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531.
Leslie Gray Patricia Guzman Kathryn Michelle Glowa Ann G. Drevno 《Local Environment》2014,19(2):187-203
Urban policymakers and sustainable food activists have identified urban agriculture as an important strategy for confronting a host of urban problems, including food insecurity, health disparities, access to urban green space and community economic revitalisation. Much recent work on urban agriculture has examined community and school gardens, but little research has been undertaken on home gardens as a solution to urban problems. This article examines a home-gardening programme in San Jose, California, La Mesa Verde, asking whether some of the benefits found in community gardens can be found in home gardens. Specifically, we look at financial, health and community benefits, examining the potential of home gardens to become forces for broader social change. We ask whether gardens can become agents of cultural preservation, self-determination, particularly for recent immigrants who use these spaces to build identities and work towards collective action and self-determination. 相似文献
532.
For the majority of insects, a female's choice of oviposition site(s) greatly influences both the success of individual offspring and her own total fitness. Theory predicts that females most strongly limited by egg number will employ greater oviposition site discrimination than those predominately subject to time limitation. The reproductive success of the butterfly Pieris virginiensis at our Connecticut, USA, field site is strongly time constrained on two fronts. First, during their three-week flight season, only 60% of days and 28% of daytime hours were suitable for flight. Second, larval survival is impacted by the rapid senescence of their spring ephemeral host plant Dentaria diphylla, with eggs laid during the first half of the flight season having approximately three times the survival chance of those laid later. Yet, on average, females choose to oviposit on only half the plants they closely inspect and fly over most ramets without any inspection. Our experiments demonstrate that the preferred host ramets confer an approximate two-fold survival advantage. Females are not choosing plants that senesce later, despite the advantage that such plants would confer. We use empirical data on female behavior and larval performance to parameterize a simulation model. Model results suggest that, despite the notable time limitation in this system, the observed level of female oviposition site preference not only increases individual larval survival, but also total female fitness. Low egg loads in this species may contribute to selection for strong host plant discrimination. 相似文献
533.
Simultaneous heavy metal removal mechanism by dead macrophytes 总被引:13,自引:0,他引:13
The use of dead, dried aquatic plants, for water removal of metals derived from industrial activities as a simple biosorbent material has been increasing in the last years. The mechanism of simultaneous metal removal (Cd2+, Ni2+, Cu2+, Zn2+ and Pb2+) by 3 macrophytes biomass (Spirodela intermedia, Lemna minor and Pistia stratiotes) was investigated. L. minor biomass presented the highest mean removal percentage and P. stratiotes the lowest for all metals tested. Pb2+ and Cd2+ were more efficiently removed by the three of them. The simultaneous metal sorption data were analysed according to Langmuir and Freundlich isotherms. Data fitted the Langmuir model only for Ni and Cd, but Freundlich isotherm for all metals tested, as it was expected. The K(F) values showed that Pb was the metal more efficiently removed from water solution. The adsorption process for the three species studied followed first order kinetics. The mechanism involved in biosorption resulted ion exchange between monovalent metals as counter ions present in the macrophytes biomass and heavy metal ions and protons taken up from water. No significant differences were observed in the metal exchange amounts while using multi-metal or individual metal solutions. 相似文献
534.
Campbell D Meisch M Demoss T Pomponio J Bradley MP 《Environmental monitoring and assessment》2004,94(1-3):217-230
Emergy provides a general accounting mechanism that allows us to view the economy and the environment on the same income statement and balance sheet. This allows an auditor to verify the economic picture by checking it against a more complete representation of the flows and storages of real wealth as measured by emergy. In this study, we constructed emergy accounts for the state of West Virginia in 1997. The income statement showed annual production, consumption, and flows of emergy and dollars into and out of the state. The balance sheet evaluated the storage of emergy in some of the state's assets. Emergy indices were used to answer questions posed by managers and gain insight into the state's economic and environmental strengths and weaknesses. West Virginia has great wealth in nonrenewable resources (9E14 sej m-2 or 17 times the U.S. average). The investment ratio of emergy purchased outside to indigenous renewable and nonrenewable emergy was 2.2:1, which indicates a high potential for future development. However, the environmental loading ratio (14:1) was already 1.5 times higher than that found at an average location in the U.S. Twice as much emergy was exported as received and standard of living indicators showed that people have largely failed to benefit from their state's wealth. We propose that, just as in business, where decisions made using financial accounts ensure solvency; decisions governing the environment should be made based on an emergy accounting of activities, assets, and liabilities for the combined system of humanity and nature. 相似文献
535.
Grouping Lakes for Water Quality Assessment and Monitoring: The Roles of Regionalization and Spatial Scale 总被引:1,自引:0,他引:1
Cheruvelil KS Soranno PA Bremigan MT Wagner T Martin SL 《Environmental management》2008,41(3):425-440
Regionalization frameworks cluster geographic data to create contiguous regions of similar climate, geology and hydrology
by delineating land into discrete regions, such as ecoregions or watersheds, often at several spatial scales. Although most
regionalization schemes were not originally designed for aquatic ecosystem classification or management, they are often used
for such purposes, with surprisingly few explicit tests of the relative ability of different regionalization frameworks to
group lakes for water quality monitoring and assessment. We examined which of 11 different lake grouping schemes at two spatial
scales best captures the maximum amount of variation in water quality among regions for total nutrients, water clarity, chlorophyll,
overall trophic state, and alkalinity in 479 lakes in Michigan (USA). We conducted analyses on two data sets: one that included
all lakes and one that included only minimally disturbed lakes. Using hierarchical linear models that partitioned total variance
into within-region and among-region components, we found that ecological drainage units and 8-digit hydrologic units most
consistently captured among-region heterogeneity at their respective spatial scales using all lakes (variation among lake
groups = 3% to 50% and 12% to 52%, respectively). However, regionalization schemes capture less among-region variance for
minimally disturbed lakes. Diagnostics of spatial autocorrelation provided insight into the relative performance of regionalization
frameworks but also demonstrated that region size is only partly responsible for capturing variation among lakes. These results
suggest that regionalization schemes can provide useful frameworks for lake water quality assessment and monitoring but that
we must identify the appropriate spatial scale for the questions being asked, the type of management applied, and the metrics
being assessed. 相似文献
536.
Davis Lodinikki Lemoy Aragão Walessa Alana Bragança de Oliveira Lopes Géssica Eiró Luciana Guimaraes Freire Alexandre Rodrigues Prado Felippe Bevilacqua Rossi Ana Cláudia da Silva Cruz Allan das Graças Fernandes Dantas Kelly Albuquerque Alan Rodrigo Leal Paz Simone Patricia Aranha Angélica Rômulo Simões Lima Rafael Rodrigues 《Environmental science and pollution research international》2022,29(10):13930-13940
Environmental Science and Pollution Research - There are a few data relating to the effects of lead (Pb) exposure on the alveolar bone, which has very distinct morphophysiological characteristics... 相似文献