Fluorometric response of photosynthetic microorganism consortium as potential bioindicator for heavy metals detection in water

Human activities can have dramatic impacts on animal populations around urban areas with heavy metal contamination being a primary cause of hazardous effects. Insects as residents of ecosystems are especially susceptible to heavy metal contamination and have the potential to serve as indicators for environmental stresses .To better understand the effect of heavy metals pollution on terrestrial insect, the detection of different heavy metals was investigated. The following metals cadmium (Cd), copper (Cu), zinc (Zn) and lead (Pb) were found and their concentrations were estimated in soil samples from either polluted or reference site. As the Cd concentration was significantly high in the polluted site, its concentration in the tissues of the studied insect Blaps polycresta (Coleoptera: tenebrionidae), was investigated as well as the antioxidant defense system and lipid peroxidation biomarkers. The results of insect's tissues in polluted site showed a significant decrease in the activity of antioxidant enzymes, glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and reduction in the level of glutathione (GSH). In addition, there was a significant decrease in the total protein content. On the other hand a significant increase of transaminases (AST, ALT), and lipid peroxidation (LPO) levels was found. In conclusion, insect can be considered as a good bioindicator species for environmental heavy metals pollution especially by cadmium that accumulates in soft tissues and has deleterious effects.

According to the need of heavy metal pollution detection in waste water. Pure graphite flake is selected as matrix material, the LIBS method of multiple enrichment of samples combined with spatial confinement is adopted to detect the heavy metals contained in the waste water, and spectral stability and limit of detection of Pb, Cu, Cd and Ni are also analyzed. The experiments uses a wavelength of 1 064 nm Nd : YAG Laser, and a optical spectrometer, which the resolution is less than 0. 1 nm to detect the characteristic spectrum of heavy metal elements content in water. The result shows that this method serves to improve sensitivity and spectral stability of heavy metal in waste water while reducing the limit of detection of heavy metals. The intensity of characteristic spectrum are about 2. 5 times better than it under the condition of non-confinement, the spectral stability has also been improved, RSD is reduced from 11.34% to 8.77% compared with non-confinement condition. The calibration curves of four heavy metal elements have been established, the limits of detection of Pb, Cu, Cd and Ni are lower than 1/6 of discharge standard of national industrial waste water, meeting the demand of heavy metal in industrial waste water online monitoring. This method provides a convincing support for discharge control and online monitoring of warning excessive discharge of heavy metal elements in industrial waste water.

Good water quality is a basic need for human health and water is naturally or artificially overlying with different trace and heavy metals. These metals have an important physiological role with the body, but the bio-toxic effects of many metals are of great health concern. Therefore, contamination of water by heavy metals could be a major concern for human health and as well as for the ecosystem. The present study deals with the elemental screening of drinking water and to compare the seasonal variation of trace and heavy metals in natural source water and their corresponding tap supply from habitat sites of Champawat district, Uttarakhand, (India). The detection of trace and heavy metals were assessed in ppm according to official method by using an Atomic absorption spectrometer. The study revealed that the concentration of trace metals such as iron, copper, manganese, zinc, and heavy metals like chromium, lead, and mercury was found within the permissible limits as prescribed by the WHO. Hence, it is concluded from the study that the amount of essential trace elements is within the permissible limit while the heavy metal was below the detectable limit. Therefore water from natural sources and their corresponding tap supplies are safe as far as trace and heavy metals are concerned.

Heavy metals were analysed in sediments and waters of Sado Estuary to estimate the potential environmental impact of several industries and urban discharge located in the north channel of the estuary. Cr, Fe, Ni, Cu, Zn, Mo, As, Ga, Hg and Pb were determined in bottom waters and in surface sediments of the estuary by PIXE method. A proton beam induced by a 2 MeV Van de Graaff accelerator and subsequent X ‐ ray emission was used. Sediment concentration factors were evaluated and geographical distribution in the estuary, of some elements are shown.

Ascidians can serve as marine pollution indicators for monitoring the release of industrial and anthropogenic wastes into the marine environment. The aim of this study was to analyze the heavy metals accumulation in ascidians, water and sediments. Selected ascidian specimens, water and sediments were collected by employing SCUBA diving in the Palk Bay region, Southeast coast of India. All these samples were analyzed by Inductive coupled plasma system (ICP) (Optical Emission Spectrophotometer by using the instrument Optima 2100DV and quantified against a known standards) for the determination of heavy metals (Fe, Zn, Cd and Pb). The heavy metals concentrations (Cd, Fe, Pb and Zn) in water, sediment and ascidians tissue, showed a distinct seasonal variation with higher values during monsoon season and low during summer season. The heavy metals concentrations in the different species of ascidians (Polyclinum madrasensis, Polyclinum indicum, Herdmania pallida, Microcosmus squamiger and Microcosmus exasperatus) were found to be the order: Iron > zinc > lead > cadmium. This might be due to the difference in the bioavailability of the individual metal and their role in metabolism of different species and accumulation efficiency by the species. Our results suggest that ascidians could be effectively used as biological indicator to monitor the environmental pollution. This will help a great deal while preparing plans to conserve or protect the marine ecosystem. Key words: Ascidians, bio indicator, heavy metals, pollution, ecosystem

