铅和铬污染包气带及再释放规律的实验研究

利用有机玻璃柱模拟包气带,研究了Pb2+和Cr6+在污染包气带时的迁移转化规律,以及雨水淋洗受污染包气带中重金属再释放规律.结果表明:包气带受重金属污染过程中,铅和铬在粗砂包气带中的迁移速率分别为7.25cm/d和0.4cm/d,远大于其在细砂包气带中的迁移速率4.46cm/d和0.36cm/d,且Cr2O72-形式存在的六价铬在包气带中的迁移速率比的铅离子迁移速率大10倍以上;在模拟实验中,溶液在通过包气带区域时六价铬还原为三价铬的反应很弱,通过包气带的水样中三价铬未检出,并且包气带介质中三价铬含量(0.006mg/kg)几乎为零;雨水淋洗铬和铅污染的粗砂和细砂包气带模拟研究中铅淋洗溶出率为0.056%和0.112%,铬淋洗溶出率为62.33%和40.36%.因此,Cr2O72-在砂质包气带中的迁移性很强且容易从介质表面淋洗去除,而铅在介质中的迁移性较差且很难从介质中淋洗去除掉.     

上海工业区玻璃表面多环芳烃分布特征与溯源

利用GC-MS对上海工业区玻璃表面16种优控多环芳烃(PAHs)进行了定量分析.结果表明,宝山工业区、吴泾化工区和金山化工区玻璃表面PAHs平均含量分别为10.66,16.48,31.94mg/m2,工业区附近对照点PAHs平均含量分别为2.7,8.86,4.18mg/m2.各采样点玻璃表面不同环数PAHs分布特征相似,以3环和4环PAHs为主,平均含量分别占∑16PAHs的25%和47%;其次为5环和6环PAHs,分别占∑16PAHs的14%和9%,最低为2环PAHs,仅占5%.单体PAH以Phe、Fluo、Py和Chry为主.源解析表明,玻璃表面PAHs主要来源于煤和焦炭燃烧,部分来源于石油燃烧.质量标准化毒性当量浓度范围在0.07~3.23mg/g之间,对毒性当量贡献最大的单体PAH分别是BaP,BbF,BkF,DahA.     

快速密闭时火区热物理参数变化规律的研究

在全尺寸巷道火灾试验中,利用48路全自动数据采集系统,研究了快速密闭条件下火区的燃烧状况及温度和压力变化规律.试验发现,作用在风门上的抽吸力很大,很快降到很小;而燃烧区的温度迅速上升,烟及挥发分的产物迅速增加,氧的相对含量下降,之后燃烧减弱,温度迅速下降;燃烧区高温烟气沿着顶板逆向迁移至密闭墙,使附近的温度迅速上升至293 ℃;快速密闭设施必须要有一定的刚性和耐火特性;对贫氧燃烧,有利于火区的惰化,而对富氧高挥发分燃料火灾,有爆炸的危险;适当减少供风量,截断供风后应及时采取惰化措施.     

蔗糖改性纳米铁原位反应带对硝基苯污染的模拟修复研究

在一维模拟装置中创建改性纳米铁原位反应带,研究反应带对硝基苯污染的修复情况,并通过反应带渗透性变化对其可持续修复能力进行评估.模拟试验结果表明:不同条件下硝基苯的去除率为45%~80%;反应带渗透性变化过程按时间分为3个阶段,分别是0~10d的快速下降期、10~30d的缓慢下降期和30~60d的稳定期,平均下降了53.2%,堵塞现象未发生,反应带可持续修复能力较好.较大的介质粒径和浆液浓度使污染物降解效率增加,硝基苯去除率可分别提高23.7%和13.7%;较高的地下水流速和污染物浓度不利于污染物的去除,硝基苯去除率均下降约46.8%.各反应带中实际参与反应的铁与硝基苯的物质的量比值分别为11.2、17.9、12.6、3.3和25.7,改性纳米铁颗粒的实际利用率较低,实际应用中浆液需要过量注入.     

辽宁沿海经济带滨海湿地资源的开发与保护研究

辽宁省拥有丰富多样的滨海湿地资源.随着辽宁沿海经济带升级为国家战略,滨海湿地资源将面临不同程度的开发影响.从辽宁滨海湿地资源禀赋与开发现状人手,分析了滨海湿地资源开发与保护中存在的主要问题,探讨了滨海湿地在沿海经济带开发中的重要功能与地位,并提出实现滨海湿地资源可持续开发利用的对策建议.     

