Amberlite XAD-7 impregnated with morpholine dithiocarbamate as trace metal extractant

Application of Amberlite XAD-7 impregnated with morpholine dithiocarbamate (MDTC) for separation and preconcentration of trace amounts of lead, copper, cobalt, iron, nickel, cadmium and zinc and determination by ICP-AES has been described. The optimum experimental parameters, such as pH, sample flow rate, eluent and effect of matrix ions on the preconcentration were investigated. Simultaneous enrichment of the seven metals was accomplished. The t _1/2 values for sorption are 2.9, 3.3, 3.7, 3.6, 2.8, 4.1 and 2.8 respectively for Pb(II), Cu(II), Co(II), Fe(III), Ni(II), Cd(II) and Zn(II). The method was applied for the determination of trace metal ions in seawater and natural water samples. The results have been compared with extraction GFAAS method.     

Identifying and Evaluating a Suitable Index for Agricultural Drought Monitoring in the Texas High Plains

Drought is a complex and highly destructive natural phenomenon that affects portions of the United States almost every year, and severe water deficiencies can often become catastrophic for agricultural production. Evapotranspiration (ET) by crops is an important component in the agricultural water budget; thus, it is advantageous to include ET in agricultural drought monitoring. The main objectives of this study were to (1) conduct a literature review of drought indices with a focus to identify a simple but simultaneously adequate drought index for monitoring agricultural drought in a semiarid region and (2) using the identified drought index method, develop and evaluate time series of that drought index for the Texas High Plains. Based on the literature review, the Standardized Precipitation‐Evapotranspiration Index (SPEI) was found to satisfy identified constraints for assessing agricultural drought. However, the SPEI was revised by replacing reference ET with potential crop ET to better represent actual water demand. Data from the Texas High Plains Evapotranspiration network was used to calculate SPEIs for the major irrigated crops. Trends and magnitudes of crop‐specific, time‐series SPEIs followed crop water demand patterns for summer crops. Such an observation suggests that a modified SPEI is an appropriate index to monitor agricultural drought for summer crops, but it was found to not account for soil water stored during the summer fallow period for winter wheat.     

Cytogenetic studies of chromium (III) oxide nanoparticles on Allium cepa root tip cells

The current study evaluates the cytogenetic effects of chromium (III) oxide nanoparticles on the root cells of Allium cepa. The root tip cells of A. cepa were treated with the aqueous dispersions of Cr₂O₃ nanoparticles (NPs) at five different concentrations (0.01, 0.1, 1, 10, and 100 μg/mL) for 4 hr. The colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size analyses. After 4 hr exposure to Cr₂O₃ NPs, a significant decrease in mitotic index (MI) from 35.56% (Control) to 35.26% (0.01 μg/mL), 34.64% (0.1 μg/mL), 32.73% (1 μg/mL), 29.6% (10 μg/mL) and 20.92% (100 μg/mL) was noted. The optical, fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as—chromosome stickiness, chromosome breaks, laggard chromosome, clumped chromosome, multipolar phases, nuclear notch, and nuclear bud at different exposure concentrations. The concentration-dependent internalization/bio-uptake of Cr₂O₃ NPs may have contributed to the enhanced production of anti oxidant enzyme, superoxide dismutase to counteract the oxidative stress, which in turn resulted in observed chromosomal aberrations and cytogenetic effects. These results suggest that A. cepa root tip assay can be successfully applied for evaluating environmental risk of Cr₂O₃ NPs over a wide range of concentrations.     

Estimating soil carbon storage and mitigation under temperate coniferous forests in the southern region of Kashmir Himalayas

Soil physical and chemical properties were quantified to assess soil organic carbon (SOC) density (t ha^-1) and SOC CO2 mitigation (t ha^-1) under six forest strata Cedrus deodara (closed) (S1), Cedrus deodara (open) (S2), Abies pindrow-Picea smithiana (closed) (S3), Abies pindrow-Picea smithiana (open) (S4), Pinus wallichiana (closed) (S5) and Pinus wallichiana (open) (S6) in the southern region of Kashmir Himalayas India. Lowest average bulk density (D_b) of 0.95 was found same in S3 (σ?±?0.07) and S5 (σ?±?0.09) and highest D_b (1.08) was observed in S2 (σ?±?0.05). A relatively higher coarse fraction was observed in all the six strata ranging from 19.23 (SD?±?4.66) in S3 to 29.37 (σ?±?6.12) in S6. Soil pH ranged from 6.09 (σ?±?0.64) in S4 to 6.97 (σ?±?0.53) in S2. The region under biotic interference has observed significant deforestation and degradation in the past two decades leading to lower SOC% values compared to other studies in the adjoining regions of Indian Himalayas and temperate coniferous forests in general. SOC% values were observed to range from 1.03 (σ?±?0.22) in S2 to 2.25 (σ?±?0.23) in S3. SOC density ranged between 25.11 (σ?±?5.41) t ha^-1 in S2 and 51.93 (σ?±?5.24) t ha^-1 in S3. SOC CO2 mitigation density was found highest 190.59 (σ?±?19.23) t ha^-1 in S3 and lowest 92.16 (σ?±?19.86) t ha^-1 in S2. A significant variation was observed in SOC density within strata. SOC density values in closed strata in general exceed to those in open strata. Primary results indicate that the average SOC stock for all the strata is low due to continuous biotic pressure in the last two decades making it a potential region for SOC buildup under plus options of REDD + (Reducing emissions from deforestation and forest degradation) which includes conservation, sustainable management of forests and enhancement of forest carbon (C) stocks.     

