"合作学习法"在排球教学中的研究

笔者以文献资料法、数理统计法、调查法、实验法为研究方法,在防灾科技学院排球基本技术教学中进行了合作教学的实验研究.结果表明:"合作学习法"是适合防灾科技学院排球基本技术教学的一种有效的教育理论;在防灾科技学院排球基本技术的教学中运用"合作学习法",学生出勤率高,学习态度踏实,教学效果明显,课外自觉参加排球运动的次数明显增加.     

浅议步云工业集中区环境安全措施与对策

根据南湖区步云工业集中区化工企业集聚、环境风险高的特点,提出强化综合决策,保障环境安全,大力发展循环经济,实施生态园区建设,加强环境监督管理等环境安全战略对策。     

边坡稳定性影响因素敏感性的两种分析结果比较

作者在刘立鹏,于红杰发表的论文基础上,采用通径系数分析方法,对影响边坡稳定性的因数进行了敏感性分析,并将分析结果与刘立鹏,于红杰灰的灰色关联分析进行了比较,结果表明：土质边坡的稳定性受土体的物理力学因素影响大,受地形地貌因素影响小;在土体的物理力学因素中,粘聚力的影响最大;在地形地貌因素中,坡角的影响最大。     

Rotary ultrasonic machining of potassium dihydrogen phosphate (KDP) crystal: An experimental investigation on surface roughness

Potassium dihydrogen phosphate (KDP) crystal, widely used for important electro-optic parts, is a typical hard-to-machine material because of its soft, brittle, and anisotropic properties. High quality is usually required for machined surfaces on KDP parts. Reported machining methods for KDP crystal include diamond turning, grinding, magnetorheological finishing, and polishing. Each of these methods has its limitations. Therefore, it is desirable to develop new machining methods for KDP crystal. This paper presents an experimental investigation on surface roughness in rotary ultrasonic machining (RUM) of KDP. It was found that the surface roughness obtained when using a tool with a chamfered corner was lower than that obtained using tools with right-angle corners. Other process variables (spindle speed, feedrate, and ultrasonic power) also affected the surface roughness obtained.     

螯合剂和泥炭对苎麻吸收土壤镉的影响

通过生物盆栽试验研究了施用螯合剂(EDTA、柠檬酸)与泥炭对强化苎麻修复重金属镉污染土壤的作用.结果表明,施加泥炭能改善土壤的理化性质,增加苎麻的生物产量,泥炭单施、螯合剂(EDTA、柠檬酸)和泥炭的组合措施的相对产量分别为1.23、1.13和1.41,因此泥炭和柠檬酸配施处理更有利于植物生长.就植物吸收镉能力来说,螯合剂(EDTA、柠檬酸)和泥炭的配施处理能更好地促进苎麻对镉的吸收,其土壤交换态镉所占镉形态质量分数为61.6%和58.3%,具有强化植物修复的效果.螯合剂(EDTA、柠檬酸)和泥炭2种组合方式的地上部富集系数分别为1.33和1.32,大于单施(EDTA、柠檬酸和泥炭)处理1.11、1.11和1.05,具有较好的富集效应,同时螯合剂(EDTA、柠檬酸)和泥炭的组合处理对土壤镉的净化率分别达到了1.13%和1.22%,而柠檬酸和泥炭配施具有较大的生物量,使植株总镉量略高于EDTA与泥炭的组合处理,因而更有利于镉污染土壤的修复.因此,利用螯合剂和泥炭的组合修复措施对强化苎麻修复镉污染土壤能取得更佳的效果.     

小城镇环境承载力评价——以江苏省铜山县为例

在大量收集铜山县近几年统计资料的基础上,根据区域环境承载力指标体系的构建原则,从人口、自然资源、生态环境和社会经济状况等方面构建指标体系。共选取指标39个,其中发展类指标27个,限制类指标12个。按照指标体系的层次结构构造判断矩阵,采用层次分析法确定指标的权重。根据铜山县“十五”期间相关部门的统计数据和监测数据,以及生态县建设的相关指标,并结合各类指标的国际国内标准和江苏省的平均标准确定指标的现状值和指标阈值。采用环境承载力相对剩余率法计算2000年-2005年的环境承载力相对剩余率。结果表明,在这一期间,铜山县的综合环境承载力整体处于超载状态,其中人口控制、第三产业发展、矿产资源以及工业废水废气的治理等指标发展较好。不足之处体现在经济的发展还是建立在高能耗、高污染物排放的基础上,人均自然资源量偏低,高新技术产业占规模以上工业比重较低,科研教育以及环保投入尚不足等。随着环境治理投入的加大,综合环境承载力呈上升趋势,环境状况逐渐好转。根据评价结果,结合铜山县的发展现状,从优化产业结构、加强污染防治以及加强生态建设和法律法规建设等方面提出提高铜山县环境承载力的途径和对策。     

