Heavy metal levels and physico--chemical quality of potable water supply in Warri, Nigeria

The interaction between man's activities and the environment is gaining world wide attention. Warri an oil producing community in Delta State of Nigeria is faced with environmental oil pollution. Since open and underground water bodies are regarded as final recipients of most environmental pollutants, this study sought to provide data on the levels of the physico-chemical parameters and contaminants in Warri metropolitan water supply. This study investigated the cadmium, lead and chromium using Atomic Absorption Spectrophotometer, physico-chemical properties such as pH, temperature, total suspended solid TSS, total dissolved solid TDS, electrical conductivity EC, biological oxygen demand BOD, dissolved oxygen DO, chemical oxygen demand COD, and total coliform count of potable water sources in Warri. Ekpan River was found to have 1.2 mg/L of cadmium, 1.0 mg/L of chromium, 1.20 mg/L of lead and 2.0 mg/L of manganese. The heavy metals levels and the pollution parameters were lowest in the borehole water samples, except pH which is more acidic in borehole water samples and conductivity which is more in well water samples in all the sampling stations. Some of the parameters were above WHO standards.     

Autotoxicity and allelopathy of 3,4-dihydroxyacetophenone isolated from Picea schrenkiana needles

Bioassay-guided fractionation of the diethyl ether fraction of a water extract of Picea schrenkiana needles led to the isolation of the phenolic compound 3,4-dihydroxy- acetophenone (DHAP). The allelopathic effects of DHAP were evaluated under laboratory conditions on P. schrenkiana, rice (Oryza sativa L.), wheat (Triticum aestivum L.), radish (Raphanus sativus L.), lettuce (Latuca sativa L.), cucumber (Cucumis sativus L.) and mung bean (Phaseolus radiatus L.). DHAP significantly inhibited seed germination and seedling growth of P. schrenkiana at concentrations of 2.5 mM and 0.5 mM (p < 0.05). Soil analysis revealed that P. schrenkiana forest soils contained exceptionally high DHAP concentrations (mean = 0.51 ± 0.03 mg/g dry soil), suf?cient to inhibit natural P. schrenkiana recruitment. DHAP also exhibited strong allelopathic potential. It significantly inhibited wheat and lettuce seed germination at concentrations of 1 mM and 0.5 mM (p < 0.05). The active compound also completely inhibited root growth of the six test species at high concentrations. Our results suggest a dual role of DHAP, both as an allelochemical and as an autotoxicant. The potential for a single plant needle-leached compound to in?uence both inter- and intra-speci?c interactions emphasized the complex effects that plant secondary metabolites might have on plant population and community structure.     

Differences in the response of wheat, soybean and lettuce to reduced blue radiation

Although many fundamental blue light responses have been identified, blue light dose-response curves are not well characterized. We studied the growth and development of soybean, wheat and lettuce plants under high-pressure sodium (HPS) and metal halide (MH) lamps with yellow filters creating five fractions of blue light. The blue light fractions obtained were < 0.1, 2 and 6% under HPS lamps, and 6, 12 and 26% under MH lamps. Studies utilizing both lamp types were done at two photosynthetic photon flux levels, 200 and 500 mumol m-2 s-1 under a 16 h photoperiod. Phytochrome photoequilibria was nearly identical among treatments. The blue light effect on dry mass, stem length, leaf area, specific leaf area and tillering/branching was species dependent. For these parameters, wheat did not respond to blue light, but lettuce was highly sensitive to blue light fraction between 0 and 6% blue. Soybean stem length decreased and leaf area increased up to 6% blue, but total dry mass was unchanged. The blue light fraction determined the stem elongation response in soybean, whereas the absolute amount of blue light determined the stem elongation response in lettuce. The data indicate that lettuce growth and development requires blue light, but soybean and wheat may not.     

