Monitoring of Phenol in Wastewater Bioremediation by HPLC

Bioremediation emphasizes the detoxification and destruction of toxic substances by microorganisms. Wastewater obtained from an industrial concern was solvent extracted with methyl alcohol and dichloromethane and analysed by GC/MS. Besides phenol, a large variety of organic compounds were detected. Under controlled laboratory conditions, the wastewater was innoculated with a mixed culture of microorganisms specially selected for their abilities to degrade phenol. Samples were collected at regular intervals from the stirred tank bioreactor and analysed for phenol by reverse phase HPLC with a C18 column. Results shows that from an initial phenol concentration of 987 ppm, slightly more than 50% was destroyed within 163 hours. The dry weight of the microorganisms and the plate count (CFU/ml) shows a steady increase from 0.5238 gms to 0.5355 gms and from 1.1E+9 to 1.94E+13 respectively over the same period. This suggested that the phenol was consumed by the microorganisms as the sole carbon source.     

Antipredator activity and endogenous biosynthesis of defensive secretion in larval and pupal Delphastus catalinae (Horn) (Coleoptera: Coccinellidae)

Delphastus catalinae (Horn) is a predatory ladybird beetle (Coccinellidae) commonly used as a biocontrol agent against greenhouse infestation by whiteflies. It belongs to the basal subfamily Microweisinae, a group for which chemical defenses have not been previously investigated. The larval and pupal stages of D. catalinae possess minute secretory hairs that produce droplets containing compounds of both isoprenoid and polyketide origin. Bioassays with the predatory ant Crematogaster lineolata showed both the larval and pupal secretions to be deterrent. Moreover, isolated secretion components, from both classes of compounds, displayed antipredator activity against the ant. Experiments with D. catalinae larvae fed isotopically labeled glucose showed ¹³C-incorporation into both categories of compounds within the pupal secretion, demonstrating that these antipredator compounds, which differ from the typical nitrogenous defensive molecules of coccinellids, are biosynthesized endogenously. This suggests that the wide use of alkaloids by more derived coccinellids may have arisen after their divergence from the more basal Microweisinae.     

Bioaccumulation and depuration of chromium in the selected organs and whole body tissues of freshwater fish Cirrhinus mrigala individually and in binary solutions with nickel

Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful e ects on human health and other organisms in the environment. Most of the studies dealing with toxic e ects of metals deal with single metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also the “critical” organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C. mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.     

Mobilization of arsenic and other trace elements of health concern in groundwater from the Salí River Basin, Tucumán Province, Argentina

The Salí River Basin in north-west Argentina (7,000 km²) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality problems, including arsenic (concentrations in the range of 12.2–1,660 μg L⁻¹), fluoride (50–8,740 μg L⁻¹), boron (34.0–9,550 μg L⁻¹), vanadium (30.7–300 μg L⁻¹) and uranium (0.03–125 μg L⁻¹). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate concentrations (50.0–1,260 mg L⁻¹) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L⁻¹ in shallow groundwater, 129–250 μg L⁻¹ in deep groundwater and 110–218 μg L⁻¹ in artesian groundwater. All exceed the WHO guideline value of 50 μg L⁻¹. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions.     

Bioaccumulation of lead and the influence of chelating agents in Catla catla fingerlings

Lead is a widespread element and one of the persistent and cumulative pollutants of the environment. The present study deals with the bioaccumulation of lead and the influence of chelating agents, meso 2,3-dimercaptosuccinic acid (DMSA), D-Penicillamine and CaNa₂EDTA in reducing the concentration of lead on the selected organs of Catla catla fingerlings for both acute and chronic exposures by using ICP-AES. It is inferred from the present findings that there was a correlation between environmental conditions and the heavy metal contents of the fish. The highest concentration of lead is found in kidney tissues and the lowest in muscle tissues. The accumulation pattern of lead in the selected organs of Catla catla is: kidney > liver > gill > brain > muscle. Also, it has been found that the treatment of chelating agents, DMSA, D-Penicillamine and CaNa₂EDTA reduces the concentration of lead significantly for both acute and chronic exposures. The results also show that DMSA is the most effective chelator of lead in reducing the body burden of C. catla fingerlings. The observed data further indicate that C. catla could be suitable for monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.     

Effect of acute concentration of zinc on the biochemical contents of brain of Labeo rohita: an FT-IR study

Heavy metal discharges to aquatic environment are of great concern due to their toxicity and accumulative behavior. Zinc is an essential trace element required for different physiological functions and plays important role in cellular metabolism. However, it becomes toxic when elevated concentrations are introduced into the environment. The aim of this work is to analyze zinc induced biochemical changes in the brain tissues of Labeo rohita fingerlings using Fourier Transformation Infrared Spectroscopy. Several important features have been observed in the zinc intoxicated brain tissues, namely, altered membrane lipid, altered protein profile and decreased glycogen content, indicating an alteration in the lipid and protein profiles leading to modification in membrane composition. Further, it is observed that the acute exposure to zinc causes some alteration in protein profile with a decrease in α-helix and an increase in random coil structures.     

