Paradigm shift of contamination risk of six heavy metals in tea (Camellia sinensis L.) growing soil: A new approach influenced by inorganic and organic amendments.

The present study provides several contamination and ecological risk indices for selected metals (Cd, Cr, Cu, Mn, Ni and Zn) in tea (Camellia sinensis L.; cv. S.3A/3) growing soil influenced by lower to higher doses of inorganic and organic amendments. While ecological risk indices were applied, it was observed that same treatment showed different risk levels but contamination risk status did not vary significantly. All the indices showed significant correlation with heavy metals' concentration in young shoots of tea plants. As the indices characterized experimental soils with different extents of contamination, it would be important to standardize the indices with long term experiments followed by generation of new index. Therefore, we formulated a new contamination index named as Tea Research Association Heavy Metal Contamination Index (TRAHMCI) for tea growing soils. TRAHMCI is based on the probable change of metal status in soil with progress of growth of tea plant. This could be useful to negate discrepancies arised from use of various existing metal contamination indices in tea growing soils amended with different doses of fertilizers. TRAHMCI was formulated based on individual contamination factor using statistical technique and applied to the present dataset which provided a more holistic understanding of overall tea growing soil behavior. The limitation of the developed TRAHMCI index is that, the index had not been validated for other crops in our study not to claim its effective use for crops other than tea. As already mentioned, this new index had been formulated by taking tea as the test crop with above mentioned six heavy metal contents in young shoot and made tea.

Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review.

Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 µg g-1, below detectable limit (BDL) to 122.4 µg g-1, BDL to 602 µg g-1, 0.275 to 13,040 µg g-1, 0.004 to 15,866 µg g-1, 0.04 to 570.80 µg g-1 and 0.01 to 1120 µg g-1, respectively. Only 3.2 µg L-1 to 7.25 mg L-1, 0.01 µg L-1 to 7 mg L-1, 3.80 µg L-1 to 6.13 mg L-1, 135.59 µg L-1 -11.05 mg L-1, 0.05 µg L-1 to 1980.34 mg L-1, 0.012 to 3.78 µg L-1, and 1.12 µg L-1 to 2.32 µg L-1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

Comparative Assessment of Copper, Iron, and Zinc Contents in Selected Indian (Assam) and South African (Thohoyandou) Tea (Camellia sinensis L.) Samples and Their Infusion: A Quest for Health Risks to Consumer.

The current study aims to assess the infusion pattern of three important micronutrients namely copper (Cu), iron (Fe), and zinc (Zn) contents from black tea samples produced in Assam (India) and Thohoyandou (South Africa). Average daily intakes and hazardous quotient were reported for these micronutrients. Total content for Cu, Fe, and Zn varied from 2.25 to 48.82 mg kg-1, 14.75 to 148.18 mg kg-1, and 28.48 to 106.68 mg kg-1, respectively. The average contents of each of the three micronutrients were higher in tea leaves samples collected from South Africa than those from India while the contents in tea infusions in Indian samples were higher than in South African tea samples. Results of this study revealed that the consumption of 600 mL tea infusion produced from 24 g of made tea per day may be beneficial to human in terms of these micronutrients content. Application of nonparametric tests revealed that most of the data sets do not satisfy the normality assumptions. Hence, the use of both parametric and nonparametric statistical analysis that subsequently revealed significant differences in elemental contents among Indian and South African tea.

Complexation of DTPA and EDTA with Cd2+: stability constants and thermodynamic parameters at the soil-water interface.

Two alkaline soils collected from the surface horizon (0-15 cm) of two agricultural fields Lakshmikantapur (LKP; 22° 06' 03″ N and 88° 18' 19″ E) and Diamond Harbour (DHB; 22° 11' N and 88° 14' E) of West Bengal, India were studied to observe the stability of cadmium (Cd) chelate complexes with diethylenetriaminepentaacetatic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA), removing organic matter (OM). The objective of the present study is "determination of the stability constants and the thermodynamic parameters of Cd-DTPA and Cd-EDTA complexes at different pH and temperatures at the soil-water interface". Complex formation of soil Cd with DTPA and EDTA at the soil-water interface was studied under different ligand-to-metal ratios, pHs and temperatures. Apparent conditional stability constants (log k´) were calculated from the concentrations of Cd chelates and free Cd2+, estimated by solid phase extraction with an ion exchanger. Standard Gibbs energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) of formation were calculated at three different temperatures. The higher stability constants of Cd-DTPA than Cd-EDTA indicated longer persistence of Cd-DTPA at the soil solution interface than Cd-EDTA complex. Increase of ΔG°, ΔH° and ΔS° with progress of temperature revealed that Cd-complex formation was facilitated by temperature. Highly negative ΔG° and positive ΔH° for Cd-complex formation indicated the reaction spontaneous and exothermic. In general, both ligands complexed high percentages of cadmium signalling their role in enhancing remobilization of Cd present in soil and preventing exchange of contaminated Cd from external source with soil mineral matrix; these phenomena may greatly reduce hazard for environment and human health. The result of this study support that DTPA increases solubility and more persistence of Cd in acidic soils within the range of temperature and mole fraction (MF = moles of Cd2+ / sum of the moles of Cd2+ and chelating agent) than that of EDTA due to higher capability of complex formation with Cd2+. Therefore, DTPA enhanced Cd toxicity in acid soils and groundwater. Complex formation in the presence of DTPA at acidic pH decreases with temperature and increases with pH. The higher per cent of Cd complexed in the presence of DTPA revealed that DTPA is a stronger chelating agent than EDTA at acidic pHs. Whereas, the capability of complex formation by EDTA is lower at lower pH but higher at higher pH.

Struvite for composting of agricultural wastes with termite mound: Utilizing the unutilized.

Although, compost is the store house of different plant nutrients, there is a concern for low amount of major nutrients especially nitrogen content in prepared compost. The present study deals with preparation of compost by using agricultural wastes with struvite (MgNH4PO4·6H2O) along with termite mound. Among four composting mixtures, 50kg termite mound and 2.5kg struvite with crop residues (stover of ground nut: 361.65kg; soybean: 354.59kg; potato: 357.67kg and mustard: 373.19kg) and cow dung (84.90kg) formed a good quality compost within 70days of composting having nitrogen, phosphorus and potassium as 21.59, 3.98 and 34.6gkg(-1), respectively. Multivariate analysis of variance revealed significant differences among the composts. The four composts formed two (pit 1, pit 2 and pit 3, pit 4) different groups. Two principal components expressed more than 97% of the total variability. Hierarchical cluster analysis resulted two homogeneous groups of composts.