Water quality characteristics of discharge from reforested loose-dumped mine spoil in eastern Kentucky

Surface mining is a common method for extracting coal in the coal fields of eastern Kentucky. Using the Forestry Reclamation Approach (FRA), which emphasizes the use of minimally compacted or loose-dumped spoil as a growth medium for trees, reclamation practitioners are successfully reestablishing forests. Yet, questions remain regarding the effects FRA has on the quality of waters discharged to receiving streams. To examine the effect of FRA on water quality, this study compared waters that were discharged from three types of spoils: predominantly brown, weathered sandstone (BROWN); predominantly gray, unweathered sandstone (GRAY); and an equal mixture of both aforementioned sandstones and shale (MIXED). The water quality parameters pH, EC, Ca, K, Mg, Na, NO-N, NH-N, SO, Cl, TC, suspended sediment concentration (SSC), settleable solids (SS), and turbidity were monitored over a 2-yr period on six 0.4-ha plots (two replications per spoil type). Generally, levels of Cl, SO, Ca, NO-N, NH-N, SS, SSC, and turbidity decreased over time. The pH for all spoils increased from about 7.5 to 8.5. The EC remained relatively level in the BROWN spoil, whereas the GRAY and MIXED spoils had downward trajectories that were approaching 500 μS cm. The value of 500 μS cm has been reported as the apparent threshold at which certain taxa such as Ephemeroptera (e.g., Mayfly) recolonize disturbed headwater streams of eastern Kentucky and adjacent coal-producing Appalachian states.     

Simulating the fine and coarse inorganic particulate matter concentrations in a polluted megacity

A three dimensional chemical transport model (PMCAMx) is applied to the Mexico City Metropolitan Area (MCMA) in order to simulate the chemical composition and mass of the major PM₁ (fine) and PM_1–10 (coarse) inorganic components and determine the effect of mineral dust on their formation. The aerosol thermodynamic model ISORROPIA-II is used to explicitly simulate the effect of Ca, Mg, and K from dust on semi-volatile partitioning and water uptake. The hybrid approach is applied to simulate the inorganic components, assuming that the smallest particles are in thermodynamic equilibrium, while describing the mass transfer to and from the larger ones. The official MCMA 2004 emissions inventory with improved dust and NaCl emissions is used. The comparison between the model predictions and measurements during a week of April of 2003 at Centro Nacional de Investigacion y Capacitacion Ambiental (CENICA) “Supersite” shows that the model reproduces reasonably well the fine mode composition and its diurnal variation. Sulfate predicted levels are relatively uniform in the area (approximately 3 μg m^?3), while ammonium nitrate peaks in Mexico City (approximately 7 μg m^?3) and its concentration rapidly decreases due to dilution and evaporation away from the urban area. In areas of high dust concentrations, the associated alkalinity is predicted to increase the concentration of nitrate, chloride and ammonium in the coarse mode by up to 2 μg m^?3 (a factor of 10), 0.4 μg m^?3, and 0.6 μg m^?3 (75%), respectively. The predicted ammonium nitrate levels inside Mexico City for this period are sensitive to the physical state (solid versus liquid) of the particles during periods with RH less than 50%.     

Matrix effect on the performance of headspace solid phase microextraction method for the analysis of target volatile organic compounds (VOCs) in environmental samples

Solid phase microextraction (SPME) is a fast, cheap and solvent free methodology widely used for environmental analysis. A SPME methodology has been optimized for the analysis of VOCs in a range of matrices covering different soils of varying textures, organic matrices from manures and composts from different origins, and biochars. The performance of the technique was compared for the different matrices spiked with a multicomponent VOC mixture, selected to cover different VOC groups of environmental relevance (ketone, terpene, alcohol, aliphatic hydrocarbons and alkylbenzenes). VOC recovery was dependent on the nature itself of the VOC and the matrix characteristics. The SPME analysis of non-polar compounds, such as alkylbenzenes, terpenes and aliphatic hydrocarbons, was markedly affected by the type of matrix as a consequence of the competition for the adsorption sites in the SPME fiber. These non-polar compounds were strongly retained in the biochar surfaces limiting the use of SPME for this type of matrices. However, this adsorption capacity was not evident when biochar had undergone a weathering/aging process through composting. Polar compounds (alcohol and ketone) showed a similar behavior in all matrices, as a consequence of the hydrophilic characteristics, affected by water content in the matrix. SPME showed a good performance for soils and organic matrices especially for non-polar compounds, achieving a limit of detection (LD) and limit of quantification (LQ) of 0.02 and 0.03 ng g⁻¹ for non-polar compounds and poor extraction for more hydrophilic and polar compounds (LD and LQ higher 310 and 490 ng g⁻¹). The characteristics of the matrix, especially pH and organic matter, had a marked impact on SPME, due to the competition of the analytes for active sites in the fiber, but VOC biodegradation should not be discarded in matrices with active microbial biomass.     