Heavy metal contaminants are harmful to both ecological systems and human health, so it is important and urgent to establish sensitive, fast and efficient methods for detecting heavy metals. The current detection techniques were established on the basis of large instruments, but the requirements on the detection conditions, time and cost are higher. So it is difficult to meet the needs of heavy metal detection. The rapid development of nanomaterials provides a good theoretical and technical support to solve the problem of heavy metal detection. Highly sensitive, high through put and rapid detection methods have been developed with the combination of functional nanomaterials and the traditional detection. This paper mainly summarizes the different types of materials for specific/selective recognition of heavy metals as well as the progress of application of several types of nanomaterials used in heavy metal detection in recent years. These nanomaterials include gold nanoparticles, magnetic nanoparticles, fluorescent semiconductor quantum dots and carbon materials. Based on the unique and excellent properties, functional nanomaterials might have a great potential in the field of heavy metal detection.

Diarrhoeal cases due to taking of contaminated water are on the increase Nakuru County. They are a leading cause of human mortality and morbidity. The current study was aimed at isolating microorganisms from Municipal’s council treated sewage and screening it for heavy metals followed by testing the efficacy of Moringa stenopetala in removing the heavy metals and treating the sewage against the microbial isolates. In addition, susceptibility test of the microbial isolates to antibiotics and Moringa stenopetala was also carried out. A total of 492 samples were collected out of which 46 % (226/492) were positive for all the microorganisms isolated and heavy metals. Standard methods were used in isolating microorganisms and screening of the sewage for heavy metals. Antimicrobial susceptibility test was carried out using Karby Bauer’s disk diffusion test. The percentage reduction of heavy metals was Cadmium (97 %), nickel (97 %), lead (83.17 %) and Chromium (88 %) after treatment of the Municipal council’s sewage with Moringa stenopetala. In addition, the microbial isolates reduced by 95.3 % after treatment with Moringa stenopetala. There was significant difference in both heavy metals (p=0.036) and microbial isolates (p=0.02) before and after treatment of Municipals council treated sewage with Moringa stenopetala. There was also a significant difference (p=0.01) in susceptibility patterns of the microorganisms against antibiotics and Moringa stenopetala. Treated municipal council’s sewage is highly contaminated with microorganisms that can cause diseases in addition to having highly harmful heavy metals if ingested in food. There is need for proper sewage treatment in Nakuru town in addition to in cooperating Moringa stenopetala in sewage treatment in the town.

Recent progress on detection of bivalent, trivalent, and hexavalent toxic heavy metal ions in water using metallic nanoparticles: A review

In small quantities, certain heavy metals are nutritionally essential for a healthy life. The heavy metals linked most often to human poisoning are lead, mercury, arsenic and cadmium. Other heavy metals, including copper, zinc and chromium are actually required by the body in small amounts, but can also be toxic in larger doses. They have the ability of dissolving in wastewaters and when discharged into surface waters, they can be concentrated and travel up the food chain. They can also seep into groundwater, hence contaminating drinking water, thereby harming the consumers of that water. The enactment of several water legislations and guidelines worldwide coupled with the need for environmental sustainability has necessitated the need for several stringent regulations for drinking water supply and wastewater discharge. To achieve unpolluted drinking water distribution and wastewater discharge, several technologies and processes for heavy metal remediation are currently in use. This review was therefore aimed at elucidating the major available technologies for heavy metal remediation in water, with emphasis on their processes and applications. Currently, no one of the existing technologies for heavy metal remediation (chemical remediation, phytoremediation or microbial remediation) is without some form of merits and demerits. There is therefore a proposed need for the utilization of safe and economical multiple/integrated approach for heavy metal remediation. The application of this may offer enormous public health, environmental and cost benefits. Key words: Heavy metals, remediation, water.

Solvothermal synthesis of CoS/reduced porous graphene oxide nanocomposite for selective colorimetric detection of Hg(II) ion in aqueous medium

