Naturally occurring thallium: a hidden geoenvironmental health hazard?

This paper illustrates a real environmental concern and draws attention to the fact that natural processes can mobilize thallium (Tl), a highly toxic metal, which may enter the food chain as a "hidden health killer" with severe health impacts on local human population. Natural processes may be exacerbated by human activities such as mining and farming, and may cause enrichment of Tl in the environment. In geochemically anomalous areas with concentrated levels of Tl in the surface environment (bedrocks, waters, soils, and crops), such as the Lanmuchang area in southwestern Guizhou Province, China, it is essential to establish base-level values and to pay heed to the geological context of "natural contamination," as high concentrations of Tl in bedrocks/ores (6-35,000 mg/kg) can lead to enrichment of Tl in the aquatic system (0.005-1100 microg/l in groundwaters and 0.07-31 microg/l in surface waters) and soil layers (1.5-124 mg/kg). In sensitive areas such as the Yanshang area of southwestern Guizhou, elevated natural levels of Tl from bedrocks may also cause higher concentrations of Tl in the surface environment, and thus more attention must be paid to geoenvironmental management of human activities if socio-economic catastrophes are to be avoided. Due to high uptake of Tl by crops, Tl can be transferred from soils to crops and remarkably concentrated in food crops. Concentrations of 1-500 mg/kg Tl based on dry weight (DW) were determined in many food crops growing on Tl-contaminated arable soils from the Lanmuchang area. The daily intake of 1.9 mg of Tl from consumed food crops was estimated for the local adult inhabitant of Lanmuchang. Thus, Tl is regarded as a latent health hazard with potential risk of toxicity in humans within areas of "natural" contamination by Tl.     

Synthesis of SnO2 quantum dots mediated by Camellia sinensis shoots for degradation of thiamethoxam

Abstract

A novel method of synthesis of tin dioxide quantum dots employing Camellia sinensis shoots as reducing agent and stabilizer is presented. The quantum dots were characterized by UV spectroscopy, X-Ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The crystalline tin dioxide quantum dots with an average size of 4.3?nm were of flake like morphology capped by phenolic compounds of Camellia sinensis. The quantum dots were employed for the photocatalytic degradation of thiamethoxam resulting in 57% degradation within 45 mins.     

Adsorption study for the removal of a basic dye: experimental and modeling

An effective adsorbent is developed from saw dust and its various adsorption characteristics are studied for removing a basic dye (crystal violet) from its aqueous solution. Equilibrium data are fitted to various adsorption isotherms. It is seen that about 341 mg of crystal violet can be removed using 1g of the adsorbent at 298 K. Kinetic study is also carried out to observe the effects of various process parameters viz. particle size of the adsorbent, initial concentration of the dye, temperature and adsorbent amount. A generalized two-resistance mass transfer model, which includes a film mass transfer coefficient (k(f)) and an internal effective diffusivity (Dp), is used to interpret the adsorption kinetic data. The model parameters (k(f) and Dp) are estimated by fitting the experimental data to the model. The evaluated parameters are used to predict the concentration profiles at various other operating conditions. The average deviation of the predicted values lies within 10% in all the cases. Sensitivity analysis is performed to observe the sensitivity of the model to the variations in the model parameters.     

Biosolids application affects the competitive sorption and lability of cadmium,copper, nickel,lead, and zinc in fluvial and calcareous soils

The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28–43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L^?1). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L^?1). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L^?1, but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L^?1 in both soils. We conclude that at low loading rate (e.g., 50 mg L^?1) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L^?1) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.     

