Groundwater characterization in major industrial and residential locations of Lagos metropolis

This study investigated the quality of groundwater collected from two industrial and residential locations, each within the Lagos metropolis. Prescribed standard procedures of the American Public Health Association (APHA) were used to measure the physicochemical parameters of each of the groundwater samples, which include pH, electrical conductivity (EC), dissolved oxygen, total dissolved solids (TDS), biological oxygen demand, chemical oxygen demand; the anions chloride (Cl^?), nitrate (NO₃^?), sulfate (SO₄^?), and phosphate (PO₄^?); and heavy metals copper (Cu), zinc (Zn), lead (Pb), manganese (Mn), iron (Fe), cobalt (Co), cadmium (Cd), and chromium (Cr). Based on the laboratory analysis, the physicochemical parameters that were measured were within the permissible ranges specified by the World Health Organization and the Nigerian Standard for Drinking Water Quality Standards Organization of Nigeria (SON), except for pH, TDS, EC, Pb, Mn, and Fe for groundwater samples from the industrial locations and for pH, Pb, Mn, and Fe for residential locations. The elevated concentrations of TDS and EC reported for groundwater samples from industrial locations were attributed to the heavy discharge of effluents from nearby industrial treatment plants as well as the dissolution of ionic heavy metals from industrial activities involving the use of heavy machines. Statistical analysis using Pearson's correlation revealed the physicochemical parameters to be moderately and strongly correlated with one another at either p < .05 or < .01. In conclusion, groundwater samples from residential locations are more suitable for drinking than those from industrial locations.     

北京市人口动态模拟与政策分析

随着城市化进程的加快,我国城市规模不断膨胀,超过1 000万的超大城市不断涌现,城市人口规模过大、增长过快以及带来的城市问题引起社会各界的关注。北京作为一个人口超过2 000万的超大城市,不仅具有超大城市的一般特征,而且具有首都所在城市的特点。本文在厘清北京人口增长机制的基础上,采用系统动力学方法,通过政策模拟,考察不同政策导向对未来北京市人口增长趋势的影响,得到以下结论:1如果保持当前的经济增长速度,并按当前的生产技术水平以及产业结构变化趋势发展,未来北京人口规模将持续快速增长,到2030年将突破3 000万人,2050年将接近5 000万人,城市面临巨大的人口压力。2单纯通过产业结构升级对调控人口作用有限。3适当放缓经济增长速度以及大力提高劳动生产率可以有效控制人口的快速增长,挤出大量的低端劳动力,人口调控效果明显。4户籍制度的适度放开在一定程度上减少了外来人口规模,但对人口总量的减少并没有起到作用。5与单纯采用一种政策调整相比,多种调控政策并举调控人口的效果更佳。由此得到以下几点启示:首先,每个城市都应该有自己的功能定位,决不能搞"大而全"和千城一面,尤其不能将城市经济增长速度和总量作为城市发展的主要目标甚至唯一目标,不顾后果和不择手段地追求GDP。否则城市人口规模的无序扩大就很难避免,也很难治理。对于北京而言,发挥其政治、文化、国际交往以及科技创新中心的首都功能,大力发展现代服务业,提高劳动生产率,优化产业结构才有利于人口的有序发展。另外,政府在人口调控方面必须有所作为,但也不能对人口调控进行大包大揽,取代市场。政府要顺应经济和社会发展的规律,顺势而为,出台相应的系列综合性调控政策。只有这样,才能对人口调控起到更好的效果。     

重庆都市圈可持续发展面临的主要生态环境问题与对策

对重庆都市圈生态环境问题进行了详细的分析;结合都市圈可持续发展和三峡水库安全运行的需求,提出了加大都市圈生态环境建设力度和绿地景观整治工程,优化产业结构与布局,扶持循环经济和生态环保产业发展,控制主城区规模、积极发展周边卫星城市,增加环保投入、加强重点环保基础设施建设、实施"净空"和"碧水"工程,建立都市圈生态环境信息管理系统和预警系统、实施都市圈生态系统管理等8条治理途径与措施。     

Characteristics of air pollution by polychlorinated dibenzo-p-dioxins and dibenzofurans in the typical industrial areas of Tangshan City, China

The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial plants. The TEQ concentrations of PCDD/PCDFs ranged from 44.2 to 394.1 fg I-TEQ/m3 with an average of 169.9 fg I-TEQ/m3. 2,3,4,7,8-PeCDF was the dominant contributor to PTEQ, contributing 41% (12% to 55%), while 1,2,3,4,6,7,8-HpCDF, OCDD and OCDF were the major congeners for the total concentrations. The ratios of PPCDF/PPCDD reached 2.54 on average, suggesting that de novo synthesis in thermal processes played an important role to the airborne pollution of PCDD/PCDFs. The similarities congener profiles indicated that TSP and PM10 active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air, and the ratios of concentrations determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles. It was found that 2,3,7,8-TCDF and OCDD were the dominating congeners in the passive PUF disks samples. Through principal components analysis, the coke industry was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan, which was possibly formed by de novo synthesis mechanism. In this study, the atmospheric impacts to the environment from di erent industrial sources could be ranked as follows (from high to low): coking, iron sintering, steel making, power generation and chlorinate alkali chemical production industries.     

