Classification of spectral data has recently drawn more and more attention in environmental and geoscience applications. In the past decade, this attention has been translated into an interest in employing unmixing techniques to retrieve accurate quantitative information suppressed in spectral data. The main task in real applications is to detect potential information regarding the physical and chemical nature of ground targets in different spectral data sources (point field and laboratory spectroscopy, hyperspectral imagery, etc.). Recently, semisupervised classification techniques have been proposed for spectral data by combining ground-truth and laboratory measured spectral signatures and advanced signal processing algorithms based on posterior probability support vector machine and Dempster-Shafer evidence theory. In this paper, the sensitivity of this combined classification method to extract and identify a small amount of settle dust over green vegetation canopy using field spectral data is examined and reported. The results are compared with the performance of selected semisupervised unmixing classification techniques.

A groundwater flow and mass transport model simulated the remediation capability of non-pumped wells with filter media placed in backfilled trenches in homogeneous and heterogeneous aquifers. For each of five homogeneous and heterogeneous aquifer settings, the model identified a base configuration of wells for a backfill hydraulic conductivity equal to the mean of the aquifer (1.5 m/d). Base configurations comprised the least number of wells necessary to contain and remove a contaminant plume. For each setting, the model also simulated base configurations with backfill hydraulic conductivity one and two orders of magnitude lower and one and two orders of magnitude higher than the mean of the aquifer. In general, backfill with a hydraulic conductivity equal to the mean of the aquifer, or slightly higher, outperformed other scenarios.

Geological barriers play an important role in preventing pollution of groundwater. Basalts are common geological media; however, there have not been any studies that report the effect of basalt type on the metal ion adsorption performance. In this study, we explored the metal ion (Zn²⁺ and Cd²⁺) adsorption ability of two kinds of weathering basalts, the origin weathering basalt (WB) and the eluvial deposit (ED), both of which were derived from same basaltic formation. Characteristics of the sediments were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Barrett-Joyner-Halenda (BJH) measurement, and the rapid potentiometric titration (RPT) method. Batch experiments were performed to evaluate the Zn²⁺ and Cd²⁺ adsorption performance of WB and ED and how adsorption was affected by contact time, initial metal ion concentration, pH, and ionic strength. Despite WB and ED having similar chemical compositions, WB exhibited better adsorption than ED likely due to the fact that WB was rougher and had more small-sized spherical structures and stronger electrostatic forces. The adsorption process fits the Freundlich isotherm model well. The adsorption efficiency decreased with a decrease of pH (from 4 to 2) and with increasing ionic strength. These results suggest that a geological barrier composed of WB media might be able to effectively sequester metallic contaminants to prevent them from reaching groundwater.

Mesoporous magnetic ferrum-yttrium (Fe-Y) binary oxide was first synthesized as an effective absorbent for the removal of arsenite [As(III)] and arsenate [As(V)] from aqueous solution. The adsorbent was characterized by field emission scanning electron microscopy (FESEM), energy dispersion X-ray spectrometer (EDX), vibrating sample magnetometer (VSM), X-ray photoelectron spectra (XPS). A series of batch experiments were conducted to estimate the adsorption capacity of arsenic and to investigate the effect of solution pH and coexisting anions on the removal of arsenic. The results demonstrate that the adsorption of arsenic by the adsorbent was pH-dependent. The optimal adsorption was realized at pH 4 for As(V) and at pH 5 for As(III). The maximum capacity of As(V) and As(III) obtained in this study was 200 and 73 mg g⁻¹, respectively. The anions concluding sulfate, chloride, and nitrate exerted a weak impact on As(V) removal, whereas phosphate greatly suppressed the adsorption of both As(III) and As(V) through competing with arsenic species for active adsorption sites on the surface of the adsorbent. All above suggest that the novel adsorbent not only works efficiently for arsenic removal, but also is stable in a wide solution pH range, which is conducive to the practical application for wastewater treatment.