Molybdenum distributions and variability in drinking water from England and Wales

An investigation has been carried out of molybdenum in drinking water from a selection of public supply sources and domestic taps across England and Wales. This was to assess concentrations in relation to the World Health Organization (WHO) health-based value for Mo in drinking water of 70 μg/l and the decision to remove the element from the list of formal guideline values. Samples of treated drinking water from 12 water supply works were monitored up to four times over an 18-month period, and 24 domestic taps were sampled from three of their supply areas. Significant (p?p?>?0.05) were detected. Tap water samples collected from three towns (North Wales, the English Midlands, and South East England) supplied uniquely by upland reservoir water, river water, and Chalk groundwater, respectively, also showed a remarkable uniformity in Mo concentrations at each location. Within each, the variability was very small between houses (old and new), between pre-flush and post-flush samples, and between the tap water and respective source water samples. The results indicate that water distribution pipework has a negligible effect on supplied tap water Mo concentrations. The findings contrast with those for Cu, Zn, Ni, Pb, and Cd, which showed significant differences (p?England and Wales.     

Variability in the chemistry of private drinking water supplies and the impact of domestic treatment systems on water quality

Tap water from 497 properties using private water supplies, in an area of metalliferous and arsenic mineralisation (Cornwall, UK), was measured to assess the extent of compliance with chemical drinking water quality standards, and how this is influenced by householder water treatment decisions. The proportion of analyses exceeding water quality standards were high, with 65 % of tap water samples exceeding one or more chemical standards. The highest exceedances for health-based standards were nitrate (11 %) and arsenic (5 %). Arsenic had a maximum observed concentration of 440 µg/L. Exceedances were also high for pH (47 %), manganese (12 %) and aluminium (7 %), for which standards are set primarily on aesthetic grounds. However, the highest observed concentrations of manganese and aluminium also exceeded relevant health-based guidelines. Significant reductions in concentrations of aluminium, cadmium, copper, lead and/or nickel were found in tap waters where households were successfully treating low-pH groundwaters, and similar adventitious results were found for arsenic and nickel where treatment was installed for iron and/or manganese removal, and successful treatment specifically to decrease tap water arsenic concentrations was observed at two properties where it was installed. However, 31 % of samples where pH treatment was reported had pH < 6.5 (the minimum value in the drinking water regulations), suggesting widespread problems with system maintenance. Other examples of ineffectual treatment are seen in failed responses post-treatment, including for nitrate. This demonstrates that even where the tap waters are considered to be treated, they may still fail one or more drinking water quality standards. We find that the degree of drinking water standard exceedances warrant further work to understand environmental controls and the location of high concentrations. We also found that residents were more willing to accept drinking water with high metal (iron and manganese) concentrations than international guidelines assume. These findings point to the need for regulators to reinforce the guidance on drinking water quality standards to private water supply users, and the benefits to long-term health of complying with these, even in areas where treated mains water is widely available.     

Geological factors controlling occurrence and distribution of arsenic in groundwaters from the southern margin of the Duero Basin,Spain

Groundwater from springs and boreholes on the southern edge of the Cenozoic Duero Basin (DB) of Spain has concentrations of arsenic (As) which are commonly above the EC drinking-water limit of 10 μg/L and reach observed values up to 241 μg/L. Groundwater compositions within the sedimentary aquifer vary from Ca–HCO₃ type, variably affected by evaporation and agricultural pollution at shallow levels, to Na–HCO₃ compositions in deeper boreholes of the basin. Groundwater conditions are mainly oxidising, but reducing groundwaters exist in sub-basins within the aquifer, localised flow paths likely being influenced by basement structure. Arsenic concentrations are spatially variable, reaching up to 38 μg/L in springs of the Spanish Central System (SCS) basement aquifer and up to 62 μg/L in springs from the DB. Highest As concentrations are associated with the Na–HCO₃ compositions in deep boreholes (200–450 m depth) within the DB. These have high pH values (up to 9.6) which can give rise to associated elevated concentrations of V and U (up to 64 and 30 μg/L, respectively). In the deep borehole waters of the DB, oxidising flows derived from the mineralised igneous–metamorphic basement and discharging via major faults, and are considered the origin of the higher concentrations. Compositions are consistent with desorption of As and other anionic species from metal oxyhydroxides in an oxic environment. Under locally reducing conditions prevalent in some low-flow parts of the DB, an absence of detectable dissolved As is coincident with low or undetectable SO₄ concentrations, and consistent with loss via formation of authigenic sulphide minerals. Mitigation measures are needed urgently in this semi-arid region where provision of alternative sources of safe drinking water is logistically difficult and expensive.     

Chemical defense of a rare mint plant

Summary Analyses of leaf extracts ofDicerandra frutescens, a highly aromatic mint plant from central Florida listed as an endangered species, revealed presence of 12 closely related monoterpenes. The principal of these, (+)—trans-pulegol, is a new natural product, the synthesis of which is described. The terpenes are produced in glandular capsules that release their contents upon injury of the leaf. Data from bioassays with ants and cockroaches indicate that the terpenes serve for defense against insects.Dicerandra does, however, have a leaf-eating enemy, the caterpillar of a pyralid moth,Pyrausta panopealis. The discovery of a new natural product from an endangered species raises questions about the chemical implications of species extinction.