A kinetic approach for simulating redox‐controlled fringe and core biodegradation processes in groundwater: model development and application to a landfill site in Piedmont,Italy

A three‐dimensional model for predicting redox controlled, multi‐species reactive transport processes in groundwater systems is presented. The model equations were fully integrated within a MODFLOW‐family reactive transport code, RT3D. The model can simulate organic compound biodegradation coupled to different terminal electron acceptor processes. A computational approach, which uses the spatial and temporal distribution of the rates of different redox reactions, is proposed to map redox zones. The method allows one to quantify and visualize the biological degradation reactions occurring in three distinct patterns involving fringe, pseudo‐core and core processes. The capabilities of the numerical model are demonstrated using two hypothetical examples: a batch problem and a simplified two‐dimensional reactive transport problem. The model is then applied to an unconfined aquifer underlying a leaking landfill located near the city of Turin, in Piedmont (Italy). At this site, high organic load from the landfill leachate activates different biogeochemical processes, including aerobic degradation, denitrification, manganese reduction, iron reduction, sulfate reduction and methanogenesis. The model was able to describe and quantify these complex biogeochemical processes. The proposed model offers a rational framework for simulating coupled reactive transport processes occurring beneath a landfill site. Copyright © 2008 John Wiley & Sons, Ltd.     

Drivers of afforestation in Northern Vietnam: Assessing local variations using geographically weighted regression

This article identifies drivers of forest transition in a province of Northern Vietnam between 1993 and 2000 by applying geographically weighted regression (GWR) analysis to remotely sensed and statistical data. The regression model highlighted the spatial variation of the relationship between the percentage of land afforested and its proximate causes. Factors identified as having a major impact on afforestation are: the presence or proximity of a wood-processing industry, the distance to highways, and land allocation to households. Whereas the two former variables are in most areas of the province positively correlated with afforestation, an unexpected negative correlation was observed for the latter. The analysis of these results, supported by an in-depth knowledge of the area and of the political context, leads to the conclusion that, during the time period considered, afforestation was largely driven by state organisations on protected state-owned land, and forestry was not a significant component of household economic activities.     

Climate change, ambient ozone, and health in 50 US cities

We investigated how climate change could affect ambient ozone concentrations and the subsequent human health impacts. Hourly concentrations were estimated for 50 eastern US cities for five representative summers each in the 1990s and 2050s, reflecting current and projected future climates, respectively. Estimates of future concentrations were based on the IPCC A2 scenario using global climate, regional climate, and regional air quality models. This work does not explore the effects of future changes in anthropogenic emissions, but isolates the impact of altered climate on ozone and health. The cities’ ozone levels are estimated to increase under predicted future climatic conditions, with the largest increases in cities with present-day high pollution. On average across the 50 cities, the summertime daily 1-h maximum increased 4.8 ppb, with the largest increase at 9.6 ppb. The average number of days/summer exceeding the 8-h regulatory standard increased 68%. Elevated ozone levels correspond to approximately a 0.11% to 0.27% increase in daily total mortality. While actual future ozone concentrations depend on climate and other influences such as changes in emissions of anthropogenic precursors, the results presented here indicate that with other factors constant, climate change could detrimentally affect air quality and thereby harm human health.     

Impact of ocean model resolution on CCSM climate simulations

The current literature provides compelling evidence suggesting that an eddy-resolving (as opposed to eddy-permitting or eddy-parameterized) ocean component model will significantly impact the simulation of the large-scale climate, although this has not been fully tested to date in multi-decadal global coupled climate simulations. The purpose of this paper is to examine how resolved ocean fronts and eddies impact the simulation of large-scale climate. The model used for this study is the NCAR Community Climate System Model version 3.5 (CCSM3.5)—the forerunner to CCSM4. Two experiments are reported here. The control experiment is a 155-year present-day climate simulation using a 0.5° atmosphere component (zonal resolution 0.625 meridional resolution 0.5°; land surface component at the same resolution) coupled to ocean and sea-ice components with zonal resolution of 1.2° and meridional resolution varying from 0.27° at the equator to 0.54° in the mid-latitudes. The second simulation uses the same atmospheric and land-surface models coupled to eddy-resolving 0.1° ocean and sea-ice component models. The simulations are compared in terms of how the representation of smaller scale features in the time mean ocean circulation and ocean eddies impact the mean and variable climate. In terms of the global mean surface temperature, the enhanced ocean resolution leads to a ubiquitous surface warming with a global mean surface temperature increase of about 0.2?°C relative to the control. The warming is largest in the Arctic and regions of strong ocean fronts and ocean eddy activity (i.e., Southern Ocean, western boundary currents). The Arctic warming is associated with significant losses of sea-ice in the high-resolution simulation. The sea surface temperature gradients in the North Atlantic, in particular, are better resolved in the high-resolution model leading to significantly sharper temperature gradients and associated large-scale shifts in the rainfall. In the extra-tropics, the interannual temperature variability is increased with the resolved eddies, and a notable increases in the amplitude of the El Ni?o and the Southern Oscillation is also detected. Changes in global temperature anomaly teleconnections and local air-sea feedbacks are also documented and show large changes in ocean–atmosphere coupling. In particular, local air-sea feedbacks are significantly modified by the increased ocean resolution. In the high-resolution simulation in the extra-tropics there is compelling evidence of stronger forcing of the atmosphere by SST variability arising from ocean dynamics. This coupling is very weak or absent in the low-resolution model.     