Metabolomics and Physiological Insights into the Ability of Exogenously Applied Chlorogenic Acid and Hesperidin to Modulate Salt Stress in Lettuce Distinctively

Recent studies in the agronomic field indicate that the exogenous application of polyphenols can provide tolerance against various stresses in plants. However, the molecular processes underlying stress mitigation remain unclear, and little is known about the impact of exogenously applied phenolics, especially in combination with salinity. In this work, the impacts of exogenously applied chlorogenic acid (CA), hesperidin (HES), and their combination (HES + CA) have been investigated in lettuce (Lactuca sativa L.) through untargeted metabolomics to evaluate mitigation effects against salinity. Growth parameters, physiological measurements, leaf relative water content, and osmotic potential as well as gas exchange parameters were also measured. As expected, salinity produced a significant decline in the physiological and biochemical parameters of lettuce. However, the treatments with exogenous phenolics, particularly HES and HES + CA, allowed lettuce to cope with salt stress condition. Interestingly, the treatments triggered a broad metabolic reprogramming that involved secondary metabolism and small molecules such as electron carriers, enzyme cofactors, and vitamins. Under salinity conditions, CA and HES + CA distinctively elicited secondary metabolism, nitrogen-containing compounds, osmoprotectants, and polyamines.     

Differential effects of hexaconazole and paclobutrazol on biomass, electrolyte leakage, lipid peroxidation and antioxidant potential of Daucus carota L

The application of triazole fungicides is a common practice in the cultivation of carrot (Daucus carota L.) plants. It is there for seems important to test the changes that are occurring in this food crop under triazoles, the non-traditional plant growth regulators, treatments in order to identify the extent to which it tolerate the fungicide application and thereby make it an economical food crop. A field experiment was conducted to find out the effects of two triazole fungicides (hexaconazole (HEX) and paclobutrazol (PBZ) at 20 mg l⁻¹ plant⁻¹) on the biomass, yield, electrolyte leakage, lipid peroxidation and antioxidant potential of carrot. The treatments were given to plants on 15, 30 and 45 days after sowing (DAS). The plants were uprooted for analyses of growth and biochemical parameters on 60 DAS. It was found that both HEX and PBZ have significant effects on the growth and biochemical parameters of this plant. Among the triazoles used, PBZ performed best in terms of anthocyanin, protein, amino acid, proline, starch and sugar, contents whereas HEX enhanced carotenoids, fresh weight, dry weight and biomass. There was no significant variation in chlorophyll (‘a’ and ‘b’) contents between the two triazole treated plants, but HEX and PBZ proved best when compared to untreated control plants. HEX and PBZ increased - and β-amylases enzymes activities to a significant level. Out of these two triazoles, PBZ performed best in increasing the starch hydrolyzing enzymes activities. The non-enzymatic antioxidant, reduced glutathione (GSH) and antioxidant enzyme ascorbate peroxidase (APX) were increased under fungicide applications. The data suggests that, the application of triazole fungicides may be a useful tool to increase the tuber quality as well as quantity in carrot plants, apart from their fungicidal properties.     

Synthesis of novel mesoporous carbon nanoparticles and their phytotoxicity to rice (Oryza sativa L.)

Despite the remarkable number of investigations on the potential risks of the engineered nanomaterials (ENMs) to terrestrial plants, there was limited knowledge regarding the effects of mesoporous carbon nanoparticles (MCNs) with different sizes on crops. The objective of our study was to evaluate the toxicity of MCNs to rice (Oryza sativa L.) seedlings. Two novel MCNs with different particle sizes (MCN1: 150 and MCN2: 80?nm) were synthesized using the high-temperature pyrolysis method and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and Raman spectra. Phytotoxicity of two MCNs was then comparatively evaluated using rice as a model plant. The rice seedlings were hydroponically exposed to both MCN suspensions with concentrations of 0, 10, 50, 150?mg/L for 20?days. Exposure to 150?mg/L MCN1 resulted in more than 21% and 29% decrease in root length and in shoot length, respectively. MCN2 significantly reduced the root and shoot lengths by approximately 70% and 57% at the concentration of 150?mg/L. Additionally, the concentrations of three endogenous phytohormones, including brassinolide (BR), indole propionic acid (IPA), and dihydrozeatinriboside (DHZR) in plant shoots were increased significantly compared with the control. Our findings illustrated that size-effects of MCNs contributed greatly in causing phytotoxicity to plants, which should have drawn our attention to the use of these novel ENMs in agriculture given the evidence of their potential risks to crops. More importantly, this is the first study on assessment of the phytotoxicity of MCNs to rice seedlings from the perspective of plant hormones.     

