Toxic Effects Of Cr Research Articles

THE EFFCT OF CrO3 – (VI) – ON THE ACTIVITY OF SOME ENZYMES IN THE BLOOD SERUM OF HYBRO CHICKEN

In this study the effect of 30 days ingestion of two different concentrations (D1=25 ug/kg b.w. and 50 ug/kg b.w) of the CrO3 - (VI) – on the activity of : gamma glutamate transferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), cholinesterase (CHe), aspartate-aminotransferase (AST) and alanine -aminotransferase (ALT) enzymes in the blood serum of Hybro chickens (N= 223; 5 weeks old) was investigated. Preliminary results showed that in the serum of chickens treated for 30 days with D1 and D2 of CrO3 the activities of GGT, LDH and ALT enzymes decrease compared to the untreated group. In the serum of chicken treated with D2 of Cr(VI) activity of AST and ALP is higher compared to the control group. Toxic effects of Cr(VI) depend on the concentration of CrO3 - (VI) – and type of enzymes.

Investigation of Cr(VI) reduction in continuous-flow activated sludge systems

The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5 mg l −1. For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time ( θ equal to 20 and 28 h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0 mg l −1). Cr(VI) reduction was favored by an increase of θ, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic–anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%.

Multiple effects of chromate on the photosynthetic apparatus of Spirodela polyrhiza as probed by OJIP chlorophyll a fluorescence measurements

Chromate (Cr) decreases the growth of Spirodela polyrhiza. The fronds lost their pigments. The O 2 evolution was also decreased. The Cr effect was found to be dose dependent. The toxic effects of Cr have further been studied on the photosynthetic activity of Spirodela polyrhiza by means of the chlorophyll a (Chl a) fluorescence transient O-J-I-P. The Chl a fluorescence transients were recorded in vivo with high time resolution and analyzed according to the JIP-test which can quantify the photosystem II behavior. Cr treated plants show a decrease in yield for primary photochemistry, ϕ Po. The performance index of PSII, PI ABS, which is the combination of the indexes of three independent parameters, (1) the total number of active reaction centers per absorption (RC/ABS), (2) yield of primary photochemistry ( ϕ Po) and (3) efficiency with which a trapped exciton can move an electron into the electron transport chain (ψ 0), decreased due to Cr treatment. Chromate sensitivity varies within plant populations. In summary Cr affects several targets of PSII. More specifically, the main targets of Cr, according to the JIP-test, can be listed as a decrease in the number of active reaction centers and damage to the oxygen-evolving complex.

Studies of Uptake and Toxic Effects of Cr(VI) on Pistia stratiotes

The uptake of Cr(VI) and toxic effects of the metal on some biochemical parameters in Pistiastratiotes L. were studied. The uptake of Cr(VI) by the plants gradually increased with increase in concentration of Cr(VI) in the culture medium. Maximum accumulation of Cr(VI) was noted within 5 days. Maximum removal (about 90%) of Cr(VI) was recorded below 5 ppm. Accumulation of Cr(VI) occurred mainly in roots. At 5 and 10 ppm, Cr(VI) promoted senescence of Pistia plants by decreasing chlorophylls, protein, RNA, Hill activity and activities of catalase, protease as well as increasing dry weight, free amino acid content, peroxidase activity and ratio of acid to alkaline pyrophosphatase activity over control values. At Cr(VI) concentrations below 5 ppm, these constituents were least affected. So, Pistia plants can be utilised as the scavenger of Cr(VI) from waste water.