Toxicología ambiental y analítica

This study was conducted to: (1) evaluate the water quality of Gans Creek (Missouri, United States), (2) assess the physical and chemical characteristics of two sewage lagoon overflows (confined animal lot lagoon overflow: CALLO, and domestic sewage lagoon overflow: DSLO) discharged into Gans Creek, and (3) understand the most significant analytical variables and major controlling processes influencing Gans Creek water quality using principal component analysis (PCA). Monthly (May 2009-February 2010) sampling was conducted along Gans Creek and at lagoon overflow points. Ammonia-nitrogen (NH3-N) in Gans Creek and the overflows was monitored for another year (March 2010-July 2011) because of its potential toxicity to stream health. Thirty-one variables including pH, electrical conductivity (EC), elemental and anionic species, total nitrogen (TN) and total organic carbon (TOC) were measured in samples. We observed that DSLO samples had the highest level of NH3-N, total phosphorus (TP), TN, TOC and B compared to the corresponding levels in both CALLO and Gans Creek samples. Major stressors for this stream system were dissolved materials and ammonia. PCA showed that the first four rotated components (RC1, RC2, RC3 and RC4) accounted for approximately 60% of the total variability of the dataset. Mineralization (RC1: 20%), sewage overflows (RC2: 19%), diffuse pollution (RC3: 12%), and runoffs from cattle grazing areas (RC4: 9%) were the major controlling processes at the study area. Over twenty water quality determinands were significant in the rotated components. Overflows from the lagoon systems need consistent treatment and management for adequate protection of Gans Creek ecosystem.

Adsorption-desorption of atrazine, metribuzin, alachlor and metolachlor on granular carbon were studied in a batch study. All herbicides were highly sorbed on the granular carbon (93.8-100%). Adsorption data were subjected to the Langmuir and the Freundlich adsorption isotherms, and fitted well to the Freundlich adsorption isotherm (r2>0.96). Except alachlor, where the isotherm was nearly linear, 1/n values for atrazine, metribuzin and metolachlor isotherms were <1, suggesting a decrease in herbicide adsorption with increasing concentration in the aqueous phase. The Freundlich adsorption parameter [Kf(1/n)] values were 6813.6, 2981.8, 1420.7 and 5661.4 for atrazine, metribuzin, metolachlor and alachlor, respectively. Thus, granular carbon showed the highest adsorption capacity for atrazine followed by alachlor, metribuzin and metolachlor. However, a desorption study suggests that, except alachlor (<3%), none of the herbicides were desorbed during three desorption cycles.
Although alachlor adsorption coefficients were higher than those of metribuzin and metolachlor, it was desorbed. The Freundlich constant Kf showed a positive correlation with solubility (S) while no correlation was observed with the octanol-water partition coefficient (Kow). Results of three sequential adsorption studies suggest that the order of herbicide adsorption was: atrazine>metribuzin>metolachlor>alachlor. This is in agreement with the desorption results, which suggested that granular carbon had poor retention capacity for alachlor. Among the herbicides used in this study, granular carbon has maximum retention capacity for atrazine.

Increasing concentration of atmospheric greenhouse gas and its implications to the global climate change is a major concern. Methane (CH4) emitted from terrestrial ecosystem by human activities and or by natural processes gets oxidized by certain group of soil microbes. Any imbalance or negative impact on these microbial groups may lead to ecosystem collapse. Due to rapid industrialization there is increasing threat of various environmental pollutants on the soil microbes. One of the recently identified pollutants is nanoparticles. This paper reviews the impact of nanoparticles on the global climate regulating methanotrophs and potential negative or positive impact of nanoparticles on the soil microbes. Here we assessed the effects of metal nanoparticles on the microorganisms and also the physiology and phylogeny of methanotrophs. Altogether, the study suggests that metal nanoparticle could significantly produce ecotoxicity and killing of phytostimulatory soil bacteria. Thus, the engineered nanoparticle (ENPs) should be further tested as a possible ecofriendly agent.

Medicinal plants are valuable natural sources effective against various infectious agents. Extracts from Libyan traditional medicinal plants were investigated for antibacterial activity. In this study, the potential antibacterial activity of extracts from eight Libyan traditional medicinal plants against methicillin-resistant Staphylococcus aureus (MRSA) was investigated in-vitro. Susceptibility assays using disc diffusion and broth microdilution test for the determination of minimum inhibitory concentration (MIC) were used to assess the antibacterial activity of methanolic extracts from medicinal plants. Extracts from all eight plants showed anti-MRSA activity with MIC values ranged between 25-50 mg/ml. Cistus salvifolius, Salvia officinalis, Pistacia atantica, Arbutus pavarii, and Myrtus communis exhibited the most potent anti-MRSA activity, whereas extracts from Teucrium polium, Thymus capitellatus, and Euphorbia dendroides showed weak anti-MRSA activity. Medicinal plants may serve as useful bactericidal agents and warrant further investigation to better evaluate their particular therapeutic potentials and optimize their application.

Powdered eye shadows are the most used eye cosmetics in Iran. 120 samples of 15 brands of pressed powder eye shadows in main seven colors: pink, white, violet, brown, golden, green and blue made from different countries were randomly purchased for analysis but a single brand may contain several colors which have been analyzed. Data was collected on the cost, brand, and color of product and batch number of the products that was sampled. The samples were analyzed according to standardized international protocols by wet digestion method (Using HNO3, HClO4, H2O2) analyzed by Atomic Absorption Spectrophotometer. Lead and cadmium detected in all colors in wide range of concentrations. The brown and golden colors in all brands have the highest concentrations of lead, while blue and green colors have the lowest Lead content and the golden and blue color have the highest and lowest concentration of cadmium respectively. Estimating the safety assessment of cosmetic products such as eye shadows is a complex issue. The concentration of cadmium shows significant differences of this heavy metal in the color main groups (p<0.005). This result reveals that the type of pigment used in eye shadows contributes to its heavy metal content. As toxic metals especially lead can rise to accumulate in body over time and repetitive metal-containing product application and probably lead to significant exposure levels, We recommended the major quality controls for the cosmetics products due to long contact with the skin of eyelids.