30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂对甜玉米田杂草的防效及安全性

研究30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在甜玉米田的应用效果,在甜玉米不同叶龄期开展田间试验,评价其对杂草的防除效果及对甜玉米的安全性。结果表明,30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在甜玉米3～4叶期或6～7叶期施药,900～1 575 g a.i./hm2剂量范围内对甜玉米品种粤甜28安全,对玉米田常见杂草凹头苋、光头稗、马唐和香附子的防效及增产效果均显著高于对照药剂38%莠去津悬浮剂2 160 g a.i./hm2播后苗前处理。推荐30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在900～1 350 g a.i./hm2范围内,甜玉米3～5叶期茎叶喷雾使用。     

Arthrobacter sp. AG1菌株降解土壤中阿特拉津研究

在阿特拉津浓度为50mg/kg干土的黄棕壤、潮土和红壤接种1.5×106CFU/g干土的降解菌Arthrobacter sp. AG1,10天后土壤中的阿特拉津分别降解至1.5、6.6和10mg/kg干土。阿特拉津的降解速率受到土壤性质的影响,但AG1仍能在不满足其生长繁殖要求的pH值的土壤中有效降解酸性土壤中阿特拉津;土壤中水分含量对降解效果影响较大,>20%时降解效果较好;土壤低含水量和低pH值会导致AG1降解阿特拉津的活力下降。不同的接种量对降解效果有一定影响,但105～107CFU/g干土接种量的AG1都能有效发挥降解作用。AG1降解完土壤中的阿特拉津后,在土壤含水量分别为5%和15%的情况下能长期保持降解活性,对60天后第2次施入黄棕壤和潮土中的50mg/kg阿特拉津4天时降解效率在65%以上。     

How increasing availabilities of carbon and nitrogen affect atrazine behaviour in soils

 The effect of increasing amounts of glucose and mineral N on the behaviour of atrazine was studied in two soils. One had been exposed to atrazine under field conditions (adapted soil), the other had not (non-adapted soil), resulting, respectively, in an accelerated degradation of atrazine in the adapted soil and in a slow degradation of the herbicide in the non-adapted soil. The dissipation of ¹⁴C-atrazine via degradation and formation of non-extractable "bound" residues was followed during laboratory incubations in soils supplemented or not with increasing amounts of glucose and mineral N. In both soils, glucose added at rates of up to 16 g C kg^–1 soil did not modify atrazine mineralization but increased the formation of bound residues; this was probably due to the retention of atrazine by the growing microbial biomass. Atrazine dealkylation was enhanced when a large amount of glucose was added. In both soils, the addition of the largest dose of mineral N (2.5 g N kg^–1 soil) decreased atrazine mineralization. The simultaneous addition of glucose and mineral N enhanced their effects. When the largest doses of mineral N and glucose were added, atrazine mineralization stopped in both soils, and the proportion of bound residues increased. Glucose and mineral N additions influenced atrazine mineralization to a greater extent in the adapted soil than in the non-adapted one, as revealed by ANOVA, although glucose addition had a greater effect than N. The competition for space and nutrients between atrazine-degrading microorganisms and the total heterotrophic microflora probably contributed to the decrease in atrazine mineralization. Received: 9 June 1998     

阿特拉津在饱和砂质壤土中非平衡运移的模拟

针对农药阿特拉津在稳定流场饱和砂质壤土中的运移 ,根据平衡与非平衡假设条件下对流—弥散方程数学模型的解析解 ,基于易混合置换实验获得的阿特拉津和示踪溶质Br- 的穿透曲线及批量平衡法求得的阻滞因子 ,应用CXTFIT 2 0软件 ,通过拟合土柱实验中溶质的出流浓度变化 ,估算了模型的有关参数 ,在此基础上模拟分析了实验土柱不同埋深处阿特拉津的出流浓度和累积淋溶量动态 ,结果表明 ,化学非平衡的两点模型对本文实验条件下阿特拉津运移的仿真具有较高的精度     

Degradability of atrazine, cyanazine, and dicamba in methanogenic enrichment culture microcosms using sediment from the Pearl River of Southern China

Degradation of three herbicides, atrazine, cyanazine and dicamba, was assessed in laboratory microcosms incubated under simulated methanogenic conditions using sediment from Pearl River of Southern China as an inoculum. Atrazine was much more resistant to degradation than cyanazine and dicamba over 300 days of incubation. Biodegradation of cyanazine and dicamba was further substantiated by establishment of enrichment transfer cultures in which the degradation of the respective herbicide was accelerated by the active microorganisms. Degradation of cyanazine initially involved the removal of chlorine and the two side chains, while that of dicamba was O-demethylation reaction forming 3,6-dichlorosalicyclic acid. Results suggest that biodegradation of xenobiotics can be established through enrichment culture transfer technique, and further mechanism of degradation and microorganisms involved can be elucidated.     

