Pollution indices of selected metals in tea (Camellia sinensis L.) growing soils of the Upper Assam region divulge a non-trifling menace of National Highway.

The study investigated the influence of a National Highway (NH) traversing tea estates (TEs) on heavy metal (HM) contamination in the top soils of Upper Assam, India. The dispersion and accumulation of six HMs, viz. cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn), within tea-growing soils were assessed using diverse indices: contamination factor (CF), degree of contamination (DC), enrichment factor (EF), geo-accumulation index (Igeo), modified degree of contamination (MDC), Nemerow pollution index (PINemerow), pollution load index (PLI), potential ecological risk factor (Eri), and potential ecological risk index (RI). The order of HM prevalence was Fe > Mn > Zn > Ni > Cu > Cd. Elevated Cd levels near the NH prompted immediate attention, while Cd and Zn showed moderate pollution in CF, EF, and RI. The remaining metals posed minimal individual risk (Eri< 40), resulting in an overall contamination range of "nil to shallow," signifying slight contamination from the studied metals. From MDC values for investigated metals, it was found to be "zero to very low degree of contamination" at all locations except the vicinity of NH. Soil pollution, as determined by PLI, indicated unpolluted soils in both districts, yet PINemerow values indicated slight pollution. The statistical analysis revealed that there is a significant decrease in most of the indices of HM as the distance from NH increases. The application of multivariate statistical techniques namely Principal Component Analysis and Cluster Analysis showed the presence of three distinct homogenous groups of distances based on different indices. This investigation underscores NH-associated anthropogenic effects on TE soil quality due to HM deposition, warranting proactive mitigation measures.

Elemental Profiling of North-East Indian Tea (Camellia sinensis) by ICP-MS and Assessment of Associated Health Risk.

Tea is a perennial crop that requires acidic soil for better plant growth. Due to the acidic nature of tea-growing soil, metals can be easily absorbed by tea plants from growing medium. Other anthropogenic activities are also the major contributor of element in the tea. This study provided a comprehensive database of 24 elements which were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Selected 24 elements belong to alkali metal (Li, Rb, Cs), alkaline earth metal (Be, Sr, Ba), transition metal (V, Cr, Mn, Co, Ni, Cu, Zn, Ag, Cd, Hg), basic metal (Al, Ga, Sn, Tl, Pb), metalloid (As), non-metal (Se), and actinide (U). Total 321 drier mouth samples were collected during 2020-2021 from eight different regions (Darjeeling, Terai, Dooars, North Bank, Upper Assam, South Bank, Cachar, and Tripura) of north-east India. No inorganic mercury as well as uranium was detected in any tested tea samples. Mean concentrations of Be, As, Ga, Tl, Li, Se, Cd, Ag, Cs, V, Co, and Pb were at trace level, whereas macro-element mean concentrations were distributed in the manner of Al > Mn > Rb > Ba > Zn > Cu > Sr > Cr > Ni > Sn. Human health risk for non-carcinogenic and carcinogenic metals was also assessed for the studied elements. Hazard quotients (HQs) and hazard index (HI) values (< 1) for non-carcinogenic elements indicated no risk. The incremental lifetime cancer risk (ILCR) values for carcinogenic elements indicated no risk for As, Cd, and Pb and medium level risk for Ni. Study concluded that north-east Indian tea would not pose any health hazard.

Persistence behaviour of milbemectin in/on tea under North-East Indian climatic condition.

A multi-location field trial was conducted under North-East Indian climatic condition viz. Siliguri and Dooars, West Bengal, India during Monsoon 2005 to evaluate the dissipation pattern of Milbemectin formulation (Milbeknock 1% EC) in/on tea field at two application rates (5 and 10 g a.i. ha(-1)). The quantitative analysis was performed using High Performance Liquid Chromatography (HPLC) with fluorescence detection at 460 nm. Following the first order kinetics the acaricide dissipates with half-life (T(1/2)) value ranges between 4.93-5.28 days and 6.84-10.76 days in made tea samples of Siliguri and Dooars field, respectively.

Validation and uncertainty analysis of a multiresidue method for 67 pesticides in made tea, tea infusion, and spent leaves using ethyl acetate extraction and gas chromatography/mass spectrometry.

A rapid, specific, and sensitive multiresidue method to determine 67 pesticides in made tea, tea infusion, and spent leaves was developed and validated for routine analysis by GC/MS with an approximately 29 min GC run time. The method was reproducible (HorRat < 0.5 at 50 ng/g) when validated at 50 and 100 ng/g. The samples were extracted with ethyl acetate-cyclohexane (9 + 1, v/v), and the extracts were cleaned up by dispersive SPE with primary-secondary amine sorbent + graphitized carbon black + Florisil. The recoveries of all the pesticides were within 70-120% with an RSD of < 20% at 50 ng/g and R2 > 0.99. The matrix effect on the signals of the compounds was corrected by using matrix-matched calibration standards. The LOQ met the requirements of the maximum residue limits for pesticides in tea as recommended by the European Union.

Validation and uncertainty analysis of a multiresidue method for 42 pesticides in made tea, tea infusion and spent leaves using ethyl acetate extraction and liquid chromatography-tandem mass spectrometry.

A rapid, specific and sensitive multiresidue method to determine 42 pesticides in made tea, tea infusion and spent leaves has been developed and validated for the routine analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method was reproducible (Horwitz ratio (HorRat) <0.5 at 50 ng/g) and validated by the analysis of sample spiked at 50 and 100 ng/g in made tea, tea infusion and spent leaves. The samples were extracted with ethyl acetate+cyclohexane (9:1; v/v), and the extracts were cleaned up by dispersive solid phase extraction with primary secondary amine sorbent+graphitized carbon black+Florisil. The recoveries of all the pesticides were between 70% and 120% with a relative standard deviation of less than 15% and correlation coefficient for each pesticide was R(2) > or =0.99. The matrix effect on signal of respective compounds was measured by comparing matrix-matched calibration standards with those in solvent-only. The limits of quantitation (LOQ) met the requirements of the maximum residue limits (MRLs) for pesticides in tea as recommended by the European Union.