West Coast Region Of India Research Articles

222Rn and progeny concentrations and equilibrium factor (F) in different types of dwellings typical of the west coast region of India

Monitoring of 222Rn, its progeny concentrations, and their diurnal variations in living environments are important for inhalation dose assessment. In this study, the indoor 222Rn and progeny concentrations were measured in dwellings constructed with different types of flooring, walls, and roofing materials. The ionization-chamber-based AlphaGuard and DRPS-based flow mode integrated samplers were used for the 222Rn and its progeny measurements respectively. Higher 222Rn concentration values were recorded in the dwelling with marble floor and the lower in the dwelling constructed using concrete blocks. The equilibrium factors (F) for different dwellings ranged from 0.28 to 0.54. The study highlights the importance of evaluating the specific value of the equilibrium factor for accurate dose assessment.

Leaf morphometric variation among the different natural sources ofCinnamomum zeylanicum Blume. in Uttara Kannada district

Cinnamomum zeylanicum Blume., native to Sri Lanka and the West coast region of India, belongs to the familyLauraceae.True cinnamon leaves are valuable NTFP and also used for the commercial extraction of essential oil. Theprotogynous dichogamy of the cinnamon flower is a natural adaptation for cross-pollination. An enormous diversity ofCinnamon has been produced by this special type of pollination behaviour. Thus, the current study aimed to determine theextent of morphological variation within and among the sources. The study was conducted during the period of 2020-22 atthe various sites in the Uttara Kannada district, Karnataka. Sixty phenotypically superior cinnamon trees were selectedamong the six different natural sources, for the evaluation of five leaf morphometric parameters. In this study, the dark greencoloured leaves were predominately expressed in all six sources and all tree had only green coloured petiole. Five types ofleaf shape viz., elliptic, oblong, ovate, ovate-elliptic and ovate lanceolate and four types of leaf apex (acuminate, acute, sub-acute and obtuse) were noticed among the six sources. Elliptic leaf shape and acuminate leaf tip was predominantlyexpressed. Leaf morphometric traits could be easily used to measure the magnitude of the diversity

Hyperspectral remote sensing-based prediction of the soil pH and salinity in the soil to water suspension and saturation paste extract of salt-affected soils of the west coast region

The study aimed to investigate hyperspectral remote sensing to predict the soil pH and salinity in the soil to water suspension and saturation paste extract of salt-affected soils of the west coast region. About 216 soil samples were collected from the salt-affected areas of the west coast region of India (State of Maharashtra, Goa, Karnataka and Kerala). The soil pH and electrical conductivity (EC) in fixed ratios of 1:1, 1:2, 1:2.5 and 1:5 soil to water extracts and soil saturation paste extract were determined and the spectral data measurement in the wavelength range of 350–2500 nm was carried out. The data was divided into a calibration dataset (70% of the total) and a validation dataset (30% of the total dataset). The spectral data (raw spectral reflectance averaged at 10 nm) was modeled using multivariate analysis techniques - partial least square regression, principal component regression and support vector regression. The average values of soil pH of 1:1, 1:2, 1:2.5, 1:5 soil: water extract and soil saturation paste (pHe) extract were 4.32, 4.96, 5.01, 5.15 and 5.33, respectively, whereas, the corresponding EC values were 14.00, 7.65, 6.37, 3.52 and 19.96 dS m−1, respectively. The pHe and EC of soil saturation paste extract (ECe) were in the range of 3.067.39 and 0.61–59.18 dS m−1. The coefficient of determination (R2) of pHe with pH of 1:1, 1:2, 1:2.5 and 1:5 soil extract ratio was 0.73, 0.73, 0.72 and 0.73 (p<0.05) respectively. The ECe had a R2 of 0.85, 0.84, 0.85 and 0.84 (p<0.05) with EC of 1:1, 1:2, 1:2.5 and 1:5 soil: water extract ratio, respectively. All these relationships were linear and significant. Thus, the regression relation of ECe with EC1:2, ECe = 2.5272 x (EC1:2) + 2.77 (R2=0.84, p<0.05) could be more useful for studies related to the salinity of salt-affected soil of the west coast region of India where soil salinity is typically associated with the acidity. A good agreement between the actual and predicted pH and EC for different ratios and the extract were exhibited by the coefficient of correlation ranging from 0.48–0.79 and 0.70–0.87, respectively. Among different multivariate techniques tested, partial least square regression outperformed principal component regression and support vector regression. Among all the parameters, the best prediction was achieved for ECe accuracy as r=0.87, R2=0.76, RMSE=5.65 and rank=4 (lowest) with partial least square regression. Thus, the soil saturation paste extract salinity of the salt-affected soils of the west coast region can be monitored using visible near-infrared remote sensing

