Effects of organic amendments on the reduction and phytoavailability of chromate in mineral soil

In this study, seven organic amendments (biosolid compost, farm yard manure, fish manure, horse manure, spent mushroom, pig manure, and poultry manure) were investigated for their effects on the reduction of hexavalent chromium [chromate, Cr(VI)] in a mineral soil (Manawatu sandy soil) low in organic matter content. Addition of organic amendments enhanced the rate of reduction of Cr(VI) to Cr(III) in the soil. At the same level of total organic carbon addition, there was a significant difference in the extent of Cr(VI) reduction among the soils treated with organic amendments. There was, however, a significant positive linear relationship between the extent of Cr(VI) reduction and the amount of dissolved organic carbon in the soil. The effect of biosolid compost on the uptake of Cr(VI) from the soil, treated with various levels of Cr(VI) (0-1200 mg Cr kg(-1) soil), was examined with mustard (Brassica juncea L.) plants. Increasing addition of Cr(VI) increased Cr concentration in plants, resulting in decreased plant growth (i.e., phytotoxicity). Addition of the biosolid compost was effective in reducing the phytotoxicity of Cr(VI). The redistribution of Cr(VI) in various soil components was evaluated by a sequential fractionation scheme. In the unamended soil, the concentration of Cr was higher in the organic-bound, oxide-bound, and residual fractions than in the soluble and exchangeable fractions. Addition of organic amendments also decreased the concentration of the soluble and exchangeable fractions but especially increased the organic-bound fraction in soil.     

Shoreline change analysis of Vedaranyam coast, Tamil Nadu, India

The coastal zone is one of the nation’s greatest environmental and economic assets. The present research aims at studying the shoreline changes along Vedaranyam coast using conventional and modern techniques including field sampling, remote sensing, and geographical information system (GIS). The study area was divided into three zones. Dynamic Land/Sea polygon analysis was performed to obtain the shore line changes at different time periods between 1930 and 2005. From the multidate shoreline maps, the rate of shoreline change was computed using linear regression rate and end point rate. Further, the shoreline was classified into eroding, accreting, and stable regions through GIS analysis. The eroding, accreting, and stable coastal stretch along Vedaranyam is observed as 18 %, 80.5 %, and 1.5 %, respectively. Net shoreline movement is seaward, i.e., the coast is progressive with an average rate of 5 m/year. A maximum shoreline displacement of 1.3 km towards the sea is observed near Point Calimere. During the Asian Tsunami 2004, the eastern part of the study area showed high erosion. Sediment transport paths derived from the grain size analysis of beach sediments collected during different seasons help to identify the major sediment source and sinks. Point Calimere acts as the major sink for sediments whereas Agastiyampalli and Kodiakkarai are found to be the major sources for the sediment supply along the Vedaranyam coast. Shoreline change study from field and satellite data using GIS analysis confirms that Vedaranyam coast is accreting in nature.     

The potential impacts of sea level rise along the coastal zone of Kanyakumari District in Tamilnadu,India

Climate change associated with sea level rise (SLR) is one of the major environmental concerns of today. This paper presents an assessment of the impacts of sea level rise on the coastal zone of Kanyakumari District in Tamilnadu, India. Digital Elevation Model (DEM) combined with overlay techniques in GIS are used in determining the inundation zones along the coastal region. The analysis evaluated the impact on coastal fishing villages, landuse, tourist spots and sensitive areas under threat. The vulnerability of the coastal areas in Kanyakumari to inundation was quantified, based on the projected sea level rise scenarios of 0.5 and 1 m. Our findings reveal that approximately 13 km² of the land area of Kanyakumari would be permanently inundated due to SLR. This would result in loss of land, alteration of the coastal zone and affects coastal ecosystem. From the study, the mitigation measures (engineering measures) and Coastal Zone Management practices that can be taken to protect human life and property from sea level rise are suggested.     