This study characterizes a biotensoactive produced by the bacterium Azospirillum lipoferum, which was isolated from the rhizospheres of contaminated plants with oil in the lower basin of the Tonala River, Villa Benito Juarez, municipality of Cardenas, Tabasco, Mexico. The following properties were analyzed: viscosity at 25 °C, elemental analysis (% mol) by scanning electron microscopy, density at different temperatures, molecular weight, acute toxicity, median lethal concentration (LC₅₀), and saponification and acidity indices. The effects of pH (6.0, 7.0, 8.0, and 9.0) and temperature (25, 30, 35, and 40 °C) on the production of the biotensoactive and the effect of NaCl on the surface tension, density, and emulsifying capacity were studied. The results showed that the viscosity remained stable between 1.0914 and 1.1276 mPa-s, so the biotensoactive was classified as low-molecular weight. Toxic effects on the population of Eisenia foetida began at surfactant concentrations above 55,000 ppm, and the LC₅₀ was 96,695 ppm. The highest yield of biotensoactive production was obtained 48 h after the beginning of the treatment at pH 8 and pH 9 and 25 °C. At 25 °C, the surface tension ranged from 44.60 mN/m at a 1 % concentration by weight of NaCl to 51.11 mN/m at 15 % NaCl, while at 60 °C, the surface tension ranged from 34.90 mN/m at 1 % NaCl to 40.22 mN/m at 15 % NaCl. The emulsifying capacity was 70 % (aqueous solution 15 % NaCl).

The spread of antimicrobial resistance (AMR) is a global concern, high research priority being given to the environmental contamination, as the prevalence of organisms exhibiting AMR continues to increase. Multiresistant bacteria carrying different mobile genetic elements have been detected in sites with different degrees of urbanization, surface waters receiving insufficiently treated effluents being at high risk. The aim of the present study was to investigate the loads, antibiotic susceptibility, and class 1 integron carriage of Enterobacteriaceae isolated from surface waters and wastewaters around a large Romanian city. Searching for a valuable genetic marker of the displayed antibiotic resistance, the link between the AMR and the presence of int1I gene was explored in a total of 166 waterborne strains. Overall, amoxicillin-clavulanate resistance displayed the highest frequency (71.1 %), followed by ampicillin (63.9 %), cefuroxime (21.1 %), ciprofloxacin (17.5 %), cefotaxime (15.7 %), ceftriaxone (10.8 %), and gentamicin (6.6 %). The frequencies of isolates resistant to ampicillin, amoxicillin-clavulanate, ciprofloxacin, and gentamicin and also the prevalence of multiresistant strains were greater in surface waters, compared to wastewaters. The Int1I gene was detected in 21.7 % waterborne Enterobacteriaceae. A decrease in coliform counts and intI1-bearing cells, but a general increase in AMR and multiresistant bacteria, occurred during the wastewater treatment. A weak positive correlation was found between multidrug resistance int1I carriage in wastewater effluent but no sufficient evidence of a linkage between phenotypic AMR and int1I, overall. The presence of class 1 integron can be associated with anthropogenic influence, but the simple detection of intI1 gene cannot explain the complex antibiotic resistance phenotype.

Radionuclides were determined in streams and rivers receiving mine drainage from old uranium mines at the center of Portugal. Results showed enhanced radioactivity levels in some areas impacted by uranium mining and milling wastes, but levels were lower than several years ago due to current water treatment of mine drainage. In some areas, such as at the village of Cunha Baixa, water from wells was contaminated by acid mine drainage, and it is not suitable anymore for human consumption and irrigation of horticulture plots. In the present, villages and towns near those old uranium mines have tap water from public networks supplied from artificial lakes built in major rivers of the region. This tap water showed compliance with the recommended limits of total alpha and total beta radioactivity, and it is suitable for human consumption. Radiation exposure of the population was therefore controlled, but current water supply is much more costly than it was with local water sources.

