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391.
Fluoride contamination in the groundwater has got great attention in last few decades due to their toxicity, persistent capacity and accumulation in human bodies. There are several sources of fluoride in the environment and different pathways to enter in the drinking water resources, which is responsible for potential effect on human health. Presence of high concentration of fluoride ion in groundwater is a major issue and it makes the water unsuitable for drinking purpose. Availability of fluoride in groundwater indicates various geochemical processes and subsurface contamination of a particular area. Fluoride-bearing aquifers, geological factors, rate of weathering, ion-exchange reaction, residence time and leaching of subsurface contaminants are major responsible factors for availability of fluoride in groundwater. In India, several studies have reported that the groundwater of several states are contaminated with high fluoride. The undesirable level of fluoride in groundwater is one of the most natural groundwater quality problem, which affects large portion of arid and semiarid regions of India. Rajasthan, Andhra Pradesh, Telangana, Tamil Nadu, Gujarat, and West Bengal are the relatively high-fluoride-contaminated states in India. Chronic ingestion of high doses of fluoride-rich water leads to fluorosis on human and animal. Over 66 million Indian populations are at risk due to excess fluoride-contaminated water. Therefore, groundwater contamination subject to undesirable level of fluoride needs urgent attention to understand the role of geochemistry, hydrogeology and climatic factors along with anthropogenic inputs in fluoride pollution. 相似文献
392.
393.
Mritunjay Kumar Singh Sultana Begam Chandan Kumar Thakur Vijay P. Singh 《Environmental Fluid Mechanics》2018,18(5):1121-1142
This study derives an analytical solution of the advection–dispersion (AD) equation commonly used to describe the transport of pollutants in a semi-infinite homogeneous aquifer. When an extra constant source term is added to the AD equation, it changes the solution of the equation. The AD equation is solved analytically using Laplace transform. Also, the equation is solved numerically using an explicit finite difference method and its stability condition is presented with the aid of matrix method. For the solution of the AD equation the following considerations are made: (1) The dispersion and velocity are considered as time-dependent; (2) dispersion is expressed as directly proportional to the square of velocity; (3) there is also diffusion; (4) there is some initial concentration and the aquifer domain is, therefore, not pollutant-free; (5) There is a time-dependent exponentially decreasing input source; and (6) the concentration gradient is assumed to be zero at the exit boundary. It is found that the contaminant concentration decreases with time contrary to what happens when the extra term is not included. 相似文献
394.
Bhawana Jain Ajaya Kumar Singh Hyunook Kim Eric Lichtfouse Virender K. Sharma 《Environmental Chemistry Letters》2018,16(3):947-967
Nowadays, the water ecosystem is being polluted due to the rapid industrialization and massive use of antibiotics, fertilizers, cosmetics, paints, and other chemicals. Chemical oxidation is one of the most applied processes to degrade contaminants in water. However, chemicals are often unable to completely mineralize the pollutants. Enhanced pollutant degradation can be achieved by Fenton reaction and related processes. As a consequence, Fenton reactions have received great attention in the treatment of domestic and industrial wastewater effluents. Currently, homogeneous and heterogeneous Fenton processes are being investigated intensively and optimized for applications, either alone or in a combination of other processes. This review presents fundamental chemistry involved in various kinds of homogeneous Fenton reactions, which include classical Fenton, electro-Fenton, photo-Fenton, electro-Fenton, sono-electro-Fenton, and solar photoelectron-Fenton. In the homogeneous Fenton reaction process, the molar ratio of iron(II) and hydrogen peroxide, and the pH usually determine the effectiveness of removing target pollutants and subsequently their mineralization, monitored by a decrease in levels of total organic carbon or chemical oxygen demand. We present catalysts used in heterogeneous Fenton or Fenton-like reactions, such as H2O2–Fe3+(solid)/nano-zero-valent iron/immobilized iron and electro-Fenton-pyrite. Surface properties of heterogeneous catalysts generally control the efficiency to degrade pollutants. Examples of Fenton reactions are demonstrated to degrade and mineralize a wide range of water pollutants in real industrial wastewaters, such as dyes and phenols. Removal of various antibiotics by homogeneous and heterogeneous Fenton reactions is exemplified. 相似文献
395.
Singh C Soni R Jain S Roy S Goel R 《Journal of environmental biology / Academy of Environmental Biology, India》2010,31(5):553-556
Six soil samples (Pantnagar, Chamoli, Almora, Ranichauri, Pithoragarh and Badrinath) belonging to different geographical locations of Western Himalayas in India, were analyzed to diversify the nitrogen fixing bacterial community using nifH gene biomarker DNA from soil samples were isolated and amplified using nifH gene specific primers. Genomic DNA and PCR amplified products were then individually subjected to restriction digestion with tetra to octacutter enzymes (AluI, MspI, BgIII, XbaI, HindIII, HaeIII, AluI, MspI and PasI. Further restriction pattern was studied by preparing dendograms on the basis of similarity matrix and compared for the nifH community. It was observed that temperate region soils (Ranichauri and Pithoragarh) were negative for nifH marker while subalpine region (Badrinath) and tarai region soils (Pantnagar) documented similar nifH community. Moreover; the direct genomic DNA restriction analysis indicated that subalpine region soil (Badrinath) was most diversified. 相似文献
396.