气相色谱法测定水生植物中的阿特拉津残留

确立了一套检测水生植物中阿特拉津残留量的方法.样品经石油醚-二氯甲烷混合液振荡萃取,经硅镁吸附剂层析柱净化后,采用气相色谱-电子捕获检测器检测水生植物中阿特拉津的残留量.该方法在0.062～1.0mg/L范围内峰面积与阿特拉津浓度的线性关系良好(r~2=0.9993).在0.5mg/L、1.0mg/L、1.5mg/L ...     

RESPONSE DIFFERENCES BETWEEN TWO SOYBEAN CULTIVARS WITH CONTRASTING UV-B RADIATION SENSITIVITIES

Abstract— Soybeans (Glycine max [L.] Men. cvs. Essex and Williams) were grown in an unshaded greenhouse under two levels of biologically effective ultraviolet-B (UV-B_BE) radiation (effective daily dose: 0 and 11.5 kJ m^-2) for 34 days. Ultraviolet-B radiation reduced leaf area and total plant mass in Essex but these parameters were unaffected in Williams. Differences in both anatomical and biochemical characteristics were found between cultivars. Some of these differences were inherently distinct between cultivars while others were variably induced by UV treatment. Specific leaf weight. an estimate of leaf thickness, was unchanged in Essex but increased in Williams with UV-B irradiation. The relative increase in concentration of UV-absorbing compounds in leaf tissues after UV-B irradiation was greater in Williams. The composition of UV-absorbing compounds in leaf tissues differed between the two cultivars but was unaffected by UV-B radiation. Although total soluble proteins and total peroxidase activity were similar between cultivars, several electrophoretically distinct peroxidase activities were detected. Therefore, the intraspecific variation in UV-B sensitivity found in soybean appears to be correlated with a suite of anatomical and biochemical differences, including leaf thickness, composition and concentration of UV-absorbing compounds in leaf tissues, and possibly differences in peroxidase activities.     

Soil applied cobalt alters the nodulation, leg-haemoglobin content and antioxidant status of Glycine max (L.) Merr

The present investigation has been carried out to estimate the effect of cobalt on the nodulation leg-haemoglobin content and antioxidant enzyme activities of soybean plants. The experiments were conducted in earthen pots containing 3 kg of air dried soil. The inner surface of pots was lined with polythene sheet. Soybean plants were raised in soil amended with different concentration of cobalt (0, 50, 100, 150, 200 and 250 mg/kg). The root nodule formation, leg-haemoglobin contents and antioxidant enzyme activities were analysed at 15 days intervals, namely 15, 30, 45, 60 and 75 days after sowing (DAS). There found a significant increase in the total number of root nodules, leg-haemoglobin content and antioxidant enzyme activities at 50 mg/kg cobalt application in the soil in all the sampling days when compared to control. Further increase in the cobalt level (100–250 mg/kg) in the soil decreased root nodules formation as well as leg-haemoglobin content antioxidant enzyme activities of soybean plants in all the sampling days.     

Exogenous Sodium Nitroprusside Mitigates Salt Stress in Lentil (Lens culinaris Medik.) by Affecting the Growth,Yield, and Biochemical Properties

Soil salinity disrupts the physiological and biochemical processes of crop plants and ultimately leads to compromising future food security. Sodium nitroprusside (SNP), a contributor to nitric oxide (NO), holds the potential to alleviate abiotic stress effects and boost tolerance in plants, whereas less information is available on its role in salt-stressed lentils. We examined the effect of exogenously applied SNP on salt-stressed lentil plants by monitoring plant growth and yield-related attributes, biochemistry of enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)) amassing of leaf malondialdehyde (MDA) and hydrogen peroxide (H₂O₂). Salinity stress was induced by NaCl application at concentrations of 50 mM (moderate salinity) and 100 mM (severe salinity), while it was alleviated by SNP application at concentrations of 50 µM and 100 µM. Salinity stress severely inhibited the length of roots and shoots, the relative water content, and the chlorophyll content of the leaves, the number of branches, pods, seeds, seed yield, and biomass per plant. In addition, MDA, H₂O₂ as well as SOD, CAT, and POD activities were increased with increasing salinity levels. Plants supplemented with SNP (100 µM) showed a significant improvement in the growth- and yield-contributing parameters, especially in plants grown under moderate salinity (50 mM NaCl). Essentially, the application of 100 µM SNP remained effective to rescue lentil plants under moderate salinity by regulating plant growth and biochemical pathways. Thus, the exogenous application of SNP could be developed as a useful strategy for improving the performance of lentil plants in salinity-prone environments.     

