Environmental impact assessment of the incineration of municipal solid waste with auxiliary coal in China

The environmental impacts of waste incineration with auxiliary coal were investigated using the life-cycle-based software, EASEWASTE, based on the municipal solid waste (MSW) management system in Shuozhou City. In the current system, MSW is collected, transported, and incinerated with 250kg of coal per ton of waste. Based on observed environmental impacts of incineration, fossil CO(2) and heavy metals were primary contributors to global warming and ecotoxicity in soil, respectively. Compared with incinerators using excess coal, incineration with adequate coal presents significant benefits in mitigating global warming, whereas incineration with a mass of coal can avoid more impacts to acidification, photochemical ozone and nutrient enrichment because of increased electricity substitution and reduced emission from coal power plants. The "Emission standard of air pollutants for thermal power plants (GB13223-2011)" implemented in 2012 introduced stricter policies on controlling SO(2) and NO(x) emissions from coal power plants. Thus, increased use of auxiliary coal during incineration yields fewer avoided impacts on acidification and nutrient enrichment. When two-thirds of ash is source-separated and landfilled, the incineration of rest-waste presents better results on global warming, acidification, nutrient enrichment, and even ecotoxicity in soil. This process is considered a promising solution for MSW management in Shuozhou City. Weighted normalized environmental impacts were assessed based on Chinese political reduction targets. Results indicate that heavy metal and acidic gas emissions should be given more attention in waste incineration. This study provides scientific support for the management of MSW systems dominated by incineration with auxiliary coal in China.     

Assessing recycling versus incineration of key materials in municipal waste: The importance of efficient energy recovery and transport distances

Recycling of materials from municipal solid waste is commonly considered to be superior to any other waste treatment alternative. For the material fractions with a significant energy content this might not be the case if the treatment alternative is a waste-to-energy plant with high energy recovery rates. The environmental impacts from recycling and from incineration of six material fractions in household waste have been compared through life cycle assessment assuming high-performance technologies for material recycling as well as for waste incineration. The results showed that there are environmental benefits when recycling paper, glass, steel and aluminium instead of incinerating it. For cardboard and plastic the results were more unclear, depending on the level of energy recovery at the incineration plant, the system boundaries chosen and which impact category was in focus. Further, the environmental impact potentials from collection, pre-treatment and transport was compared to the environmental benefit from recycling and this showed that with the right means of transport, recyclables can in most cases be transported long distances. However, the results also showed that recycling of some of the material fractions can only contribute marginally in improving the overall waste management system taking into consideration their limited content in average Danish household waste.     

Balancing fuelwood and biodiversity concerns in rural Nepal

An agent-based model is developed to explore the pattern of fuelwood collection in an 1178 ha forest area in rural mountainous Nepal. The model relates fuelwood collection intensity and amount of dead wood available for collection to the diversity of polypore species, a group of strictly dead wood dependent fungi which can be used as indicators of the biodiversity associated with dead wood. By analysing scenarios of increased collection the model shows that the relative impact on polypore diversity is rising more rapidly than the time used for collection. This indicates that better market access in the future could potentially imply a major threat to biodiversity associated with dead wood.     

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/.     

Spatial optimization of protected area placement incorporating ecological, social and economical criteria

We describe two approaches for spatial optimization of protected area placement, both based on maximizing an objective function that incorporates ecological, social, and economical criteria. Of these, a seed cell selection procedure works by evaluating potential cells for protection one by one, picking the one that maximizes the objective function, adding seed cells. This continues to full protection of the project area. The other is a Monte Carlo approach, which uses a likelihood sampling procedure based on weighted importance layers of conservation interest to evaluate alternative protected area sizing and placement. This is similar to the objective function of Marxan, a priority-selection decision-support tool based on optimization algorithms using geographic information system data. The two approaches are alternative options in a common spatial optimization module, which uses the time- and spatial-dynamic Ecospace model for the evaluations. The optimizations are implemented as components of the Ecopath with Ecosim approach and software. In a case study, we find that there can be protected area zoning that will accommodate economical and social factors, without causing ecological deterioration. We also find a tradeoff between including cells of special conservation interest, and the economic and social interests. While this does not need to be a general feature, it emphasizes the need to use modeling techniques to evaluate the tradeoff.     