Soil and Water Conservation Measures Improve Soil Microbial Activity and Carbon Sequestration: A Study on High Density Cashew in West Coast Region of India

Soil and Water Conservation Measures Improve Soil Microbial Activity and Carbon Sequestration: A Study on High Density Cashew in West Coast Region of India

Monitoring properties of the salt-affected soils by multivariate analysis of the visible and near-infrared hyperspectral data

The study aimed to estimate the properties of the salt-affected soils (SAS) using hyperspectral remote sensing. The study was carried out on typical SAS from 372 locations covering 17 coastal districts from the west coast region of India. The spectral reflectance of processed soil samples was recorded in the wavelength range of 350–2500 nm. The full dataset (n = 372) was split into two as a calibration dataset (n = 260, 70% of full dataset) to develop the model and validation dataset (n = 112, 30% of full dataset) to evaluate the performance of the model independently. The spectral data were calibrated using the laboratory estimated soil properties with five different multivariate techniques (a) Linear – partial component regression (PCR) and partial least square regression (PLSR) and (b) Non-linear– multivariate adaptive regression spline (MARS), random forest (RF) and support vector regression (SVR). In general, the spectral reflectance from the soils decreased with increasing levels of salinity (electrical conductivity, EC). The wavelengths 427, 487, 950, 1414, 1917, 2206, 2380 and 2460 nm showed peculiar absorption characteristics. The study showed significant achievement in predicting soil pH, salinity (EC), bulk density, soil available nitrogen, exchangeable magnesium, soil available zinc, and boron with acceptable to excellent predictions (ratio of performance to deviation ranged 1.48–2.06). Amongst predicted models, SVR, PLSR, and PCR were found to be more robust than MARS and RF. The results of the study indicated that the visible near-infrared spectroscopy has the potential to predict properties of the SAS.

Soil and water conservation measures improve soil carbon sequestration and soil quality under cashews

Land degradation is becoming a serious problem in the west coast region of India where one of the world's eight biodiversity hotspots, the ‘Western Ghats’, is present. Poor land management practices and high rainfall have led to increasing problems associated with land degradation. A long-term (13-year) experiment was done to evaluate the impact of soil and water conservation measures on soil carbon sequestration and soil quality at three different depths under cashew nut cultivation on a 19% slope. Five soil and water conservation measures - continuous contour trenches, staggered contour trenches, half-moon terraces, semi-elliptical trenches, and graded trenches all with vegetative barriers of Stylosanthes scabra and Vetiveria zizanoides and control were evaluated for their influence on soil properties, carbon sequestration, and soil quality under cashews. The soil and water conservation measures improved significantly the soil organic carbon, soil organic carbon stock, carbon sequestration rate and microbial activity compared to the control condition (without any measures). Among the measures tested, continuous contour trenches with vegetative barriers outperformed the others with respect to soil organic carbon stock, sequestration rate, and microbial activity. The lower metabolic quotient with the measures compared to the control indicated alleviation of environmental stress on microbes. Using principal component analysis and a correlation matrix, a minimum dataset was identified as the soil available nitrogen, bulk density, basal soil respiration, soil pH, acid phosphatase activity, and soil available boron and these were the most important soil properties controlling the soil quality. Four soil quality indices using two summation methods (additive and weighted) and two scoring methods (linear and non-linear) were developed using the minimum dataset. A linear weighted soil quality index was able to statistically differentiate the effect of soil and water conservation measures from that of the control. The highest value of the soil quality index of 0.98 was achieved with continuous contour trenches with a vegetative barrier. The results of the study indicate that soil and water conservation measures for cashews are a potential strategy to improve the soil carbon sequestration and soil quality along with improving crop productivity and reducing the erosion losses.

