Pathways towards the integration of periurban agrarian ecosystems into the spatial planning system

Introduction:The potential of periurban agrarian ecosystems is recognized as one of the cornerstones for improving urban sustainability;however,this potential has been disregarded in spatial planning and decision making.The main goal of the PAEc-SP project was to assess the feasibility of integrating periurban agricultural areas into spatial planning by developing a viable ecosystem services-based methodology.Methods:The research unfolded along three axes:i)mapping ecosystem services in periurban areas,distinguishing between the current state and the future potential by applying a set of indicators;ii)analyzing the regulatory framework,identifying gaps in the consideration of agrarian ecosystem services;and iii)analyzing the perceptions of these areas held by local actors.Provisioning services(food)are widely recognized by actors and plans,but this leads to weak protection.Results:Cultural services(identity,recreation)are also recognized by all actors and addressed by local urban planning,though this is not connected to farming practices.Regulating services(CO_(2) storage,water quality)are barely addressed by spatial planning and actors do not value them either.Supporting services(biodiversity)are mostly associated with natural areas.Most technicians are reluctant to changes,while new farmers and civil society demand a new holistic approach.Conclusion:The reluctant attitude to change of some actors and the inadequate understanding of ecosystem services,render it imperative to adopt a comprehensive approach through a participatory process of urban planning.Mapping ecosystem services,calculations,and graphs are a valuable communication tool both in discussing the consequences of the loss of agrarian ecosystems with different actors and in planning future scenarios.

Potential Changes in Net Primary Productivity and Carbon Input of Periurban Agroecosystems Treated with Biosolids in Buenos Aires, Argentina

Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human management. The values of NPP and C input in periurban agroecosystems are insufficient or missing. The objective was to use local databases to estimate NPP and C input in periurban areas(south, north and west) of Buenos Aires City, Argentina, using different biosolids application scenarios(low and high effects). The NPP varied with crop and vegetable types(P < 0.05), with maize(Zea mays) and wheat(Triticum aestivum) presenting the highest production, soybean(Glycine max) medium and sunflower(Helianthus annuus) the lowest. Tomato(Lycopersicon esculentum Mill.) presented the highest production in the south area(La Plata). West and north areas, where Vertic and Typic Argiudolls are the main soils, presented the lowest NPP and C input. According to the low and high effect scenarios,only vegetables presented significant differences(P < 0.05) in average and cumulative NPP and C input between areas. Vegetables contributed with the highest proportion(> 70%) to NPP in both projected scenarios. For both scenarios, average C input by crops and vegetables presented similar proportions. Biosolids addition in periurban agroecosystems could be a viable practice to elevate NPP and C input.

六合蒋家湾蔬菜基地重金属污染现状与评价

以位于南京市城市边缘带的六合区蒋家湾蔬菜基地为研究区,对土壤进行了高密度样品采集与分析,阐明了该地区土壤重金属污染状况并进行了相关评价。研究数据表明:该区As、Cu、Zn、Cd、Cr、Pb等6种重金属在土壤中的含量均低于背景值,而土壤中Hg含量严重超标,为该地区主要的土壤污染因子。Hg进入土壤的途径可能包括蔬菜地高强度的农化产品投入、工业和生活垃圾施用,但没有证据显示与灌溉水源有关。

近20年城乡交错带土壤养分时间空间变异特征分析——以北京市大兴区为例

以北京市大兴区为城乡交错带的分析样区,通过对1982年、2000年2期土壤养分变化情况进行时间空间变异特征分析,结果发现:1982～2000年近20年间大兴土壤养分除土壤速效K含量略有下降外,其他土壤养分含量均呈上升趋势,尤以速效P含量增长最多。各项养分增加值分别为有机质31.02%、全N 50 %、碱解N 37.89%、速效P 177%,而速效K则减少6.97%。1982年的5种土壤养分中,速效P的变异系数最高,为0.50;全N次之,为0.4;有机质、速效K、碱解N的变异系数较小,在0.28～0.32之间。2000年的5种土壤养分中,变异系数最高的仍是速效P,为0.57;速效K次之,为0.36;有机质、全N和碱解N含量的变异系数较小,在0.19～0.23之间。1982年有机质的块金值与基台值之比为45.32%,2000年的为26.54%,说明其在小尺度上的空间相关性增强。1982年速效K的块金值与基台值之比为36.96%,2000年的为29.82%。2000年全N、碱解N和速效P的块金值与基台值的比值大于1982年的比值。2000年各项土壤养分的空间相关距离均比1982年增大,基本上趋向于以大块状变异为主,具有较强的渐变性分布规律。

城市和城市边缘带农业的环境与健康问题

城市和城市边缘带农业是现代农业的重要组成部分,它可以解决城市人口的食物供应问题,增加就业机会,改善城市生态。但是城市和城市边缘带农业同时也会带来一些新老环境问题,如果没有正确的管理和合理的规划,它也会给城市环境造成危害,进而影响人类的健康。笔者结合都市农业给环境和人类健康的潜在危害做了具体的分析,并提出管理和控制措施。

芜湖市城市边缘区土壤重金属污染空间特征研究

通过对安徽省芜湖市城市边缘区14个典型土壤采样点重金属As、Hg、Pb、Cd、Zn、Cr污染现状的调查与分析,以本地区自然土壤中重金属元素自然含量的平均值作为评价标准,分别计算出各调查区土壤单因子污染指数,应用对应分析技术,初步研究了芜湖市城市边缘区土壤重金属污染的空间分异特征。结果表明,芜湖城市边缘区土壤重金属污染已相当显著,且各区域间土壤重金属污染水平具有明显的差异。总体上看,鸠江、马塘、西江等样点较其他区域污染严重,各区域间Pb、Hg污染水平差异明显,但As、Cd、Zn、Cr污染水平差异不大。

Study of the Possibility of Reusing Rain and Purified Water in the City of Fez, Morocco

The current work seeks firstly the integration of a rainwater reuse system that will be of use in the watering of the green spaces, and secondly the re-use of purified water in the irrigation of agriculture spaces, which are in the nearby of wastewater treatment plant. The results show that 41% of the green spaces in the city of Fez require a renovation and installation of adequate watering systems taking into account the specificity of the city which is crossed by several rivers badly exploited for watering. The purified wastewater is of much better quality than the Moroccan reuse standards and is discharged with a flow that is large enough for the irrigation water requirements of the fields close to wastewater treatment plant.

北京市边缘区土壤重金属污染的初步研究

基础资料为采集于北京城市边缘区的29个土壤剖面表层和底层58个样品6种重金属全量分析数据,以本区重金属自然土壤元素背景值作为评价标准,计算出各样点剖面表层和底层土壤单因子污染指数。应用对应因子分析手段, 初步揭示了北京市边缘区土壤重金属污染的空间分异特征。结果表明,北京市边缘区土壤重金属总体污染状况不明显,只有Hg元素属于轻微污染范围。不同样点间重金属污染水平比较显示,Hg污染水平差异明显,Pb、Cd、As、Zn、Cu污染差异不大。