The bulk deposition of both PAHs and metals is a significant, mounting issue for the urban ecological environment. However, studies generally performed on these pollutants have focused on the regions surrounding a pollution source; thus, it most likely overestimated pollutants in the cities. Therefore, 72 atmospheric bulk deposition samples were collected from six sites located along a transect from the suburbs to the city center in Shanghai over a 1-year period (February 1, 2012 to January 31, 2013). The seasonal variation, spatial distribution, and sources of multiple metals (Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, K, Na, and Mg) and 16 polycyclic aromatic hydrocarbon (PAH) compounds were determined. The results indicated that the annual average rate of dust deposition in Shanghai was 43,100 ± 54,800 mg/m²/year. There were significant or high enrichments of Cu, Zn, Cd, and Pb, and higher depositional fluxes were observed for Zn, Pb, and Cd in the Huangpu district and for Cu in the Minhang district. The deposition fluxes of the PAHs exhibited the following order: urban fringe zone > city center > rural zone (background site). However, unlike in northern Chinese cities, the high-molecular-weight PAHs accounted for most of the PAHs. Furthermore, there were higher depositional fluxes of PAHs in March, July, and October. Overall, the factors influencing urban air quality may include construction, fossil fuel combustion, the abrasion of tires and brake linings (directly related to traffic), the corrosion of galvanized protection barriers, and increasing population density.

The effects of soil micro-particles and micro-pores on the release of total petroleum hydrocarbons (TPH) were investigated using long-term weathered, TPH-contaminated soil samples. The TPH concentrations were analyzed using various extraction schemes (i.e., total extraction, weak extraction, solvent extraction with or without ultrasound). The particle size distribution (<2 mm, 0.063–2 mm, <0.063 mm), micro-pore volume (<0.38 mm), and TPH fraction (C8–14, C16–28, C30–40) of selected samples were also determined to better understand the factors controlling TPH release from contaminated soils. TPH concentrations varied greatly among different fractions of each soil sample, but were highest in the micro-fraction (<0.063 mm) of each sample. In weathered soil samples, TPH was not only weakly or strongly adsorbed on soil particles, but also trapped in soil micro-pores. Moreover, heavier fractions of TPH were released slowly and lesser extent from contaminated soils. Results showed that the solvent extraction method with and without ultrasound could be used to assess relative binding strength of TPH to contaminated soils. These findings imply that to achieve a remediation goal, some contaminated soils require only relatively mild extraction with solvent, but soils with TPH trapped in micro-pores require physical destruction along with chemical extraction.

Currently, there are increasing efforts to utilize nanoremediation as an environmental technology for cleaning up polluted environments using nanoscale zero-valent iron (nZVI); however, concerns exist regarding the long-term environmental impact of this strategy. In this study, an innovative methodology for evaluating nZVI impact on soil bacteria is utilized, based on transcriptional analysis of three novel biomakers: tnaA, sodB and trx genes. At the same time, classical toxicological bioassays with the nematode Caenorhabditis elegans were performed. Microcosms treated with 1, 5 and 10 % w/w of nZVI were set up using a commercial standard soil and incubated for 21 days. The tnaA gene, involved in indole production, was significantly upregulated at all assessed nZVI concentrations, suggesting that bacterial cells used this molecule to inform the rest of the community about the changes produced upon nZVI soil treatment. The higher the exposure time, the lower nZVI concentration needed to detect these changes. Consequently, soil bacteria activate a cellular adaptive response to cope with the nZVI-induced oxidative stress, increasing the expression of genes encoding key reactive oxygen species (ROS)-scavenging enzymes; in fact, an upregulation of the sodB and katB genes was recorded upon nZVI exposure. On the contrary, C. elegans survival and growth endpoints were not affected at any nZVI concentration whereas the exposure time significantly increased nematode growth in the soil. Therefore, despite the lack of toxicity revealed by the classical conducted tests, the transcriptional analyses demonstrated the usefulness of combining the set of proposed biomarkers for early detection and monitoring the impact of nZVI on soil bacteria after environmentally important periods of exposure.