High Cr Accumulation Research Articles

Comparative Study of Chromium Phytoremediation by Two Aquatic Macrophytes.

Chromium (Cr) occurs in several oxidation states from trivalent to hexavalent. However, hexavalent forms are more toxic and mainly produced by anthropogenic activities. A hydroponic experiment was conducted to analyse the comparative remediation of Cr by Marsilea minuta and Pistia stratiotes. Plants were exposed to four concentrations of Cr (0.5, 1.0, 1.5, and 2.0 mM) for 3 days. The highest accumulation of Cr was seen at the 1.5 mM concentration after 3 days in Marsilea (11.96mg/g) and Pistia (18.78mg/g). Dry weights decreased and malondialdehyde (MDA) levels increased in response to increasing Cr concentrations. Results indicate that both macrophytes are suitable candidates for Cr phytoremediation. Antioxidant-enzyme activity as a function of metal tolerance is imperative for a coherent understanding of plant physiology under metal stress.

MicroRNAomic profiling of maize root reveals multifaceted mechanisms to cope with Cr (VI) stress

Chromium (Cr) contamination of soil and water poses serious threats to agricultural crop production. MicroRNAs (miRNAs) are conserved, non-coding small RNAs that play pivotal roles in plant growth, development and stress responses through fine-tuning of post-transcriptional gene expression. To better understand the molecular circuit of Cr-responsive miRNAs, two sRNA libraries were prepared from control and Cr (VI) [100 ppm] exposed maize roots. Using deep sequencing, we identified 80 known (1 up and 79 down) and 18 downregulated novel miRNAs from Cr (VI) challenged roots. Gene ontology (GO) analysis reveals that predicted target genes of Cr (VI) responsive miRNAs are potentially involved in diverse cellular and biological processes including plant growth and development (miR159c, miR164d, miR319b-3p and zma_25.145), redox homeostasis (miR528–5p, miR396a-5p and zma_9.132), heavy metal uptake and detoxification (miR159f-5p, 164e-5p, miR408a, miR444f and zma_2.127), signal transduction (miR159f, miR160a-5p, miR393a-5p, miR408–5p and zma_43.158), cell signalling (miR156j, 159c-5p, miR166c-5p and miR398b). Higher accumulation of Cr in maize roots might be due to upregulation of ABC transporter G family member 29 targeted by miR444f. Instead of isolated increase in SOD expression, significant decline in GSH:GSSH ratio and histochemical staining strongly suggest Cr (VI) stress mediated disruption of ROS scavenging machinery thus unbalancing normal cellular homeostasis. Moreover, miR159c-mediated enhanced expression of GAMYB might be a reason for impaired root growth under Cr (VI) stress. In a nutshell, the present microRNAomic study sheds light on the miRNA–target gene regulatory network involved in adaptive responses of maize seedlings to Cr (VI) stress.

A combined survey and exposure study reveals the distribution characteristic of chromium in fish head.

In this study, the content of chromium (Cr) in three main edible tissues (dorsal muscle, ventral muscle, and head) of 14 different fish species was determined. As expected, Cr level in fish head is generally higher than that in fish muscle. To elucidate the deposition of Cr in the fish head, bighead carp (Hypophthalmichthys nobilis) was chosen as the model fish and a 14-day-exposure experiment of 1 mg/L Cr was subsequently conducted. The fish head was divided into 7 parts, and the results showed that, in different parts of the head, Cr was significantly accumulated in the brain, the muscle after gills, and the muscle of others, and the bone after the fish was exposed to 1-mg/L Cr for 14 days. Additionally, the health risk assessment showed that there was no potential non-carcinogenic risk of consuming the dorsal muscle, the ventral muscle, and the head of the 14 fish species to children, teenagers, and adults as the THQ values were less than 1. However, there was potential carcinogenic risk of consuming the fish head for adults in the 14 fish species. It is worth noting that, in the exposure experiment, the consuming of the lips and the bone of fish head also posed potential carcinogenic risk to adults while there was no potential risk of consuming the total fish head. Overall, compared to the fish muscle, the fish head usually had a high accumulation of Cr, and the Cr was mainly deposited in the position of the bone, which may pose potential carcinogenic risk to adults. Thus, the potential health risk of consuming the fish head is mainly associated with the content of the bone in the head, and, in the health risk assessment, the influence of the bone in the head should be considered, which may overstate the risks as fish head bone is usually not to be eaten.