Shukla OP Singh PK Deshbhratar PB 《Journal of environmental biology / Academy of Environmental Biology, India》2010,31(5):575-580
Multiple cropping (i.e. intercropping or mixed cropping) plays an important role in agriculture because of the effective utilization of resources, significantly enhancing crop productivity compared with that of monocultured crops. The study was planed to assess the effect of various concentrations (00, 30, 60, 90 kg ha(-1)) of phosphorous on the biochemical composition of grains of Hordeum vulgare L. (NDB-1050) in mixed cropping system with Chickpea. Phosphorous is an essential ingredient for plants to convert atmospheric N (N2) into an ammonium (NH4) as a useable form. The available nitrogen content was found more in the year 2006 (131 kg ha(-1)) than year 2005 (105 kg ha(-1)). The results of available nitrogen content were showed that the mixed cropping system enhances N fixation process because phosphorous also influences nodule development through its basic functions in plants as an energy source. Reducing, non reducing and total sugar content of H. vulgare L. were influenced by changes in the phosphorous doses. Maximum protein (13.43%) was obtained at 60 kg P2O5 ha(-1) during the year 2006. Lysine, tryptophan and methionine content were found maximum in year 2006, respectively. Total mineral content of grains of plant (0.99 g 100g(-1)) was found maximum by the application of 60 kg P2O5 ha(-1). It is possible that there was an increase in the soil N made available by the leguminous chickpea species, and this could be another reason why there was an increase in Hordeum vulgare L. shoot mass per plant with intercropping with chickpea. 相似文献
397.
Accumulation and translocation of heavy metals in soil and plants from fly ash contaminated area 总被引:3,自引:0,他引:3
Singh R Singh DP Kumar N Bhargava SK Barman SC 《Journal of environmental biology / Academy of Environmental Biology, India》2010,31(4):421-430
The present investigation deals with the accumulation of heavy metals in fields contaminated with fly ash from a thermal power plant and subsequent uptake in different parts of naturally grown plants. Results revealed that in the contaminated site, the mean level of all the metals (Cd, Zn, Cr, Pb, Cu, Ni, Mn and Fe) in soil and different parts (root and shoots) of plant species were found to be significantly (p<0.01) higher than the uncontaminated site. The enrichment factor (EF) of these metals in contaminated soil was found to be in the sequence of Cd (2.33) > Fe (1.88) > Ni (1.58) > Pb (1.42) > Zn (1.31) > Mn (1.27) > Cr (1.11) > Cu (1.10). Whereas, enrichment factor of metals in root and shoot parts, were found to be in the order of Cd (7.56) > Fe (4.75) > Zn (2.79) > Ni (2.22) > Cu (1.69) > Mn (1.53) > Pb (1.31) > Cr (1.02) and Cd (6.06) approximately equal Fe (6.06) > Zn (2.65) > Ni (2.57) > Mn (2.19) > Cu (1.58) > Pb (1.37) > Cr (1.01) respectively. In contaminated site, translocation factor (TF) of metals from root to shoot was found to be in the order of Mn (1.38) > Fe (1.27) > Pb (1.03) > Ni (0.94) > Zn (0.85) > Cd (0.82) > Cr (0.73) and that of the metals Cd with Cr, Cu, Mn, Fe; Cr with Pb, Mn, Fe and Pb with Fe were found to be significantly correlated. The present findings provide us a clue for the selection of plant species, which show natural resistance against toxic metals and are efficient metal accumulators. 相似文献
398.
Singh RP Tewari A Shah S Tewari B 《Journal of environmental biology / Academy of Environmental Biology, India》2010,31(3):297-299
Fruits of Aisandra butyracea (Roxb.) Lamb. were collected from two sites located at different altitudes in Kumaun Himalaya for analyzing the seed maturity in relation to various fruit and seed characters. The mean seed size (length x width) across the collection dates varied between 186.44 +/- 0.05 and 238.17 +/- 0.5 mm2 across both the elevations. The fruit colour changed from dark green in the beginning to pale yellow on the maturity. The range of seed moisture content (62.83 +/- 1.33 to 63.46 +/- 0.89%) coincided with maximum germination. The colour change and seed moisture content appear to be the major indicators of seed maturation in A. butyracea. 相似文献
399.
Carbon supply and storage in tilled and nontilled soils as influenced by cover crops and nitrogen fertilization 总被引:2,自引:0,他引:2
Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)} and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha(-1)) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha(-1). The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 cm in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha(-1) yr(-1) for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha(-1) yr(-1). The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha(-1) yr(-1) than in weeds with 0 kg N ha(-1) yr(-1), regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop. 相似文献
400.
An investigation of dye decolorization from synthetic dye solutions using the non-ionic, water-soluble, high molecular weight seed gums Ipomoea dasysperma and guar gum as coagulants was undertaken. The use of galactomannans derived from plants in this system presents a sustainable method of textile effluent treatment. These natural coagulants extracted from plants proved to be workable alternatives to conventional coagulants like polyaluminum chloride, as they are biodegradable, safe to human health, are cost effective when compared to imported chemicals and have a wider effective dosage range for flocculation of various colloidal suspensions. Coagulant dose and coagulation pH are important factors influencing the mechanism of coagulation. Also the type and chemical structure of the dye plays an important role in the coagulation process. The seed gums alone were found to be effective for decolorization of direct dye and in combination with PAC their coagulation efficiency was well extended even for reactive and acid dyes. 相似文献