Oceans and human health: Emerging public health risks in the marine environment

There has been an increasing recognition of the inter-relationship between human health and the oceans. Traditionally, the focus of research and concern has been on the impact of human activities on the oceans, particularly through anthropogenic pollution and the exploitation of marine resources. More recently, there has been recognition of the potential direct impact of the oceans on human health, both detrimental and beneficial. Areas identified include: global change, harmful algal blooms (HABs), microbial and chemical contamination of marine waters and seafood, and marine models and natural products from the seas. It is hoped that through the recognition of the inter-dependence of the health of both humans and the oceans, efforts will be made to restore and preserve the oceans.     

Seasonal and spatial variation in lipid and triacylglycerol levels in juvenile chinook salmon (Oncorhynchus tshawytscha) from the Bridge River, British Columbia

Triacylglycerols (TAGs) are the primary form of energy storage in fish, but little work has been done on the dynamics of TAG storage and use in relation to environmental conditions. We sampled age-0 chinook salmon (Oncorhynchus tshawytscha) in two reaches of a regulated river in British Columbia, Canada that had different discharge regimes. During the summer, fish from the reach with high freshet flows grew more slowly and had lower TAG levels than those from the reach with lower and more stable flows. In addition, smaller individuals had lower TAG levels than larger ones. We suggest that in the reach with higher flows fish were unable to obtain sufficient surplus energy for somatic growth and lipid storage. In the fall, when flows were lower, TAG storage increased and the proportion of total lipids that were TAGs were similar for both small and large fish. The allocation of energy to TAG stores was likely a strategy to ensure individuals had sufficient energy for overwintering. Our results suggest that individual-based variation in TAG levels may be sensitive to environmental factors and can be used as a measure of fish condition and performance, but more work is needed to fully understand lipid dynamics in seasonally and spatially variable rearing environments.     

The El Cielo Biosphere Reserve: Forest Cover Changes and Conservation Attitudes in an Important Neotropical Region

This article combines approaches to better understand both forest cover changes and attitudes toward environmental conservation in the El Cielo Biosphere Reserve in northeastern Mexico. Satellite images are used to document the extent and response of forest cover in the reserve before and after its designation as a biosphere reserve. Ethnographic interviews are also employed to examine the attitudes of local people toward the costs and benefits of the biosphere reserve in their lives. Our research found that unlike many “paper parks,” large-scale deforestation has stopped and forest cover has expanded after the biosphere reserve was created. Our research also found that local people value both tangible and intangible benefits created by the biosphere reserve.     

Glaciological Features in the Initial Quiescent Phase of Kuannersuit Glacier, Greenland

This paper describes glaciological features observed on the surface of the large outlet glacier Kuannersuit Glacier on Disko Island, West Greenland, during its initial quiescent phase after a major surge event occurred in 1995–98 in order to classify the glaciomorphological surge system. Focus is on surge features either associated with active surging such as a propagating surge front and serac formation or formed as a consequence of surging such as looped medial moraines and potholes; and on hydrological features related to the evolution of the glacier drainage system such as the supraglacial routing, moulin types and chasms. A chronological glaciomorphological model of the initial quiescent phase of Kuannersuit Glacier, which can be regarded as representative for large outlet surge‐type glaciers with terrestrial terminal regime and long quiescent phase, is proposed.     

LAI and chlorophyll estimation for a heterogeneous grassland using hyperspectral measurements

The study shows that leaf area index (LAI), leaf chlorophyll content (LCC) and canopy chlorophyll content (CCC) can be mapped in a heterogeneous Mediterranean grassland from canopy spectral reflectance measurements. Canopy spectral measurements were made in the field using a GER 3700 spectroradiometer, along with concomitant in situ measurements of LAI and LCC. We tested the utility of univariate techniques involving narrow band vegetation indices and the red edge inflection point, as well as multivariate calibration techniques, including stepwise multiple linear regression and partial least squares regression. Among the various investigated models, CCC was estimated with the highest accuracy (, ). All methods failed to estimate LCC (), while LAI was estimated with intermediate accuracy ( values ranged from 0.49 to 0.69). Compared with narrow band indices and red edge inflection point, stepwise multiple linear regression generally improved the estimation of LAI. The estimations were further improved when partial least squares regression was used. When a subset of wavelengths was analyzed, it was found that partial least squares regression had reduced the error in the retrieved parameters. The results of the study highlight the significance of multivariate techniques, such as partial least squares regression, rather than univariate methods such as vegetation indices in estimating heterogeneous grass canopy characteristics.