Ecological Risk Assessment of Potential Toxic Elements in Salt Marshes on the East Coast of the Red Sea: Differential Physiological Responses and Adaptation Capacities of Dominant Halophytes

The impact of the mutual interactions between salinity and the phytoavailability of potential toxic elements (PTEs) on the adaptation of halophytes in their natural habitat is complex and far from clear. Herein, we aimed to evaluate salinity- and PTE-induced oxidative stress in selected halophytes and the antioxidant responses of these plants. For that, five salt marshes were selected, and the physiological responses of dominant halophytes (Tamarix nilotica, Heliotropium crispum, Zygophyllum coccineum, Halopeplus perfoliata, and Avicennia marina) were evaluated against the physicochemical features of their rhizosediments. The tested locations varied in their physicochemical properties and showed various levels of salinity stress and a low fertility status. Distinct variations in ten PTE concentrations were recognized among locations and within plants, with Cr and Co showing the highest ecological risk indices. The high levels of salinity and PTEs were associated with higher foliar levels of malondialdehyde, particularly in A. marina and Z. coccineum. The bio-concentration ratio revealed hyperaccumulating potentials of PTEs by the tested halophytes. Z. coccineum showed effective accumulation of Co, Fe, and Pb, while T. nilotica exhibited effective accumulation of Cu, Cd, and Zn. H. perfoliate had higher accumulation of Cr and Hg, whereas A. marina accumulated a significant amount of Hg, Cd, Zn, and Mn. H. crispum leaves accumulated the highest Ni levels among the tested halophytes. Altogether, our results highlight the potential risk of pollution of the tested areas with PTEs and the efficient physiological adaptation of each of the tested halophytes as a unique biological system. They also reflect the high capabilities of the tested halophytes as phytoextractors of their corresponding PTEs and their potential as efficient tools for phytoremediation of salt- and PTE-affected lands.

Effects of biochar and foliar application of selenium on the uptake and subcellular distribution of chromium in Ipomoea aquatica in chromium-polluted soils

The potential toxicity of Cr to plants poses a severe threat to human health. Biochar and Se can reduce the absorption of Cr and its phytotoxicity in plants, but the associated mechanisms at subcellular levels have not been addressed in depth. A study was designed to investigate the effects of biochar, foliar application of Se, and their combination on the physicochemical and biological properties of the soil, Cr availability, Cr absorption, and Cr subcellular distribution in each part of the plant, and biomass and quality of two water spinach (Ipomoea aquatica) genotypes. The results showed that biochar, Se, and their combination increased the organic matter content and available NPK nutrients in the soil and improved the urease, phosphatase, catalase, and sucrase activities in the soil. Furthermore, they also increased the number of bacteria, actinomycetes, and fungi in the soil, were conducive to dry matter accumulation in I. aquatica, and increased the contents of soluble sugar and soluble protein in its leaves. The Cr contents in the roots and shoots of I. aquatica under different treatments were reduced compared with those in the control group. The content of Cr(VI) in the root-soil of I. aquatica with low Cr accumulation and the contents of Cr in various parts of I. aquatica were lower than those in I. aquatica with high Cr accumulation, and the absorbed Cr was mainly accumulated in the roots. Cr was mainly distributed in the cell walls and soluble fractions of the roots, stems, and leaves of I. aquatica and was less distributed in the organelles. Biochar and Se helped to increase the proportion of Cr in the cell walls of the roots and soluble fractions of the leaves of I. aquatica. The effects of improving the soil properties, passivating and inhibiting Cr absorption by I. aquatica, and reducing the Cr proportion in the organelles of biochar were superior to those of Se application. The foliar application of Se and biochar had no synergistic effect on inhibiting Cr absorption by I. aquatica. Based on these findings, the application of biochar in Cr-contaminated soil or foliar application of Se with low Cr-accumulating plants may be effective means of reducing the Cr absorption by plants and its toxicity to ensure the safe production of agricultural products in Cr-contaminated regions.

Evaluation of chromium accumulation and resulting histopathological changes in Libyan jirds (Mammals, Rodentia), affected by effluent from Ghazghan leather industrial town, Iran.