Trace Metals in Microcrustaceans and Brazilian Waterweed from a Contaminated Chilean Wetland Using Total Reflection X-Ray Fluorescence Spectrometry

The trace element content of individual copepod specimens and of the Brazilian water weed (Egeria densa) from a metal-contaminated wetland in Southern Chile were determined using total reflection X-ray fluorescence spectrometry. Sampling of the water and the organisms was carried out at three sampling sites during 2004. Enhanced concentrations of dissolved Fe and Mn were found in the column water and in the pore water. The Fe content in the benthic copepods was significantly elevated compared to other aquatic organisms from different Chilean lakes. Regarding E. densa, healthy (green coloured) plants showed mass fractions of Fe, Mn, Ni, Cu and Zn which were typical for uncontaminated systems. In contrast, damaged (brownish coloured) plants exhibited very high Fe and Mn concentrations indicative of contamination or processes which changed the element load from the environment to the plant.     

Distribution characteristics and source tracing of petroleum hydrocarbons in the northeastern South China Sea

In recent years, oil spills caused by human activities have occurred frequently, and the resultant oil pollution has received extensive attention worldwide. In this paper, a total of 50 water samples were collected from the northeastern part of the South China Sea, and total petroleum hydrocarbons (TPHs) and n-alkane content in the samples were analyzed by gas chromatography-flame ionization detector (GC-FID) technology. The petroleum hydrocarbon characteristic indices, such as carbon predominance index (CPI) and terrigenous/aquatic ratio (TAR), were calculated to trace the source of petroleum hydrocarbons. The measured value of TPHs ranged from 121.31–603.02 μg/L. For surface waters, the TPHs in the northern coastal waters and the central waters were higher than that in the far shore. For vertical waters, the TPHs sharply decreased at first, and then increased slowly and finally reached a steady state. The n-alkanes in the water samples were concentrated in C10-C38, and they were mainly from terrestrial higher plant. The waters in the near shore, mid-layer and deep sea showed a strong reducing terrestrial characteristic, while the surface waters in the open sea showed an obvious oxidizing endogenous characteristic.     

Toxicity testing of chemicals without use of animals

A series of publications on the studies of phytotoxicity of chemicals (pollutants, ecotoxicants), carried out by the author and his research group, have been reviewed. Tests (bioassays) based on experiments with many higher plant species, both terrestrial and aquatic ones (macrophytes), were used in these studies. Among the chemicals tested there were various organic (synthetic detergents, surfactants, and pesticides) and some inorganic (e.g., metal oxide nanoparticles) compounds. New methods for bioassay using plant species never used before have been developed by the author. New facts of phytotoxicity of a synthetic detergent have been discovered and reported. Specifically, an aqueous solution of liquid detergent Frosch (Werner & Mertz, FRG) at a concentration of 0.25 mL/L (and higher concentrations) inhibited the elongation rate of seedlings of Lens culinaris higher plant species. Also, phytotoxicity of synthetic cationic surfactant dodecyltrimethylammonium bromide has been reported for the first time. This surfactant at a concentration of 4 mg/L inhibited the elongation of Lens culinaris plant seedlings. The phytotesting methods contribute to the development of alternative approaches to studying the toxicity of chemicals through non-animal testing.     

Investigations on the substitution of dichloromethane in pesticide residue analysis of plant materials

According to the multiresidue analysis method DFG S 19, different approaches for the substitution of dichloromethane in the liquid/liquid partition step were investigated. Due to maximum residue limits (MRL), fortification experiments with 17 GC/ECD and GC/NPD detectable pesticides were carried out in concentrations of 1 and 0.1 mg/kg apples, 1 and 0.05 mg/kg tomatoes, 1 and 0.1 mg/kg lettuce, respectively. In supplementary greenhouse experiments, lettuce was cultivated and a mixture of 10 plant protection products was applied in commonly used amounts. In both cases, the comparison of pesticide recoveries shows that several less toxic solvents like cyclohexane, light petroleum and tertiary butyl methyl ether are suitable substitutes for the more toxic and persistent dichloromethane.     

