Two species of Pb-adapted shrubs, Alyssum montanum and Daphne jasminea, were evaluated in vitro for their tolerance to elevated concentrations of cadmium. Shoot cultures were treated with 0.5, 2.5, and 5.0 μM CdCl₂ for 16 weeks and analyzed for their organogenic response, biomass accretion, pigment content, and macronutrient status. Cadmium accumulation and its root-to-shoot translocation were also determined. In both species, rooted microplantlets, suitable for acclimatization, were obtained in the presence of Cd applied as selection agent. In A. montanum, low and moderate dose of Cd stimulated multiplication, rooting, and biomass production. Growth tolerance index (GTI) in Cd-treated shoots ranged from 120 to 215%, while in the roots 51–202%. In turn, in Cd-treated D. jasminea proliferation and rooting were inhibited, and GTI for shoots decreased with increasing doses of Cd. However, roots exposed to Cd had higher biomass accretion. Both species accumulated Cd in developed organs, and its content increased with increasing CdCl₂ dose. Interestingly, D. jasminea accumulated higher amounts of Cd in the roots than A. montanum and immobilized this metal in the root system. On the contrary, A. montanum translocated some part of accumulated Cd to the shoots, but with low efficiency. In the presence of Cd, A. montanum maintained macronutrient homeostasis and synthesized higher amounts of phytosynthetic pigments in the shoots. D. jasminea accumulated root biomass, immobilized Cd, and restricted its translocation at the expense of nutrient balance. Considering remediation potential, A. montanum could be exploited in phytoextraction, while D. jasminea in phytostabilization of polluted substrate.

A magnetic chitosan-modified Fe₃O₄@SiO₂ with sodium tripolyphosphate adsorbent (MTPCS) was synthesized by surface modification of Fe₃O₄@SiO₂ with chitosan using sodium tripolyphosphate (STPP) as the cross-linker in buffer solution for the adsorption of Cu(II) ions from aqueous solution. The structure and morphology of this magnetic nanoadsorbent were examined by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area measurements, Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of initial pH, adsorbent amount, and initial concentration of heavy metal ions were investigated by batch experiments. Moreover, adsorption isotherms, kinetics, and thermodynamics were studied to understand the mechanism of adsorbing metal ions by synthesized MTPCS. The results revealed that adsorption kinetics was best depicted by the pseudo-second-order rate mode and intraparticle-diffusion models. The adsorption isotherm fitted well to the Langmuir model. Moreover, thermodynamic study verified the adsorption process was endothermic and spontaneous in nature. The maximum adsorption occurred at pH 5 ± 0.1, and the adsorbent could be used as a reusable adsorbent with convenient conditions.

Biomarkers such as oxidase enzyme activity from flora exposed to chemicals in the water column and sediments have been widely used by ecotoxicologists to assess the quality of an environment. Biomarkers such as oxidase enzymes are especially useful indicators because they represent a direct biological response to environmental toxicity. A luminometer was used to quantify oxidase enzyme production in watercress (Nasturtium officinale) due to toxic chemical exposure of E85 (85% ethanol and 15% gasoline blend), gasoline, and 99% pure ethanol over a 72-h period in aquatic root exposure and volatile leaf exposure experiments. Aquatic exposure to E85 caused an increase in oxidative enzyme production while gasoline and ethanol caused no significant changes in oxidase concentrations. Aquatic root exposure results were compared to volatile leaf exposures where effects of E85, gasoline, and ethanol caused increases in oxidase production. Morphometric measurements were also conducted as plant stress comparisons to oxidative enzyme analyses. Measurements of root length showed increases in root growth at some concentrations of fuels with only the highest concentration of E85 resulting in a decrease in root growth when compared to the control.

In isolated areas without direct human impact where several species of seabirds nest, transformations affecting the soil come mainly from natural processes, such as chemical enrichment caused by seabirds. Penguins constitute an important bird biomass in the Southern Hemisphere, where they breed in colonies on different sites from 100 to thousands of individuals. The accumulation of trace elements and nutrients in soils within two perennial colonies of Humboldt penguins (Spheniscus humboldti) located in north western Chile and three colonies of Adélie penguins (Pygoscelis adeliae) in the Antarctic Peninsula area were investigated here. Surface soil samples were collected directly from nesting sites. Control samples were taken outside the colonies within sites adjacent to the nesting areas, but not affected by bird excrement. The contents of Cd, Co, Cr, Cu, Mo, Ni, Sr, V and Zn were determined by inductively coupled plasma optical emission spectrometry. Ammonium (NH₄) and nitrate (NO₃) ions were determined colorimetrically. Extractable potassium (K) was determined by flame emission spectrometry, and available phosphorus (Olsen-P) was determined by spectrophotometry. The highest concentrations of trace metals (Cd, Co, Cr, Cu, Mo, V and Zn) and macronutrients (available N, K and P), along with an increase in salinity and acidity levels, were found directly below the seabird colony, a situation occurring in northern Chile as well as in the Antarctic Peninsula area, highlighting the role that penguins have as bio-vectors on generating geochemical changes in different ecosystems. Some terrestrial plants and animals that live near those penguin colonies might be affected at a greater level than the organisms that live in sites similar but distant from colonies of birds. New data about the role of these species of seabirds as bio-vectors of chemical contaminants are added.

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.