Seasonal variation in physicochemical properties of coastal waters of Kalpakkam, east coast of India with special emphasis on nutrients

A study pertaining to the seasonal variation in physicochemical properties of the coastal waters was carried out at Kalpakkam coast for a period of 1 year (February 2006 to January 2007). It revealed that the coastal water was significantly influenced by freshwater input during North East (NE) monsoon and post-monsoon periods. Concentration of all the nutrients and dissolved oxygen (DO) was relatively high during the NE monsoon, whereas, salinity and chlorophyll-a (chl-a) were at their minimum level during this period. Phytoplankton production peak was observed in summer during which a typical marine condition prevailed. The present observed values of nitrate, phosphate, silicate, and turbidity are significantly high (five to ten times) compared to that of the pre-Tsunami period from this coast. Relatively low DO and chl-a concentration was noticed during the post-Tsunami period. A notable feature of this study is that though nutrient concentration in the coastal waters during post-Tsunami period has increased significantly, turbidity, the most single dominating factor, was found to adversely affect the phytoplankton production during post-Tsunami period as reflected by relatively low chl-a concentration. Thus, the post-Tsunami period may result in a change in coastal biodiversity pattern concomitant with change in coastal water quality.     

Impact of metals on histopathology and expression of HSP 70 in different tissues of Milk fish (Chanos chanos) of Kaattuppalli Island, South East Coast, India

Histological and Immunohistochemical studies were carried out to document the possible impact of heavy metal contamination in different tissues of Chanos chanos. Heavy metals such as Cu, Pb, Zn, Cd, Mn and Fe were predominant in water, sediment and biota of Kaattuppalli Island and varied significantly between two different sites. Histological changes such as swelling of muscle fiber and break down of muscle bundles were noted in the muscle. Similarly gill filament cell proliferation, increase in intercellular spaces and primary and secondary lamellar epithelium were evident in gills. The hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish collected from polluted site compared to that from the less polluted site. The impact of pollution was also assessed in different tissues by immunohistochemistry using primary antibody (mouse monoclonal HSP70 antibody 1:2000) and secondary antibody (HRP conjugated antibody) for expression of stress protein. Immunostaining analysis showed expression of HSP70 with high intensity in the tissues of fish collected from polluted site compared to less polluted sites. Further, HSP70 positive cells were analyzed from six locations per fish tissue section. One-way analysis of variance (ANOVA) followed by least significant difference (LSD) was used to check if the expression was significant. Results indicate that the values are statistically significant at the two different sampling sites (P<0.05).     

Recycle of bio-waste banana and sisal fiber filled harmlessness epoxy hybrid composite for automotive roof application

Insists of polymer matrix composite is prepared by using natural fiber facilitates high tensile, flexural, and impact toughness properties. The natural fiber utilization in the polymer matrix can overcome the synthetic fiber demerits of poor compatibility, high moisture absorption, and high cost. The present research investigates developing a low-cost, environmentally eco-friendly epoxy hybrid composite using different volume percentages of chopped natural waste banana (0Vol%, 5Vol%, 10Vol%, and 15Vol%) and sisal fiber (0Vol%, 15Vol%, 10Vol%, and 5Vol%) through hand mould hot compression technique. The presence of natural waste banana and sisal fiber on tensile strength, flexural strength, and thermal adsorption properties of the epoxy hybrid composite are evaluated by ASTM test standards. The ASTM standard measured test results of epoxy hybrid composite with and without natural waste banana and sisal fiber were compared and sample three was identified by good tensile strength, flexural strength, and better thermal adsorption properties compared to all others. The sample three epoxy hybrid sample is recommended for automotive roof application.     

Perchlorate contamination of groundwater from fireworks manufacturing area in South India

Perchlorate contamination was investigated in groundwater and surface water from Sivakasi and Madurai in the Tamil Nadu State of South India. Sensitive determination of perchlorate (LOQ?=?0.005 μg/L) was achieved by large-volume (500 μL) injection ion chromatography coupled with tandem mass spectrometry. Concentrations of perchlorate were <0.005–7,690 μg/L in groundwater (n?=?60), <0.005–30.2 μg/L in surface water (n?=?11), and 0.063–0.393 μg/L in tap water (n?=?3). Levels in groundwater were significantly higher in the fireworks factory area than in the other locations, indicating that the fireworks and safety match industries are principal sources of perchlorate pollution. This is the first study that reports the contamination status of perchlorate in this area and reveals firework manufacture to be the pollution source. Since perchlorate levels in 17 out of 57 groundwater samples from Sivakasi, and none from Madurai, exceeded the drinking water guideline level proposed by USEPA (15 μg/L), further investigation on human health is warranted.     

