Contrasting pattern of mitochondrial population diversity between an estuarine bivalve, the Kumamoto oyster Crassostrea sikamea, and the closely related Pacific oyster C. gigas

The Kumamoto oyster (Crassostrea sikamea) shows a spatially restricted distribution, favoring estuarine tideland environment. On the other hand, the Pacific oyster (C. gigas) has a broader range of habitat. The present study compared the mitochondrial population structure between the two closely related species. For accurate species identification of oysters sampled from Japanese and East Asian continental coasts, we performed sequencing analysis of the mitochondrial DNA (mtDNA) and PCR-RFLP assay of the first internal transcribed spacer of nuclear rRNA genes. Then, we estimated the extent of population differentiation within each of C. sikamea and C. gigas based on the mtDNA data. Few haplotypes were shared among the sites of sampling in C. sikamea, which contrasted with an extensive haplotype sharing among C. gigas samples. We discuss the mechanisms of elevated population differentiation observed in C. sikamea in light of the ecology and the ancient ocean geography around the present-day habitats.     

甲硫氨酸和水分对土壤挥发性有机硫化物通量的影响

通过静态箱采样和Entech7100预浓缩仪-GC-MS分析了甲硫氨酸和土壤水分对羰基硫(COS)、二甲基硫醚(DMS)、二硫化碳(CS2)和二甲二硫醚(DMDS)等4种挥发性有机硫化合物(VOSCs)吸收或释放的影响.结果表明,土壤水分主要影响土壤COS和DMS通量,含水量低时,土壤吸收COS,释放DMS;接近或超过最大持水量时,土壤释放COS和DMS,且DMS释放速率显著增加,这可能主要受土壤Eh值的影响.添加甲硫氨酸后,土壤DMDS和DMS释放量显著增加,两者释放量接近所观测四种VOSCs总释放量的100%,说明甲硫氨酸是DMDS和的DMS重要前体物,DMDS与DMS释放速率峰值出现时间相同,而COS与CS2释放速率峰值出现时间基本一致,可能是不同VOSCs受不同土壤微生物和酶的影响所致.     

The effect of predation risk on post-copulatory sexual selection in the Japanese pygmy squid

Behavioral Ecology and Sociobiology - The pace-of-life syndrome (POLS) hypothesis predicts that behavior and physiology covary with life history. Evidence for such covariation is contradictory,...     

The impact of institutional factors on the performance of genuine savings

This study investigates institutional factors affecting the performance of genuine savings (GS), which are often used in assessing sustainable development, and adopts a model of autoregressive conditional heteroscedasticity in mean. We pay particular attention to the contribution of institutions to decrease the volatility level of the GS path. The estimation results show that there are two ways in which institutions affect GS performance. First, high quality of institutions enhances the GS level directly. Second, high quality of institutions enhances the GS level via stabilizing the volatility of the GS path. Considering both effects in their totality, institutional improvement plays an important role in realizing a sustainable development path.     

基于稳定碳同位素的济南市二元羧酸类SOA的污染特征与形成机制

为研究济南市冬季PM_2.5中二元羧酸类二次有机气溶胶（SOA）的来源、液相形成机制及影响因素,于2016年1-2月昼夜共采集46个PM_2.5样品,并对二元羧酸类SOA （包括二元羧酸、酮羧酸与α-二羰基化合物）与左旋葡聚糖的昼夜变化特征进行分析.研究结果表明,二元羧酸、α-二羰基化合物与左旋葡聚糖均呈昼低夜高的变化特征,而酮羧酸的昼夜变化特征与之相反.二元羧酸类SOA的分子组成特征以草酸（C₂）的浓度最高,其次是丁二酸（C₄）和丙二酸（C₃）,与受生物质燃烧较显著的二元羧酸类SOA的分子组成是相同的.C₂/总二元羧酸的浓度（TDACs）、甲基乙二醛（mGly）/乙二醛（Gly）、C₂/SO₄^2-比值的昼夜变化特征与稳定碳同位素（δ¹³C）的组成特征均表明济南市冬季夜晚气溶胶的氧化程度比白天深.C₂及其前体物（Gly、mGly）与SO₄^2-、相对湿度（RH）、液相水含量（LWC）与气溶胶的实际酸度（pH_is）的相关性均较强,表明C₂及其前体物是在液相中经酸催化氧化反应产生的.夜晚二元羧酸类化合物的δ¹³C值高于白天,且随着含碳量的升高二元羧酸的δ¹³C值随之降低.C₂的δ¹³C值随气溶胶的老化而偏正,这是由于同位素动力学效应（KIEs）导致的.     

