Emissions from mechanically biologically treated waste landfills at field scale

Modern waste management tends towards greater sustainability in landfilling, with the implementation of strategies such as the pretreatment of solid waste. This work assesses the behaviour of rejects from a refining stage of mechanically biologically treated municipal solid waste at the landfill. The main results of 18 months’ monitoring of an experimental pilot cell with waste from a full-scale plant are presented. This first stage is expected to be the most problematic period for this type of waste. The evolution of the temperature and the composition of leachate and gas at various points within the cell are included. During the first weeks, pollutant concentrations in the leachate exceeded the reference ranges in the literature, coinciding with a rapid onset of methanogenic conditions. However, there was a quick wash, reducing concentrations to below one-third of the initial values before the first year. pH values influenced concentrations of some pollutants such as copper. These results indicate that, right from the beginning of disposal, such facilities should be prepared to treat a high pollution load in the leachate and install the gas emissions control elements due to the rapid onset of methanogenesis.     

Records of organochlorine pesticides in soils and sediments on the southwest of Buenos Aires Province,Argentina

The present study fills a gap in the knowledge in regards to the occurrence of banned pesticides at both coastal and inland locations at the Southwest Buenos Aires region, Argentina. Superficial sediment and soil samples were collected from different sites along the Bahia Blanca Estuary and surrounding sites to assess the concentration levels and spatial distribution of 12 selected organochlorine pesticides (OCs); 13 spatial locations including inland and shore-coast were sampled to evaluate occurrence and concentration levels of hexachlorocyclohexanes α-HCH, β-HCH, δ-HCH, γ-HCH, dichlorodiphenyltrichloroethane and its degradation products (DDXs: p,p′-DDT, o,p′-DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD, o,p′-DDD) and the polychlorobenzenes PeCB (pentachlorobenzene) and HCB (hexachlorobenzene). After cleaning and extractions steps, samples were analyzed by means of gas chromatography/mass spectrometry. ∑OCs (sum of all studied compounds) ranged between 0.206 and 1040 ng g^?1 dw (mean?=?82.4 and SD?=?277 ng g^?1 dw). Total HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) ranged from 0.0858 to 0.876 ng g^?1 dw (mean?=?0.43 and SD?=?0.23 ng g^?1 dw), DDXs (sum of p,p′and o,p′ isomers) from 0.080 to 1040 ng g^?1 dw (mean?=?81.3 and SD?=?277 ng g^?1 dw). Lower concentrations were found for PeCB (mean?=?0.095 and SD 0.17 ng g^?1 dw) and HCB (mean?=?0.56 and SD 1.7 ng g^?1 dw). Principal component analysis (PCA) permitted the extraction of underlying information about common factors, providing an overview of the distribution of pesticides and allowing the characterization of sites in regards to the major pesticide signature.     

Temporal and spatial dynamics in aquatic macroinvertebrate communities along a small urban stream

Urbanization is a current and increasing threat to biodiversity. The effects of urbanization on the functional and taxonomic composition of macroinvertebrate assemblages were investigated in two seasons along a small urban stream. Species composition was determined by the rate of urbanization; however, response of species richness could not be evidenced. Relative abundance of the sensitive macroinvertebrate groups (EPT%) was negatively related to urbanization. Almost all feeding groups showed a sharp decline in the number of specimens along the increase of urbanization. The study supports the view that urbanization has a negative effect on the biological quality of a stream, yet, this obvious impact can be overridden by different measures such as modification in streambed morphology. The altered conditions and new circumstances in urban environments lead to the creation of novel ecosystems, inhabited by macroinvertebrate communities with species richness approaching that of low impacted sites. However, species composition of these communities could be basically different from that of the natural ones.     

