Nutrient cycling in bedform induced hyporheic zones

The hyporheic zone is an ecotone connecting the stream and groundwater ecosystem that plays a significant role for stream biogeochemistry. Water exchange across the stream-sediment interface and biogeochemical reactions in the streambed concur to affect subsurface solute concentrations and eventually nutrient cycling in the fluvial corridor. In this paper we investigate the interplay of hydrological and biogeochemical processes in a duned streambed and their effect on spatial distribution of solutes. We employ a numerical model to simulate the turbulent water flow and the pressure distribution over the dunes, and then to evaluate the flow field and the biogeochemical reactions in the hyporheic sediments. Sensitivity analyses are performed to analyze the influence of hydrological and chemical properties of the system on solute reaction rates. The results demonstrate the effect of stream velocity and sediment permeability on the chemical zonation. Changing sediment permeability as well as stream velocity directly affects the nutrient supply and the residence times in the streambed, thus controlling the reaction rates under the dune. Stream-water quality is also shown to influence the reactive behavior of the sediments. In particular, the availability of dissolved organic carbon determines whether the streambed acts as a net sink or source of nitrate. This study represents a step towards a better understanding of the complex interactions between hydrodynamical and biogeochemical processes in the hyporheic zon

Real estate values, tree cover, and per-capita income: An evaluation of the interdependencies in buffalo city (ny)

The variables that influence the price formation mechanisms of urban real estate units concern both the socio-economic both the infrastructural and environmental system of the city. In literature, the links between real estate and territory are not widely investigated. This is especially with reference to the correlation levels between Real Estate Prices and the provision of urban greening. In this perspective, aim of the research is to examine functional relations between property prices, environmental factors, and socio-economic parameters. The applied methodology is based on statistical correlation analysis. This supports the construction of an innovative model for the estimation of the function that explains the dependence of property values on social and environmental factors that characterize the city. The elaborations concern data derived with the Tool i-Tree Landescape. Through Geographic Information Systems (GIS), these data are useful to obtain thematic maps illustrating the spatial distribution of Real Estate Prices, Tree Cover, and Per-Capita Income. The surveyed geographical units are the Census Blocks of Buffalo City in New York State (USA)

Implementing and managing urban forests: A much needed conservation strategy to increase ecosystem services and urban wellbeing

Megacities contain at least 10 million people whose wellbeing largely depends on ecosystem services provided by remote natural areas. What is, however, most often disregarded is that nature conservation in the city can also contribute to human wellbeing benefits. The most common mind set separates cities from the rest of nature, as if they were not special kinds of natural habitats. Instead, awareness that urban systems are also nature and do host biodiversity and ecosystem services opportunities, should push urban people towards increased urban forest conservation and implementation strategies. This research estimated existing and potential, tree cover, and its contribution to ecosystem services in 10 megacity metropolitan areas, across 5 different continents and biomes. We developed estimates for each megacity using local data to transform i-Tree Eco estimates of tree cover benefits to reductions in air pollution, stormwater, building energy, and carbon emissions for London, UK. The transformation used biophysical scaling equations based on local megacity tree cover, human population, air pollution, climate, energy use, and purchasing power parity. The megacity metropolitan areas ranged from 1173 to 18,720 sq km (median value 2530 sq km), with median tree cover 21%, and potential tree cover another 19% of the city. Megacities had a median tree cover density of 39 m2/capita, much smaller than the global average value of 7800 m2/capita, with density lower in desert and tropical biomes, and higher in temperate biomes. The present median benefit value from urban trees in all 10 megacities can be estimated as $482 million/yr due to reductions in CO, NO2, SO2, PM10, and PM2.5,$11 million/yr due to avoided stormwater processing by wastewater facilities, $0.5 million/yr due to building energy heating and cooling savings, and$8 million/yr due to CO2sequestration. Planting more trees in potential tree cover areas could nearly double the benefits provided by the urban forest. In 2016 there were 40 megacities, totaling 722 million residents, nearly 10% of the human population, who would benefit from nature conservation plans where they work and live. Nature conservation strategies in megacities should work to sustain and grow the benefits of the urban forest, and improve accounting methods to include additional ecosystem services provided by the urban forest