Removal of sulfamethoxazole and sulfapyridine by carbon nanotubes in fixed-bed columns

Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have gained increasing attention because of the ecological risks these substances pose to plants, animals, and humans. This work systematically investigated the removal of SMX and SPY by carbon nanotubes (CNTs) in fixed-bed columns under a broad range of conditions including: CNT incorporation method, solution pH, bed depth, adsorbent dosage, adsorbate initial concentration, and flow rate. Fixed-bed experiments showed that pH is a key factor that affects the adsorption capacity of antibiotics to CNTs. The Bed Depth Service Time model describes well the relationship between service time and bed depth and can be used to design appropriate column parameters. During fixed-bed regeneration, small amounts of SMX (3%) and SPY (9%) were irreversibly bonded to the CNT/sand porous media, thus reducing the column capacity for subsequent reuse from 67.9 to 50.4 mg g^?1 for SMX and from 91.9 to 72.9 mg g^?1 for SPY. The reduced column capacity resulted from the decrease in available adsorption sites and resulting repulsion (i.e., blocking) of incoming antibiotics from those previously adsorbed. Findings from this study demonstrate that fixed-bed columns packed with CNTs can be efficiently used and regenerated to remove antibiotics from water.     

Validation of an analytical method for the quantification of pyrethrins on lemons and apricots using high-performance liquid chromatography/mass spectrometry

An analytical procedure has been developed for the determination of natural pyrethrins (pyrethrin I, pyrethrin II, jasmolin I, jasmolin II, cinerin I and cinerin II) in lemon and apricot. The QuEChERS method, which stands for quick, easy, cheap, effective, rugged and safe was used for extraction. Analysis of the extract was performed by liquid-chromatography-electrospray ionisation-tandem mass spectrometry. The ions prominent in the ESI spectra were [M+H]+ for the six compounds. A Zorbax SB-C18 column was used with a programmed gradient mobile phase consisting of (A) water containing 0.1% formic acid and 5 mM ammonium formate and (B) ACN. The method was linear within the investigated concentration range, displaying a calibration curve correlation factor of 0.99. The coefficients of variation obtained (RSD) were below 20% and the recoveries were in the 70-110% range.     

Determination of sixteen pesticides in peppers using high-performance liquid chromatography/mass spectrometry

A method for the detection and quantification of 16 pesticides: flufenoxuron, fenoxycarb, dimethomorph, acetamiprid, imidacloprid, lufenuron, thiacloprid, thiabendazole, thiophanate-methyl, spinosad, fenbutatin oxide, methoxyfenozide, oxamyl, clothianidin, thiamethoxam and carbendazim has been developed based on high-performance liquid chromatography-mass spectrometry. Pesticide residues were extracted from the samples according to the QuEChERS method which stands for quick, essay, cheap, effective, rugged and safe. Homogenised analytical portions (10 g ± 0.1) of samples of peppers were spiked at two levels (10 and 100 μg kg?1) with a small volume of an appropriate standard mixture solution containing each pesticide. Analyses were performed using electrospray ionization (ESI) and a MSD trap system. Chromatography separation was achieved using a ZORBAX SB-C18 3.5 μm particle size analytical column, 2.1 × 50 mm from Agilent, with gradient elution at a flow-rate of 0.4 mL/min with mobile phases: waters-0.1 % HCOOH-5 mM HCOONH? and MeOH-5 mM HCOONH?. The method has been validated based on the SANCO European Guidelines. Under the optimized conditions the recoveries (n = 7) were in the range 70-110 % with satisfactory precision (CV ≤ 20 %). A linear dynamic range was obtained over a range of concentrations from 10 to 100 μg kg?1 for each of the analytes, with correlation coefficients >0.997.     

Statistical accuracy for estimations of large wood blockage in a reservoir environment

Environmental Fluid Mechanics - The blockage of weirs or bridges by in-stream wood can reduce the flood discharge capacity, leading to hazardous situations. To assess the related risk, blocking...     

