A study on mountain front recharge by using integrated techniques in the hard rock aquifers of southern India

Mountain front recharge (MFR) is the contribution of mountains to recharge the aquifers in the adjacent basins. The estimation of MFR is essential to obtain a detailed investigation of recharge of the groundwater at the mountain front. This study summarises the current understanding of recharge processes by comparing daily groundwater fluctuation to daily rainfall and identifies the recharge rates. The recharge rates vary with time due to difference in water table depth and travel time. Thus to understand the MFR along the foothills of Courtallam, a total of 14 surface water, rainwater and groundwater samples were collected and measured for stable isotopes. The isotopic data were used to investigate the recharge process and to identify the elevations to recharge. The study findings also suggest that predominantly rainfall along the foothills contributes recharge to the riparian zone (basin block region), whereas foothill regions receive recharge from rainfall over mountain block.     

Influence of multi-industrial activities on trace metal contamination: an approach towards surface water body in the vicinity of Dhaka Export Processing Zone (DEPZ)

Industrial wastewater discharged into aquatic ecosystems either directly or because of inadequate treatment of process water can increase the concentrations of pollutants such as toxic metals and others, and subsequently deteriorate water quality, environmental ecology and human health in the Dhaka Export Processing Zone (DEPZ), the largest industrial belt of 6-EPZ in Bangladesh. Therefore, in order to monitor the contamination levels, this study collected water samples from composite effluent points inside DEPZ and the surrounding surface water body connected to effluent disposal sites and determined the environmental hazards by chemical analysis and statistical approach. The water samples were analysed by inductively coupled plasma mass spectrometry to determine 12 trace metals such as As, Ag, Cr, Co, Cu, Li, Ni, Pb, Se, Sr, V and Zn in order to assess the influence of multi-industrial activities on metal concentrations. The composite effluents and surface waters from lagoons were characterized by a strong colour and high concentrations of biochemical oxygen demand, chemical oxygen demand, electrical conductivity, pH, total alkalinity, total hardness, total organic carbon, Turb., Cl(-), total suspended solids and total dissolved solids, which were above the limit of Bangladesh industrial effluent standards, but dissolved oxygen concentration was lower than the standard value. The measurement of skewness and kurtosis values showed asymmetric and abnormal distribution of the elements in the respective phases. The mean trend of variation was found in a decreasing order: Zn > Cu > Sr > Pb > Ni > Cr > Li > Co > V > Se > As > Ag in composite industrial effluents and Zn > Cu > Sr > Pb > Ni > Cr > Li > V > As > Ag > Co > Se in surface waters near the DEPZ. The strong correlations between effluent and surface water metal contents indicate that industrial wastewaters discharged from DEPZ have a strong influence on the contamination of the surrounding water bodies by toxic metals. The average contamination factors were reported to be 0.70-96.57 and 2.85-1,462 for industrial effluents and surface waters, respectively. The results reveal that the surface water in the area is highly contaminated with very high concentrations of some heavy/toxic metals like Zn, Pb, Cu, Ni and Cr; their average contamination factors are 1,460, 860, 136, 74.71 and 4.9, respectively. The concentrations of the metals in effluent and surface water were much higher than the permissible limits for drinking water and the world average concentrations in surface water. Therefore, the discharged effluent and surface water may create health hazards especially for people working and living inside and in the surrounding area of DEPZ.     

Evaluating the last remnants of Butea monosperma (Lam.) Kuntze Forest for their in situ conservation: a case study

This paper summarizes the findings obtained in a monitoring study to understand the sources and processes affecting the quality of shallow and deep groundwater near central air conditioning plant site in Trombay region by making use of physicochemical and biological analyses. All the measured parameters of the groundwaters indicate that the groundwater quality is good and within permissible limits set by (Indian Bureau of Standards 1990). Shallow groundwater is dominantly of Na–HCO₃ type whereas deep groundwater is of Ca–Mg–HCO₃ type. The groundwater chemistry is mainly influenced by dissolution of minerals and base exchange processes. High total dissolved solids in shallow groundwater compared to deeper ones indicate faster circulation of groundwater in deep zone preferably through fissures and fractures whereas groundwater flow is sluggish in shallow zone. The characteristic ionic ratio values and absence of bromide point to the fact that seawater has no influence on groundwater system.     

Solid speciation and mobility of potentially toxic elements from natural and contaminated soils: a combined approach