In situ and nondestructive characterization of mechanical properties of heritage stone masonry

The necessity of conserving and preserving the heritage is nowadays a developing study line for several researchers. From a civil engineering perspective, one of the most important issues for the conservation of historical buildings is to ensure the structural stability. For this purpose, it is necessary to determine the mechanical properties of the ancient construction materials. However, these structures cannot be evaluated by destructive tests due to politics and restrictions for preserving the heritage built. As a consequence, new methods that do not put in risk the integrity of the materials and the structure are becoming useful tools for researchers who work on structural engineering of heritage buildings. This paper presents a nondestructive method (NDM) that has been used to characterize the mechanical properties of different constructive systems of the San Antonio de Padua Temple, which is a religious icon in Aguascalientes, Mexico. This method includes the measuring of seismic waves’ travel time in order to obtain shear and compressional velocity waves. Results show that with this method mechanical properties of masonry can be obtained such as Young’s modulus, Poisson ratio and bulk density, which are needed for the structural analysis using numerical simulation models.     

A numerical model in predicting the initial karst development in porous limestone

The numerical model proposed in this paper represents a new method in predicting initial karst spatial distribution of carbonate aquifers. Karstification Index, \( \varPhi_{\text{K}} \), is a measure of the possible largest amount of calcite that can be dissolved from a unit area of rock and transported by groundwater flow during a unit length of time. Mathematically, it is defined as \( \varPhi_{\text{K}} = q \cdot s \), where q is the flux of groundwater and s is the rock solubility; and Karstification Index, \( \varPhi_{\text{K}} \), is the function of flow, heat, and calcium concentration. The numerical model simulates the time- and space-dependent susceptibility to, and process of, karstification by iterative calculations between \( \varPhi_{\text{K}} \) and hydraulic conductivity. A sample calculation is presented on a hypothetical limestone plateau with steep escarpment, a spring, and a river on one side, a vertical no flow boundary on the other side, and a horizontal impermeable base. The rock has an equivalent porous-medium hydraulic conductivity of K?=?5E?8 ms^?1, which is characteristic to non-karstified limestone. Initially, the spring is located at the intersection of the water table and the escarpment’s face some distance above the river. The simulation result showed that the water table is lowered in 2325 years across the plateau, but the spring’s drop is stopped after 65 years. Karstification is most intensive along the water table due to the higher value of Karstification Index which resulted from the intensive flux of the water. The continual decline of the water table results in a laterally elongated and progressively expanding body of karstified rock and finally as a horizontal conduit at river level. The concentration of Ca²⁺ and conduit diameter decrease from the spring toward the impermeable vertical wall on the opposite side and downward to the base of the plateau. The results are consistent with general theories and empirical observations of karst and cave evolution.     

Investigation of the climate-driven periodicity of shallow groundwater level fluctuations in a Central-Eastern European agricultural region

The distribution and amount of groundwater, a crucial source of Earth’s drinking and irrigation water, is changing due to climate-change effects. Therefore, it is important to understand groundwater behavior in extreme scenarios, e.g. drought. Shallow groundwater (SGW) level fluctuation under natural conditions displays periodic behavior, i.e. seasonal variation. Thus, the study aims to investigate (1) the periodic behavior of the SGW level time series of an agriculturally important and drought-sensitive region in Central-Eastern Europe – the Carpathian Basin, in the north-eastern part of the Great Hungarian Plain, and (2) its relationship to the European atmospheric pressure action centers. Data from 216 SGW wells were studied using wavelet spectrum analysis and wavelet coherence analyses for 1961–2010. Locally, a clear relationship exists between the absence of annual periodic behavior in the SGW level and the periodicity of droughts, as indicated by the self-calibrating Palmer Drought Severity Index and the Aridity Index. During the non-periodic intervals, significant drops in groundwater levels (average 0.5 m) were recorded in 89% of the wells. This result links the meteorological variables to the periodic behavior of SGW, and consequently, drought. On a regional scale, Mediterranean cyclones from the Gulf of Genoa (northwest Italy) were found to be a driving factor in the 8-yr periodic behavior of the SGW wells. The research documents an important link between SGW levels and local/regional climate variables or indices, thereby facilitating the necessary adaptation strategies on national and/or regional scales, as these must take into account the predictions of drought-related climatic conditions.     

Intraplate volcanism in the Danube Basin of NW Hungary: 3D geophysical modelling of the Late Miocene Pásztori volcano

International Journal of Earth Sciences - Three-dimensional geophysical modelling of the early Late Miocene Pásztori volcano (ca. 11–10 Ma) and adjacent area in the Little...