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203.
通过Quick Bird、ZY-3商业卫星影像遥感解译提取台雄水库周围区域2008年、2018年共2期的土地利用数据,基于叠图法、景观指数法分析了水库建设前后土地利用空间分布格局、变化特征等。主要结论如下:台雄水库采取了有效的植被恢复措施,工程建设对自然植被尤其是森林植被的影响有限,工程建设和运行基本未改变生态系统总体异质性,对区域生态体系的阻抗稳定性影响不大。 相似文献
204.
Implications of Land Use/Land Cover Change in the Buffer Zone of a National Park in the Tropical Andes 总被引:2,自引:0,他引:2
The impacts of land use and land cover (LULC) change in buffer zones surrounding protected ecological reserves have important
implications for the management and conservation of these protected areas. This study examines the spatial and temporal patterns
of LULC change along the boundary of Rio Abiseo National Park in the Northern Peruvian Andes. Landscape change within four
ecological zones was evaluated based on trends expected to occur between 1987 and 2001. Landsat TM and ETM imagery were used
to produce LULC classification maps for both years using a hybrid supervised/unsupervised approach. LULC changes were measured
using landscape metrics and from-to change maps created by post-classification change detection. Contrary to expectations,
tropical upper wet montane forest increased despite being threatened by human-induced fires and cattle grazing of the highland
grasslands inside the park. Within the park’s buffer zone, tropical moist forest remnants were fragmented into more numerous
and smaller patches between 1987 and 2001; this was in part due to conversion into agricultural land. The methods used in
this study provide an effective way to monitor LULC change detection and support the management of protected areas and their
surrounding environments. 相似文献
205.
青岛近岸海域二甲基硫排放和大气中二甲基硫浓度变化 总被引:7,自引:1,他引:6
为研究我国受人为干扰严重的近岸海域DMS排放规律,利用固体吸附-解吸的富集采样方法和冷却预浓缩的分析方法,分别在2001年夏秋季和2002年春秋季,对青岛近岸海域海水和大气中的二甲基硫进行了采样和分析.结果表明,海水中DMS浓度和海气排放通量呈现明显的空间分布和季节变化.夏季,青岛近岸的海水DMS平均浓度最高,达1169.47 ng·L-1;春季最低,只有226.99 ng·L-1.河口区、风景旅游区和奥运赛场区在夏季有显著的从高到低的浓度梯度变化,而春秋季不明显.DMS海气排放通量主要由海水浓度决定,因此两者呈现一致的变化规律.海洋大气中的DMS也呈现夏季较高(256.44 ng·m-3),秋季较低(195.64 ng·m-3)的季节变化.文中还初步探讨了大气DMS的日变化情况. 相似文献
206.
Lake Sapanca is exposed to heavy urbanization and industrialization because of its natural beauty and its proximity to the
metropolitan İstanbul, Turkey. In this study, it was aimed to investigate seasonal changes of some heavy metals (Pb, Cr, Cu,
Mn, Ni, Zn and Cd) concentration of surface sediment. Nine different stations were chosen as sampling points. Samples were
taken every three months and the seasonal and annual average concentration of the elements were determined. Seasonal highest
values of heavy metals were observed as follows; Cr, Cu, Mn, Ni and Zn in Summer, Cd in Autumn. There was no seasonal difference
for Pb, Cr and Cd. It seems that Lake Sapanca has not been polluted yet. However, it was found that Cu and Ni concentrations
in surface sediment exceed lowest effect level. 相似文献
207.
The spring waters of Tuzla–Icmeler are on the Marmara Sea coast in Tuzla town of Istanbul city. The springs discharge a natural
sodium chloride mineral water that consumed for ages for therapeutic purposes attributed to their chemical properties. Development
of springs commenced during the Ottoman times and a surface collection structure was built at the discharge point of the main
spring. Two deep wells were drilled to tap mineral water within the past decades. The bottled water of these springs is also
sold for a couple of years and its consumption as a beverage is increasing. The geochemical properties of these springs were
investigated by several researchers in the past. This study comprises geochemical and geophysical measurements performed between
July 2001 and July 2002 in order to construct a conceptual hydrogeological model for environmental and land use planning purposes.
The seasonal evaluation of Tuzla–Icmeler (mineral spring) shows that the chemical properties fluctuate from the beginning
of summer until the beginning of winter. This indicates that the overdraft of water during the summer season causes the movement
and mix of normal groundwater with the mineralized groundwater. As a result, mixing of less mineralized groundwater decreases
the salinity of mineralized groundwater. Using the site-specific hydrogeological, geochemical and geophysical data, zones
of protection areas were delineated in order to prevent a possible pollution access to the springs and surroundings from nearby
dockyards, dwellings and vehicle traffic. For this purpose, a new land use plan was proposed using the existing settlement
sustainability plans. 相似文献
208.
Isoprene is a dominant constituent of the global biogenic volatile organic compounds budget. It plays an important role in
regulating the atmospheric trace gas composition including tropospheric ozone concentrations. In this study, monthly measurements
of isoprene emission rates were carried out over a 1-year period (December 2002–November 2003) from four Indian deciduous
tree species, namely Ficus relegiosa, Ficus infectoria, Pongamia pinnata, and Morus alba, using branch enclosure method. Significantly high monthly variations in isoprene emission rates were observed in all four-plant
species. Also, each plant species exhibited pronounced seasonal variation in isoprene emission. Maximum isoprene emissions
were observed during summer and minimum during the winter or spring months. 相似文献
209.
Simultaneous ground-based measurements of ozone and carbon monoxide were performed at Oki, Japan, from January 2001 to September 2002 in order to investigate the O(3) and CO characteristics and their distributions. The observations revealed that O(3) and CO concentrations were maximum in springtime and minimum in the summer. The monthly averaged concentrations of O(3) and CO were 60 and 234 ppb in spring and 23 and 106 ppb in summer, respectively. Based on direction, 5-day isentropic backward trajectory analysis was carried out to determine the transport path of air masses, preceding their arrival at Oki. Comparison between classified results from present work and results from the year 1994-1996 was carried out. The O(3) and CO concentration results of classified air masses in our analysis show similar concentration trends to previous findings; highest in the WNW/W, lowest in N/NE and medium levels in NW. Moreover, O(3) levels are higher and CO levels are lower in the present study in all categories. 相似文献
210.
In this study, a denitrification (DN)–partial nitritation (PN)–anaerobic ammonia oxidation (Anammox) system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device, and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control environment were explored. The results showed that as the seasonal temperature decreased from 34°C to 11.3°C, the total nitrogen removal rate of the DN-PN-Anammox system gradually decreased from the peak value of 1.42 kg/(m3?day) to 0.49 kg/(m3?day). At low temperatures (<20°C), when the nitrogen load (NLR) of the system is not appropriate, the fluctuation of high NH4+-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal. At temperatures of 11°C–15°C, the NLR of the system is controlled below 0.5 kg/(m3?day), which can achieve stable nitrogen removal and the nitrogen removal efficiency can reach above 96%. The abundance of Candidatus Brocadia gradually increased with the decrease of temperature. Nitrosomonas, Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature. 相似文献