The study area (Szklary Massif, SW Poland) comprises three sites of different soil provenance: (1) natural serpentine Cambisol, (2) anthroposol situated on waste dump and (3) cultivated Inceptisol developed on glacial tills next to the dump. Potentially toxic elements (PTE) have either lithogenic or anthropogenic origins in these sites. The chemical partitioning of Co, Cr, Cu, Ni, Pb and Zn among solid forms was determined by sequential extractions coupled with direct mineral identifications (SEM, electron microprobe analysis - EMPA, and XRD). Examination of solid residues after several extraction steps was conducted in order to discuss the indirect speciation obtained by the extraction method. Total concentrations of PTE having anthropogenic origin greatly exceed those of lithogenic origin. Mobility of studied PTE is variable in the different environments except for Cr which is always mostly found in residual fractions of extractions. Cu and Pb are more mobile than Cr and Co in all soils. Zn is more stable (Cu>Pb>Ni>Co>Zn>Cr) in the serpentine soil and cultivated epipedon (Pb>Cu>Zn>Ni>Co>Cr) than in the anthroposol (Zn>CuPb>Ni>Co>Cr). PTE of lithogenic origin are generally less mobile than those from anthropogenic origin except Ni which is more mobile in the serpentine soil. Nonetheless, mineral forms of metals better determine their mobility than metal origin. Identification by direct methods of the PTE mineral form was not possible for metals present at low concentrations (Cu, Pb). However, direct mineralogical examinations of the solid residues of several extractions steps improved the assessment of the PTE solid speciation and mobility, particularly for Cr, Ni and Zn.     

A technical mixture of 2,2',4,4'-tetrabromo diphenyl ether (BDE47) and brominated furans triggers aryl hydrocarbon receptor (AhR) mediated gene expression and toxicity

Polybrominated diphenyl ethers (PBDE) are found as ubiquitous contaminants in the environment, e.g., in sediments and biota as well as in human blood samples and mother's milk. PBDEs are neuro- and developmental toxins, disturb the endocrine system and some are even carcinogenic. Structural similarities of PBDEs with dioxin-like compounds, e.g., 2,3,7,8-tetrachloro-dibenzodioxin (TCDD), have raised concern about a possible "dioxin-like" action of PBDEs. TCDD exerts its toxicity via binding to and activation of the aryl hydrocarbon receptor (AhR). AhR ligands are in contrast to PBDEs usually coplanar compounds. Thus, PBDEs are not likely to be strong AhR agonists. The aim of this study was to analyze the effects of the most abundant PBDE congener, 2,2',4,4'-tetrabromo diphenyl ether (BDE47), on AhR activity and signaling. Initially, we measured cytochrome P450 1A1 (Cyp1A1) induction as a readout for AhR activation by BDE47. Low grade purified BDE47 increased CYP1A1 levels in transformed and primary rat hepatocytes and human hepatoma cells. Chemical analysis of the BDE47 sample identified trace contaminations with brominated furans such as 2,3,7,8-tetrabromo dibenzodioxin (TBDF), which most likely were responsible for the observed activation of AhR. Subsequently, the BDE47 mixture was studied for its effect on AhR mediated toxicity and global gene expression. Indeed, in rat hepatoma cells and in zebrafish embryos the BDE47 mixture provoked changes in gene expression and toxicity similar to known AhR agonists. In addition to the dioxin-like actions, the BDE47 sample enhanced Cyp2B and Cyp3A expression suggesting that commercial PBDE mixtures, which also often contain brominated furans, may disturb cellular homeostasis at multiple levels.     

Persistent organochlorine residues in estuarine and marine sediments from Ha Long Bay, Hai Phong Bay, and Ba Lat Estuary, Vietnam

To assess the organochlorine contamination in the northeast coastal environment of Vietnam, a total of 41 surface sediments were collected from Ha Long Bay, Hai Phong Bay, and Ba Lat estuary, and analyzed for their organochlorine content. Organochlorine compounds (OCs) were widely distributed in the Vietnamese coastal environment. Among the OCs measured, DDT compounds predominated with concentrations ranging from 0.31 to 274 ng g(-1). The overall contamination level of DDTs in coastal sediments from northern Vietnam is comparable with those from other Asian countries. However, concentrations exceeding 100 ng g(-1) are comparable with high concentrations reported from India and China, the largest DDT consumers in the world. The overall concentrations of PCBs, HCHs, and chlordanes in surface sediments were in the ranges of 0.04-18.71 ng g(-1), not detected (n.d.) - 1.00 ng g(-1), and n.d. - 0.75 ng g(-1), respectively. Ha Long Bay and Hai Phong Bay were relatively more contaminated with DDTs and PCBs than other regions, respectively. In contrast, the distribution of HCHs was relatively homogeneous. OCs contamination in the coastal environment of Vietnam is closely related to shipping and industrial activities. The levels of DDT compounds in harbors and industrial areas exceeded their sediment quality guideline values suggested by Environment Canada [CCME (Canadian Council of Ministers of the Environment), 2002. Canadian sediment quality guidelines for the protection of aquatic life. In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Winnipeg, MB] and Australian and New Zealand [ANZECC and ARMCANZ, 2000. National water quality management strategy. Paper No. 4, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, vol. 1, The Guidelines. Australia. Document: http://www.deh.gov.au/water/quality/nwqms/volume1.html], indicating that adverse effects may occur to marine species in that areas.     

