Insights into multidimensional transport flux from vertical observation and numerical simulation in two cities in North China

This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM_2.5) within the ABL during heavy pollution. From the perspective of the transport flux balance relationship, differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect. The FT mainly flowed into the ABL in BJ, while in SJZ, the outflow from the ABL to the FT was more intense. Combined with an analysis of vertical wind profile distribution, BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter, while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ. In addition, we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event. These results showed that ABL-FT interaction played an important role in PM_2.5 concentration within the ABL during heavy pollution. Especially in the early stage of heavy pollution, FT transport contributed as much as 82.74% of PM_2.5 within the ABL. These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.     

陆地与海洋气溶胶的相互输送及其对彼此环境的影响

陆地和海洋源产生的气溶胶通过大气的流动向对方的环境系统输送，从而改变了对方环境大气的化学组成，影响着大气污染物的化学反应过程和反应速度，其沉降过程也会对对方的生态系统产生一定的影响。；沿海的岖稠密的人口。较为发达的经济活动，较高的大气污染排放强度，使得陆海气溶胶的交换和沉降对谝我域的环境具有不可忽视的影响。     

上海地区高空气流长距离输送轨迹及其与酸雨的关系

分析了影响上海地区的高空气流输送轨迹。不同月份影响上海的高空气流来向不一。轨迹输送路径与天气系统的变化密切有关,且与上海地区出现的酸雨有关。研究表明,上海地区的酸雨,除与局地污染有关外,还与远处输送的外来污染有关。这些外来污染影响,主要来自上海西南向的北部湾和两广等地。也有部分来自东北——东方向的南朝鲜和日本西部地区。     

细河底泥污染特征分析

应用分析技术手段 ,对细河底泥污染状况进行监测、调查 ,从而了解细河底泥污染状况 ,并分析主要污染物的分布特征     

阿拉伯半岛沙尘时空分布特征及气象条件

通过对阿拉伯半岛地面90个气象站20年沙尘天气、AI指数及风场的时空分布特征结合气象条件分析，确定该区域沙尘天气的发生规律及传输路径.结果表明：永久多尘地区是半岛扬沙发生最频繁的区域，从2月开始扩张，并在6月达到最大.浮尘的时空分布与扬沙类似，但还存在希贾兹山脉北部和波斯湾沿岸的高值中心，3月与永久多尘地区的高值区连成一片，6~7月达到最大，然后开始收缩并分裂成几个小中心.AI指数存在一个像倒箭头的相对高值中心，其变化具有明显的单峰分布，强度和范围在6月最大.10~4月和5~9月半岛分别盛行顺时针、逆时针旋转的风向，它们将沙尘远程传输到下游地区.天气学分析表明，冷锋入侵半岛使得来自北方的冷空气快速锲入暖空气之下，是导致沙尘天气出现的主要原因；后向轨迹聚类分析显示，半岛存在3类传输路径，其重要性依次为西北方向撒哈拉沙漠的远程传输、反气旋风场将来自伊拉克或伊朗的沙尘远程传输和本地的沙尘源传输.     

Impact of triazophos insecticide on paddy soil environment

ＩｎｔｒｏｄｕｃｔｉｏｎＲｉｃｅｉｓｔｈｅｓｔａｐｌｅｄｉｅｔａｒｏｕｎｄ 3 0 %ｏｆｔｈｅｗｏｒｌｄｐｏｐｕｌａｔｉｏｎａｎｄａｒｏｕｎｄ 60 %ｏｆｔｈｅＡｓｉａｎｐｏｐｕｌａｔｉｏｎ .Ｔｈｉｓｃｒｏｐｉｓｐｒｅｆｅｒｅｎｔｉａｌｌｙｏｒｇｅｎｅｒａｌｌｙｃｕｌｔｉｖａｔｅｄｕｎｄｅｒｓｕｂｍｅｒｇｅｄｓｏｉｌｃｏｎｄｉｔｉｏｎｓｆｏｒｒｅａｓｏｎｓｏｆｂｅｔｔｅｒｙｉｅｌｄｓａｎｄｔｏｐｏｇｒａｐｈｉｃａｌｓｉｔｕａｔｉｏｎｓ(Ｒｅｉｃｈａｒｄｔ,1 997) .Ｔｈｅｉｍｐｏｒｔａｎｃｅｏｆｓｏｉｌｍ…     

