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361.
This paper examines the impact of urban afforestation on infant health outcomes by exploiting a quasi-experimental setting where one million new trees were planted in New York City (NYC), but not in counties surrounding NYC over the same time period. Using a near-universal birth record of NYC and surrounding counties over 2004–2015 and employing both the synthetic control method and a difference-in-differences model, we find that an approximately 20% increase in urban forest cover decreased prematurity and low birth weight among mothers in NYC by 2.1 and 0.24 percentage points, respectively, relative to similar mothers outside of NYC. The low birth weight finding is equivalent to getting a mother smoking two cigarettes a day during pregnancy to quit. An internal validity test suggests that changes in the composition of NYC mothers cannot explain the observed effects. Additionally, we find evidence that declines in PM2.5 concentrations and increases in outdoor walks are potential causal mechanisms. Results suggest that urban afforestation may be able to complement existing policies aimed at improving infant health. 相似文献
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We compared the composition of diatom assemblages collected from New Jersey Pinelands blackwater streams draining four different land uses, including forest land, abandoned-cranberry bogs, active-cranberry bogs, and developed and upland-agricultural land. Over a 2-year period (2002-2003), we collected 132 diatom taxa at 14 stream sites. Between-year variability in the composition of stream samples was high. Most diatom species were rarely encountered and were found in low abundance. Specific conductance and pH were higher at developed/agricultural sites compared with all other site types. Neither species richness nor genus richness was significantly different between stream types. However, clear community patterns were evident, and a significant difference in species composition existed between the developed/agricultural sites and both cranberry and forest sites. The primary community gradient, represented by the first axis of a DCA ordination, was associated with variations in pH and specific conductance. Although community patterns revealed by ordinating the data collected in 2002 differed from those obtained using the 2003 data, both ordinations contrasted the developed/agricultural sites and the other sites. Acidobiontic and acidophilous diatoms characterized the dominant species at forest, abandoned-bog, and cranberry sites, whereas indifferent species dominated the developed/agricultural samples. Although our study demonstrated a relationship between the composition of diatom assemblages and watershed conditions, several factors, including taxonomic problems, the large number of diatom species, incomplete pH classifications, and year-to-year variability may limit the utility of diatom species as indicators of watershed conditions in the New Jersey Pinelands. 相似文献
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The effect of dairy farming on water quality in New Zealand streams has been identified as an important environmental issue. Stream fencing, to keep cattle out of streams, is seen as a way to improve water quality. Fencing ensures that cattle cannot defecate in the stream, prevents bank erosion, and protects the aquatic habitat. Stream fencing targets have been set by the dairy industry. In this paper the results of a study to identify the factors influencing dairy farmers' decisions to adopt stream fencing are outlined. Qualitative methods were used to gather data from 30 dairy farmers in four New Zealand catchments. Results suggest that farm contextual factors influenced farmers' decision making when considering stream fencing. Farmers were classified into four segments based on their reasons for investing in stream fencing. These reasons were fencing boundaries, fencing for stock control, fencing to protect animal health, and fencing because of pressure to conform to local government guidelines or industry codes of practice. This suggests that adoption may be slow in the absence of on-farm benefits, that promotion of stream fencing needs to be strongly linked to on-farm benefits, and that regulation could play a role in ensuring greater adoption of stream fencing. 相似文献
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Xiaofeng Huang Chuan Wang Jianfei Peng Lingyan He Liming Cao Qiao Zhu Jie Cui Zhijun Wu Min Hu 《环境科学学报(英文版)》2017,29(1):342-351
Knowledge of particle number size distribution(PND) and new particle formation(NPF)events in Southern China is essential for mitigation strategies related to submicron particles and their effects on regional air quality,haze,and human health.In this study,seven field measurement campaigns were conducted from December 2013 to May 2015 using a scanning mobility particle sizer(SMPS) at four sites in Southern China,including three urban sites and one background site.Particles were measured in the size range of15-515 nm,and the median particle number concentrations(PNCs) were found to vary in the range of 0.3× 10~4-2.2 × 10~4 cn~(-3) at the urban sites and were approximately 0.2 × 10~4 cm~(-3) at the background site.The peak diameters at the different sites varied largely from 22 to 102 nm.The PNCs in the Aitken mode(25-100 nm) at the urban sites were up to 10 times higher than they were at the background site,indicating large primary emissions from traffic at the urban sites.The diurnal variations of PNCs were significantly influenced by both rush hour traffic at the urban sites and NPF events.The frequencies of NPF events at the different sites were0%-30%,with the highest frequency occurring at an urban site during autumn.With higher SO_2 concentrations and higher ambient temperatures being necessary,NPF at the urban site was found to be more influenced by atmospheric oxidizing capability,while NPF at the background site was limited by the condensation sink.This study provides a unique dataset of particle number and size information in various environments in Southern China,which can help understand the sources,formation,and the climate forcing of aerosols in this quickly developing region,as well as help constrain and validate NPF modeling. 相似文献
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新世纪企业环境战略研究 总被引:1,自引:1,他引:1
介绍了环境营销的定义,开展环境营销的必要性及其给企业和社会带来的好处,指出在新世纪,为了实现可持续发展,企业不仅要做好自身的污染防治工作,更应变被动为主动,选择环境营销导向,从战略的高度来审视企业的环境活动和行为,并对企业进行重新组织,同时本文还对企业建立环境营销战略的具体环境行为作了进一步探讨。 相似文献