Leaching of dissolved organic carbon in soil following anhydrous ammonia application

The transport of anhydrous NH₃-solubilized soil organic matter from surface to subsurface soils may affect subsurface microbial activity. In the present study we determined the impact of anhydrous NH₃-N fertilizer on organic C solubilization and the propensity of solubilized C to leach with percolating water. In fertilized treatments, anhydrous NH₃ was subsurface-banded at 20g N m^-2 in ridge or valley areas of a ridge tillage system. In contol treatments, 0g N m^-2 was banded into the valley area of a ridge tillage system. Rainfall (17 cm) was applied with a drop-type artificial rainfall simulator 3, 10, and 24 days after the fertilizer application. The treatments were replicated twice. Grid lysimeters (15 by 15 cm) were placed 75 cm below the soil surface of a Brandt silty clay loam (fine-silty over sandy or sandy skeletal mixed Pachic Udic Haploboroll). Lysimeters were used to collect percolating water temporally and spatially. The application of N fertilizer increased dissolved organic C concentrations in percolating water when rainfall was applied 3 days after the fertilizer application. However, when the rainfall was applied 24 days after the fertilizer application the dissolved organic C concentrations in percolating water was not influenced by anhydrous NH₃ application. The smaller dissolved organic C concentrations in percolating water with a longer incubation time were most likely the result of microbial assimilation or respiration of solubilized C.     

Microbial mineralization of atrazine and 2,4-dichlorophenoxyacetic acid in riparian pasture and forest soils

Microbial biomass and mineralization of atrazine [2-chloro-4(ethylamino)-6(isopropylamino)s-triazine] and 2,4-D (2,4-dichlorphenoxyacetic acid) were examined in the top 10 cm of riparian pasture soils and in the litter layer and top 10 cm of mineral soils of riparian forest ecosystems. The riparian forest litter had higher levels of active and total fungal biomass than forest or pasture mineral soils in winter, spring, and fall. Active bacterial biomass was higher in forest litter than in forest and pasture mineral soils in spring and autumn, and higher in forest mineral soils than in pasture soils in summer. Total bacterial biomass was higher in forest mineral soils than in pasture soils during all seasons. In spring, it was also higher in forest litter than in pasture soils. Atrazie and 2,4-D mineralization in pasture soils was exceeded by that in forest litter in spring and autumn and by that in forest mineral soils in summer and autumn. There was no correlation between either active or total fungal and bacterial biomass with pesticide degradation.     

农田气象条件下阿特拉津在土壤中淋溶动态的数值模拟

阿特拉津(Atrazine)是我国华北地区夏玉米田常用的除草剂,而夏玉米生育期又是该地区的主要降雨时段,对这一时段Atrazine在田间尺度的淋溶风险进行评价,对保护浅层地下水环境具有重要意义。以北京市通州区永乐店试验站一块27 m×27 m的农田为背景,通过田间采样、测试分析土壤样品并收集2001年的气象数据,基于简化土壤水三维流场的柱模型假设,在同时考虑土壤水力学参数、Atrazine运移和吸附参数空间变异性的情况下,对该农药在农田尺度下淋溶动态的空间分布进行了数值模拟。在此基础上,对夏玉米不同生育期耕层20 cm深度处的土壤水负压、水流通量和Atrazine浓度的空间变异结构进行了地质统计学分析。结果表明,在整个夏玉米生育期内这三个参量的半方差模型基本上为球状模型,它们的变程多在8~10 m。本研究案例对布设农田尺度土壤水分和Atrazine动态监控网具有一定的参考意义。     

酶联免疫法测定土壤中莠去津

用定量酶联免疫法对土壤中莠去津的残留进行初筛,然后对阳性样品用气相色谱-质谱法进行确证,并对两种方法的回收率、精密度及检测限进行评价。向土壤样品中分别添加0.3、1.0、3.0μg/kg浓度水平的莠去津标准品时,ELISA的平均回收率为92.20%～97.14%,变异系数为1.69%～4.11%,检测限为0.04μg/kg;GC-MS的平均回收率为85.46%～87.68%,变异系数为2.93%～4.05%,检测限为0.03μg/kg。对酶联免疫试剂盒筛选的3个阳性样品用GC-MS进行确证,测定结果基本一致,结果满意。研究表明酶联免疫法重复性好、准确度较高,是一种土壤中莠去津残留的快速筛选方法。     

除草剂阿特拉津的气相色谱法残留分析

使用ＧＣ－９Ａ气相色谱仪附氮磷检测器测定了阿特拉津在玉米植株及其土壤中的残留情况，检测极限０．０５ｎｇ，变异系数小于１％。