The North American design community typically regards green roofs as inhospitable environments for native plants due to the infrastructure’s characteristic thin soils,low organic matter,temperature fluctuations,and w...The North American design community typically regards green roofs as inhospitable environments for native plants due to the infrastructure’s characteristic thin soils,low organic matter,temperature fluctuations,and wind exposure.Consequently,green roofs are often planted with an industry-standard palette of non-native Sedum and Phedimus species that are adept at withstanding stress,but lack biodiversity and visual interest,and offer little food or shelter to native birds and insects.Regionally specific reference plant communities that thrive in similarly harsh growing conditions can positively influence green roof design throughout North America,and consequently provide ecosystem services,contribute to habitat conservation,and increase human exposure to the beauty and benefits of native plants.展开更多
The effect of mine tailings and sewage sludge was evaluated on sorption, desorption, availability and distribution of copper in two soils, one high （sandy soil） and one low in copper （clay soil）. In both soils con...The effect of mine tailings and sewage sludge was evaluated on sorption, desorption, availability and distribution of copper in two soils, one high （sandy soil） and one low in copper （clay soil）. In both soils contaminated by mine tailings the copper sorption capacity and the affinity of the substrate for the metal decreased substantially compared to the uncontaminated soils, however, the sorption remained always high in the clay soil substrates. In the substrates with sandy soil, the high Cu content and lower clay content were determining factors in the lower magnitude of the sorption. Similarly, metal desorption was closely related to these two parameters, and it was higher in clay soil with lower pH. In general, the application of sewage sludge favored the sorption of Cu in soils contaminated and uncontaminated with mine tailings, and in all cases desorption decreased, an effect that remained for at least 30 days. Simple extraction of Cu with CaCl2 and diethylenetriaminepentaacetic acid gave contradictory results, so a careful choice of the procedure is required, depending on the level of metal in the soil and on the acting principle of the extracting agent. In that relation, more complete information on the changes in the metal forms was obtained by application of the sequential extraction procedure proposed by the European Community Bureau of Reference.展开更多
文摘The North American design community typically regards green roofs as inhospitable environments for native plants due to the infrastructure’s characteristic thin soils,low organic matter,temperature fluctuations,and wind exposure.Consequently,green roofs are often planted with an industry-standard palette of non-native Sedum and Phedimus species that are adept at withstanding stress,but lack biodiversity and visual interest,and offer little food or shelter to native birds and insects.Regionally specific reference plant communities that thrive in similarly harsh growing conditions can positively influence green roof design throughout North America,and consequently provide ecosystem services,contribute to habitat conservation,and increase human exposure to the beauty and benefits of native plants.
基金supported by the National Fund for Scientific and Technological Development (FONDECYT) under Project No. 1080632
文摘The effect of mine tailings and sewage sludge was evaluated on sorption, desorption, availability and distribution of copper in two soils, one high （sandy soil） and one low in copper （clay soil）. In both soils contaminated by mine tailings the copper sorption capacity and the affinity of the substrate for the metal decreased substantially compared to the uncontaminated soils, however, the sorption remained always high in the clay soil substrates. In the substrates with sandy soil, the high Cu content and lower clay content were determining factors in the lower magnitude of the sorption. Similarly, metal desorption was closely related to these two parameters, and it was higher in clay soil with lower pH. In general, the application of sewage sludge favored the sorption of Cu in soils contaminated and uncontaminated with mine tailings, and in all cases desorption decreased, an effect that remained for at least 30 days. Simple extraction of Cu with CaCl2 and diethylenetriaminepentaacetic acid gave contradictory results, so a careful choice of the procedure is required, depending on the level of metal in the soil and on the acting principle of the extracting agent. In that relation, more complete information on the changes in the metal forms was obtained by application of the sequential extraction procedure proposed by the European Community Bureau of Reference.
