Linear-no-threshold concept for evaluating arsenic toxicity in rice grains.

Arsenic (As) is a potent carcinogen that enters the human food chain mainly through rice, which is one of the staple food crops worldwide. During February 2022, a market survey was conducted and 500 samples of rice grains were collected across 41 different locations in Mumbai/Navi-Mumbai. On the basis of grain As-accumulation, samples were grouped into three categories including low- (0-30 ng g DW), medium- (31-70 ng g DW) or high- (>71 ng g DW).

Metal removal by metallothionein and an acid phosphatase PhoN, surface-displayed on the cells of the extremophile, Deinococcus radiodurans.

The utility of surface layer proteins (Hpi and SlpA) of the radiation resistant bacterium, Deinococcus radiodurans, was investigated for surface display and bioremediation of cadmium and uranium. The smtA gene, from Synechococcus elongatus (encoding the metal binding metallothionein protein), was cloned and over-expressed in D. radiodurans, either as such or as a chimeric gene fused with hpi ORF (Hpi-SmtA), or fused to the nucleotide sequence encoding the SLH domain of the SlpA protein (SLH-SmtA).

Nitrogen supply influences arsenic accumulation and stress responses of rice (Oryza sativa L.) seedlings.

In the present study, the effects of nitrogen supply (low nitrogen: LN and high nitrogen: HN) on As stress (25 μM) responses of rice seedlings were monitored for 7 d. The mean length of primary, adventitious and lateral roots and number of adventitious and lateral roots were significantly improved in LN+As, while further reduced in HN+As, as compared to As alone treatment at 7 d. The LN+As treatment resulted in significant decline in As (848 μg g DW) than that in As alone treatment (1434 μg g DW) in roots but no significant effect was seen in shoot.

Investigation of arsenic accumulation and biochemical response of in vitro developed Vetiveria zizanoides plants.

Vetiver grass (Vetiveria zizanoides L. Nash) is found to be a suitable candidate for the phytoremediation of heavy metals. An investigation of arsenic (As) accumulation, translocation and tolerance was conducted in V.

Cloud point extraction and electrothermal atomic absorption spectrometry of Se (IV)--3,3'-diaminobenzidine for the estimation of trace amounts of Se (IV) and Se (VI) in environmental water samples and total selenium in animal blood and fish tissue samples.

This paper presents a method based on the cloud point extraction for the separation and preconcentration of Se (IV) and Se (VI) in environmental water samples as well as total selenium in animal blood and tissue samples. 3,3'-Diaminobenzidine (DAB) is a selective and sensitive reagent and is known to form an intense yellow compound piazselenol with selenium (IV). When a system consisting of sample, DAB and surfactant Triton X-114 is warmed above the cloud point of the surfactant, it was seen that the DAB-Se (IV) complex gets extracted into the surfactant rich phase while the Se (VI) remains in the aqueous phase.

Characterization of As (V), As (III) by selective reduction/adsorption on palladium nanoparticles in environmental water samples.

Hydrazine (HZ) and sodium borohydride (BH) are commonly used reagents for the production of palladium nanoparticles (PdNP) in aqueous solution and also for the reduction of arsenic from higher oxidation state to lower oxidation state. A methodology based on the quantitative adsorption of reduced arsenic species on PdNP generated in situ by BH and HZ is described to characterize As (V) and As (III) in environmental water samples. It was observed that PdNP obtained by BH gave quantitative recovery of As (V) and (III) and the PdNP obtained by HZ could account for As (III).

Direct determination of uranium in seawater by laser fluorimetry.

A method for estimation of uranium in seawater by using steady state laser flourimetry is described. Uranium present in seawater, in concentration of approximately 3 ng ml(-1) was estimated without prior separation of matrix. Quenching effect of major ions (Cl(-), Na(+), SO(4)(-), Mg(+), Ca(+), K(+), HCO(3)(-), Br(-)) present in seawater on fluorescence intensity of uranium was studied.

Characterization of arsenic (V) and arsenic (III) in water samples using ammonium molybdate and estimation by graphite furnace atomic absorption spectroscopy.

Arsenic (V) is known to form heteropolyacid with ammonium molybdate in acidic aqueous solutions, which can be quantitatively extracted into certain organic solvents. In the present work, 12-molybdoarsenic acid extracted in butan-1-ol is used for quantification of As (V). Total arsenic is estimated by converting arsenic (III) to arsenic (V) by digesting samples with concentrated nitric acid before extraction.