长三角城市群“空间流”网络结构特征——基于公路运输、火车客运及百度指数的综合分析

信息技术的应用与社会信息技术的传输,使大量的要素(人流、物流、信息流)在城市群空间内集聚与扩散,加密城市群空间内城市联系。在基于公路运输、普通列车、高速列车以及百度指数4个要素的综合分析基础上,对长三角城市群"空间流"网络结构特征进行探析。研究结果表明:(1)长三角城市群区域内城市联系虽具备了网络化规模,但城市间的联系不均衡,以上海、南京、杭州等城市为多中心的协调网络发展格局特征明显;(2)长三角城市群16个核心城市"空间流"特征呈现三角形网络结构,其三角形的顶角分别由上海(沪)、南京(宁)与杭州(杭)3个核心节点城市构成。在空间结构内部,形成若干次级城市网络连线;在空间分布上,北翼网络化程度较高于南翼线性联系程度,区域联系强度以"沪—宁"、"沪—杭"沿线向两侧递减;(3)上海、南京、杭州、苏州、无锡5个核心城市排名处于网络中心的前列,扬州、南通、泰州、舟山等周边城市相对靠后,这与区域经济发展过程的"吸虹效应"有关,随着区域经济一体化程度的加深,中心城市会向周边地区提供服务与经济辐射,完善整个长三角城市群网络体系。     

Reinventing the bicycle: how calculative practices shape urban environmental governance

The concept of sustainability transitions has become increasingly prominent in academic and policy discourses during recent decades, but the importance of the link between knowledge-producing epistemic practices and urban governance has been underappreciated in this discourse. Based on a case study of cycling in Copenhagen between 1900 and 2015, and drawing upon a governmentality-inspired analytical framework, this research demonstrates that transformative governance may be initiated by epistemic practices that render urban systems visible in other ways. Urban cycling has been reconstructed over time in Copenhagen as a traffic safety ‘problem’, a component of the experiential and liveable city, and a health-producing (and hence economically valuable) regional transport mode. The research findings emphasise that epistemic practices can provide a powerful stimulus for creating changes in urban governance. The results also provide support for initiatives to broaden the terms of academic debate on sustainability transitions.     

Effect of deforestation on fertility attributes of Mollisols in the NW of Iran

The impacts of deforestation on soil fertility indices – are still not well understood in the forest lands of Iran characterised by Mediterranean type climate. Consistent with this, 8 soil pedons and 32 soil cores were described and sampled from four different soil types of forest and adjacent cultivated soil along a Mollisols transect. The results revealed a considerable depletion in the values of soil organic carbon (by 60–88%), total N (by 67–88%), available K (by 20–45%), cation exchange capacity (by 9–21%), and the diethylene-triamine pentaacetic acid (DTPA) fraction of Fe (by 40–72%), Mn (by 10–60%), and Zn (by 49–80%) after deforestation. In contrast, soil pH (by 0.36–0.9 units), C:N ratio (by 3–84%), available P (22–139%), and DTPA Cu (by 4–55%) tended to increase due to deforestation. Cultivated soils showed a drop of 70–82% in the values of the soil productivity index than to those of the forest soil, indicating a degrading and declining effect of deforestation on soil productivity capacity. It was found that the majority of soil fertility indices were affected negatively by deforestation and more than half of the organic matter was lost to deforestation, which, in turn, could lead to deterioration in soil quality or land productivity capacity.     

肠道微生物对土壤中铜、锌、锰生物可给性的影响

为了更全面、准确地评价土壤中金属元素对人体的健康风险,研究土壤中金属元素在结肠阶段的生物可给性具有重要意义。通过采集我国一些地区的6种土壤,利用in vitro方法(PBET和SHIME联用)研究土壤中Cu、Zn、Mn在胃、小肠、结肠阶段的生物可给性。研究显示,土壤中Cu、Zn、Mn在胃阶段的生物可给性分别为23.8%~63.0%、21.2%~64.4%、11.7%~35.6%;从胃阶段到小肠阶段,土壤中Cu的生物可给性提高了0.4%~14.4%,而土壤中Zn在小肠阶段的生物可给性降低了6.7%~38.7%。结肠阶段,土壤中Cu、Zn、Mn的生物可给性分别为2.4%~12.9%、5.7%~18.7%、6.2%~18.9%,与小肠阶段相比,分别降低了21.7%~56.9%、0.4%~36.8%、4.5%~19.1%。结果表明,在肠道微生物存在的情况下,土壤中Cu、Zn、Mn在结肠阶段有较低的人体健康风险。     

Trace element content in soils of the King George and Elephant islands,maritime Antarctica

Trace element concentrations were studied in soils of the King George and Elephant islands in the maritime part of West Antarctica. The lowest concentrations of Cu, Pb, Cd, Zn, Ni and Mn were typical for the pristine soil of Elephant Island. The highest concentrations of these elements were found in the Fildes Peninsula and revealed the influence of human activities in the area of the Bellingshausen station and adjacent waste disposal sites. Ornithogenic soils of the Fildes Peninsula have shown low concentrations of Cd and As. Using geoaccumulation indexes, all the pristine soils of King George and Elephant islands and ornithogenic soils of the Fildes Peninsula were classified as unpolluted; the human-affected soils were mainly identified as moderately polluted. Obtained data can be used as background concentration levels for further researches.     