Influence of phosphorus on Microcystis growth and the changes of other environmental factors

The growth processes of Microcystis aeruginosa （FACHB-41） in simulated Taihu Lake water with different phosphorus concentrations were investigated using laboratory microcosms. The algal biomass increased with the increase of phosphorus concentration when it was lower than 0.445 mg/L, while the dissolved oxygen （DO） and pH increased, dissolved inorganic nitrogen （DIN） and light intensity underwater（I） decreased. Responding to the changes of the “environmental factors”, the cellular carbohydrate and its ratio to cellular protein decreased generally as phosphorus increased. However, when phosphorus concentration was higher than l. 645 mg/L, the biomass, the “environmental factors”, the cellular carbohydrate and its ratio to cellular protein did not change likewise. Since the environmental factors and the physiological and biochemical responses are important factors, the change of environmental factors and cell physiology and biochemistry induced by phosphorus may become the key factors that steer the growth and dominance of Microcystis under certain conditions. To sum up, phosphorus not only stimulate the growth of Microcystis directly by supplying nutrient element, but also has complex interactions with other “environmental factors” and play important roles in the growth processes of Microcystis .     

不同生态区土壤溶磷微生物的分布特征及影响因子

研究了盐渍区、重金属污染区和磷矿区土壤中溶磷微生物的数量、组成及与部分土壤化学因子的关系。结果表明,溶磷微生物在不同生态区土壤中的分布各不相同,磷矿区土壤中溶磷微生物数量和种群丰度普遍高于重金属污染区和盐渍区,但优势种属间数量差异不明显。重金属污染土壤中溶磷细菌比例较高,但种群单一,主要以巨大芽孢杆菌(Bacillus megaterium)为优势种,重金属污染区溶磷细菌比例与土壤重金属综合污染指数呈显著正相关(P<0.01),溶磷细菌丰度与有机质含量呈显著正相关(P<0.05)。盐渍土中溶磷细菌比例小,优势种群为巨大芽孢杆菌、假单胞杆菌属(Pseudomonassp.)和黄单胞杆菌属(Flavobacteriumsp.),其数量和种群丰度分别与有机质和有效磷含量呈显著相关关系(P<0.05)。     

南岳旅游客源市场开拓存在的问题及营销策略

客源是旅游业发展的原动力,客源市场分析准确与否,直接决定着旅游投资资金的可行性和安全性．而要把握好旅游客源市场,必须进行深入细致的市场调查与分析．南岳作为全国五大名山之一,近年来虽然旅游环境不断优化,产业素质明显增强,产业规模迅速扩大．但与国内各大知名旅游景区相比,南岳还有很大的差距,许多方面还存在着严重的不足,特别是在旅游市场开拓方面还有巨大的潜力需要发掘,为此,从客源市场特征反映的角度对南岳旅游做出一番有益的探讨,旨在为南岳的旅游发展提出建设性的措施．表4,参3．     

蚯蚓生物滤池处理剩余污泥的效果

以上海市某污水厂剩余污泥为研究对象,对未投加蚯蚓的生物滤池(CBF)和投加蚯蚓的生物滤池(EBF)处理城市剩余污泥的效果进行了比较. 结果表明, EBF 的悬浮固体浓度(SS)减量率、挥发性悬浮固体浓度(VSS)减量率分别可达49.5%~55.6%和60.0%~63.2%,比CBF 分别提高了14.4%~21.7%和22.3%~26.4%. EBF 的出泥VSS/SS,污泥的沉降性比(SVI), 污泥比阻(SRF)分别由原泥的64.8%, 103.4mL/g,5.19×1011m/kg 降至51.8%, 38.4mL/g, 2.00×1011m/kg,而CBF 的出泥VSS/SS、SVI、SRF 则分别为61.0%, 51.8mL/g, 4.12×1011m/kg. 通过蚯蚓－微生物协同作用可以显著提高剩余污泥的减量化和稳定化效果,还能较好地优化污泥的沉降性能、脱水性能.     

交通网络建设与成渝城市群一体化发展——基于交通设施网络和需求网络的分析

交通基础设施建设是城市群一体化发展基本内容和重要保障。以成渝城市群为研究案例，利用复杂网络分析方法，探讨了交通设施网络和交通需求网络下城市群一体化格局，并分析了交通基础设施建设对城市群一体化的影响。结果表明：（1)交通基础设施建设拓展了城市间的联系渠道，有助于形成多中心、均衡化的交通设施网络格局，并塑造城市带和城镇密集区的雏形。（2)以客流衡量的交通需求网络依然呈现以成都和重庆主城为中心的双核心格局，多中心态势并不显著，但高铁的开通增强了城市客流网络。（3)交通设施网络的完善推动了成渝城市群形式一体化，但人口流动、产业合作等表现出的功能一体化水平依然偏低。因此，未来成渝城市群在完善区域交通运输系统的同时需要探索以交通促进城际人口流动、产业合作、城乡统筹等的发展路径，以交通网络建设带动城市群空间结构的优化调整，最终实现区域深度一体化。