Biodegradation of Poly(ε-caprolactone) (PCL) Film by <Emphasis Type="Italic">Alcaligenes faecalis</Emphasis>

The biodegradation behavior of PCL film with high molecular weight (80,000 Da) in presence of bacterium Alcaligenes faecalis and the analysis of degraded polymer film have been carried out. Thin Films of PCL were prepared by means of solution casting method and the bacterial degradation behavior was carried in basal medium, in presence of bacteria with time variation after UV treatment. It was observed that after UV treatment the degradation of polymer film was increased and the degradation rate followed a three steps degradation mechanism. The degraded polymer film was analyzed by means of Differential Scanning Calorimeter (DSC), Thermo Gravimetric Analyzer (TGA) and Fourier Transform Infrared Spectroscope (FTIR). DSC results revealed that at the initial stages of the degradation up to 15–20 days, the bacterium preferentially degrades the amorphous parts of the polymer film over the crystalline zone. Thermo gravimetric analysis highlighted the low temperature stability of degraded films with extent of degradation. FTIR results showed the chain scission mechanism of the polymer chains and also supported the preferential degradation of amorphous phase over crystalline phase in the initial stages of the degradation.     

Spatial variation in 2-methyl-4-chlorophenoxyacetic acid mineralization and sorption in a sandy soil at field level

The phenoxyacetic acid herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) is frequently detected in groundwater beneath Danish agricultural fields. We investigated spatial variation in microbial MCPA mineralization potential in a flat agricultural field of fine sandy soil (USDA classification: Humic Dystrudept) located on the Yoldia plains of Northern Jutland, Denmark. Samples for determination of MCPA mineralization and sorption were collected from the Ap and Bs horizons at 51 sampling sites located in a 200 x 220 m grid. Spatial variation in sorption was low in both horizons (distribution coefficient, 0.36-4.16 L kg(-1)). Sorption correlated strongly with soil organic carbon content in both horizons (CV, 93 and 83%, respectively) and negatively with soil pH. [Ring-(14)C]-MCPA mineralized readily in the Ap horizon, with 49 to 62% of the (14)C-MCPA being converted to (14)CO(2) during the 67-d incubation period. With the subsoil, mineralization of (14)C-MCPA varied considerably between samples (0.5-72.8%). At neither depth was there correlation between (14)C-MCPA mineralization and sorption, soil pH, organic carbon content, clay content, number of colony-forming units (CFU), pseudomonad CFU, or any of the four microbial activity parameters measured. The presence of microbial genes encoding for the TfdA enzyme was quantified using real-time polymerase chain reaction. No correlation was found between MCPA mineralization potential and the natural background number of tfdA genes present in the soil samples. The degradation kinetics suggests that the high (14)C-MCPA mineralization rate detected in soil samples was linked to growth of the MCPA-degrading soil microbial community.     

Transport and reaction processes affecting the attenuation of landfill gas in cover soils

Methane and trace organic gases produced in landfill waste are partly oxidized in the top 40 cm of landfill cover soils under aerobic conditions. The balance between the oxidation of landfill gases and the ingress of atmospheric oxygen into the soil cover determines the attenuation of emissions of methane, chlorofluorocarbons, and hydrochlorofluorocarbons to the atmosphere. This study was conducted to investigate the effect of oxidation reactions on the overall gas transport regime and to evaluate the contributions of various gas transport processes on methane attenuation in landfill cover soils. For this purpose, a reactive transport model that includes advection and the Dusty Gas Model for simulation of multicomponent gas diffusion was used. The simulations are constrained by data from a series of counter-gradient laboratory experiments. Diffusion typically accounts for over 99% of methane emission to the atmosphere. Oxygen supply into the soil column is driven exclusively by diffusion, whereas advection outward offsets part of the diffusive contribution. In the reaction zone, methane consumption reduces the pressure gradient, further decreasing the significance of advection near the top of the column. Simulations suggest that production of water or accumulation of exopolymeric substances due to microbially mediated methane oxidation can significantly reduce diffusive fluxes. Assuming a constant rate of methane production within a landfill, reduction of the diffusive transport properties, primarily due to exopolymeric substance production, may result in reduced methane attenuation due to limited O(2) -ingress.     

Bioaccumulation and toxicity of a cationic surfactant (DODMAC) in sediment dwelling freshwater invertebrates

Dimethyldioctadecylammonium chloride (DODMAC, CAS No. 107-64-2) is the principal active component of Di(hydrogenated tallow alkyl) dimethylammonium chloride (DHTDMAC, CAS No. 61789-80-8), a cationic surfactant formerly used principally in laundry fabric softeners. After discharge to water, DODMAC partitions strongly to sediment, therefore the assessment of the effects of DODMAC to benthic organisms is essential in any risk assessment. Chronic toxicity studies were conducted with Lumbriculus variegatus (Oligochaete), Tubifex tubifex (Oligochaete) and Caenorhabditis elegans (Nematode). NOECs were greater than 5738, 1515 and 1351 mg/kg dw, respectively, even for sub-lethal effects. Measurement of the route of uptake of DODMAC by L. variegatus demonstrated the relative importance of uptake via ingestion (86%) compared with direct contact with the sediment and via pore water (14%). The overall tendency of DODMAC to bioaccumulate, however, was low with measured accumulation factors of 0.22 and 0.78 for L. variegatus and T. tubifex, respectively.