Impact of raking and bioturbation-mediated ecological manipulation on sediment–water phosphorus diagenesis: a mesocosm study supported with radioactive signature

The study examined the impact of raking and fish bioturbation on modulating phosphorus (P) concentrations in the water and sediment under different trophic conditions. An outdoor experiment was set to monitor physicochemical and microbiological parameters of water and sediment influencing P diagenesis. A pilot study with radioactive ³²P was also performed under the agency of raking and bacteria (Bacillus sp.). Raking was more effective in release of P under unfertilized conditions by significantly enhancing orthophosphate (35%) and soluble reactive phosphate (31.8%) over respective controls. Bioturbation increased total and available P in sediments significantly as compared to control. The rates of increase were higher in the unfertilized conditions (17.6–28.4% for total P and 12.2 to 23.2% for available P) than the fertilized ones (6.5–12.4% for total P and 9.1 to 15% for available P). The combined effects of raking and bioturbation on orthophosphate and soluble reactive phosphate were also stronger under unfertilized state (54.5 and 81.8%) than fertilized ones (50 and 70%). The tracer signature showed that coupled action of introduced bacteria and repeated raking resulted in 59.2, 23 and 16% higher counts of radioactive P than the treatments receiving raking once, repeated raking and bacteria inoculation, respectively. Raking alone or in sync with bioturbation exerted pronounced impact on P diagenesis through induction of coupled mineralization and nutrient release. It has significant implication for performing regular raking of fish-farm sediments and manipulation of bottom-grazing fish to regulate mineralization of organic matter and release of obnoxious gases from the system. Further, they synergistically can enhance the buffering capacity against organic overload and help to maintain aquatic ecosystem health.

     

Sediment quality,elemental bioaccumulation and antimicrobial properties of mangroves of Indian Sundarban

Environmental Geochemistry and Health - Mangroves have wide applications in traditional medicines due to their several therapeutic properties. Potentially toxic elements (PTEs), in mangrove...     

Efficacy of Vermicompost against fertilizers on Cicer and Pisum and on population diversity of N2 fixing bacteria

Vermicompost is a very important biofertilizer produced through the artificial cultivation of worms i.e. Vermiculture. Vermicompost is enriched with all beneficial soil bacteria and also contain many of the essential plant nutrients like N, P, K and micronutrients. It increases soil aeration, texture and jilt. In this work, study is being carried out to find out the effect of different fertilizers such as DAF, FYM and Vermicompost on various morphological parameters and on the in vitro growth of bacterial colonies and its diversity in relation to two important leguminous plants such as Pisum sp. and Cicer sp. Results showed that plant grown in Vermicompost pretreated soil exhibited maximum increase in all morphological parameters such as root length, shoot length, number of root branches, number of stem branches, number of leaves, number of flowers, number of pods and number of root nodules in four months sampling in comparison to untreated, FYM treated and DAP treated soils. Further in Vermicompost pretreated soil, number of N2 fixing bacterial colony was maximum and showed highest diversity indices (1.6 and 0.99 and 2.0 and 0.99 for Cicer sp. and Pisum sp. respectively) than FYM, DAP and untreated control. Thus not only does the Vermicompost stimulate plant growth but also it increases the N2 fixing bacterial population in soil and also its diversity.     

Assessing the potential ecological risk of Co,Cr, Cu,Fe and Zn in the sediments of Hooghly–Matla estuarine system,India

Environmental Geochemistry and Health - Hooghly–Matla estuarine system along with the Sundarbans mangroves forms one of the most diverse and vulnerable ecosystems in the world. We have...     

Air quality analysis and indexing of Kolkata city with respect to vertical floor heights and seasonal variation

Air pollution is one of the most important global environmental issues. Urban air quality is generally becoming vulnerable especially in the developing countries due to various developmental activities. Several national and international studies prove that air pollution is harmful to human health and its long term exposure contributes to even mortality. Current study has been designed to determine the vertical floor wise air quality status of the city of Kolkata and the seasonal variation of the pollutants during two consecutive years. Particulate matter (PM₁₀ and suspended particulate matter), oxides of nitrogen, sulfur dioxide and carbon monoxide were analyzed for a total number of 135 air quality samples throughout the study area and period. Pollutants were found positively correlated with each other and with the floor heights. According to the air quality indexing, all the places were found affected from moderate to severe air pollution irrespective of the vertical floor heights, seasons and places. Although, no such seasonal trend has been emerged from the study but the number of samples beyond standard is found highest during the winter season followed by pre-monsoon.     

Predicting climate change and its impact on future occurrences of vector-borne diseases in West Bengal,India

Environment, Development and Sustainability - Climate change is a concerning matter nowadays. It has a long-term effect on human health by spreading vector-borne diseases throughout the world, and...