农牧交错带典型区土壤氮磷空间分布特征及其影响因素

土壤氮磷在土壤物理、化学和生物过程中扮演着重要角色,明确土壤氮磷含量和空间分布对土壤资源管理和利用具有重要意义.利用经典统计学和地统计学方法对准格尔旗土壤全氮和全磷空间分布特征及影响因子进行研究.结果表明,研究区土壤肥力水平较低,0~100 cm深度土壤全氮和全磷含量加权平均值分别为0.29 g·kg^-1和0.26 g·kg^-1.土壤全氮和全磷的块金效应值分别集中在0.15~0.43和0.34~0.53之间,表明土壤全氮（0~10 cm和80~100 cm除外）和全磷呈中等空间依赖性,空间变异由结构性和随机性因子共同主导.土壤全氮和全磷空间分布特征与土层和元素有关,即使在同一深度,土壤氮磷的空间分布特征亦不相吻合.土壤全氮主要受有机碳的影响,而土壤全磷主要受纬度、海拔、土地利用类型和土壤质地的影响.     

Responses of decomposition rate and nutrient release of floating-leaved and submerged aquatic macrophytes to vertical locations in an urban lake (Nanhu Lake,China)

A leaf-bag field experiment was conducted to investigate the decomposition and release of nutrients from leaves of two aquatic macrophytes (floating-leaved Trapa bispinosa and submerged Vallisneria natans) deposited in the four vertical locations (i.e. air-water interface, AW; sediment-water interface, SW; buried at a depth of 10?cm, B10; buried at a depth of 20?cm, B20) of littoral zone in Nanhu Lake, China, for 60 days from July to August 2015. Leaf initial quality significantly influenced mass loss and nutrient release except TN (total nitrogen) remaining. Compared to V. natans, T. bispinosa leaves decomposed faster under the same treatments. The decomposition was greatly affected by both leaf chemical quality and the location of deposition. With the increasing depth of vertical locations, leaf biomass loss and nutrient release of both T. bispinosa and V. natans decreased. In addition, initial N:P ratio and cellulose were the major determinants for decomposition in AW and SW treatments while total phenol in B10 and B20. Our results suggest that the combined effect of leaf chemical quality and burial could mediate macrophyte mass loss and release of nutrients and carbon, which in turn can influence organic matter accumulation and nutrient cycling in shallow freshwater lakes.     

Urban Flora as a Component of the Urban Ecosystems in the Taiga Zone: An Example of Karelian Cities

Cities are areas of increased diversity of species in the taiga zone. The aboriginal fraction of Karelian flora is a stable natural system whose main characteristics are preserved in the urban flora. The adventive fraction, which is a dynamic component of the flora, has not been completely formed in the cities, as well as in eastern Fennoscandia as a whole. It has become substantially richer during the past 20–25 years. Cities of the taiga zone may serve as objects for monitoring the anthropogenic processes of flora transformation in the North.     

Natural and Anthropogenic Methane Emission from Coastal Wetlands of South India

For the first time, the methane emissions from diverse coastal wetlands of South India have been measured. Annual emission rates varied widely, ranging from 3.10 mg/m²/hr (Bay of Bengal) to 21.56 mg/m²/hr (Adyar River), based on nature of the perturbance to each of the ecosystems studied. Distinct seasonality in methane emission was noticed in an unpolluted ecosystem (mangrove: 7.38 mg/m²/hr) and over a twofold increase was evident in the ecosystem that was disturbed by human activities (21.56 mg/m²/hr). The wide ranges in estimate suggest that methanogenesis occurs by both natural and anthropogenic activities in these coastal wetlands. Several physical and chemical factors such as salinity, sulfate, oxygen, and organic matter content influenced methanogenesis to a large degree in each of these ecosystems in addition to individual responses to human-induced stress. For example, there was a clear negative correlation between oxygen availability (0.99), sulfate (0.98), and salinity (0.98) with CH₄ emission in the Adyar river ecosystem. Although similar results were obtained for the other wetland ecosystems, CH₄ emission was largely influenced by tidal fluctuations, resulting in a concomitant increase in methanogenesis with high sulfate concentrations. This study demonstrates that coastal wetlands are potentially significant sources of atmospheric methane and could be a greater source if anthropogenic perturbations continue at the current rate. RID=" ID=" *Author to whom correspondence should be addressed.     

Remote Sensing of Landscape-Level Coastal Environmental Indicators

Advances in technology and decreases in cost are making remote sensing (RS) and geographic information systems (GIS) practical and attractive for use in coastal resource management. They are also allowing researchers and managers to take a broader view of ecological patterns and processes. Landscape-level environmental indicators that can be detected by Landsat Thematic Mapper (TM) and other remote sensors are available to provide quantitative estimates of coastal and estuarine habitat conditions and trends. Such indicators include watershed land cover, riparian buffers, shoreline and wetland changes, among others. With the launch of Landsat 7, the cost of TM imagery has dropped by nearly a factor of 10, decreasing the cost of monitoring large coastal areas and estuaries. New satellites, carrying sensors with much finer spatial (1-5 m) and spectral (200 narrow bands) resolutions are being launched, providing a capability to more accurately detect changes in coastal habitat and wetland health. Advances in the application of GIS help incorporate ancillary data layers to improve the accuracy of satellite land-cover classification. When these techniques for generating, organizing, storing, and analyzing spatial information are combined with mathematical models, coastal planners and managers have a means for assessing the impacts of alternative management practices.