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91.
92.
A. Siva Reddy G. C. Mishra K. Seetharamiah 《Journal of the American Water Resources Association》1972,8(1):55-62
Using Schwarz-Christoffel transformation, an analysis is presented for finding the pressure distribution and exit gradients for a weir on an anisotropic drained stratum. 相似文献
93.
94.
Resource conservation strategies for rice‐wheat cropping systems on partially reclaimed sodic soils of the Indo‐Gangetic region,and their effects on soil carbon 下载免费PDF全文
V.K. Mishra S. Srivastava A.K. Bhardwaj D.K. Sharma Y.P. Singh A.K. Nayak 《Natural resources forum》2015,39(2):110-122
The Indo‐Gangetic plain is characterized by intensive agriculture, largely by resource‐poor small and marginal farmers. Vast swathes of salt‐affected areas in the region provide both challenges and opportunities to bolster food security and sequester carbon after reclamation. Sustainable management of reclaimed soils via resource conservation strategies, such as residue retention, is key to the prosperity of the farmer, as well as increases the efficiency of expensive initiatives to further reclaim sodic land areas, which currently lay barren. After five years of experimentation on resource conservation strategies for rice‐wheat systems on partially reclaimed sodic soils of the Indo‐Gangetic region, we evaluated changes in different soil carbon pools and crop yield. Out of all resource conservation techniques which were tested, rice‐wheat crop residue addition (30% of total production) was most effective in increasing soil organic carbon (SOC). In rice, without crop residue addition (WCR), soils under zero‐tillage with transplanting, summer ploughing with transplanting and direct seeding with brown manuring showed a significant increase in SOC over the control (puddling in rice, conventional tillage in wheat). In these treatments relatively higher levels of carbon were attained in all aggregate fractions compared to the control. Soil aggregate sizes in meso (0.25‐2.0 mm) and macro (2‐8 mm) ranges increased, whereas micro (< 0.25 mm) fractions decreased in soils under zero‐till practices, both with and without crop residue addition. Direct seeding with brown manuring and zero tillage with transplanting also showed an increase of 135% and 95%, respectively, over the control in microbial biomass carbon, without crop residue incorporation. In zero tillage with transplanting treatment, both with and without crop residue showed significant increase in soil carbon sequestration potential. Though the changes in accrued soil carbon did not bring about significant differences in terms of grain yield, overall synthesis in terms of balance between yield and carbon sequestration indicated that summer ploughing with transplanting and zero tillage with transplanting sequestered significantly higher rates of carbon, yet yielded on par with conventional practices. These could be appropriate alternatives to immediately replace conventional tillage and planting practices for rice‐wheat cropping systems in the sodic soils of the Indo‐Gangetic region. 相似文献
95.
Water availability in arid regions is both sporadic and highly variable in quantity. If the water quality shows large variations
of salinity and concentration of other chemical constituents with depth and time span, it has considerable effect on the entire
hydrological set up of the area. In the Saidabad tahsil area, the deep aquifers that supply water to borewells in the alluvial
plain of the Mathura region, Uttar Pradesh, have higher salinity than those of the dugwells from the shallow aquifers. The
excessive drilling of tubewells and high yield tubewells are resulting in deterioration of water quality of the shallow aquifers.
On the contrary, the chemical constituents such as, Na+, K
+, Cl
-, andHCO
3
- show higher concentration in shallow aquifers than deep aquifers. A study carried out to monitor water quality in this region
reveals that the groundwater quality varies with depth and time span in shallow and deep aquifers. Factors controlling variations
in salinity and concentration of chemical constituents of the water in the two types of aquifers are discussed. The relative
merits of the shallow water for potability are pointed out with respect to salinity concentrations and public health. 相似文献
96.
Mohanty M Pattnaik MM Mishra AK Patra HK 《Environmental monitoring and assessment》2012,184(2):1015-1024
Mine waste water at South Kaliapani usually contains toxic levels of hexavalent Cr(VI). The present in situ study was conducted at South Kaliapani chromite mine area in Orissa state, India, to assess the phytoremediation ability
of three plants, namely, rice (Oryza sativa L.), paragrass (Brachiaria mutica), and an aquatic weed (Eichhornia crassipes), in attenuating Cr(VI) from mine waste water and to correlate the bio-concentration factors (BCF) of Cr. Water hyacinth
(E. crassipes) showed 24% to 54% reduction whereas paragrass (B. mutica) was able to reduce 18% to 33% of Cr(VI) from mine water. This reduction was studied over a period of 100 days of plant growth.
