The levels and composition of particulate matter in Ash Meadows National Wildlife Refuge (NWR) that hosts the only population of the endangered Devil’s Hole pupfish (Cyprinodon diabolis) were examined to obtain baseline air quality information. PM₁₀ and PM₂.₅ mass concentrations were measured using continuous monitors over a period of 12 months. In addition, integrated PM₁₀ and PM₂.₅ filter samples were collected and a subset chemically analyzed for elements, ions, elemental carbon, and organic carbon. The average filter-based PM₁₀ (10.9 μg m⁻³) and PM₂.₅ (5.1 μg m⁻³) levels at Ash Meadows NWR are similar to those previously measured at rural and continental background sites in the southwestern USA. Mineral dust accounted for the largest percentage of aerosol mass, with the highest concentrations being measured during fall months of 2009. Elemental and organic carbon levels were generally low, except for August 29, 2009. During this event, transport of wildfire smoke was suggested, by the passage of air masses over wildfires in California, Utah, and Arizona. Ammonium sulfate varied with season, with the highest concentrations in spring and the lowest in fall and winter. Halite (NaCl) quantities were very low, except for the filter samples collected during a windy period on October 4, 2009 indicating the possible contribution of alkaline playa dust upwind of the site. Above average concentrations of crustal calcium compounds, including carbonates and gypsum, were measured in the PM₁₀ sample collected on November 9, 2009 as well as the two preceding months, ascribed to wind-driven dusty conditions prevailing throughout the late summer and fall of 2009.

Cr interactions with TiO₂were systematically studied using batch and spectroscopic investigations. Sorption of chromium on TiO₂at pH 4.5 increases with increasing Cr concentration. The sorption of Cr(III) is in good agreement with Langmuir isotherm model, whereas that of Cr(VI) is better accounted for by the Freundlich model. At pH 7.0, however, the uptake of Cr(III) by TiO₂is over 95 %, while the extent of Cr(VI) sorption on TiO₂is much less than that of pH 4.5. These results are consistent with SEM observations showing that precipitates of Cr(III) are dominant under neutral pH. The sorption of Cr(VI) on TiO₂decreases with increasing pH. However, Cr(VI) sorption decreases with increasing ionic strength below pH 4.5 whereas the sorption increases with ionic strength above pH 4.5. These observations suggest that Cr(VI) sorption is sensitive to ionic strength, and Cr(VI) could form weakly bound adsorption complexes at the TiO₂–water interface. Phosphate competes with Cr(VI) for TiO₂surface sites during sorption processes, and Cr(VI) desorption accelerates and increases in the presence of phosphate. It is noted that the reduction of Cr(VI) is induced by sunlight on the TiO₂surface, but not detected in acidic solution throughout batch experiments at pH ≥ 4.5 for 24 h.

A novel alginate–montmorillonite biopolymer-clay composite bead formulation for water defluoridation was developed in this study. Montmorillonite was dispersed alginate solution, and the mixture was cross-linked in an aqueous solution of aluminum(III). The resulting cross-linked beads were characterized using FTIR, SEM, and mechanical measurements. In order to reveal the defluoridation capacity of the beads, batch adsorption experiments were carried out. Optimum conditions and effect of competing ions were investigated. Experimental data were modeled using several isothermal, kinetic, and thermodynamic models. Maximum Langmuir adsorption capacity was reached as 31.0 mg g⁻¹at 25 °C. It is also found that the adsorption is physical in nature and follows the Elovich kinetic model, and the fluoride removal efficiency is not affected by the presence of most competing anions. The results show that aluminum alginate–montmorillonite composite beads can be used as effective and natural sorbents for fluoride removal from water.