The leather industry is one of the major producers of wastewater, releasing large amounts of various chemicals into the environment. Chromium (Cr) is the most commonly used agent in the tanning industry. Accumulation in the animal body can adversely affect the functioning of animal tissues. The current study investigated the toxic effects of Cr on lung, kidney, liver, and testicular tissues in Libyan jirds (Meriones libycus) inhabiting the area surrounding Ghazghan leather industrial town, Mashhad, Iran. Average Cr concentrations were found to be significantly higher in samples from contaminated areas than controls (p < 0.05). The highest accumulation of Cr was found in lung tissue, while the liver tissue showed the lowest. The results also showed that sex and age had no significant effect on Cr accumulation in any tissue at either sampling area (p < 0.05). Histological analyses showed that Cr accumulation had caused changes in tissue samples from Libyan jirds from the contaminated area. Hyperemia was observed in all tissues. In kidney tissue, necrosis and degeneration of the epithelial cells of the tubules were seen as well, and in one case, we also observed hemorrhage. In liver tissue, necrosis, degeneration, and inflammation were observed, along with one case, of fibrosis. In lung tissue, we observed emphysema, hemorrhage, and inflammation. Testicular tissue also showed a considerable lesion. Given the proximity of specimens' habitat to an area of importance, i.e., the industrial town, and the species' dependence on its habitat for nutrition, Libyan jirds are particularly useful for monitoring. Thus, they can be used to monitor the level of contamination in future studies.

Temporal and spatial variability of heavy metals in bottom sediments and the aquatic macrophyte Paspalum repens of the Orinoco River floodplain lagoons impacted by industrial activities.

This study investigated the water parameters and the levels of several heavy metals in leaves and roots of the aquatic macrophyte Paspalum repens and in bed sediments of one unpolluted lagoon and two polluted lagoons of the Orinoco River floodplain to know the impact of the alumina refining wastes on these ecosystems. The sampling was performed during four hydrological periods, covering one hydrological year. Chemical parameters in water (pH, conductivity, and total dissolved solids) and the levels of Al, Pb, Cr, and Cu in sediments were the highest in Macanillal (LMaca) lagoon, whereas sediments of Punta Cuchillo (LPC) lagoon also had elevated concentrations of Al and Fe in comparison with Las Aruhacas (LArh) lagoon (unpolluted lagoon). Chemical parameters in waters returned almost to natural values during high water stage because of the huge inundation of the Orinoco River during the high discharge periods. The solid/liquid discharges of industrial effluents over these systems also affected the grain size distribution of sediments in the lagoons. In all the studied lagoons, the distribution of elements in leaves of P. repens was in the order K ≥ Cr > Ca > Mg > Al > Fe > Mn > Cu > Pb, whereas Al was found to be the more abundant element in roots. The high abundance of Cr in P. repens was related with the high Cr accumulation potential shown by aquatic macrophytes. Despite this, the concentration of elements in P. repens did not show differences between the plants collected in the polluted lagoons versus the plants collected in the unpolluted lagoon. This suggests that P. repens is unsuitable for bio-monitoring studies of heavy metals in these aquatic environments impacted by alkaline residues.

Imbalance of redox homeostasis and antioxidant defense status in maize under chromium (VI) stress

The present study assesses the toxicity of hexavalent chromium [Cr(VI)] on maize (Zea mays L.) seedlings. Three different levels of Cr stress [50, 100 and 200 mg/l CrO3] were imposed and maize seedling growth performances were monitored at 2d and 4d. Modulation of antioxidant genes expression, metabolites, membrane damage, in vivo ROS detection, foliar H2O2 and proline accumulation were studied in detail to get an overview of Cr stress response of maize. Prime stress responses included marked reduction in plant height and biomass, loss of root cell viability with decreased APX-1, Cu/Zn SOD and DHAR expression and high accumulation of Cr in roots with little translocation to shoots. Higher uptake of Evans blue by Cr challenged roots indicates loss of root cells viability. In vivo detection of superoxides and H2O2 as dark blue and deep brown spots in stressed leaves supported with CM-H2DCFDA and DHE staining of roots strongly suggest severe oxidative burst under Cr stress. Marked decline in MDAR and DHAR expression in 200 mg/l Cr challenged leaves at 4d with non-significant change in AsA/DHA ratio indicate futile recycling of ascorbate pool which might lead to disturbance in redox homeostasis. Isolated increase in GR expression coupled with high GSH/GSSG do not seem to prevent cells from oxidative damages, as evident from high foliar MDA level in Cr challenged seedlings. Moreover, enhanced proline accumulation in maize leaves does not give much protection against Cr stress. Over all, this study facilitates our understanding of the plant’s adaptive mechanisms to Cr stress.