Manure storages, and in particular those storing digested manure, are a source of ammonia (NH₃) emissions. Installing floating manure covers provide resistance to gas transfer from manure storage surface to air and reduces NH₃ emissions; however, performance can be limited to durability. Biochar and steam-treated wood have strong potential as manure storage covers as they are capable of repelling water, resistant to microbial degradation, and could be applied to crop acreage. An additional benefit of biochars as a cover is their capability of NH₃ sorption trapping TAN (total ammoniacal N) before it is volatilized resulting in further abatement. Installation of permeable manure storage covers is difficult and adding covers with agitators could facilitate implementation. This study measured NH₃ emissions from laboratory scale storages of digested manure with raw wood (white birch, Betula papyrifera), steam-treated wood, wood biochar, and corncob biochar covers. Additional treatments included mixing biomass treatments into manure storages to measure the reduction potential of incorporated biomass. All treatments reduced emissions of NH₃ from the control by 40 to 96%. The highest NH₃ emissions reductions of 96% were achieved with the wood biochar cover. The primary mechanism for treatment was resistance to gas transfer provided by the physical barrier of covers as NH₃ sorption did not correspond to reductions. Covering digested manure storages with any of the treatments can reduce NH₃ emissions; biochar covers are a more effective barrier to NH₃ emissions and are recommended to minimize NH₃ manure storage losses.

The herbicides 2,4-diclorophenoxiacetic and 4-chloro-2-methylphenoxyacetic acids (2,4-D and MCPA) are widely used in agricultural practices worldwide. Not only are these practices responsible of surface waters contamination, but also agrochemical industries through the discharge of their liquid effluents. In this investigation, the ability of a 2,4-D degrading Delftia sp. strain to degrade the related compound MCPA and a mixture of both herbicides was assessed in batch reactors. The strain was also employed to remove and detoxify both herbicides from a synthetic effluent in a continuous reactor. Batch experiments were conducted in a 2-L aerobic microfermentor, at 28 °C. Continuous experiments were carried out in an aerobic downflow fixed-bed reactor. Bacterial growth was evaluated by the plate count method. Degradation of the compounds was evaluated by UV spectrophotometry, gas chromatography (GC), and chemical oxygen demand (COD). Toxicity was assessed before and after the continuous process by using Lactuca sativa seeds as test organisms. Delftia sp. was able to degrade 100 mg L⁻¹ of MCPA in 52 h. When the biodegradation assay was carried out with a mixture of 100 mg L⁻¹ of each herbicide, the process was accomplished in 56 h. In the continuous reactor, the strain showed high efficiency in the simultaneous removal of 100 mg L⁻¹ of each herbicide. Removals of 99.7, 99.5, and 95.0% were achieved for 2,4-D, MCPA, and COD, respectively. Samples from the influent of the continuous reactor showed high toxicity levels for Lactuca sativa seeds, while toxicity was not detected after the continuous process.

Fe₃O₄ decorated multi-walled carbon nanotube (Fe₃O₄/MWCNT) nanocomposites were synthesized by co-precipitation process and used as heterogeneous Fenton catalyst for degradation of phenol and p-nitrophenol (p-NP). The Fe₃O₄ nanoparticles with size less than 20 nm were well-dispersedly coated on the surface of MWCNTs at relatively low loading. Some aggregations appear at high Fe₃O₄ content in composite. The Fe₃O₄/MWCNT with about 25 wt.% of Fe₃O₄ is the most cost-effective catalyst compared with others, whose phenol conversion and COD removal rates could, respectively, reach to 99.20 and 58.09%. And a high H₂O₂ utilization efficiency was achieved (about 132.41%) for this catalyst. For the p-NP degradation, the optimal reaction condition was that: 2.0 mg/L of catalyst dosage, 3 mmol/L of initial H₂O₂ concentration, 3 of pH value, and 40 °C of reaction temperature. At this condition, the removal rates of p-NP and COD in 120 min achieved 97.16 and 67.71%, respectively. And the Fe₃O₄/MWCNT nanocomposite also exhibits an acceptable stability and reusability.

TiO₂ nanoparticles and nanofibers have been used to carry out a comparative study of the destruction of H₂S gas. Effects of sulphur doping have also been incorporated to assess the maximum destruction potential of the nanomaterials. An analysis has been made in this paper to evaluate and compare the performance of pure and sulphur-doped TiO₂ nanoparticles and nanofibers for the destruction of H₂S gas using photocatalysis under laboratory conditions. Regression modelling has been performed to ascertain the individual degradation rates of the nanoparticles and nanofibers. In addition, oxidation rates of H₂S gas using the nanoparticles and nanofibers have been used to further elucidate our findings. It was observed that the destruction potential of nanofibers was 10 times more as compared to nanoparticles.

Rapid increase in impervious surfaces due to urbanization often intensifies the frequency of flooding which in turn increases runoff of environmental pollutants. The Brays Bayou watershed (BBW) is a heavily urbanized and densely populated watershed located mostly in Harris County, TX. The objectives of our study are (1) to analyze and interpret the spatial and temporal land use and land cover changes in BBW and (2) to determine nutrient, heavy metal, and bacterial contamination in the Brays Bayou. Water and sediment samples were collected from selected sampling locations along the Brays Bayou and analyzed for various nutrient and metal concentrations. Bacterial analysis was conducted to enumerate the fecal coliform bacteria in water samples. Landsat Thematic Mapper (TM) satellite images sampled from over three decades (1980–2010) for the BBW study area were processed and analyzed for land use and land cover changes. Our remote sensing analysis revealed that the BBW lost about 28.4% (9463 acres) vegetation during the period of 1984 to 2010. The loss in vegetative areas resulted in increased impervious surface areas. In sediment samples, increasing trends for Al, Cu, Fe, Pb, and Zn were observed towards the downstream of Brays Bayou. Lead concentrations were found at the highest concentration (70 mg/kg) in certain Brays Bayou sampling locations. Escherichia coli concentrations decreased towards the downstream of Brays Bayou and were found below 200 maximum probable numbers/100 ml. Integration of remote sensing along with the chemical and biological analysis helped to understand the impact of land cover changes on the bayou water quality.