禾草灵对水稻生长和典型土壤酶活性的影响

禾草灵是一种广泛使用的除草剂,在土壤中大量残留,对非靶标生物产生危害。为探究除草剂对环境生物的毒性作用,本研究模拟水稻自然生长的环境,评估禾草灵对水稻及土壤微生物的影响。研究结果表明,低浓度禾草灵(200 μg L^-1)处理4 d对土壤微生物量没有显著影响(P>0.05);8 d时,水稻生长没有明显变化,但土壤微生物量较对照组显著升高(P<0.05)。高浓度禾草灵(1 000 μg L^-1)处理4天后,土壤脲酶、酸性磷酸酶和过氧化氢酶的活性显著下降(P<0.05),下降幅度分别为8.9%,16.6%和10.2%;处理8 d后,水稻幼苗鲜重显著降低(P>0.05),叶绿素a和叶绿素b含量分别下降了13.5%和13.3%。本研究证实高浓度的禾草灵残留会对植物和土壤微生物产生不良的影响。     

基于高通量测序的工业园区地下水和土壤细菌群落结构比较研究

为探究工业园区地下水和土壤细菌群落结构、多样性变化特征,采用高通量测序技术对地下水和土壤细菌16S r RNA基因高变区域进行序列测定。通过对Alpha多样性、物种组成、丰度和群落结构的分析,比较地下水和土壤细菌群落结构的异同。Alpha多样性的比较结果表明,土壤细菌群落多样性和丰富度明显高于地下水,地下水细菌群落多样性指数反映出地下水已受到周边污染源的影响。物种注释结果表明,地下水样品共检出48个细菌门,土壤样品共检出50个细菌门。变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)是地下水细菌群落的优势类群,共占93.54%,且该工业园区地下水细菌群落呈现出典型的淡水种群特征;土壤中优势细菌门为Proteobacteria、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、Firmicutes和芽单胞菌门(Gemmatimonadetes),共占85.21%。由于地下水和土壤两者的生态系统和理化环境的差异,致使Actinobacteria、Acidobacteria、绿弯菌门(Chloroflexi)、硝化螺旋菌门(Nitrospirae)、α-变形菌纲(Alphaproteobacteria)、δ-变形菌纲(Deltaproteobacteria)和Gemmatimonadetes占比在地下水和土壤细菌群落间差异显著,同时使地下水和土壤细菌群落各含有一些特有的优势细菌属(地下水2个,土壤4个)。基于高通量测序技术对工业园区样品的测序结果可以为地下水和土壤环境的生态评价提供方法依据。     

Growth in urban extent and allometric analysis of West African cities

Urban area expansion is happening at much faster rates in Asian and African cities than elsewhere in the world. This study uses multi-temporal Landsat images to map the urban extent of six small to large cities in West Africa at four different time steps from the early 1970s–2010. The selected cities are Kumasi of Ghana, Daloa of Cote d’Ivoire, Abuja and Kano in Nigeria, Kindia of Guinea, and Ouagadougou of Burkina Faso. All cities revealed significant urban growth in both urban area and population; however, it was apparent that there was a lot of variability in urban area development. Exponential urban growth rates in the cities were measured as ranging between 0.026 and 0.077, with allometric scaling factors matching those of other countries.     

Occurrence and distribution of trifluralin,ethalfluralin, and pendimethalin in soils used for long-term intensive cotton cultivation in central Greece

In the present study, a soil monitoring program was undertaken in Greek cotton cultivated areas in 2012. Twenty-seven soil samples were collected from the entire Thessaly plain in early summer of 2012, corresponding to approximately three months (current use of pendimethalin), up to one year (for the banned ethalfluralin), and three years (for the also banned trifluralin), after the last dinitroaniline application. Low but not negligible levels of dinitroanilines were detected, ranging from 0.01 to 0.21 μg g^?1 d.w. for trifluralin and 0.01–0.048 μg g^?1 d.w. for pendimethalin, respectively. Trifluralin was the herbicide most frequently detected (44.4%). The high historic application of trifluralin and its high persistence and accumulation potential is in line with the abundance of the detected residues. The present data indicate that soil samples contain extractable residues of banned trifluralin, but based on the comparison of the theoretical PECplateau for trifluralin (0.277 µg g^?1) and the maximum Measured Environmental Concentration, it was concluded that the detected residues should be attributed to previous years’ application. The latter suggested the need for continual monitoring of the dinitroaniline family of pesticides, including the banned substances, aiming thus to an improved environmental profile for agricultural areas.     

Nutritional evaluation,bioaccumulation and toxicological assessment of heavy metals in edible fruits of FicussurForssk (Moraceae)

Ficussur (Moraceae) is an indigenous medicinal plant with a wide distribution in Africa. In this study, the nutritional potential fruit of this indigenous plant to meet domestic food demands and reduce food insecurity in KwaZulu-Natal. South Africa, was investigated. The proximate composition and concentrations of metals in the edible fruits collected from eight different sites in KwaZulu-Natal were determined to assess for nutritional value and the concentrations of metals in the growth soil was determined to evaluate the impact of soil quality on elemental uptake. The fruits contained high levels of moisture (88.8%) and carbohydrates (65.6%). The concentrations of elements in the fruits were found to be in decreasing order of Ca>Mg >Fe >Zn>Cu >Mn> Se with low levels of toxic metals (As, Cd, Co and Pb). This study shows that the consumption of the fruits of F. sur can contribute positively to the nutritional needs of rural communities in South Africa for most essential nutrients without posing the risk of adverse health effects.