Predicting herbicides concentrations in paddy water and runoff to the river basin

This study was conducted to investigate the dissipation pattern and runoff of herbicides to the river basin from the paddy fields. Pesticide paddy field model(PADDY) was applied to predict herbicide concentration in paddy fields. A field study was conducted in a paddy farm of Higashi Hiroshima City, Hiroshima Prefecture, Japan in the year of 2003 paddy season. The herbicides were mefenacet, thiobencarb, and bensulfuron methyl. The sample water was analyzed by using gas chromatography and HPLC after solid phase extraction. Predicted dissipation rate of thiobencarb in paddy water was higher( DT50=4.36) than that measured, with a lower k value(-0.069). Two weeks after application no thiobencarb was detected in the drainage channel and down stream. In the down stream, thiobencarb was detected until 3d after application, with a range of 0.02% to 0.08% of applied herbicide. The predicted dissipation rate(k) and half-life (DT50) of mefenacet was not significantly different from that of measured. In the drainage channel, upstream and downstream mefenacet was found during the whole study period. In downstream, the maximum concentration of mefenacet was present 0.6l % of applied in the paddy field on 3DAH. The dissipation rate(k) of BSM varied from -0.0860 to -0.1059 to with half-life(DT50) 3.5 and 2.84 d. In upstream water, no BSM was detected except trace amounts(0.01μg/L) at 3d after application. However, in the drainag echannel 8%, 6% and 1.58% of applied BSM was present at 0, 1 and 3 d after application respectively. In the down stream, the highest concentration was 1.06%, shortly after application.     

滇池风场的基本特征分析

采用滇池周围气象站和一期高密度的地面风观测资料，初步分析了不同季节滇池风场的基本特征和风场的日变化情况，并给出了滇池风场的4种环流型结构。即湖风环流型，陆风环流型，偏西风环流型和偏东风环流型。     

地勘企业高危作业危害辨别及控制措施

根据目前地勘企业的生产状况，指出了地勘企业生产过程中存在高危作业危害，如非煤矿山开采，基础灌注工程施工，有毒有害化学物品及易燃、易爆品等，管理不好，都会产生危害。本文还探讨了安全防治措施。     

中心流场湿式除尘器的试验研究

中心流场湿式除尘器通过在筒体内设置导流百叶窗来减轻内涡旋 ,使除尘器的压力损失大大降低 ,同时在筒体上设两根进水管 ,采用湿式除尘 ,又提高了除尘器的除尘效率。本文介绍了该除尘器的结构特点、工作原理、试验台系统的设计以及主要性能的测试结果     

半无限体压入问题的流函数解法

对平冲头压入半无限体问题建立了流函数速度场,证明该场散度为零,旋度不为零,为管形场。采用上界定理对该速度场积分结果与滑移线结果一致,流线为一族曲线滑移线。     

氟化氢对水稻和青菜产量的影响

利用开顶式熏气装置,对水稻和青菜进行长时间的HF暴露试验。通过在熏气过程中对叶片电导率、含氟量和脯氨酸的分析比较,以及在熏气结束后对水稻穗数、千粒重和青菜鲜重的生物量统计测定,讨论和评价了HF对该作物产量的影响。     

佘山台地磁场长期变化基本特征

本文根据佘山台1900年~2004年地磁观测资料,对该地区F、H、Z、D地磁各要素长期变基本特征进行了分析总结,对深入研究地球基本磁场的变化有一定意义。     

佳木斯台形变观测对东北地区几次浅震"场兆"异常的探讨

大地震在主破裂前往往行成地壳变形,高应力作用下进入峰值后的变形阶段,反映到地倾斜观测日均值曲线上,表现为固体潮形变趋势异常,这些异常能否指示远距离的地震,近年来不少研究者发现,远场前兆往往出现在对应力、应变变化反应灵敏的特殊构造部位.佳木斯台可能处于这种特殊的构造部位,对东北地区浅源地震短期前兆异常"场兆"的趋势性变化具有一定的意义.     

乌江下游德江县喀斯特石漠化及其防治

基于TM影像解释和实地考察,查清了德江县石漠化面积为70 693 hm~2、占全县土地总面积的34．1％,划分了石漠化强度(中度以上的石漠化面积占全县总面积的16．6％),明确了德江县石漠化的空间分布格局;分析了德江石漠化的危害;从地形地貌、岩性、降水、耕种方式等方面探讨了石漠化的成因,最后提出了德江县石漠化综合防治对策。     

A new O2-microelectrode and its application

A new oxygen microelectrode was introduced. An internal guard cathode was added besides its normal cathode sensor. It has a low zero measuring current, high signal stability and its easy to construct. As it is small in size and high in stability, it may be used not only for routine environmental application, but for other scientific research work as well.