Assessment of drain water receiving effluent from tanneries and its impact on soil and plants with particular emphasis on bioaccumulation of heavy metals.

In the present study, impact of tannery and other industrial effluents on the physico-chemical characteristics of loamy drain water and their consequent impact on soil and plants irrigated with effluent have been studied. The study reveals most of the parameter pH, BOD5 and COD at sampling station I was higher than station II. Waste water quality at both Stations I and II exceeded prescribed limits (BIS) for safe disposal of effluents into the surface water Samples of soil and vegetables from the land irrigated with loamy drain water has been collected and analyzed for Cu, Zn, Ni, Cr Pb and Cd. The different metals showed different enrichment factor for loamy drain water irrigated soil and are as follows: Cd 30% (max), Pb 26%, Zn 18%, Cr 5%, Cu 5%, Ni 2% (min). For plant samples collected at polluted sites are Ni 46% spinach (whole plant) (max), Zn 42% spinach (whole plant), Cr 39% spinach (whole plant), Cu 33% spinach (whole plant), Pb 20% potato tuber, Cd 20% potato tuber (min). The levels of Zn 145, Cu 5.25, and Ni 39.25 microg/ g in spinach, Pb 29.25, Cr 38. 25 and Cd 3.2 microg/g in potato tuber grown on polluted soil irrigated with contaminated drain water were found more than the reference value, which may create chronic health hazard problem to human and cattle through food chain in long run. Accumulation of toxic heavy metals may be build up in the agriculturally productive land where it is treated with contaminated effluent enrich with metals in turn bio-concentrated in the edible fodder/plants.

Accumulation of heavy metals (Cd, Cr, Cu, Ni and Zn) in Raphanus sativus L. and Spinacia oleracea L. plants irrigated with industrial effluent.

Effluent from electroplating industry contains various heavy metals like Cd, Cr, Cu, Ni and Zn, which are used in electroplating process of industry. Effluent was slightly greenish in colour and pungent in odour. Physico-chemical properties like total suspended solids (TSS), total solids (TS), alkalinity, Biological oxygen demand (BOD), and Chemical oxygen demand (COD) showed higher values in effluent with high metal contents like Cd, 0.013; Cr, 0.093; Ni, 0.935 and Zn 4.76 mg l(-1). plants of S. oleracea and R. sativus were raised in uncontaminated alluvial soil of Lucknow by soil pot culture method and irrigated with industrial effluent, showed visual toxic symptoms like stunted growth, necrosis followed by chlorosis in leaves and finally death of the plants. Severity of toxicity was less in plants treated with diluted effluent (50%). High accumulation of Cr, 302.0; Cu, 81.2; Ni, 155.1 and Zn 146.8 microg g(-1) dry weight in S. oleracea and Cr, 198.0; Cu, 41.0; Ni, 84.3 and Zn, 140.2 microg g(-1) dry weight in R. sativus were determined. Tissue concentration of metals and toxic effects was more in S. oleracea plants. The tissue concentration of metals showed much higher values in treated plants than that of their respective control.

Relationship of fluorescence and thermal emission from isolated thylakoids under light stress conditions.

Simultaneous measurements of fluorescence and thermal emission have been made by a combined fluorescence and photoacoustic techniques on isolated thylakoids pretreated by a prolonged illumination of saturating light. The traces of the signals are used to calculate four characteristic parameters, energy storage, half-saturation intensity, number of photons to close reaction center, and a constant for quasi-equlibria between (re)oxidized and reduced quinone acceptors. These parameters are used to study the response of photosynthetic apparatus functioning under photoinhibition stress. The defense mechanism seems to possess an efficient cooperativity of reaction centers under stress conditions.

Action of K-crown ether on photosystem II electron transport: characterization of the site of action.

We have investigated the inhibitory effect of K-crown (18-crown-6 potassium picrate) on photosystem II (PSII)-enriched membrane fragments and O2-evolving core complexes. K-crown at 2-4 microM inhibits about half the control level of O2-evolution activity in both types of PSII samples. Oxygen-evolution studies demonstrated that the ether works by inactivating the centres and not by interfering with antenna function or energy transfer to the reaction centre. K-crown does not disrupt binding of the extrinsic proteins associated with O2 evolution nor complex with bound Ca2+ or Cl- cofactors, but rather it directly inhibits electron transfer after the tetrameric Mn cluster. Fluorescence studies on active and Tris-treated samples showed that K-crown does not prevent artificial donors from transferring electrons to PSII but like DCMU inhibits on the acceptor side after QA, the primary quinone acceptor. However, the ether is a leaky inhibitor and may also act as a weak donor when the Mn cluster is not present. Oxygen-production experiments using silicomolybdate as an artificial acceptor (which accepts from both pheophytin and QB in PSII membranes) demonstrated that the inhibition is at or near the DCMU site.