Spatial distribution of DDT in sediments from estuarine rivers of central Florida

Sediments may act as both a carrier for and a potential source of contaminants such as toxic organics in aquatic environments. This study investigated the spatial distribution of the pesticide DDT [1,1, 1-trichloro-2,2-bis(p-chlorophenyl)ethane] in sediments from the Cedar and Ortega Rivers located in the lower St. Johns River basin, Florida, USA, using field measurements and three-dimensional kriging analysis. High DDT concentrations were found near the junction of the Cedar and Ortega Rivers and at the north end of the Ortega River in the upper 0.5 m of the sediments, indicating that the sediment was enriched with DDT in the top layer although use of this chlorinated compound was banned in 1972. Further study revealed that the influence of sediment grain size or texture on DDT contamination was negligible in this river system and no linear correlations existed among DDT and its metabolites such as DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane] and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene]. Comparison of three-dimensional distribution of DDT content to the Florida sediment quality assessment guideline or probable effect level (PEL) showed several "hot spots" in the Ortega River sediments, where DDT contents exceeded the PEL value of 4.78 microg kg(-1). Such contamination may pose a significant hazard to aquatic life.     

生物修复重金属污染土壤的研究进展

重金属污染土壤的生物修复是一种环境友好型的污染治理技术，是利用生物体将重金属降解、富集、转移而恢复土壤生态功能的过程。综述了植物修复（植物体内降解、植物根系钝化、植物吸收富集、植物气化）、微生物修复、动物修复等技术的研究进展，分析了生物修复技术在实际应用中存在的问题，并展望了研究方向。     

永磁磁轨制动技术在轨道交通中的应用

介绍国外永磁制动技术在轨道交通中的应用情况;阐述旋转型永磁制动器和直线型永磁制动器的结构和工作原理;对永磁磁轨制动安装方式、控制方法、联合制动模式进行探讨。介绍了直线型永磁制动器的3种磁化形式:Halbach磁化、水平磁化和垂直磁化;运用准静态磁场分析方法,得出了各部分的磁场分布控制方程,矢量磁势A、磁感应强度B和涡流损耗的分布;从而得出了制动力的计算方法。实践证明永磁磁轨制动技术在轨道交通有着广阔的应用前景。     

可持续发展实验区灾害风险定量估算方法研究

作者将探索性数据分析方法引入区域灾害风险的定量估算，系统地建立了区域灾害风险的定量估算方法。计算实例表明，文中给出的方法可便捷地用于可持续发展实验区灾害风险评估。     

Growth responses of the newly-discovered Cd-hyperaccumulator Rorippa globosa and its accumulation characteristics of Cd and As under joint stress of Cd and As

Rorippa globosa has been identified as a newly-found Cd-hyperaccumulating species. In the present study, growth responses of Rorippa globosa and its accumulation characteristics of Cd and As were examined under joint stress of Cd and As. The results showed that Cd and As had an antagonistic effect on enhancing the growth of Rorippa globosa plants and Cd uptake and accumulation under the low concentration Cd and As treatments. When the concentration of Cd in the soil was 10 mg/kg and the concentration of As was 50 mg/kg, the highest growing height of the plant was up to 35.9 cm and the dry weight of the shoots was up to 2.2 g/pot, respectively. Meanwhile, the accumulation of Cd in the leaves under the joint stress was higher than that at the same level under single Cd pollution. However, there were synergic adverse effects on plant growth and Cd uptake under the combined pollution from a high concentration of Cd and As. Meanwhile, the accumulation of As in the roots was greater than that in the shoots, the translocation factor (TF) was ?0.3 and the bioaccumulation factor (BF) was ?0.6, thus showing that Rorippa globosa had an excluding effect on As uptake. These results confirmed that Rorippa globosa had a strong tolerant ability to the joint stress of Cd and As, and the potential for phytoremediation of soils contaminated by Cd and As.     

裸项栉鰕虎鱼仔鱼日摄食量及摄食节律研究

研究裸项栉鰕虎鱼早期发育阶段的日摄食量及昼夜摄食规律,为种苗培育提供技术依据.以孵化7 d的裸项栉鰕虎鱼仔鱼为研究对象,设自然昼夜组(对照组)、持续光照组和持续黑暗组三组,各组每隔2 h取样15尾仔鱼,检查并计算每尾仔鱼胃中的轮虫数,结果表明三组的轮虫日摄食量分别为36.5个/尾、70.7个/尾和1.57个/尾;白天摄食量比例分别为总摄食量的88.0%,67.6%和74.4%;对照组和持续光照组在傍晚(18:00)出现摄食高峰;黑暗组在正午(12:00) 出现一个摄食峰;持续光照组日摄食量为对照组的193.9%,而黑暗组仅为对照组的4.1%,另外,裸项栉鰕虎鱼仔鱼属白天摄食类型,光照对仔鱼摄食影响显著,仔鱼饲育的光照持续时间可比自然白昼延长4 h,投饵主要应在有光时进行.     

我国的环境现状,类型与变化

本文结合区域的社会经济发展状况，通过采用一定的数学模型，分析了我国区域环境现状、类型及其变化，得出了一些有参考价值的结论。     

江苏陆地海岸线绿潮藻种类组成及分布特征

2012年12月—2013年5月对江苏启东蒿枝港至连云港西大堤长约730 km岸线内的69个岸滩堤坝站点进行了绿潮藻种类组成及数量分布调查.结果表明:绿潮藻出现的站点占总设置站点的26.09%,出现绿潮藻岸线长度约占整个江苏调查岸线长度的22.83%;岸滩上绿潮藻主要生长在沿岸石堤、养殖围坝和植被较浅相对稀疏的草滩上,绿潮藻种类组成主要有浒苔(Ulva prolifera)、曲浒苔(Ulva flexuosa)和缘管浒苔(Ulva linza).1—3月浒苔为主要优势种,4—5月曲浒苔为主要优势种,缘管浒苔在历次调查中其湿重生物量均很低.5月岸滩上固着绿潮藻量约36.7 t,不及海上飘来附着在岸滩上绿潮藻量的1/10,岸滩上固着绿潮藻中浒苔的量约为同期海上飘来浒苔湿重生物量的0.6%,岸滩堤坝不会是引起绿潮暴发的主要源头.     

检测细胞DNA断裂损伤效应的彗星实验法的改良

为了解决彗星实验过程中常出现的脱胶、细胞核分离操作繁琐、重复性低等问题,对彗星实验方法进行了改良,初步建立了彗星实验的快速操作流程。结果显示,通过对载玻片进行预处理,可确保凝胶悬挂均匀;采用改良机械法分离的细胞核浓度适中;以0.5%(w/v)涂层琼脂糖作为基层、以1.5%(w/v)低熔点包埋琼脂糖作为叠加层的"双层凝胶法",辅以"推片法"铺胶,操作便捷且不发生脱胶现象;细胞核膜经裂解处理后再进行电泳和荧光观察,彗星图像清晰,杂质少。应用改良后的彗星实验方法,操作简便,耗时更短,实验效果良好,可快速检测出细胞DNA损伤效应。