Evaluation of chromium phyto-toxicity, phyto-tolerance, and phyto-accumulation using biofuel plants for effective phytoremediation

Contamination of chromium signifies one of the major threats to soil system. Phytoremediation is a promising technique to reclaim metal-contaminated soil using plants which are capable to tolerate and accumulate heavy metals within in their tissues. The experiment reported in this article was carried out with six biofuel plant species, Cyamopsis tetragonoloba, Glycine max, Avena sativa, Abelmoschus esculentus, Sesamum indicum and Guizotia abyssinica, were subjected to eight Cr concentrations (0.5, 2.5, 5, 10, 25, 50, 75 and 100 mg kg−1 soil) to investigate Cr toxicity, tolerance and accumulation. After 12 weeks of experiment, Cr phytotoxicity on morphological and biochemical parameters were evaluated. For six plant species, seed germination and most of growth parameters were significantly (p < 0.05) reduced under high Cr stress. Chlorophyll contents were also decreased with increased Cr concentrations. Accumulation of Cr was higher in roots than shoot in all studied plants. Significant Cr accumulation was in the order of C. tetragonoloba > A. sativa > A. esculentus > S. indicum > G. max > G. abyssinica. Bioconcentration factor, bioaccumulation coefficient, translocation factor and phytoremdiation ratio suggested that C. tetragonoloba, A. sativa and A. esculentus being more tolerant; having higher Cr accumulation and could be a high efficient plants for reclamation of Cr-contaminated soils.

Combined effect of Cr-toxicity and temperature rise on physiological and biochemical responses of Atriplex halimus L.

An experiment was conducted to evaluate the combined effect of temperature (26 and 30 °C) and Cr toxicity (0, 100 and 1000 μM Cr) on growth, photosynthesis, water content, Cr and nutrients uptake and translocation. The role of antioxidative enzyme towards stresses tolerance was also investigated. Results showed that the maximum relative growth rate and leaf area per plant of Atriplex halimus L. were recorded at 100 μM Cr and 26 °C. However, presence of Cr reduced net photosynthetic and stomatal conductance rates. Overall, temperature rise enhanced the toxic effect of Cr by reducing growth and photosynthesis and inducing antioxidant enzymes activities. Furthermore, temperature rise increased nutrient uptake, as well as nutrient translocation to aboveground tissues; while it diminished Cr translocation. Finally, roots were the main sink for Cr accumulation in A. halimus. At 1000 μM Cr, root Cr concentrations reached 7.2 and 9.1 mg g−1 at 26 and 30 °C, respectively; while shoot Cr concentrations were 0.45 and 0.44 mg g−1 (26 and 30 °C, respectively). The high Cr-accumulation in roots suggests that A. halimus presents a great potential for phytoremediation, especially phytostabilisation of Cr contaminated soils.

Ascorbate-Glutathione Cycle and Ultrastructural Analyses of Two Kenaf Cultivars (Hibiscus cannabinus L.) under Chromium Stress.

Kenaf (Hibiscus cannabinus L.) with high tolerance to chromium (Cr) can be used in the phytoremediation of chromium-contaminated soil. However, the mechanisms of chromium accumulation and tolerance in kenaf are still unclear. A hydroponic experiment was taken to screen two kenaf cultivars with Cr tolerance among nine kenaf cultivars via a tolerance index. This is first time the ascorbate-glutathione (AsA-GSH) cycle and chloroplast structural changes involved in Cr tolerance of two kenaf cultivars are explored. This study indicated that enhancement of chromium concentrations reduced nine kenaf growth rates and plant biomass. In addition, in all the nine cultivars, the roots had higher Cr accumulation than the shoots. Cr-tolerant cultivar Zhe70-3 with the maximum tolerant index had the significantly higher enzymatic activities of ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and mono- dehydroascorbate reductase (MDHAR) in non-enzymatic antioxidant system compared to Cr-sensitive cultivar Zhe77-1. In addition, higher GSH and AsA contents and lower damages of chloroplast ultrastructure were observed in Zhe70-3 under Cr treatment. In conclusion, Cr stress can cause less oxidative stress and destruction of chloroplast ultrastructure in Cr-tolerant cultivar Zhe70-3, and the AsA-GSH cycle may play a crucial role in kenaf Cr tolerance.

