干旱区生态环境知识资源中心

We studied the physical characteristics and the main chemical components found in sealed municipal landfills in semi-arid environments. This research was focused primarily on the identification of the main limiting factors for establishment and growth of plants on landfill surfaces, and the comparison of these factors with other soils in the area. Such information may be applicable to the future use of landfill sites. Variance analysis of our soil data showed that significant differences existed for 20 of the 36 parameters analyzed. The percentage of bare soil was much higher in landfills. Fine sand, sift, apparent density, and structural instability were greater in landfill covers than in other types of habitats. Field capacity and wilting point were low, and soil permeability to water was very low in the landfill covers. Electrical conductivity and pH were clearly higher in these environments, while organic matter and total N were much lower. Chloride, sulfate, fluoride, and sodium content were higher in landfill covers. The levels of heavy metals (Fe, Mn, Cr, and Pb) were also higher in landfill samples. The comparison of the edaphic cover of landfills with soils in the surrounding herbaceous communities showed that physical factors contributed to unfavorable growth conditions for plants in converted dump areas. All of the factors were related to technical aspects of landfill design and sealing. Soil salinity and local higher content of some trace elements were the most noticeable aspects, both being related to pollution problems. High values of trace elements in some samples indicated that local toxicity problems may exist. Finally, the low content of organic matter of landfill soils was worrisome, and therefore, the establishment and improvement of a vegetation cover and the subsequent increase in soil organic matter became the key factors in reclaiming such lands.