Potential benefits of drought and heat tolerance in groundnut for adaptation to climate change in India and West Africa

Climate change is projected to intensify drought and heat stress in groundnut (Arachis hypogaea L.) crop in rainfed regions. This will require developing high yielding groundnut cultivars that are both drought and heat tolerant. The crop growth simulation model for groundnut (CROPGRO-Groundnut model) was used to quantify the potential benefits of incorporating drought and heat tolerance and yield-enhancing traits into the commonly grown cultivar types at two sites each in India (Anantapur and Junagadh) and West Africa (Samanko, Mali and Sadore, Niger). Increasing crop maturity by 10 % increased yields up to 14 % at Anantapur, 19 % at Samanko and sustained the yields at Sadore. However at Junagadh, the current maturity of the cultivar holds well under future climate. Increasing yield potential of the crop by increasing leaf photosynthesis rate, partitioning to pods and seed-filling duration each by 10 % increased pod yield by 9 to 14 % over the baseline yields across the four sites. Under current climates of Anantapur, Junagadh and Sadore, the yield gains were larger by incorporating drought tolerance than heat tolerance. Under climate change the yield gains from incorporating both drought and heat tolerance increased to 13 % at Anantapur, 12 % at Junagadh and 31 % at Sadore. At the Samanko site, the yield gains from drought or heat tolerance were negligible. It is concluded that different combination of traits will be needed to increase and sustain the productivity of groundnut under climate change at the target sites and the CROPGRO-Groundnut model can be used for evaluating such traits.     

Metabolic variation in rice cultivars of contrasting salt tolerance and its improvement by zinc in sodic soil

The severity of Zn deficiency increased with increase in soil exchangeable sodium percentage (ESP) with salt sensitive variety M1-48 scoring 6 at ESP 62 as against only score 3 by salt tolerant variety Pokkali under similar soil conditions. Strikingly, zinc contents were much higher in salt tolerant variety than in salt sensitive one. Zinc application increased zinc concentration in the roots by a factor of 2.85 to 3.87 in Pokkali whereas it rose from 2.37 to 4.35 times in M1-48 depending upon ESP but in the leaves it registered increase of 1.5 to 1.8 times only. In general, the concentrations of reducing sugar were less (about 2.2%) than that of non-reducing (about 3.8%) in both the varieties under normal soil conditions. However, the concentration of reducing sugar doubled (4.2-4.4%) at the highest ESP 62, whereas the concentration of non-reducing sugar though increased (4.1 to 5.1%) but not as vigorously as reducing one. Zinc application reduced the concentration of reducing sugar but not that of non-reducing at similar ESP values. In Pokkali, the concentrations of total sugar increased from 6% at ESP 20 to 9.34% at ESP 62, whereas it registered enhancements of 5.98 to 8.6% in M1-48 under similar conditions. The nitrate reductase (NR) activity decreased with increase in soil sodicity however, the varietal differences in NR activity were wider under Zn-stress than under conditions of applied zinc with Pokkali registering higher NR activities. Carbonic anhydrase activities were higher in salt tolerant variety. Inhibition in carbonic anhydrase activity amounted to 23 and 45% in salt-sensitive variely M1-48 whereas only 19 and 33% in salt-tolerant variety Pokkali at ESP 41 and 62, respectively. The effects of zinc application at higher soil sodicity were more obvious in salt-sensitive variety than in salt-tolerant one. The findings suggest that the tolerance to Zn stress runs parallel to salt tolerance abilities of rice varieties.     