Metal hyperaccumulating Brassicaceae from the ultramafic area of Yahyalı in Kayseri province, Turkey

AbstractMany of the plants found in serpentine areas are endemics and they may accumulate Ni at high concentration. High accumulation of Cr is rare, or in some views, never properly demonstrated. Generally, a very small proportion of any serpentine flora shows high accumulation of Ni, in some serpentine areas Ni accumulators are completely absent. There are approximately 570 hyperaccumulator plant species found on earth, 450 of them are Ni hyperaccumulators. A few of the Ni accumulators have potential for phytoremediation or phytomining. In the present study, 19 different Brassicaceae members growing in serpentine habitats in the district of Yahyalı, Kayseri province, Turkey viz., members of genera Aethionema, Alyssum, Arabis, Heldreichia, Hesperis, Iberis, Isatis, Microthlaspi, Odontarrhena, Pseudosempervivum and Thlaspi were investigated. Nickel concentrations in the soil and underground and aboveground parts of plants were determined by using ICP‐OES. It was observed that Ni concentrations of seven taxa (Odontarrhena muralis, O. oxycarpa, Isatis cappadocica subsp. cappadocica, Microthlaspi perfoliatum, Pseudosempervivum sempervivum, Thlaspi triangulare, Thlaspi rosulare) reach the threshold criterion of 1,000 mg kg−1 for Ni hyperaccumulation. In this study Ni concentrations in aboveground tissues of I. cappadocica subsp. cappadocica are determined as 5,587 mg kg−1 (in dry weight). Accordingly, it is suggested that this taxon be added to the list of Ni hyperaccumulator plants.

Assessment of Accumulation of some Heavy Metals in Mosses of Idukki District, Kerala (Western Ghats, India)

Bryophytes constitute an important proportion of the vegetation in the Western Ghats. Recent developmental activities cause an increase in the metal contaminants in the environment which ultimately accumulate in the plant system. Mosses have been used as indicator to monitor level of environmental pollution. In the present study, eighteen moss species and their soil substrata were analyzed to evaluate the accumulation capacity of heavy metals in mosses of different sites of Idukki District of Kerala. Statistically metal concentrations showed significant differences (p=5%) in interspecies, while the accumulation capacity of Campylopodium khasianum was higher than others. The substratum showed highest content of Cr followed by Ni and Pb in all the five selected sampling sites. All the mosses showed high accumulation of Cr (III) as compared to other metals (Cd, Cu, Pb, Ni) irrespective of their sampling sites. Among 18 mosses, Campylopodium khasianum was found to accumulate highest content of Cr, Cd, Ni and Pb, indicating that this moss can be used to reclaim soil contaminated with these metals.

Effect of treated sewage effluents on heavy metals contents of three dominant wild plants at Wadi Al Rummah, Qassim Region, Saudi Arabia

A total of 132 plant samples from the aerial and underground parts of Halox-ylon salicornicum, Pulicaria undulata and Suaeda vermiculata, collected from Wadi Al Rummah, before and after Al Rass sewage Plant, were examined to assess their heavy metal contents. The results revealed highest Fe content and lowest Cd concentration in the three plant species examined. The aver-age metal concentration pattern in the aerial parts were: Fe&gt; Mn&gt; Zn&gt; Cr&gt; Cu&gt; Ni&gt; Pb&gt; Cd. The concentrations of these eight elements in the aerial and underground parts were species dependant, but Mn was found to be pre-dominantly highly accumulated in the aerial parts, whereas Cu had the ten-dency to accumulate in the underground parts. The three plant species stud-ied, showed a decrease in Mn concentration and increased values in Zn, Cu, Fe, and Cr both in the aerial and underground parts after the Sewage Plant compared to their concentrations before the Sewage Plant (control.). The high accumulation of Cr in the plants examined (compared to typical concen-trations, suggested that the wild plants of the area should be used with cau-tion to feed livestock. The results also showed that P. undulata had the high-est accumulation of Zn, Cu, Ni, Fe, Mn and Cr, whereas the underground parts of H. salicornicum showed highest values for Pb and Cd.