Hybridity Assessment in Experimental F1s of Rice (Oryza sativa L.) using Microsatellite Markers

The present investigation was undertaken to assess the hybridity of experimental F1 plants derived from the crossing of salinity and/or submergence tolerant landraces with the high-yielding popular varieties of the west coast region of India. Seven microsatellite markers were utilized for confirming the hybridity of the 16 F1 plants developed from four cross combinations, viz. Karjat-3 X KS-19-2 (Cross 1), Goa dhan-3 X Jaddubatta (Cross 2), Jaya X KS-19-2 (Cross 3) and Karjat-3 X Jaddubatta (Cross 4). Polymorphism survey using above seven markers between the parents of all the four crosses revealed that six of them were polymorphic, whereas one marker was monomorphic. The marker RM21539 was found to be polymorphic in all the four cross combinations, followed by RM493, RM3412, RM206 and RM10843 exhibiting polymorphism in three crosses, while marker RM25181 was polymorphic in two crosses. The screening of F1s with polymorphic markers revealed that the F1s from Cross 3 exhibited heterozygosity (showing alleles from both the parents) at six marker loci, whereas the F1s from Cross 1 and Cross 4 at five loci and Cross 2 at two marker loci, thereby confirming hybridity in all the 16 tested F1 plants.

Stable water isotope signatures of dual monsoon precipitation: A case study of Greater Cochin region, south-west coast of India

Precipitation samples of various spatio-temporal scales were collected from coastal, midland and urban regions of Greater Cochin, Ernakulam district, Kerala for a period of 1 yr (2015–2016). The collected samples were analysed for stable water isotopes (SWI) (δD and δ18O), to understand these variations in the precipitation source and the factors governing its isotopic characteristics during precipitation. The δ18O in rainwater varies from −8.73‰ to 0.29‰ in urban, −12.21‰ to 2.59‰ in midland and −9.99% to 0.97‰ in lowland regions. Spatio-temporal variations in SWI were observed in various regions, suggesting altitude and continental effect followed by the establishment of a regional overall local meteoric water line (LMWL) δD = 8.06 (±0.15) δ18O + 12.5 (±0.68). Among the coastal, midland and urban regions, the highest slope (~8.3) and intercept (~13.0) were observed in the urban region, which designates the variations in temperature along spatial and different layers of the atmosphere in the urban region, resulting in the deviation of isotopic characteristics. The overall deuterium excess (d-excess) value is ~10‰ during the south-west monsoon (June–September), suggesting a moisture source of marine origin. A d-excess of ~13‰ is observed during the north-east monsoon, indicating a moisture source from the continental contribution (October–December). The results of the moisture source obtained from the d-excess value are also supported by back-trajectory analysis. Thus, the present study on isotopic characterisation of precipitation and its controlling factor may enhance our understanding of the Indian monsoon and its dynamics in the west coast region of India.

A five years study on the selection of rice based cropping systems in Goa, for west coast region of India

Aim: Field experiments were conducted for five years during 2010-11 to 2014-15 to select productive and profitable rice based cropping systems for West coast region of India at ICAR-Central Coastal Agricultural Research Institute, Goa. Methodology: Cropping systems viz. rice-cowpea, rice-groundnut, rice-brinjal and rice-sweet corn were tested for their production potential, economic feasibility, nutrient balance and energy budgeting along with rice-fallow as control. Results: The data indicated significantly higher rice equivalent yield (23.5 t ha) with rice-sweet corn followed by rice-brinjal (14.1 t ha) as compared to a predominant rice-fallow system of the region (5.50 t ha). Higher potential usable residue was also found higher with rice- sweet corn system (36.9 t ha). Results of the energy ratio (46.5), specific energy (0.65 MJ kg) and energy productivity (1.52 kg MJ) indicate that the rice-sweet corn is most energy efficient system among all the evaluated systems. Although, rice-brinjal system depicted higher onfarm employment potential (217 man days ha year) with an increase of 317 % over monocropping, while the economic analysis indicted higher net return (. 95350) and benefit cost ratio (2.57) in rice-sweet corn system. The nutrient balance were positive for N and P, while in all the cropping systems the K balance was found negative. Interpretation: The rice-sweet corn system was found to be the most productive, economical and energy efficient cropping system for the West coast region of India under protective irrigated conditions.