The reduction was observed through a passage of a sum total of 2,000 sq. ft. cultivated plots and ponds separately. Reduction
in Cr(VI) content in mine water varies with plant age as well as with the distance of passage. Cr accumulation and BCF values
increased with high soil Cr levels as well as the age of plants. High BCF and transportation index (Ti) values, i.e., 10,924
and 32.09, respectively, were noted for water hyacinth. The Ti values indicated that the root-to-shoot translocation of Cr
was very high after 100 days of growth. The total accumulation rate was maximum (8.29 mg Cr kg dry biomass − 1 day − 1) in paragrass. The BCF values for roots were noted to be higher than those of leaves, stems, and grains of the 125-day-old
plants. Hence, paragrass and water hyacinth may be used as tools of phytoremediation to combat the problem of in situ Cr contamination. 相似文献
97.
Dey RK Swain SK Mishra S Sharma P Patnaik T Singh VK Dehury BN Jha U Patel RK 《Environmental monitoring and assessment》2012,184(5):3279-3291
The present investigation reports the assessment of hydrochemical/geochemical processes controlling the concentration of fluoride
in groundwater of a village in India (Boden block, Orissa). Boden block is one of the severely affected fluoride-contaminated
areas in the state of Orissa (India). The sampling and subsequent analysis of water samples of the study area was carried
out following standard prescribed methods. The results of the analysis indicate that 36.60% groundwater F− concentration exceeds the limit prescribed by the World Health Organization for drinking water. The rock interaction with
groundwater containing high concentration of HCO3− and Na+ at a higher pH value of the medium could be one of the important reasons for the release of F− from the aquatic matrix into groundwater. Geochemical classification of groundwater based on Chadha rectangular diagram shows
that most of the groundwater samples having fluoride concentration more than 1.5 mg L−1 belongs to the Na-K-HCO3 type. The saturation index values evaluated for the groundwater of the study area indicated that it is oversaturated with
respect to calcite, whereas the same is undersaturated with respect to fluorite content. The deficiency of calcium ion concentration
in the groundwater from calcite precipitation favors fluorite dissolution leading to excess of fluoride concentration. The
risk index was calculated as a function of fluoride level in drinking water and morbidity of fluorosis categorizes high risk
for villages of Amera and Karlakote panchayat of Boden block. 相似文献
98.
Swayamprabha Mishra Monalisa Mohanty Chinmay Pradhan Hemanta Kumar Patra Ritarani Das Santilata Sahoo 《Environmental monitoring and assessment》2013,185(5):4347-4359
The present investigation aims to assess the phytoremediation potential of six aquatic macrophytes, viz. Eichhornia crassipes, Hydrilla verticillata, Jussiaea repens, Lemna minor, Pistia stratiotes and Trapa natans grown in paper mill effluent of JK Paper mill of Rayagada, Orissa, for remediation of heavy metals. The experiment was designed in pot culture experiments. Assessment of physico-chemical parameters of paper mill effluent showed significant decrease in pH, conductivity, total dissolved solids, total suspended solids, chlorine, sulphur, biological and chemical oxygen demand after growth of macrophytes for 20 days. Phytoremediation ability of these aquatic macrophytic species for copper (Cu) and mercury (Hg) was indicated by assessing the decrease in the levels of heavy metals from effluent water. Maximum reduction (66.5 %) in Hg content of untreated paper mill effluent was observed using L. minor followed by T. natans (64.8 %). L. minor showed highest reduction (71.4 %) of Cu content from effluent water followed by E. crassipes (63.6 %). Phytoextraction potential of L. minor was remarkable for Hg and Cu, and bioaccumulation was evident from bioconcentration factor values, i.e. 0.59 and 0.70, respectively. The present phytoremediation approach was considered more effective than conventional chemical treatment method for removing toxic contaminants from paper mill effluent. 相似文献
99.
100.
Mishra VK Upadhyay AR Pandey SK Tripathi BD 《Environmental monitoring and assessment》2008,141(1-3):49-58
Five heavy metals Cu, Cd, Mn, Pb and Hg were found in high concentration from three sampling sites located in Asia’s largest
anthropogenic lake Govind Ballabh Pant GBP Sagar. Concentrations of these heavy metals were measured in Water, bottom sediment
and in different parts of the aquatic macrophytes collected from the reservoir. Plants collected from the lake were Eichhornia crassipes, Azolla pinnata, Lemna minor, Spirodela polyrrhiza, Potamogeton pectinatus, Marsilea quadrifolia, Pistia stratiotes, Ipomea aquqtica, Potamogeton crispus, Hydrilla verticillata and Aponogeton natans. These plants have shown the high concentrations of Cu, Cd, Mn, Pb and Hg in their different parts due to bioaccumulation.
In general plant roots exhibited higher concentrations of heavy metals than corresponding sediments. A comparison between
different morphological tissues of the sampled plants reveled the metal concentration in following order roots > leaves. Analyses
of bottom sediment indicated the higher concentrations of Cd, Mn, Cu and Pb. Strong positive correlations were obtained between
the metals in water and in plants as well as between metal in sediment and in plants. Indicating the potential of these plants
for pollution monitoring of these metals. 相似文献