Effects of the presence of nutrients in the removal of high concentrations of Cr(III) by Typha domingensis

The aim of this work was to study the influence of nutrients on the tolerance, removal efficiency and accumulation of high concentration of Cr(III) by Typha domingensis. This species was exposed to the following Cr(III) treatments, arranged in triplicate: 200 mg L−1 Cr; 600 mg L−1 Cr; 200 mg L−1 Cr + 50 mg L−1 P + 50 mg L−1 N; 600 mg L−1 Cr + 50 mg L−1 P + 50 mg L−1 N; without metal or nutrient additions (control 1); 50 mg L−1 P + 50 mg L−1 N, without metal addition (control 2). In order to simulate extreme events, the concentrations studied were higher than the concentrations commonly found in constructed wetlands. Cr and nutrient concentrations in water decreased in all treatments along time. Nutrient addition did not affect Cr removal for the two concentrations studied. In tissues, the highest Cr concentrations were observed in roots in all treatments. The mass balance showed that sediment showed the highest accumulation of Cr. Metals caused growth inhibition and a decrease in chlorophyll concentration. Despite these sublethal effects, T. domingensis demonstrated that it could accumulate Cr. These results confirm the high tolerance of this species ensuring the survival plant and wetland efficiency in time.

Ultrastructural features, chromium content and in situ immunodetection of 5-methyl-cytosine following Cr (VI) treatment in two strains of Scenedesmus acutus M. (Chlorophyceae) with different chromium sensitivity

Two strains of the unicellular green alga Scenedesmus acutus (F.J.F. Meyen) with different sensitivity to chromium (VI) were compared to evaluate their ultrastructural morphology in chromium-free and -supplemented medium with a sub-lethal concentration of Cr(VI) for 72 hours. The ultrastructural alteration in different cytological compartments indicated that Cr(VI) induced earlier and stronger alterations in the wild type (wt) compared with the chromium-tolerant strain (Cr-t). After Cr treatments, ICP-MS (Inductively Coupled Plasma Mass Spectrometry) showed a higher Cr accumulation in the wild type than in the Cr-tolerant strain, suggesting a more efficient chromium-exclusion mechanism in the latter. The Cr treatment induced an increase in the nuclear area and a rearrangement in the eu-heterochromatic fraction, suggesting that chromatin remodelling could be at the basis of differential gene expression and metal tolerance. To gain additional information on the remodelling of the nuclear chromatin, we analysed DNA methylation by immunolocalization of 5-methyl-cytosine, before and after Cr exposure. Significant differences in the quantification of the immunolabelling of DNA cytosine-rich zones between the two strains were observed. These data suggest that an epigenetic mechanism could be at the basis of the Cr tolerance in S. acutus, as supported by previous data reporting that the acquired tolerance was inherited and maintained through the progeny.

Chromium (VI)-induced phytotoxicity in river catchment agriculture: evidence from physiological, biochemical and anatomical alterations in Cucumis sativus (L.) used as model species

ABSTRACT The present study investigates the impact of different Cr(VI) (50–200 µM) treatments on Cucumis sativus L. seedlings which is worldwide grown in river catchments. Chromium (VI) treatments showed significant (P < .05) reduction in growth, photosynthetic pigments, total protein content and PSII performance, which was in concurrence with a significant (P < .05) increase in the accumulation of Cr(VI) (up to 587 ± 18.19 µg Cr g−1 in roots), lipid peroxidation (MDA: up to 483%), H2O2 (up to 453%) and (up to 551%) compared to the control seedlings. Chlorophyll fluorescence parameters, such as F m, F v, F v/F m, F m/F 0 and F v/F 0, were declined while F 0 showed enhancements (P < .05). Energy flux parameters, such as Phi_E0, Psi_0, PIABS, declined; however, ABC/RC, ET0/RC, DI0/RC and TR0/RC increased significantly (P < .05) under Cr(VI) treatments as compared to control. In addition, the levels of qP were reduced while NPQ was appreciably enhanced under different Cr(VI) treatments. The histochemical observations of H2O2 and were in accordance with their total estimation. Furthermore, Cr(VI) also severely injured the anatomical structure of roots. This study suggests that a higher accumulation of Cr(VI) in cucumber seedlings warrants serious attention in the studied catchments of the Ganges river to avoid any food contamination and biomagnifications to higher trophic levels.