Anti-oviposition activities of used sock media against a dengue vector: prospects of eco-friendly control and solutions to pollution

Yearly, huge amounts of sock refuse are discarded into the environment. Socks contain many molecules, and worn ones, which are rich in smell-causing bacteria, have a strong influence on animals’ behaviors. But the impacts of sock odor on the oviposition behavior of dengue vectors are unknown. We assessed whether Aedes albopictus changes its oviposition activity in response to the presence of used socks extract (USEx) in potential breeding grounds, using choice and no-choice bioassays (NCB). When furnished even chances to oviposit in two sites holding USEx and two others containing water (control), Ae. albopictus deposited significantly less eggs in USEx than in water sites. A similar pattern of oviposition preference was also observed when there were more oviposition options in water. When there were greater oviposition opportunities in USEx sites, Ae. albopictus oviposited preferentially in water. Females laid significantly more eggs during the NCB involving water than USEx. Also, significantly more mature eggs were retained by females in the NCB with USEx than in that with water. These observations strongly suggest the presence of molecules with either repellent or deterrent activities against Ae. albopictus females and provide an impetus to advocate the integration of used socks in dengue control programs. Such applications could be a realistic end-of-life recourse to reroute this waste from landfills.

     

Biodegradation of heavy crude oil Maya using spent compost and sugar cane bagasse wastes

Experiments were carried out to evaluate the use of some agroindustrial wastes as supports in solid state cultures for the biodegradation of crude oil Maya in static column reactors over 15-20 days periods. Spent compost and cane bagasse wastes showed superior qualities over peat moss waste as support candidates with the advantage that they contain appreciable densities of autochthonous microorganisms in the order of 10(2) cfu g(-1). Mercuric chloride (2%) was able to completely inhibit growth of these microfloras. Biodegradation was enhanced in the presence of the IMP consortium and highest when microflora from cane bagasse only was the bioaugmentation partner (180.7 mg kg(-1) day(-1)). Combination of these waste materials (3:1 ratio, respectively) was observed to significantly biodegrade the crude oil by approximately 40% in 15 days from an initial concentration of 10,000 mg kg(-1) with a four order of magnitude increase in microbial density during this period. Spent compost and cane bagasse wastes are veritable solid support candidates for use in the biodegradation of crude oil polluted systems.     

Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora,México

Environmental Science and Pollution Research - Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and...     

Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city

Particle-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air were monitored together with particulate matter less than 10 μm (PM₁₀) at three sampling sites of the Andean city of Manizales, Colombia; during September 2009 and July 2010. PCDD/Fs ambient air emissions ranged from 1 fg WHO-TEQ m⁻³ to 52 fg WHO-TEQ m⁻³ in particulate fraction. The PM₁₀ concentrations ranged from 23 μg m⁻³ to 54 μg m⁻³. Concentrations of PM₁₀ and PCDD/Fs in ambient air observed for Manizales - a medium sized city with a population of 380 000 - were comparable to concentrations in larger cities. The highest concentrations of PCDD/Fs and PM₁₀ found in this study were determined at the central zone of the city, characterized by public transportation density, where diesel as principal fuel is used. In addition, hypothetical gas fractions of PCDD/Fs were calculated from theoretical K_p data. Congener profiles of PCDD/Fs exhibited ratios associated with different combustion sources at the different sampling locations, ranging from steel recycling to gasoline and diesel engines. Taking into account particle and gas hypothetical fraction of PCDD/Fs, Manizales exhibited values of PCDD/Fs equivalent to rural and urban-industrial sites in the southeast and center of the city respectively. Poor correlation of PCDDs with PM₁₀ (r = −0.55 and r = 0.52) suggests ambient air PCDDs were derived from various combustion sources. Stronger correlation was observed of PCDFs with PM₁₀. Poor correlation between precipitation and reduced PM₁₀ concentration in ambient air (r = −0.45) suggested low PM₁₀ removal by rainfall.     

Genomic erosion in a demographically recovered bird species during conservation rescue

The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400–480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993–2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.