Spatial distribution of particulate matter (PM10) in Warri metropolis,Nigeria

This study examined the spatial distribution of particulate air pollution in the Warri metropolis. This was done to ascertain the differences between the distribution of particulate matter (PM10) in the urban area and the surrounding rural areas. To achieve this, the study generated data from field measurement of PM10 levels for the year 2003. Analysis of variance, the U-test, and simple regression statistical techniques were used to analyze the data. The major finding of the study was that the Warri metropolitan area is polluted with PM10 levels of over 126 μg/m³, which is 81% over the 70 μg/m³ threshold of the World Health Organization. However the built-up area of the Warri metropolis is 150% more polluted with PM10 particulates than the surrounding rural areas. While the traffic-clogged area of Enerhen, Jakpa, Deco, and Estate Junctions are the most polluted areas with levels of 151 μg/m³, traditional areas had the lowest levels of 128 μg/m³. The daily distribution of PM10 showed that Mondays were the most polluted days with levels of 145 μg/m³ and Fridays were the least polluted days with levels of 141.5 μg/m³ in the built-up area, whereas in the rural area Wednesdays were the most polluted days with levels of 57.1 μg/m³ and Sundays were the least polluted days with levels of 53.5 μg/m³. Mondays generally recorded the highest PM10 values because of the large amount of industrial operation, heavy vehicular traffic in the peak period, and increased commercial activities. The study also showed significant variation in the level of PM10 particulates within the urban areas of the Warri metropolis with a calculated F-value (3.29), which is greater than the critical F-value of 3.14 at the 0.05 significance level. It is therefore recommended that urban environmental management policy should be vigorously pursued to curb the adverse consequences of increased PM10 levels in urban areas of the Warri metropolis.     

京津冀地区近20年NDVI时空变化特征

健康稳定的自然生态系统是保障城市发展的重要基础.了解京津冀城镇快速发展过程中自然生态系统的变化,有助于该区域城镇绿色协调可持续发展.植被指数NDVI时空变化特征可反映地区自然生态系统状况及其演变规律.基于MOD13Q1和Landsat遥感影像数据,利用一元线性回归趋势分析法分析近20年(2000—2019年)京津冀地区...     

The consequences and policy implications of urban encroachment into flood-risk areas: the case of Ibadan

Urban encroachment on floodplains has exacerbated flood disasters owing to the reduction in the floodplain’s capacity to mitigate flooding, thereby bringing more settlements and people at flood risk. This study examined the consequences and policy implications of urban encroachment into Ibadan’s flood-risk areas. The survey-based study relied on primary and secondary data, with multistage sampling procedures selecting 15% of the flood-affected buildings in 2011, from which a structured questionnaire was administered to 402 households. The study revealed that the institutional arrangements with respect to responsibilities, regulations and control of urban floodplains were fragmented and non-participatory. At least 62% of all the affected buildings encroached into the statutory setbacks to rivers. Household property lost/damaged included domestic goods (75%), domestic animals and pets (60%), working instruments/machines (31%), the source of domestic water (34%) and vehicles (29%). Strong direct correlations were found between the urban and peri-urban communities in (1) the number of damaged/lost property and (2) the number of households that suffered health-related challenges. The paper recommends that the overall co-ordination of flood management activities be entrusted to an institution that can assume responsibility for legal, technical, administrative and financial matters related to urban planning and flood-risk management.     

Building contraventions and incidence of flood in the Lagos Metropolis,Nigeria

Frequent floods have led to loss of lives and destruction of property in both coastal and landlocked cities across the globe, particularly where floodplains have been developed without recourse to space standards. This paper investigated the contributions of contravention of building codes to flooding in flood-prone areas in the Lagos metropolis. Global Positioning Systems (GPSs) were used to determine the location and elevation above sea level of 1,025 buildings situated in 211 streets that were prone to flooding. The distance of buildings from drainage channels/the lagoon was determined in ArcGIS 10.2 environment. Findings revealed that building code contravention contributed significantly to flooding (r = 0.926). About 63.5% and 63.3% of sampled buildings contravened building-plot ratio and statutory setbacks from drainage channels/the lagoon, respectively. Proactive urban planning, strict enforcement of building codes and development control regulations are required to reduce flooding and its consequences in cities of developing nations where flooding has become an annual occurrence.     

长江三角洲都市连绵区边界界定研究

都市连绵区的边界界定对象包括两个方面,都市连绵区的整体空间范围边界界定和内部结构边界界定。对长江三角洲及其周边地区所有的238个县、市、区的就业人口结构和空间分布特征进行主成分分析和聚类分析,探讨相应都市区的结构特征以及都市区的空间组合特征等,进而确定了长江三角洲地区的整体范围边界和内部结构边界。其结论包括①长三角都市连绵区的整体空间范围包括苏州、无锡、宁波的全部以及上海、南京、常州、杭州、镇江、扬州、泰州、南通和绍兴、舟山的部分县市区;②长三角的内部结构可分为三大部分,以上海为中心的环太湖城镇密集区,以南京为中心形成沿长江城镇区,以杭州、宁波为中心形成环杭州湾城镇密集区,其内部边界界线分别以镇江丹徒区、嘉兴—湖州为边界地带。从核心城市上海角度看,整个长江三角洲都市连绵区的内部结构呈现“圈层推进+轴线延伸”的空间特征。     

网络分析法在城市绿网优化中的应用

2005-2020年天津总规之绿地系统规划(总规绿网),由于缺乏绿网优化配置,其生态效益仍将不尽如人意。为此,采用图论和网络分析法(ANP),构建、评价了4个具有不同连接度和生态水平的绿网方案。ANP模型计算结果表明,绿网4最大化地利用现状和潜在廊道、连接各斑块,效益排序最优,成本次优,综合效益最高,且敏感度分析证明当效益与成本比大于0.25时,首位排序稳定。协调土地利用与交通等相关规划要素,给出基于网络4的绿地系统规划方案,为总规绿网优化提供依据。ANP适用于多目标、多因子、多方案决策,可解决以往网络指数与景观指数分离问题,实现不同顶点位置的网络评价,是绿网优化的有力工具。