Effects of Chelate-Assisted Chromium (Cr+6) on Growth, and Chromium Bioaccumulation in Paragrass (Brachiaria mutica Forssk.Stapf)

The growth pattern, toxicology and chromium bioavailability in 45 days grown Paragrass (Brachiaria mutica Forssk.Stapf) in response to applications of ionic Chromium (Cr+6) and chelate-assisted Cr+6 were undertaken. Root and shoot length of Paragrass significantly decreased with increasing concentration of Cr+6. Paragrass plants grown both in Cr+6 (300 ppm) and chelate(EDTA/CA)-assisted Cr+6 (300 ppm) showed noticeable decrease in root and shoot length, fresh and dry matters whereas ionic Cr+6 or chelate assisted Cr+6- EDTA/ Cr+6-CA stimulated growth at low concentration (10 ppm). Root phytotoxicity was highest (56%) in Cr+6-EDTA (300 ppm) treatment whereas shoot phytotoxicity was 36% in Cr+6 (300 ppm) treatment. High Cr accumulation was found in root (46.65 mg kg- 1) when supplemented with Cr+6-EDTA (300 ppm) as compared to other treatments. Transportation index (Ti) values are high depicting the plants with high translocation for the seedlings grown in ionic and chelate assisted Cr using 10 and 100 ppm concentrations of Cr+6.Bioconcentration Factor (BCF) of Cr increases in chelate assisted chromium treatment than chromium treatment only. Total Accumulation Rate (TAR) in different treated plants (both ionic and chelate assisted) showed increasing trend with increase in chromium treatments which indicates that the plant is tolerant in nature could survive under diverse chemospheric conditions.

Human health risk assessment of heavy metals in tropical fish and shellfish collected from the river Buriganga, Bangladesh.

Although fish, crustacean, and shellfish are significant sources of protein, they are currently affected by rapid industrialization, resulting in increased concentrations of heavy metals. Accumulation of heavy metals (V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Sb, Ba, and Pb) and associated human health risk were investigated in three fish species, namely Ailia coila, Gagata youssoufi, and Mastacembelus pancalus; one crustacean (prawn), Macrobrachium rosenbergii; and one Gastropoda, Indoplanorbis exustus, collected from the Buriganga River, Bangladesh. Samples were collected from the professional fishermen. Cu was the most accumulated metal in M. rosenbergii. Ni, As, Ag, and Sb were in relatively lower concentrations, whereas relatively higher accumulation of Cr, Mn, Zn, and Se were recorded. Mn, Zn, and Pb were present in higher concentrations than the guidelines of various authorities. There were significant differences in metal accumulation among different fish, prawn, or shellfish species. Target hazard quotient (THQ) and target cancer risk (TR) were calculated to estimate the non-carcinogenic and carcinogenic health risks, respectively. The THQ for individual heavy metals were below 1 suggesting no potential health risk. But combined impact, estimated by hazard index (HI), suggested health risk for M. pancalus consumption. Although consumption of fish at current accumulation level is safe but continuous and excess consumption for a life time of more than 70 years has probability of target cancer risk.

ANALYSIS OF TOXIC EFFECT OF INDUSTRIAL EFFLUENT ON LABEO ROHITA IN THE RIVER RAM GANGA AT MORADABAD

The industrial waste effluents generally contain heavy metals like Pb, Cr and Cu etc., dumped into rivers. In present study, the toxicity of industrial effluent was investigated using fish “Labeo Rohita” and found that fish was unable to survive even in 15% concentration of the effluent. An interesting feature of the study was that when the pH of the effluent decreased the toxicity of the effluent increased several times. It also found by the study that among three metals Pb, Cr and Cu, Chromium is more toxic than other two metals. The results also shows that the Cr toxicity in enhanced at lower pH- 5.5. This result is in agreement with the already established toxicity which reported that high Cr accumulation occurred at lower pH- 6.5 that of high pH- 7.8. It also established by the present investigation that as the pH decreases, the toxicity of the metal increases.