The Fate of Glyphosate in Soil and Water: A Review

The fate of glyphosate in soil and water is dependent on the properties of glyphosate and its envoronement. Behaviour of glyphosate in soil, sediment and water is strongly influenced the way by which it can be adsorbed by soils, sediments, and suspended material in water. The role of soil organic matter, clay mineral, and amorphous minerals on the adsorption of glyphosate depends primarily on the nature and properties of the soil itself and the properties of glyphosate. Environmental factors have some influence on sorption and degradation of glyphosate. Glyphosate is rapidly inactivated in soil, is in part due to adsorption. Some soil properties have been identified strongly influence adsorption of glyphosate, such as clay minerals, composition of cations in exchangeable site of clay and organic matter, unoccupied phosphate adsorption site, degree of humification, and soil pH. Adsorption limits the availability of glyposate for microbial degradation. The sorbed glyphosate is not directly available to microorganisms in soil. Evidence also suggests that not only a strongly sorbed compound such as paraquat but also weakly sorbed compounds such as flumetsulam and picloram can persist for long periods when they are sorbed by soil constituents. This suggests that the interaction between sorption and biodegradation should be considered in predicting the fate of pesticides in soils and sediments.

Evaluation of the physico-chemical state of the soil contaminant isolate indigenous bacterial species

The aim of the study is to isolate indigenous bacterial species which have the ability to degrade crude oil. Samples were collected from an oil polluted site in Ejama-Ebubu Eleme Rivers state. The samples were taken from five spot (A-E), of depth 0-15 (A1– E1) and 15-30 (A2– E2) in sterile polyethylene bags, using appropriate equipment, then taken to the laboratory for analysis, Physicochemical parameters such as pH, nitrate, sulphate, phosphate, total petroleum hydrocarbon (TPH), poly aromatic hydrocarbon (PAH), salinity, temperature, conductivity and heavy metals (iron, zinc, nikel, lead, chromium) were determined, The THB count was determined using the spread plate method on nutrient agar. Soil, sediment and water physicochemical parameters determined indicated that the samples had been exposed to hydrocarbon contamination. The Gram negative bacteria belonging to the genus pseudomonas is the most frequent. Other genera isolated were Nocardia, Micrococcus,Chromobacterium, Burkholdia, Corynebacterium. The study revealed the presence of petroleum hydrocarbons in the Ejama_Ebubu site as well as known genera of hydrocarbon utilizing bacteria. The biases associated with culture-dependent microbial enumeration techniques may limit the full description of the bacterial diversity in Ejama-Ebubu site. From the study, it is concluded that microorganisms that can degrade hydrocarbons are found in oil contaminated soil and can easily be isolated from these contaminated sites, although it is very difficult to work with aromatic hydrocarbons due to their volatility and toxic effects.

Development and Applications of an In Situ Probe for Multi-Element High-Resolution Measurement at Soil/Sediment-Water Interface and Rice Rhizosphere

The biogeochemistry of multi-elements, such as sulfur (S), phosphorus (P) and arsenic (As), is interlinked especially at interfaces of soil/sediment–water and plant rhizosphere. To explore the biogeochemical behavior of multi-elements such as S-P-As at interfaces, an in situ and high-resolution technology is required. In this study, we developed an in situ probe (LDHs-DGT) based on the diffusive gradients in thin-films technique using a single binding layer to realize the co-measurement of multi-elements including sulfide and oxyanions. Mg-Al layered double hydroxides (LDHs) were synthesized and incorporated into the probe’s binding layer. Laboratorial characterization showed that the LDHs-DGT probe had a high capacity for sulfide, phosphate and arsenate and can effectively determine their levels across a wide range of solution conditions, i.e., pH from 5 to 8 and ionic strengths from 0.005–0.01 mol L−1 NaNO3. The application potential of the LDHS-DGT probe in capturing the concentration profiles of sulfide and oxyanions across the soil/sediment–water interface at a centimeter scale was demonstrated. The synchronous co-variations of labile sulfide and phosphate were observed along an intact river sediment core, demonstrating the redox driven behaviors of oxyanions at aerobic–anaerobic transition zones. Moreover, the LDHS-DGT probe was further used to acquire the dynamic distributions of multi-elements in the plant rhizosphere at a two-dimensional millimeter scale. Compared to treatments of sodium sulfate and mercaptopygorskite fertilization, the addition of elementary S promoted the reduction of sulfate to sulfide along the whole growth stage and thus inhibited the activation of toxic metals in the rice rhizosphere. Collectively, this study provides a tool for convenient measurement of nutrients and metal(loid)s across soil–water/root interfaces at high resolution and thus, a broad application prospect of the tool in sustainable agriculture is expected.