Soil dehydrogenase, phosphomonoesterase and arginine deaminase activities in an insecticide treated groundnut (Arachis hypogaea L.) field

Chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2 pyridyl phosphorothioate) 20 EC and Quinalphos (O,O-diethyl O-quinoxalin-2-yl phosphorothioate) 25 EC, were applied in groundnut (Arachis hypogaea L.) field as seed treatment at 25 ml/kg and soil treatment at 4 l/ha in 1998 and 1999. The residues of these insecticides were monitored during the entire crop season and their effect on the soil enzymes dehydrogenase, phosphomonoesterase and arginine deaminase were studied. Ninety nine percent of chlorpyrifos residues were dissipated within 60 days from seed treated soil and 98% dissipation was observed in soil treated field for the same days. Its half lives in seed treated soil were 8 days and 7 days and in soil treated field were 9.2 days in and 7.5 days in 1998 and 1999 respectively. Dissipation of quinalphos in comparison to chlorpyrifos was slow both in seed treated and soil treated field. Eighty seven percentage to 92% dissipation of quinalphos residues were observed from seed treated soil and 98% residues were dissipated from soil treated field within 75 days. Its half lives in seed treated soil were 20 days and 18 days and in soil treated field, its half lives were 13 days and 17 days 1998 and 1999 respectively. Inhibition in dehydrogenase activity followed by recovery was observed both in seed and soil treatments with chlorpyrifos. An inhibition of 17.2% was estimated after 60 days of seed treatment in comparison to control. Dehydrogenase activity was significantly reduced to 63% after 15 days of quinalphos seed treatment in comparison to control in 1998. Similar trends were observed in 1999. A significant inhibition in dehydrogenase activity was observed after soil treatment both in 1998 and 1999. Phosphomonoesterase activities were significantly inhibited upto 25.2% as compared to the control, on the 15th day of chlorpyrifos seed treatment in 1998 and similarly, after one day of treatment in 1999. Quinalphos inhibited the phosphomonoesterase activity till the end of the experimental period in the soil treated fields, whereas recovered within 30-60 days of treatment in the seed treated fields. Arginine deaminase activity was significantly stimulated within one day after chlorpyrifos seed and soil treatments in both years. The activity was almost threefold higher on the 30th and the 15th day of soil treatment in 1998 and 1999, respectively. A temporary inhibition of arginine deaminase activity was observed after quinalphos treatment. It was observed that in most of cases insecticides have temporary inhibitory effect on soil enzymes. However, inhibition was smaller in seed treated soil than in direct soil treatment.     

APPLICATION OF THE CONTINUOUS STORMWATER POLLUTION SIMULATION SYSTEM (CSPSS): PHILADELLPHIA CASE STUDY1

ABSTRACT: This paper describes the Continuous Stormwater Pollution Simulation System (CSPSS) as well as a site-specific application of CSPSS to the Philadelphia urban area and its receiving water, the Delaware Estuary. Conceptually, CSPSS simulates the quantity and quality or urban stormwater runoff, combined sewer overflow, municipal and industrial waste water effuent, and upstream flow on a continuous basis for each time step in the simulation period. In addition, receiving water dissolved oxygen, suspended solids, and lead concentrations resulting from these pollutant sources may be simulated. However, only rceiving water dissolved oxygen (DO) response is considered in this paper. The continuous Do receiving water response model was calibrated to existing conditions usinv observed data at Chester, Pennsylvnia, located on the Delaware Estuary approximately 10 miles down stream from the study area. Average annual pollutant loads to the receiving water were estimated for all major sources and receiving water quality improvements resulting from removal of various portions of these pollutant loads were estimated by application of the calibrated stimultion model. It was found that the removal of oxygen-demanding pollutants from combined sewer overflow and urban stormwater runoff would result in relatively minor improvements in the overall dissoved oxygen resources of the Delaware Estuary; whereas. removal of oxygen demanding pollutants from waste water treatment plant effluent would result in greater improvemens. The results of this investigation can be used along with appropriate economic techniques to identify the most cost-effective mix of point and nonpoint source pollution control measures.     

Economic rent : Incidence in selected metals and minerals

The magnitude of the ‘economic rent’ and its distribution among producing countries, mineral exploitation companies and consumers has become a dominant issue in national and international policy formulation, but the difficulties in measuring the rent add to the problems of determining its equitable distribution. This paper examines the nature of the rent and estimates its incidence in bauxite, copper, iron ore, phosphate rock, tin and petroleum. Rents were found to be low for bauxite and iron ore. Bauxite, phosphates and petroleum producers have increased their share of the rent, though this trend now seems to be reversing for bauxite and phosphates. Only in tin, and to a lesser extent petroleum, have the exporting countries captured significant shares in total rent. Otherwise, the rent is largely concentrated at the processing stage, which suggests that processing plant would have to shift to the producing countries if they are to claim a larger share.