Population genetic structure of North American <Emphasis Type="Italic">Ophiactis</Emphasis> spp. brittle stars possessing hemoglobin

With the discovery of previously unreported populations of hemoglobin-possessing Ophiactis from the Texas coast in the Gulf of Mexico, an investigation into its population structure, including populations of O. simplex from the Pacific coast of California and O. rubropoda from the Atlantic coast of Florida, was undertaken using DNA sequence data from the mitochondrial COI gene. The reconstructed haplotype network suggests that California populations contain the ancestral source of mtDNA variation, and there is no evidence of recent introductions into Texas. Population genetic analyses reveal the California, Florida, and Texas Ophiactis populations to each be significantly differentiated from one another. Sequence divergence among the three areas is shallower than would be predicted given biogeographic history. Texas and Florida populations are equally genetically diverged from California populations as they are to one another, despite the greater potential for gene flow between these areas. The genetic distinctiveness of the Texas populations and the concordance of this pattern with phylogeographic patterns in other brittle star systems indicate an isolated and independent evolutionary history and we hypothesize that the three geographic regions included in this study each serve as hypotheses of population-level lineages that remain to be tested with independent sources of data.     

A method for building spatial model of annual weed seed dispersal from experimental data and its application to simulating Bromus sterilis population dispersal

Spatial model of annual weed seed dispersal, in this article, was theoretically derived. According to the requirements of building the spatial model, we designed and done an indoor experiment of weed seed dispersal by wind. In the experiment, the seeds of Bromus sterilis were released at 100 cm height under different wind velocity conditions. Based on the experimental data, the spatial models of seed dispersal of the weed species were built, which were divided into three types according to the coefficient β < 0, β = 0, β > 0. The results showed that dispersal of annual weed seed in any direction obeyed an approximate Gaussian distribution; under the experimental conditions, spatial distribution type of weed seed dispersal changed with variation of wind velocity. Well-known Howard et al.'s model (Howard et al., 1991) of Bromus sterilis seed dispersal is an especial example of the model built in this article. The result of model analysis indicated that the distribution type described by Howard's model was similar to that of seed dispersal of the weed species at the height of 100 cm under the condition of lower wind velocity (about 2.18 m/s). Using CA simulation analysis we found that mean control agent applying to a cell with weed should have a decrease with an increase of wind velocity to prevent weed with the initial configuration from spreading, which implicated less herbicide needs spraying in every cell with weed on average when wind velocity increases.     

A field experiment on cation exchange-affected multicomponent solute transport in a sandy aquifer

A field experiment was performed in an aquifer in order to study multicomponent cation-exchange processes under natural flow conditions. The aquifer is a glacial outwash plain with sandy aquifer material having a cation-exchange capacity (CEC) of 1.0 meg/100 g. A continuous injection of groundwater spiked with sodium and potassium as chlorides was accomplished over 37 days to resemble leachate contamination from landfills. The plume was monitored by sampling in a dense spatial network (length 100 m, width 20 m) over a period of 2.5 years in order to obtain breakthrough curves and spatial contour maps of the chemical compounds. Na and especially K showed a substantial retardation caused by cation-exchange processes despite the low CEC of the aquifer material. The average velocity of K⁺ was only 10% of the velocity of chloride (0.7 m day⁻¹). The relative migration velocity of Na⁺ was not a constant in the plume, but apparently influenced by dilution. Ca²⁺ and Mg²⁺ were expelled from the cation-exchange sites of the aquifer material and subsequently transported with the same velocity as chloride. The breakthrough curves of the various compounds showed multiple peaks and low concentration zones. It was concluded by calculations with PHREEQE that changes in calcite equilibrium may occur in the lower part of the aquifer, while complexation processes seem to be of no importance. Cation exchange is then the most important process in this field experiment, and further evaluation of the data by a geochemical transport model including cation exchange is recommended.     

Fate of organic contaminants in the redox zones of a landfill leachate pollution plume (Vejen, Denmark)

Samples from 75 sample locations in a landfill leachate pollution plume reveal a significant disappearance of specific organic compounds (SOC's) within the first 100 m of the plume. Only the herbicide Mecoprop® (MCPP) migrates further. Since sorption and dilution cannot account for the decreasing concentrations, degradation is considered to be the governing process. Non-volatile organic carbon shows a corresponding fate probably acting as a substrate for the microbial processes. The first 20 m of the plume are methanogenic/sulfidogenic, judged on the chemistry of the groundwater, followed by a significant ferrogenic zone exhibiting a substantial capacity to degrade the SOC's. The presence of intermediary products (here an oxidized camphor compound) supports the concept of degradation within the ferrogenic zone. This investigation draws the attention to the significant natural attenuation of organic contaminants and to the so far neglected ferrogenic zone in controlling the fate of organic contaminants in leachate plumes.