Modelling C and N mineralization during decomposition of anaerobically digested and composted municipal solid waste.

Application of municipal solid waste (MSW) to arable land can be used to close the nutrient cycle between urban and rural areas. The aim of the current study was to quantify net N mineralization and respiration from composted MSW (CMSW) and anaerobically digested MSW (ADMSW) applied to soil, and to test whether a simple relationship between net N mineralization and respiration that was developed for plant materials, was applicable for these types of MSW. In a laboratory experiment, CMSW and ADMSW were incorporated into soil and incubated at 15 degrees C. During the 149-day experiment, netN mineralization and respiration were determined. Cumulative respiration derived from both MSW types was very steep during the first 30 days, after which it levelled off. However, calculated on the basis of applied C, the ADMSW was 10 times more degradable than the CMSW. Both MSW types caused initial net N immobilization followed by re-mineralization. A simple model based on the relationship between net N mineralization and respiration was only applicable for the MSW after significant modifications. If farmers are to recognize CMSW and ADMSW as valuable fertilizers, it is important that they can be produced with higher maturity, in order to avoid initial N immobilization.     

The relevance of environmental conditions for departure decision changes en route in migrating geese

The timing of life-cycle events crucially influences fitness, particularly in migratory birds, which visit chains of sites with varying seasonality. Here, we used a proportional hazards model to identify local environmental factors, which a long-distance migrant, the Pink-footed Goose (Anser brachyrhynchus), uses for departure decisions on multiple sites along its spring flyway from Denmark via Norway to Svalbard. Our results not only identified day length, local accumulated temperature, and their interaction as likely candidates, but also (more importantly) showed for the first time that their relevance changes en route. The results suggest that the birds switch on a "migratory program" in their wintering grounds, with day length providing general information on time of the year and integrated temperatures providing information on larger scale climate trends. Thereafter, on the stopover sites, local accumulated temperatures allow the geese to infer information on the advancement of spring, which is then used to adjust the speed of progressing northward.     

Critical Loads of Acidity for Forest Soils: Tentative Modifications

We reviewed the current methods for calculatingcritical loads of acidity for forest soils. The consequencesof four sets of assumptions concerning the soil modelstructure, parameter values and the critical loads criterionwere explored by comparing the values of the averageaccumulated exceedance (AAE) calculated for Finland withdeposition values for the year 1995. The AAE index is given inthe unit of deposition and is a measure of how far a region isfrom being protected in terms of fulfilling a certaincriterion, taking into account the size of the ecosystem areas.Using a critical limit for the molar ratio of theconcentrations of base cations to aluminium in soil solutiongave the lowest average accumulated exceedance. Assumingorgano-aluminium complexes and leaching of organic anions gaveAAE = 4 eq ha^-1 a^-1, which was close to the valueobtained with the standard approach used in Finland, assuminggibbsite equilibrium and no leaching of organic anions,yielding AAE = 5 eq ha^-1 a^-1. With a critical basesaturation limit, instead of the concentrations criterion, theAAE index was 17 eq ha^-1 a^-1. The highest averageaccumulated exceedance (AAE = 25 eq ha^-1 a^-1),corresponding to the lowest critical load, was obtained whenthe effects-based criterion (critical concentration or criticalbase saturation) was substituted with one restricting thedeterioration of the neutralizing capacity of the soil, ANC _le(crit) = 0. These tests illustrate the variabilityof the critical load values for acidity that can be introducedby changing the criterion or by varying the calculation method,without, however, representing the extreme values of criticalloads that could be derived.     

An inventory of tree species in Europe—An essential data input for air pollution modelling

We present a detailed tree species inventory covering Europe, parts of Africa and parts of Asia. The inventory contains 39 groups of species that are important for biogenic VOCs or pollen emission calculations. For example: oak (Quercus), poplar (Populus), pines (Pinus), spruce (Picea), birch (Betula) and alder (Alnus). The inventory is based on national forest inventories and national statistics and gives tree species distribution in percentage within broadleaved as well as conifer forests. The inventory includes data from 799 regions and is redistributed into the 50 km × 50 km EMEP grid. The inventory is therefore prepared for easy implementation into atmospheric transport models by providing an extension to already applied land use data such as the Corine Land Cover (CLC2000) or Global Land Cover (GLC2000). The gridded version of the data set will be available on the webpage http://www.dmu.dk/International/Air/Models/Background/Trees/.     

Reducing nitrogen loading of inland and marine waters--evaluation of Danish policy measures to reduce nitrogen loss from farmland

An evaluation in December 2003 of the Danish National Action Plan for the Aquatic Environment II showed that nitrogen leaching from farmland had declined to almost half the amount of that in 1989. This can be ascribed to successful implementation of several measures, the most efficient of which were related to the use of fertilizers: lowered nitrogen standards for crops, increased nitrogen utilization in manure and catch crops. Although the objectives of the plan were almost met and measurements have shown a similar, but not percentually as high a decrease in nitrogen concentrations in both inland and coastal waters, the ecological impact in estuaries and coastal areas is not yet satisfactorily significant. As a consequence, a new National Action Plan for the Aquatic Environment III, including both nitrogen and phosphorus reduction from farming, was agreed to in April 2004. To ensure that good ecological status can be achieved in water bodies according to the requirements of the European Union Water Framework Directive, the national measures will be combined with additional measures for individual river basins.     

pH-dependent release of cadmium,copper, and lead from natural and sludge-amended soils

The pH-dependent release of cadmium, copper, and lead from soil materials was studied by use of a stirred flow cell to quantify their release and release rates, and to evaluate the method as a test for the bonding strength and potential mobility of heavy metals in soils. Soil materials from sludge-amended and nonamended A horizons from a Thai coarse-textured Kandiustult and a Danish loamy Hapludalf were characterized and tested. For each soil sample, release experiments with steady state pH values in the range 2.9 to 7.1 and duration of 7 d were performed. The effluent was continuously collected and analyzed. Release rates and total releases were higher for the Hapludalf than the Kandiustult and higher for the sludge-amended soils than the nonamended soils. With two exceptions the relative release rates (release rate/total content of metal in soil) plotted vs. steady state pH followed the same curves for each metal, indicating similar bonding strengths. These curves could be described by a rate expression of the form: relative release rate = k[H+]a, with specific a (empirical constant) and k (rate constant) parameters for each metal demonstrating that metal release in these systems can be explained by proton-induced desorption and dissolution reactions. With decreasing pH, pronounced increases in release rates were observed in the sequence cadmium > lead > copper, which express the order of metal lability in the soils. The flow cell system is useful for comparison of metal releases as a function of soil properties, and can be used as a test to rank soils with respect to heavy metal leaching.     

Self-healing Ability of Epoxy Vitrimer Nanocomposites Containing Bio-Based Curing Agents and Carbon Nanotubes for Corrosion Protection

Journal of Polymers and the Environment - Epoxy is extensively used for anti-corrosion coatings on metallic materials. Conventional epoxy coatings have a permanent crosslink network that is unable...