Evaluation of rainfall extremes. Northeast and West coast regions of India as case study

The response of climate change is the increase in the frequency and intensity of extreme weather events. An attempt has been made to study the trends in heavy rainfall amount and the highest rainfall value in 24 hours over Northeast region (NER) and West coast region (WCR) of India with the period ranging from 1901-2009. A standard statistical analysis concludes that the majority of the stations in NER and WCR indicates increasing trend in annual and monsoon rainfalls. Further, the increasing trends in heavy rainfall were investigated and the associated synoptic conditions were identified. The study reveals that the increase in heavy rainfall over the WCR can be attributed to the synoptic systems namely monsoon trough, cyclonic circulation, depressions and lows.

Prevalence, Serogroups, Shiga-toxin Genes and Pulsed Field Gel Electrophoresis Analyses of Escherichia coli Isolated from Bovine Milk

Shiga toxin-producing Escherichia coli (STEC) including non-O157 strains have been linked to outbreaks and sporadic cases of illness worldwide. A total of 647 milk samples were collected at different levels of collection and processing (udder, milking utensils, milk collection centres and receiving dock) within West Coast region of India. The milk samples were screened for the presence of E. coli and further tested for the Shiga-toxin (stx) genes by PCR. The isolates were characterized for their serogroups and XbaI digestion patterns of total DNA separated by pulsed-field gel electrophoresis (PFGE). A total of 77 (11.90 %) isolates were confirmed as having E. coli. The serogroups reported were O4, O60, O112, O56, O159, O120, O2, O83, O88, O95, O141, O21, O25, O80, O140, O97, O24, O166, O146, O51, O169, O147, O103, O18, O100, O15, O69, O43, O7, O3, O45, O124, O110, O84, and O114. Out of the 77 E. coli isolates, 25 (32.46 %) could be classified as Shiga-toxigenic based on PCR results. Of these 11, 3 and 11 isolates were positive for stx1, stx2, and both stx1 and stx2, respectively. PFGE profiles indicated genetic diversity of E. coli strains. Much variation was observed among isolates recovered at different levels of collection. Further research is needed to uncover unique characteristics and resistance of non-O157 STEC strains.

Effect of Drying on the Index Properties of Lateritic Soils

Due to significant variation in geological and climatic conditions the characteristics of lateritic soils vary from place to place. Because of the prevailing climatic conditions, the laterites and lateritic soils of a particular region may be different from those found in other parts of the world. Some investigators report that the pretest drying has significant effect on the properties of soils. In such studies the authors associate the effect of drying on the properties of soils due to the mineralogy of soil. From this context there is a need to investigate the effect of sample preparation on lateritic soils prior to testing. In the present study lateritic soils from different sources in west coast region of India were studied to investigate the effect of drying on their index properties. Due to pretest drying it is observed from the results that there is a significant change in Atterberg limits and other properties of soils tested. These changes are attributed due to aggregation of particles. The observed changes are found to be permanent.

Interactions Between Soils and Laboratory Simulated Electrolyte Solution

To study the impact of salt water intrusion on two types of soils from west coast region of India were investigated in the laboratory. The key characteristics evaluated included Atterberg limits, compaction characteristics, hydraulic conductivity and chemical characteristics of selected soils. The sea at this coast receives effluent from different points and hence the characteristics change with time and locality. Therefore, to maintain uniform composition, 0.5 N sodium chloride solution (NaCl) was prepared in the laboratory and batch tests were used to determine the immediate effect on soils. Soil specimens were prepared by mixing the soils with 0.5 N NaCl in the increments of 0, 5, 10 and 20% by weight to vary the degree of contamination. Experimental results of soils mixed with 0.5 N NaCl showed that the maximum dry density increases and the optimum moisture content (OMC) decreases with increasing sodium chloride concentration. The study also revealed that the hydraulic conductivity of the soils tested increases with increase in sodium chloride concentration. The Atterberg limits of contaminated specimens show a remarkable change when compared with uncontaminated specimens.