Biomarker responsiveness in different tissues of caged Ruditapes philippinarum and its use within an integrated sediment quality assessment

Biomarkers comprising activities of biotransformation enzymes (ethoxyresorufin-O-deethylase -EROD-, dibenzylfluorescein dealkylase -DBF-, glutathione S-transferase -GST), antioxidant enzymes (glutathione reductase -GR- and glutathione peroxidase -GPX), lipid peroxidation -LPO- and DNA strand breaks were analyzed in the clam Ruditapes philippinarum caged at Cádiz Bay, Santander Bay and Las Palmas de Gran Canaria (LPGC) Port (Spain). Sediments were characterized. Digestive gland was the most sensitive tissue to sediment contamination. In Cádiz Bay, changes in LPO regarding day 0 were related with metals. In LPGC Port, DBF, EROD, and GST activity responses suggested the presence of undetermined contaminants which might have led to DNA damage. In Santander Bay, PAHs were related with EROD activity, organic and metal contamination was found to be associated with GR and GST activities and DNA damage presented significant (p < 0.05) induction. R. philippinarum was sensitive to sediment contamination at biochemical level. Biomarkers allowed chemical exposure and sediment quality assessment.     

Use of recycled fine aggregate in concretes with durable requirements

The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete.     

Detection of human-induced environmental disturbances in a show cave

Purpose  

We investigated the effects of human-induced disruption in a subterranean stable environment containing valuable Palaeolithic paintings and engravings (Ardales Cave, Southern Spain) using a double analytical approach.     

Chitosan/albumin/CaCO3 as mimics for membrane bioreactor fouling: genesis of structural mineralized-EPS-building blocks and cake layer compressibility

Membrane bioreactor biofouling is usually described as an extracellular matrix in which biopolymers, inorganic salts and active microbes co-exist. For that reason, biomineralization (BM) models can be useful to describe the spatial organization and environmental constraints within the referred scenario. BM arguments were utilized as background in order to (1) evaluate CaCO₃ influence on flux decline; pore blocking and cake layer properties (resistance, permeability and compressibility) in a wide range of Chitosan/Bovine serum albumin (BSA) mixtures during step-pressure runs and, (2) perform membrane autopsies in order to explore the genesis of mineralized extracellular building blocks (MEBB) during cake layer build up. Using low molecular weight chitosan (LC) and BSA, 2 L of 5 LC/BSA mixtures (0.25-1.85 ratio) were pumped to an external ultra filtration (UF) membrane (23.5 cm², hydrophobic, piezoelectric, 100 kDa as molecular weight cut-off). Eight different pressure steps (40 ± 7 to 540 ± 21 kPa) were applied. Each pressure step was held for 900 s. CaCO₃ was added to LC/BSA mixtures at 0.5, 1.5 and 3 mM in order to create MEBB during the filtration tests. Membrane autopsies were performed after the filtration tests using thermo gravimetric, scanning microscopy and specific membrane mass (mg cm⁻²) analyses. Biopolymer-CaCO₃ step-pressure filtration created compressible cake layers (with inner voids). The formation of an internal skeleton of MEBB may contribute to irreversible fouling consolidation. A hypothesis for MEBB genesis and development was set forth.     