论交通结构调整与交通可持续发展

从社会经济可持续发展理论出发，分析了交通发展对资源和环境的影响，阐述了交通可持续发展的内涵，针对当前交通发展所面临的问题，提出了当前要加快交通结构调整的方针，并指明了要做好的相关工作，以促进交通可持续发展。     

Paradise Threatened: Land Use and Erosion on St. John, US Virgin Islands

2 /yr, respectively. Geomorphic evidence indicates that plantation agriculture during the 18th and 19th centuries did not cause severe erosion. Since about 1950 there has been rapid growth in roads and development due to increasing tourism and second-home development. Our field investigations identified the approximately 50 km of unpaved roads as the primary source of anthropogenic sediment. Field measurements of the road network in two catchments led to the development of a vector-based GIS model to predict road surface erosion and sediment delivery. We estimate that road erosion has caused at least a fourfold increase in island-wide sediment yields and that current sedimentation rates are unprecedented. Paving the dirt roads and implementing standard sediment control practices can greatly reduce current sediment yields and possible adverse effects on the marine ecosystems surrounding St. John.     

PROFILE: Hungry Water: Effects of Dams and Gravel Mining on River Channels

/ Rivers transport sediment from eroding uplands to depositional areas near sea level. If the continuity of sediment transport is interrupted by dams or removal of sediment from the channel by gravel mining, the flow may become sediment-starved (hungry water) and prone to erode the channel bed and banks, producing channel incision (downcutting), coarsening of bed material, and loss of spawning gravels for salmon and trout (as smaller gravels are transported without replacement from upstream). Gravel is artificially added to the River Rhine to prevent further incision and to many other rivers in attempts to restore spawning habitat. It is possible to pass incoming sediment through some small reservoirs, thereby maintaining the continuity of sediment transport through the system. Damming and mining have reduced sediment delivery from rivers to many coastal areas, leading to accelerated beach erosion. Sand and gravel are mined for construction aggregate from river channel and floodplains. In-channel mining commonly causes incision, which may propagate up- and downstream of the mine, undermining bridges, inducing channel instability, and lowering alluvial water tables. Floodplain gravel pits have the potential to become wildlife habitat upon reclamation, but may be captured by the active channel and thereby become instream pits. Management of sand and gravel in rivers must be done on a regional basis, restoring the continuity of sediment transport where possible and encouraging alternatives to river-derived aggregate sources.KEY WORDS: Dams; Aquatic habitat; Sediment transport; Erosion; Sedimentation; Gravel mining     

Development of Layered Sediment Structure and its Effects on Pore Water Transport and Hyporheic Exchange

Hyporheic exchange is known to provide an important control on nutrient and contaminant fluxes across the stream-subsurface interface. Similar processes also mediate interfacial transport in other permeable sediments. Recent research has focused on understanding the mechanics of these exchange processes and improving estimation of exchange rates in natural systems. While the structure of sediment beds obviously influences pore water flow rates and patterns, little is known about the interplay of typical sedimentary structures, hyporheic exchange, and other transport processes in fluvial/alluvial sediments. Here we discuss several processes that contribute to local-scale sediment heterogeneity and present results that illustrate the interaction of overlying flow conditions, the development of sediment structure, pore water transport, and stream-subsurface exchange. Layered structures are shown to develop at several scales within sediment beds. Surface sampling is used to analyze the development of an armor layer in a sand-and-gravel bed, while innovative synchrotron-based X-ray microtomography is used to observe patterns of grain sorting within sand bedforms. We show that layered bed structures involving coarsening of the bed surface increase interfacial solute flux but produce an effective anisotropy that favors horizontal pore water transport while limiting vertical penetration.