Antimicrobial and Antioxidant Activities of Streptomyces sps Isolated from Muthupettai Mangrove Soil

Muthupet mangrove forest soil sediment was the abundant resource of the actinomycetes with distinct nature of bioactive compounds. The soil sediment was collected at 1-3meter away from bank. The present study was focused on isolation, identification and antimicrobial activity of the actinomycetes from Muthupet mangrove soil samples. Totally 32 actinomycetes strains was isolated and screened for antimicrobial activity against bacterial and fungal pathogens. Among 32 isolates 16 have antibacterial activity and 10 have antifungal activity but MG-3 and MG-4 showed maximum activity against both all the test pathogens. These two strains are gram-positive, rod-shaped, MG-3 possessing an earthy characteristic odour and MG-4 produce purple color pigment. The isolates were confirmed as Streptomyces sp. based on morphological, cultural, biochemical and physiological observations, as well as identification using the 16S rRNA gene sequence, it showed 98% similarity with Streptomyces parvus for MG-3 and Streptomyces californicus for MG-4. Bioactive compounds were extracted from Streptomyces using different solvents such as ethyl acetate, methanol, chloroform, hexane and antibacterial activities were assayed against test pathogens, ethyl acetate extract showed maximum zone of inhibition when compared with other solvents. The Minimum inhibitory concentration of ethyl acetate extract was found ranged between 1.96-3.9 μg/ml. The invitro antioxidant capacity of the crude extract was estimated by DPPH, ferric reducing power assay, H202 radical scavenging assay, phosphomolybdenum assay and total antioxidant activities. The characterization of crude extracts was analyzed by FTIR and GC-MS. From the results, it is clear that the ethyl acetate crude extract of S.parvus MG-3 and S.californicus MG-4 possesses high antimicrobial and antioxidant activity and suggested that the isolated strains could be a potential for the nature resource of pharmaceutical.

Proposal to correct for the effect of background and density in the determination of gamma emitters using sodium iodide detectors

This study develops a modification to the spectra decomposition method for sodium iodide scintillation equipment, including correcting the natural background counts for the activity concentration calculation. A comparison of the results obtained between two sodium iodide detectors of 2 X 2 in and 3 x 3 in versus a hyper-pure germanium detector of 50 % relative efficiency is performed for soil, sediment, and water samples. It is found that background correction significantly improves activity concentration results in higher energy regions. The concentration values determined by the different spectrometric systems for the samples analyzed do not show significant differences, which supports the results obtained with the proposed calculation method. The uncertainty associated with the measurement and detection limits for the NaI (Tl) detectors is higher than those obtained with the GeHp detector due to the operation of the two technologies and the presence of interferences in the regions of interest. The study carried out in this work establishes an analytical milestone. The methodological model proposed makes it possible to quantify, with reliable results, low concentration levels of NORM materials and even 131I using sodium iodide detectors, among other analytical applications of general interest.

Potentially Toxic Element Contaminations and Lead Isotopic Fingerprinting in Soils and Sediments from a Historical Gold Mining Site

Lead (Pb) isotopes have been widely used to identify and quantify Pb contamination in the environment. Here, the Pb isotopes, as well as the current contamination levels of Cu, Pb, Zn, Cr, Ni, Cd, As, and Hg, were investigated in soil and sediment from the historical gold mining area upstream of Miyun Reservoir, Beijing, China. The sediment had higher 206Pb/207Pb ratios (1.137 ± 0.0111) than unpolluted soil did (1.167 ± 0.0029), while the soil samples inside the mining area were much more variable (1.121 ± 0.0175). The mean concentrations (soil/sediment in mg·kg−1) of Pb (2470/42.5), Zn (181/113), Cu (199/36.7), Cr (117/68.8), Ni (40.4/28.9), Cd (0.791/0.336), As (8.52/5.10), and Hg (0.168/0.000343) characterized the soil/sediment of the studied area with mean Igeo values of the potentially toxic element (PTE) ranging from −4.71 to 9.59 for soil and from −3.39 to 2.43 for sediment. Meanwhile, principal component analysis (PCA) and hierarchical cluster analysis (HCA) coupled with Pearson’s correlation coefficient among PTEs indicated that the major source of the Cu, Zn, Pb, and Cd contamination was likely the mining activities. Evidence from Pb isotopic fingerprinting and a binary mixing model further confirmed that Pb contamination in soil and sediment came from mixed sources that are dominated by mining activity. These results highlight the persistence of PTE contamination in the historical mining site and the usefulness of Pb isotopes combined with multivariate statistical analysis to quantify contamination from mining activities.

Phytoremediation: In situ Alternative for Pollutant Removal from Contaminated Natural Media: A Brief Review

Phytoremediation is an in situ application by planting crops in areas of contaminated soil. The contaminated media treated by phytoremediation are soil, sediment, sludge, ground, surface, and wastewater. It is a potential method to prevent toxic contaminants from entering the food chain and conserves biological diversity. This innovative technique uses plant species with good biomass yield to alleviate contaminant toxicity in various polluted media in an ecosystem, and harvestable parts of the plants will turn up into bioenergy. This sustainable and cost-effective technology is a fast emerging alternative as compared to conventional remediation methods. Based on literature obtained from different search engines, this review will be beneficial in gathering and critically analyzing the earlier published data for making a new milestone in the field of phytoremediation.

Synergetic CT, XRF and Geoelectric Imaging for Non-Destructive Soil and Sediment Stratigraphic Study

This paper presents the application of three non-destructive techniques in the study of an agricultural area on the west coast of Peloponnese, Greece. The applied methods include (a) electromagnetic geophysical research using a handheld EM profiler (EMP-400 GSSI), (b) computed tomography (CT) with coring data, and (c) X-ray Fluorescence (XRF) scanning. As electrical conductivity is mainly influenced by the bulk soil, including water content, clay content and mineralogy, organic matter, and bulk density, a comparison of the three applied techniques indicates the same soil stratification and same soil properties with depth. Moreover, the ground-truthing by the undisturbed soil and sediments core retrieved in the centre of the site as well as the laboratory analyses of soil and sediment properties confirm the reliability of the geophysical research and the revealed soil/sediment stratification.