Assessment of oral bioaccessibility of arsenic in playground soil in Madrid (Spain): a three-method comparison and implications for risk assessment

Three methodologies to assess As bioaccessibility were evaluated using playground soil collected from 16 playgrounds in Madrid, Spain: two (Simplified Bioaccessibility Extraction Test: SBET, and hydrochloric acid-extraction: HCl) assess gastric-only bioaccessibility and the third (Physiologically Based Extraction Test: PBET) evaluates mouth-gastric-intestinal bioaccessibility. Aqua regia-extractable (pseudo total) As contents, which are routinely employed in risk assessments, were used as the reference to establish the following percentages of bioaccessibility: SBET - 63.1; HCl - 51.8; PBET - 41.6, the highest values associated with the gastric-only extractions. For Madrid playground soils - characterised by a very uniform, weakly alkaline pH, and low Fe oxide and organic matter contents - the statistical analysis of the results indicates that, in contrast with other studies, the highest percentage of As in the samples was bound to carbonates and/or present as calcium arsenate. As opposed to the As bound to Fe oxides, this As is readily released in the gastric environment as the carbonate matrix is decomposed and calcium arsenate is dissolved, but some of it is subsequently sequestered in unavailable forms as the pH is raised to 5.5 to mimic intestinal conditions. The HCl extraction can be used as a simple and reliable (i.e. low residual standard error) proxy for the more expensive, time consuming, and error-prone PBET methodology. The HCl method would essentially halve the estimate of carcinogenic risk for children playing in Madrid playground soils, providing a more representative value of associated risk than the pseudo-total concentrations used at present.     

Heavy metal contamination in sediments of an artificial reservoir impacted by long-term mining activity in the Almadén mercury district (Spain)

Sediments from the Castilseras reservoir, located downstream on the Valdeazogues River in the Almadén mercury district, were collected to assess the potential contamination status related to metals(oids) associated with river sediment inputs from several decommissioned mines. Metals(oids) concentrations in the reservoir sediments were investigated using different physical and chemical techniques. The results were analyzed by principal component analysis (PCA) to explain the correlations between the sets of variables. The degree of contamination was evaluated using the enrichment factor (EF) and the geoaccumulation index (Igeo). PCA revealed that the silty fraction is the main metals(oids) carrier in the sediments. Among the potentially harmful elements, there is a group (Al, Cr, Cu, Fe, Mn, Ni, and Zn) that cannot be strictly correlated to the mining activity since their concentrations depend on the lithological and edaphological characteristics of the materials. In contrast, As, Co, Hg, Pb, and S showed significant enrichment and contamination, thus suggesting relevant contributions from the decommissioned mines through fluvial sediment inputs. As far as Hg and S are concerned, the high enrichment levels pose a question concerning the potential environmental risk of transfer of the organic forms of Hg (mainly methylmercury) from the bottom sediments to the aquatic food chain.     

Characterization and sources assignation of PM2.5 organic aerosol in a rural area of Spain

The results from a year-long study of the organic composition of PM2.5 aerosol collected in a rural area influenced by a highway of Spain are reported. The lack of prior information related to the organic composition of PM2.5 aerosol in Spain, concretely in rural areas, led definition of the goals of this study. As a result, this work has been able to characterize the main organic components of atmospheric aerosols, including several compounds of SOA, and has conducted a multivariate analysis in order to assign sources of particulate matter. A total of 89 samples were taken between April 2004 and April 2005 using a high-volume sampler. Features and abundance of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and acids were separately determined using gas chromatography/mass spectrometry and high performance liquid chromatography analysis. The Σn-alkane and ΣPAHs ranged from 3 to 81 ng m^?3 and 0.1 to 6 ng m^?3 respectively, with higher concentrations during colder months. Ambient concentrations of Σalcohols and Σacids ranged from 21 to 184 ng m^?3 and 39 to 733 ng m^?3, respectively. Also, several components of secondary organic aerosol have been quantified, confirming the biogenic contribution to ambient aerosol. In addition, factor analysis was used to reveal origin of organic compounds associated to particulate matter. Eight factors were extracted accounting more than 83% of the variability in the original data. These factors were assigned to a typical high pollution episode by anthropogenic particles, crustal material, plant waxes, fossil fuel combustion, temperature, microbiological emissions, SOA and dispersion of pollutants by wind action. Finally, a cluster analysis was used to compare the organic composition between the four seasons.