Mesoscale characteristics and prediction of an unusual extreme heavy precipitation event over India using a high resolution mesoscale model

Numerical prediction experiments using a high resolution mesoscale model NCAR MM5 were performed to simulate an unusual extreme precipitation event that occurred over west coast region of India on 26 July 2005. During this event, unprecedented precipitation of 90–100 cm was recorded over northeast parts of Mumbai City, India causing enormous losses while southern parts received only 10 cm. Model prediction with analysis nudging for 12 h followed by 36 h of integration produced the best simulation with 55 cm of precipitation in 24 h and with the location over north Mumbai agreeing with the observations. Model diagnostics of the vorticity, divergence, vertical velocity and lower tropospheric moisture convergence show the mesoscale characteristics of the convective system with a horizontal extent of 50 km2 and of a sudden cloud burst for 3–6 h followed by few shorter rain spells. The model simulates the veering of the wind with height due to warm air advection to favor convection but a moist layer at lower levels capped by dry air inhibited convection. The simulated circulation features indicate that a mesoscale convective system formed in the monsoon westerlies due to passage of a synoptic disturbance across the east coast strengthening the monsoon flow, and dry air incursion at middle levels suppressed convection and contributing to increase of potential instability at lower levels. All this helped the sudden initiation of deep convection and cloud burst with heavy precipitation rate. Stretching term associated with vorticity contributes most for the increase of cyclonic vorticity indicating the interaction of convection with mesoscale circulation.

Effect of pH on the geotechnical properties of laterite

Environmental Geotechnology has emerged as an interdisciplinary science, aiming and forecasting, analyzing and solving the geotechnical problems involving the influence of environmental factors. Lateritic soil of west coast region of India was studied to investigate the effect of soaking on the engineering properties and chemical characteristics of soil, soaked in different pH solutions (pH = 5.0, pH = 7.0, pH = 8.0). 12 N hydrochloric acid and 15 M ammonia solution were used to monitor the pH of the solution for about ninety days. Results showed that the pH of the solution has strong influence on the chemical characteristics of lateritic soil. The engineering properties of soil are altered when compared with the initial characteristics of the soil. The reason for this observed behavior of the soil is addressed in this paper.

IN-SITU CHARACTERIZATION OF UNSATURATED SOIL HYDRAULIC PROPERTIES OF A LATERITE SOIL PROFILE IN COASTAL KARNATAKA

ABSTRACT Unsaturated laterite soil formations play an important hydrologic role in the West Coast region of India. However, very little information on the hydraulic/hydrologic properties of lateritic soils exists in literature. The present study was taken up to characterize the unsaturated soil water retention curves and hydraulic conductivity function of a sandy lateritic soil profile located in the coastal district of Dakshina Kannada, Karnataka State. This was achieved by conducting a field internal drainage test involving measurements of soil moisture contents and soil water pressures at various depths within a 1.5 m deep soil profile over a period of 39 days. Soil moisture contents were measured using a sophisticated Time Domain Reflectrometry (TDR) probe and soil water suction pressures were measured using tensiometers. The water retention curve for each depth layer was characterized by fitting the popular van Genucthen model to observed moisture contents and suction pressures. Depth-wise differences in the shapes of the water retention curves were evident. Observed temporal variations in moisture content and suction pressures during internal drainage were analyzed using well-established procedures to calculate unsaturated hydraulic conductivity values. Results indicated more or less homogeneous depth-wise drainage behaviour and a single relationship based on van Genucthen's model was sufficient to describe the hydraulic conductivity variations with moisture content for the entire profile. Computed hydraulic conductivities showed extreme sensitivity to soil moisture contents and varied from a low value of 0.47 cm/d at moisture content of 0.208 cm3/cm3 to as high as 134.82 cm/d at 0.261 cm3/cm13. Results of this study can provide useful inputs in applications of mathematical models to describe water flow and solute transport in unsaturated lateritic soil media. This may lead to better understanding of the role of the unsaturated soil zone in the hydrologic cycle in the West Coast region and thereby lead to more efficient designs of water conservation structures.

Natural radioactivity in South West Coast of India

Soil samples from South West Coast region of India were analysed for their 226Ra, 232Th, and 40K activities by gamma spectrometry. The 226Ra concentration varied in the range of 8.2–68.4 Bq kg −1 with a mean of 30.6 Bq kg −1, 232Th in the range of 5.9–77.2 Bq kg −1 with a mean of 38.2 Bq kg −1, and 40K in the range of 14.6–344.9 Bq kg −1 with a mean of 152.2 Bq kg −1 in 0–5 cm soil profile. Depth profile studies showed a uniform distribution of these radionuclides throughout the soil depth in most of the sampling stations. The 226Ra and 232Th activities show significant positive correlation with the organic matter content of the soil.