The aim of this work is to increase the information on trace metals in seabirds and coastal soils in the Antarctica. Concentrations (mg kg⁻¹dry weight) of Cd, Cu, Cr, Ni, Mn, Zn and Pb were determined by ICP-MS in fresh excreta and feathers of Gentoo penguins as well as in soils around the nesting sites where this species inhabits. Samples were collected in four locations throughout the Antarctic Peninsula (January 2014): O’Higgins Base, Stranger Point, Neko Harbor and Doumer Island. The highest levels of elements were found in excreta from O’Higgins Base (2.92, 266.83, 2.99, 44.75, 18.15, 1.68 and 317.92 for Cd, Cu, Cr, Mn, Ni, Pb and Zn, respectively) and Stranger Point (1.97, 222.51, 2.98, 36.62, 13.41, 1.46 and 201.18 for Cd, Cu, Cr, Mn, Ni, Pb and Zn, respectively. Similarly, the highest levels were found in feathers from O’Higgins Base (0.21, 20.89, 1.44, 1.19, 5.90, 0.63 and 64.07 for Cd, Cu, Cr, Mn, Ni, Pb and Zn, respectively) and Stranger Point (0.14, 19.65, 1.47, 1.23, 3.85, 0.60 and 64.19 for Cd, Cu, Cr, Mn, Ni, Pb and Zn, respectively). In soils, the highest levels were found in O’Higgins Base (4.31, 421.94, 64.75, 404.76, 28.13, 281.54 and 484.99 for Cd, Cu, Cr, Mn, Ni, Pb and Zn, respectively), whereas the lowest levels were found in Neko Harbor and Doumer Island. These results observed could be related to the major human presence in the northern area of the Antarctic Peninsula and large-scale transport of pollutants. The metals detected in the excreta of the Gentoo penguin can contribute to increase the contamination of coastal terrestrial ecosystems, which could also affect other living organisms.

Suspended sediments can decrease the apparent bio-concentration factor of organic pollutants through adsorption. However, whether this process also weakens the toxicity of organic pollutants to non-target aquatic organisms is not clear. Therefore, natural sediments were chosen as suspended sediment examples in this research applying atrazine as the target pollutant and Brachydanio rerio (more recently, Danio rerio (Zebrafish)) as the target organism to conduct acute toxicity experiments. The concentration of atrazine in aqueous solution was measured as a time series. Results show that without suspended sediments, the 96-h LC₅₀of atrazine to Brachydanio rerio is 29.06 mg/l at 95 % confidence interval (24.41 to 40.70 mg/l). For suspended sediments of 7500 and 15,000 mg/l, the LC₅₀(i.e., concentration resulting in 50 % mortality) equates to 30.74 and 39.51 mg/l, respectively, and the corresponding confidence intervals are between 27.17 and 40.91 mg/l and between 30.43 and 126.93 mg/l in that order. Probit analysis, which is a type of regression used to analyze binomial response variables, was applied using the Statistical Package for the Social Sciences. For the series of no suspended solids (SS), 7500 and 15,000 mg/l SS, the so-called no-observed-effective concentrations were 3, 9, and 15 mg/l, correspondingly. The uptake quantity and uptake rate of atrazine by B. rerio according to atrazine concentrations in the aqueous solution were computed. The research indicates that suspended sediments can decrease the absorbed rate of atrazine by B. rerio. Thus, suspended sediments weaken the acute toxicity of atrazine to B. rerio.

The feasibility of cyanobacteria removal from freshwater by a dielectric barrier discharge (DBD) process is investigated. Seven commercial and environmental cyanobacteria strains, as well as real algae-laden water, were tested. The removal of the cyanobacteria was evaluated by analyzing the changes in chlorophyll a content, total organic carbon (TOC) concentration, and cell morphology. Nearly total removal of chlorophyll a was achieved within 20 min, while the TOC analysis exhibited an increase-decrease-increase trend in 60 min of treatment, likely due to the oxidation of intracellular and intercellular materials. Observation under light microscopy revealed the disruption of intracellular and intercellular structures within 5 min of DBD treatment and thus supported the TOC analysis. Increasing the salinity of the medium from 0 to 5 parts per thousand (ppt) improved treatment efficiency, where similar level of chlorophyll a removal (around 93 %) was achieved in only half the treatment time. Application of DBD on real algae-laden water from a fish farm yielded higher treatment efficiency than in synthetic medium, indicating the promising application of DBD as a means to control cyanobacteria bloom in fresh and estuary water bodies.