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr⁺³) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr⁺³) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.     

Allelopathic effect of the ethanol extract and fractions of the aerial parts of Lippia alba (Verbenaceae)

Lippia alba, belonging to the Verbenaceae family, is one of the most commonly utilized medicinal plants in folk medicine. The allelopathic activity was assessed using seeds of Lactuca sativa (lettuce) and Allium cepa (onion) by assessing the growth of the radicle and hypocotyl. The tests showed allelopathic efficiency in inhibiting the growth of lettuce and onion seeds. The best results for allelopathic activity were presented by the dichloromethane (DCM) fraction of the fresh plant, which inhibited radicle (23.04–100% lettuce and 64.17–66.36% onion) and hypocotyl (16.77–100% lettuce and 65.10–69.43% onion) formation, and as well as the DCM fraction of the dry plant, which also inhibited radicle (30.74–82.83% lettuce and 63.50–93.67% onion) and hypocotyl (24.12–70% lettuce and 69.07–79.95% onion) formation. Based on these results, it was found that the aerial parts of L. alba are rich in bioactive substances, suggesting the possibility of using of L. alba as a natural herbicide.     

Chromium removal technologies

Chromium can exist in different oxidation states (e.g. 0, III, VI). Chromium can be both beneficial and toxic to animals and humans depending on its oxidation state and concentration. At low concentration, Cr(III) is essential for animal and human health. Chromium(VI) compounds are highly soluble, mobile and bioavailable compared to trivalent chromium. Chromium(VI) is dangerous for humans due to its toxicity and carcinogenic properties. The presence of hexavalent chromium in waste water is a potential hazard to aquatic animals and humans. Various methods are adopted for the removal of hexavalent chromium from industrial effluents. Among these different techniques, biosorption is the most promising one. In this process, the various components present in biomaterial reduce the toxic hexavalent chromium to non-toxic trivalent chromium. Algae, fungi and bacteria have biosorption properties, and cell walls are responsible for biosorption of dead biomaterial. But this process removes chromium from waste water very slowly. So for chemical modification of biosorbents, optimization of biosorption parameters is required to increase the effectiveness of this process.     

Certified reference materials for the quality control of analysis in the environment

Summary The Community Bureau of Reference (BCR) has undertaken the production of a wide range of certified reference materials (CRMs) for the improvement of accuracy and measurement harmony in various areas of concern at European Community level. This paper provides an overview of the sectors of the BCR-programme in the field of environment i.e. for water systems (water, sediment, biota), soil analysis (soil, fertiliser, waste), plant analysis (aquatic and terrestrial plants), analysis related to animals (e.g. muscle or liver) or man (e.g. industry and food).     

Aldose reductase inhibitory, anti-cataract and antioxidant potential of selected medicinal plants from the Marathwada region, India

The water, ethanol and chloroform extracts of selected plants such as Adhatoda vasica (L.) (Acanthaceae), Caesalpinia bonduc (L.), Cassia fistula (L.) (Caesalpiniaceae) and Biophytum sensitivum (L.) (Oxalidaceae) were evaluated for rat lens aldose reductase inhibitory (RLAR) potential, anti-cataract and antioxidant activities. All the samples inhibited the aldose reductase considerably and exhibited anti-cataract activity, while C. fistula (IC(50), 0.154 mg mL(-1)) showed significant RLAR inhibitory activity as compared to the other tested samples, and was further found to be more effective in maintaining sugar-induced lens opacity in the rat lens model. The antioxidant potential of plant extracts was determined using DPPH (2,2-diphenyl-1-picryl hydrazine), hydroxyl (OH), nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) scavenging activities, along with determination of reducing power, ferrous ion chelating ability and inhibition of polyphenol oxidase (PPO). The extracts of the tested plant showed significant free radical scavenging activities and inhibited the activity of enzyme PPO, a model oxidising enzyme. The plant samples were found to possess considerable amounts of vitamin C, total polyphenols and flavonoids.