Spatio-temporal variation in physicochemical properties of coastal waters off Kalpakkam, southeast coast of India, during summer, pre-monsoon and post-monsoon period

Seasonal observations on water-quality parameters and chlorophyll-a in the coastal waters off Kalpakkam, southeast coast of India, was carried out covering an area of about 30 km(2) to find out the variations in physicochemical properties during a monsoonal cycle of the year. Most of the parameters exhibited a significant spatial and seasonal variation. It revealed that the coastal water was significantly influenced by freshwater input from the nearby backwaters during North-east monsoon and post-monsoon periods. A marginal increase in pH from coast towards offshore was noticed during the observation. Relatively low salinity values were observed during pre and post monsoon when compared to summer. Bottom water was found to be highly turbid during summer and pre-monsoon conditions when compared to surface. This could be attributed to the strong northerly wind and northward current prior to the onset of southwest monsoon. N, P and Si based nutrients are relatively high in their concentration in the bottom water. Nitrate was significantly high during post-monsoon and contributed greatly towards total nitrogen as evident from the statistical correlation. Ammonia concentration was relatively high in the bottom samples during all the seasons except on a few occasions during post-monsoon. In general, phosphate and total phosphorous values remained low and particularly so in the surface water. Higher silicate concentration was observed in the bottom water, and there was a reducing trend towards offshore. High chlorophyll-a values were observed during summer and surface water was found to have higher pigment concentrations as compared to the bottom. Results show that phosphate acts as the limiting factor for phytoplankton production particularly during post-monsoon period whereas; none of the nutrients were found to be limiting the phytoplankton growth during other seasons.     

Assessment of temporal and spatial water quality in international Gomishan Lagoon,Iran, using multivariate analysis

Coastal lagoon ecosystems are vulnerable to eutrophication, which leads to the accumulation of nutrients from the surrounding watershed over the long term. However, there is a lack of information about methods that could accurate quantify this problem in rapidly developed countries. Therefore, various statistical methods such as cluster analysis (CA), principal component analysis (PCA), partial least square (PLS), principal component regression (PCR), and ordinary least squares regression (OLS) were used in this study to estimate total organic matter content in sediments (TOM) using other parameters such as temperature, dissolved oxygen (DO), pH, electrical conductivity (EC), nitrite (NO₂), nitrate (NO₃), biological oxygen demand (BOD), phosphate (PO₄), total phosphorus (TP), salinity, and water depth along a 3-km transect in the Gomishan Lagoon (Iran). Results indicated that nutrient concentration and the dissolved oxygen gradient were the most significant parameters in the lagoon water quality heterogeneity. Additionally, anoxia at the bottom of the lagoon in sediments and re-suspension of the sediments were the main factors affecting internal nutrient loading. To validate the models, R², RMSECV, and RPDCV were used. The PLS model was stronger than the other models. Also, classification analysis of the Gomishan Lagoon identified two hydrological zones: (i) a North Zone characterized by higher water exchange, higher dissolved oxygen and lower salinity and nutrients, and (ii) a Central and South Zone with high residence time, higher nutrient concentrations, lower dissolved oxygen, and higher salinity. A recommendation for the management of coastal lagoons, specifically the Gomishan Lagoon, to decrease or eliminate nutrient loadings is discussed and should be transferred to policy makers, the scientific community, and local inhabitants.     

Rapid adsorption of toxic Pb(Ⅱ) ions from aqueous solution using multiwall carbon nanotubes synthesized by microwave chemical vapor deposition technique

Multiwall carbon nanotubes(MWCNTs) were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT samples were tested for their performance in terms of Pb(Ⅱ)binding. The synthesized MWCNT samples were characterized using Fourier Transform Infrared(FT-IR), Brunauer, Emmett and Teller(BET), Field Emission Scanning Electron Microscopy(FESEM) analysis, and the adsorption of Pb(Ⅱ) was studied as a function of p H,initial Pb(Ⅱ) concentration, MWCNT dosage, agitation speed, and adsorption time, and process parameters were optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, Qmaxwas calculated to be 104.2 mg/g for the microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modeled using pseudo first-order and pseudo second-order equations. Different thermodynamic parameters, viz., ΔH0, ΔS0and ΔG0were evaluated and it was found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis revealed that the optimum conditions for the highest removal(99.9%) of Pb(Ⅱ) are at p H 5, MWCNT dosage 0.1 g, agitation speed 160 r/min and time of 22.5 min with the initial concentration of 10 mg/L. Our results proved that microwave-synthesized MWCNTs can be used as an effective Pb(Ⅱ) adsorbent due to their high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.