular, the significance of non-equilibrium processes was investigated by comparing different CDE formulations accounting for preferential finger flow, particle-facilitated transport and kinetic sorption. The traditional CDE assuming 'local equilibrium' based on 24 h batch sorption data gave poor results (model efficiency - 1.1). It strongly underestimated leaching of imazapyr in the first 4 months following application, thus confirming the importance of non-equilibrium transport processes. Accounting for short-term sorption kinetics made little difference, giving similar results to the 'local equilibrium' CDE simulation. A simulation accounting for particle-facilitated transport could accurately match this accelerated transport, and also gave the best overall fit to the data (model efficiency 0.76). However, not even this model could match the long-term retention of imazapyr residues observed close to the soil surface more than 1 year after application, and it also underestimated the time of breakthrough to groundwater. This strongly suggests that a long-term retention/sorption process not included in any of the models tested (i.e. sorption hysteresis or bound residues) acted to retard leaching. The formation of 'protected' residues was also indicated by a much slower degradation of imazapyr more than 1 year after application. Industry.     

三唑醇及其对映异构体在3种不同类型土壤中的降解动态

实验室条件下,初步研究了手性农药三唑醇及其非对映异构体三唑醇A(对映异构体1R,2S体和1S,2R体的混合物)与三唑醇B(对映异构体1R,2R体和1S,2S体的混合物)在浙江杭州潮土(有机质含量1.90%,pH 6.85)、金华水稻土(有机质含量1.63%,pH 4.94)和兰溪红土(有机质含量0.38%,pH 4.03)中的降解动态及对映体之间相互转化的情况。结果表明:三唑醇在潮土、水稻土和红土中的降解半衰期分别为56.4、105.0和154.0 d,180 d时降解率分别为91.9%、79.2%和57.7%;三唑醇在潮土中发生两次三唑醇A体向B体转化和1次三唑醇B体向A体的转化,而在水稻土和红土中,三唑醇A体与B体之间相互各转化1次。表明三唑醇对映异构体的降解动态因土壤性质不同而存在差异。研究结果为三唑醇的科学合理使用及其环境风险评估提供参考。