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近年来,快速发展的高速铁路、城际轨道等高速交通方式对旅游的影响日益显现。本文以珠三角地区运营和规划城际轨道为例,基于GIS网络分析技术和通达性指标,探讨了城际轨道通车前后对珠三角地区旅游空间格局的影响。结果表明:城轨开通将会产生显著的"时空压缩"效应,旅游景点总通达时间降幅达32.87%,旅游景点平均通达时间减少0.7 h;不同区域通达性水平提升具有差异性,城际轨道站点及其周边地区成为通达性水平提升最大的地区,随着与站点距离逐渐增加,通达性变化程度逐渐降低;城轨开通后各地区通达性水平差异逐渐缩小,并趋于均衡;城轨影响下的旅游景点通达性的影响具有"廊道效应"与"隧道效应"相结合的特征,空间格局由开通前的"中心-外围"态势向面状均衡分布格局转变。城际轨道带来的"时空压缩"效应,在扩大了旅游景点市场范围的同时,由于通行时间成本降低,进一步提高了旅游出行的效率。 相似文献
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SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0,whereby sulfite is yielded from the disassociation of protons.We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension.Chlorella sp.XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions.Under light conditions,sulfite concentration in the algal suspension reduced linearly over time,and was completely converted into sulfate within 8 h.The highest sulfite transformation rate(3.25 mmol/(L·h)) was obtained under the following conditions:35°C,light intensity of 300μmol/(m2·s),NaHCO3 concentration of 6 g/L,initial cell density(OD540) of 0.8 and pH of 9-10.There was a positive correlation between sulfite transformation rate and the growth of Chlorella,with the conditions favorable to algal growth giving better sulfite transformation.Although oxygen in the air plays a role in the transformation of SO2-3 to SO2-4,the transformation is mainly dependent on the metabolic activity of algal cells.Chlorella sp.XQ-20044 is capable of tolerating high sulfite concentration,and can utilize sulfite as the sole sulfur source for maintaining healthy growth.We found that sulfite 20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae.Thus,the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp.XQ-20044,without preliminary removal of SO2,assuming there is adequate control of the pH. 相似文献
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