Modified accumulation of selected heavy metals in Bt transgenic rice

Safety assessment of genetically modified crops generally does not take into account the potential hazard of altered patterns of heavy metal accumulation in plants. A pot experiment was conducted under greenhouse conditions to evaluate the impact of heavy metal amendments on the accumulation of Cd, Cu, Pb and Zn in a Bt transgenic rice Ke-Ming-Dao (KMD) and its wild-type Xiushui 11 (Xs11). In control soils, significant di erence was only found in contents of Cu (p < 0.01) and Pb (p < 0.05) in straw between KMD and Xs11. At three levels of Cd amendments (5, 10, and 20 mg/kg), the Cd contents in grain and straw of KMD were significantly higher than those of Xs11, and all grain Cd contents were significantly higher than the International Criteria (0.2–0.4 mg/kg) as specified by the Codex Alimentarius Commission (CAC). These results implied that it may be unsafe for growing Bt transgenic rice in heavily Cd-polluted areas. No significant di erence in Zn was found between the two varieties with the exception of roots at Zn amendment level of 600 mg/kg, while Pb contents in KMD were much higher in the straw at the lead amendment level of 1000 mg/kg and in the root at 250 mg Pb/kg. Data on the heavy metal accumulation patterns for the genetically modified rice may be used for the selection of growing areas as well as for plant residue management for Bt rice.     

持久性有机污染物的作物吸收及迁移模型研究进展

持久性有机污染物(Persistent Organic pollutant,POPs)是指通过各种环境介质(大气、水、生物体等)能够长距离迁移并长期存在于环境中的人工合成的有机污染物。本文阐述了全球POPs的主要环境过程和各环境介质中POPs的暴露水平,探讨了作物对POPs的吸收过程、吸收机制和生态效应,并基于现有的环境多介质逸度模型和根区水质模型,分析了持久性有机污染物作物吸收过程模拟模型中存在的问题及未来的发展方向。目前,对POPs作物吸收机制及其模拟的研究较少,但随着我国对粮食安全和农业可持续发展的持续关注,这一领域的模拟研究将对科学解析POPs归趋、合理制定风险管控措施和有效确保粮食质量安全等提供重要科学支撑。     

Stabilization of hexavalent chromium with pretreatment and high temperature sintering in highly contaminated soil

• Separate reduction and sintering cannot be effective for Cr stabilization. • Combined treatment of reduction and sintering is effective for Cr stabilization. • Almost all the Cr in the reduced soil is residual form after sintering at 1000°C. This study explored the effectiveness and mechanisms of high temperature sintering following pre-reduction with ferric sulfate (FeSO₄), sodium sulfide (Na₂S), or citric acid (C₆H₈O₇) in stabilizing hexavalent chromium (Cr(VI)) in highly contaminated soil. The soil samples had an initial total Cr leaching of 1768.83 mg/L, and Cr(VI) leaching of 1745.13 mg/L. When FeSO₄ or C₆H₈O₇ reduction was followed by sintering at 1000°C, the Cr leaching was reduced enough to meet the Safety Landfill Standards regarding general industrial solid waste. This combined treatment greatly improved the stabilization efficiency of chromium because the reduction of Cr(VI) into Cr(III) decreased the mobility of chromium and made it more easily encapsulated in minerals during sintering. SEM, XRD, TG-DSC, and speciation analysis indicated that when the sintering temperature reached 1000°C, almost all the chromium in soils that had the pre-reduction treatment was transformed into the residual form. At 1000°C, the soil melted and promoted the mineralization of Cr and the formation of new Cr-containing compounds, which significantly decreased subsequent leaching of chromium from the soil. However, without reduction treatment, chromium continued to leach from the soil even after being sintered at 1000°C, possibly because the soil did not fully fuse and because Cr(VI) does not bind with soil as easily as Cr(III).     

有毒物质对水生态系统效应研究的进展

本文总结了近年来有毒物质对水生态系统的生态效应研究现状及发展趋势,提出了今后测定有毒物质生态效应应该注意的问题。