One of the most widely used carbon nanomaterials is fullerene (C₆₀), a lipophilic organic compound that potentially can behave as a carrier of toxic molecules, enhancing the entry of environmental contaminants in specific organs. Microcystins (MC) are cyanotoxins very toxic for human and environmental health. Several studies showed that exposure to MC or C₆₀generates reactive oxygen species (ROS) and changes in antioxidant levels. Also, another factor that can come to enhance the toxic potential of both MC and C₆₀is UVA radiation. Therefore, it was evaluated the effects on oxidative stress parameters of ex vivo co-exposure of MC and C₆₀(5 mg/l) in gills of the fish Cyprinus carpio under UVA radiation incidence. The results showed that (a) there was a loss of antioxidant capacity after low MC concentration (L, 50 μg/l) + C₆₀co-exposure under UVA, (b) C₆₀under UVA decreased glutathione-S-transferase (GST) activity, (c) high MC concentration (H, 200 μg/l) + C₆₀co-exposure decreased the concentrations of glutathione (GSH) under UVA or in the dark, (d) L under UVA increased lipid peroxidation, and (e) C₆₀did not cause a higher bioaccumulation of MC in gills. The lowering of GSH in H + C₆₀co-exposure should compromise MC detoxification mediated by GST, although toxin accumulation is not influenced by C₆₀.

Biochar is an organic carbon (OC) and plant nutrient-rich substance that may be an ideal amendment for bolstering soil organic matter and nutrient contents. Two biochars were produced by pyrolysis at 350 °C from pine chips (Pinus taeda) and swine manure solids (Sus scrofa domesticus). The biochar total elemental composition was quantified using inductively coupled plasma spectrometer and their surface chemical composition examined using a combination of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). The biochars were mixed into triplicate pots containing Lauderhill muck (Euic, hyperthermic Lithic Haplosaprist) at 0, 2.5, 5, and 10 % (dry mass). Four simulated water infiltration events were conducted during the 124-day incubation to assess the potential alteration in the leaching potential of soluble soil nutrients. At termination, the muck’s fertility characteristics were assessed, and dissolved cations were measured in water leachates. Neither biochars significantly increased the muck’s OC contents. Swine manure biochar contained higher K, Mg, Na, and P concentrations, and these differences were observable in SEM and EDS as differing amounts of surface-precipitated Mg and K salts. Correspondingly, swine manure biochar at all three applications rates significantly increased Mehlich 1-s K, P, Mg, and Na concentrations. Pine chip biochar only improved the Mehlich 1-extractable K concentration but did reduce soluble P concentrations. Water leachates from swine manure biochar treated wetland soil contained significantly higher soluble P concentrations that could create water quality issue in downstream ecosystems.

Mercury (Hg) in aquatic ecosystems is of great concern due to its toxicity, bioaccumulation, and magnification in the food web. The Tibetan Plateau (TP) is endowed with the highest and largest lakes on earth, whereas Hg distribution and behavior in lake waters are least known. In this study, surface water samples from 38 lakes over the TP were collected and determined for the total Hg (THg) concentrations. Results revealed a wide range of THg concentrations from <1 ng to 40.3 ng L⁻¹. THg in lake waters exhibited an increasing trend along the southeast to northwest transect over the TP. Strong positive correlations were observed between THg concentrations and salinity and salinity-related environmental variables, especially for total dissolved solids (TDS) and some of the major ions such as Na⁺, K⁺, and Cl⁻, suggesting the enrichment of Hg in saline lakes. The large-scale geographical pattern of climatic and environmental factors shows a decreasing precipitation and an increasing evaporation northwards and westwards and thereby induces gradient-enhanced enrichment of soluble substances in lake waters, which are likely to complex more Hg in northwestern TP. Our study provides the first comprehensive baseline data set of Hg in Tibetan lake waters and highlights the concurrent high Hg and salinity, representing valuable references and fundamental rules in further understanding the behavior and fate of Hg in lakes over the TP and perhaps high-altitude regions beyond.

Glyphosate applied in association with atrazine provides the best cost/benefit for weed control for genetically modified corn. Therefore, the aim of this work was to evaluate the effects of applying glyphosate in mixture with atrazine on soil microbial population and on herbicides fate in a representative Oxisol from Brazil. The treatments consisted in applying the recommended field rate of glyphosate in association with 0, 1, and 2 times the recommended field rate of atrazine (and vice versa), plus the control (without herbicides application). The presence of atrazine temporarily (21 days) decreased soil microbial biomass (SMB) and increased soil carbon mineralization (SCₘᵢₙ, up to 13 times) and microbial metabolic quotient (qCO₂) due to the stresses caused by its toxicity. When the mixture was applied independent of the rates, SMB was recovered and the amounts of extractable and non-extractable¹⁴C-residues were the same for both herbicides at 63 days. These results suggest that glyphosate may mitigate atrazine’s temporary impact on soil microbes by supplying them nutrients during their adaptation.