Electrochemical process is mainly relying on the nature of electrode material. An ideal electrode has to offer some features such as good physicochemical properties and wide potential range. Diamond is one of unique materials with outstanding properties including wide potential window approximately to 3-4 V, low adsorption ability and low background current that leads to its extensive utilization in electrochemical processes like electro-analysis of specific compound and electro-oxidation (EO) of organics. Diamond-like carbon (DLC) also have superior characteristic similar to diamond and composed of sp2 and sp3 carbon structure. However, there are few studies on the DLC-based electrochemical techniques. Therefore, the purpose of this thesis was to fabricate a high performance BDD-DLC electrode with wide potential, low background current which can be adapted for wastewater treatment and heavy metal detection. In this study, BDD-DLC thin film was coated on several Ti based substrate such as Ti, Ti-SiC and Ti-Pt by HFCVD. Surface analysis such as SEM, AFM, Raman, XRD and XPS were conducted to determine the morphology, chemical composition and crystal structure of the BDD-DLC film. CV and LSV was performed to determine the electrochemical properties of BDD-DLC film. The capability of as grown and polarized BDD-DLC in detecting heavy metal ion such as Pb, Cu and Hg in aqueous solution was studied using direct LSV method without stripping. Performance of BDD-DLC to anodically degrade organic was tested using an azo dye – metanil yellow (AY36) as target pollutant. The pH and electrolyte effects were studied. A hybrid module combining EO/MF process was develop to study the BDD-DLC EO capability when it is incorporated with MF system to simultaneously removed soluble organic (AY36) and particle pollutant (simulated by kaolin). A 2 µm thick BDD-DLC film with 3000 ppm B/C ratio was successfully deposited on the Ti based substrate. Background CV of as grown BDD-DLC on various Ti based substrates reveals that the film grown on Ti exhibited higher oxygen evolution overpotential (at 2.5 V), wider potential window (4 V, from －1500 to ＋2500 mV) and smaller background current (10 µA/cm2) compared to those grown on Ti-SiC and Ti-Pt. This result demonstrated that Ti is the most suitable substrate to coat BDD-DLC. Based on SEM and AFM image, it is clear that the BDD-DLC film contains dense nanocrystalline grains that aggregated into rough sphere forming cauliflower structure. Raman spectra of the BDD-DLC shows several peaks that associated with diamond Csp3 peak, graphitic G and D band as well as G’ and G’’ band. XRD spectra show diamond peak at 44.4° and graphite at 43°. Based on the XPS survey, carbon, boron, titanium and oxygen are evidently present. The existence of both sp2 and sp3 carbon was also confirmed. Surface analysis results confirm the existence of both diamond and graphitic carbon in the film with relative higher Csp2 than commercial diamond electrode. However, the results reveal polarization can improve the electrochemical properties of BDD-DLC film similar or even better than diamond electrode in other studies. In the feasibility test of heavy metal detection, detection limits for Hg, Cu and Pb in ppm were 1.34E-01, 6.49E-03 and 2.90E-01 with sensitivity of 0.057, 0.104 and 0.014 μA μM-1 cm-2, respectively. In anodic oxidation experiments, results show that acidic condition is slightly more favorable for decolorization compared to basic and neutral condition, with color removal reach > 99%. The EO/MF hybrid module in dye wastewater treatment practice can achieve satisfactory performance with respect to COD removal, decolorization and turbidity removal. In conclusion, the BDD-DLC/Ti electrode is applicable for both EO treatment practices and as the working electrode for electro-analysis of heavy metal ions due to its outstanding electrochemical properties.

The study aimed at documenting the key land cover and land use types along the Likii River from the upstream to downstream and establishing the presence or absence of heavy metals (arsenic, mercury, lead) and pesticide residue (atrazine, β-endosulfan-isomer, mirex) along the altitudinal gradient. Land cover and land use analysis were undertaken through field missions conducted within the 2km zone on both sides of the river while water quality was based on surface water samples from 32 water sampling points along the altitudinal gradient from 2014 m to 1852 m. Heavy metal detection was done through Inductively Coupled Plasma Mass Spectrometry (ICP-MS) while the pesticide analysis was undertaken through the Solid-Phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GCMS). The land cover and land use analysis established that the river system was characterized by over ten zones along the altitudinal gradient. Arsenic was detected in the river between 1893-1938 m, with the highest concentration of 1.23 µg As/L at 1910 m, near the Likii low-income residential area. The mean lead concentration was 2.72 mgPb/L with the highest mercury concentration at 7.1µgHg/L between 1938 m and 1893 m in the Likii low-income residential area. The presence of atrazine was detected from below 2018 m near the Kariki Flower Farm after which the level increased downstream to a maximum of 76 µg/L at 1864 m. The maximum concentration of β-endosulfan-isomer at 56.7 µg/L was well above the WHO tentative limit of 20 µg/L in most sections of the river below 2015 m. The mean level of Mirex was 49.7 µg/L with two distinguishable peaks near the Kariki Flower Farm and the Likii low-income residential area. The findings indicated that the water in the Likii River was largely unsafe for human consumption below 2018 m because of the presence of heavy metals (below 1910 m for lead and mercury) and pesticide residue (1934 m for atrazine, 1938 m -2018 m for mirex and 2015 m for β-endosulfan-isomer).

Scarcity of water resources has compelled to develop techniques for effective wastewater treatments and reutilization of it. Industrial and municipal wastewaters are the biggest pollutants of natural water resources. Wastewaters from these sources are rich in suspended particles, dyes, toxic organic chemicals, heavy metals and nutrient content such as nitrogen and phosphorus. The removal of these chemicals and particles is biggest challenge for effective wastewater treatment and its disposal. Without proper treatment it poses a serious threat to environment and safety of living organisms. Physical and chemical methods are widely used in the treatments but due to certain limitations, other alternative methods are being explored. Biological methods are emerging as effective, environmental friendly and economical alternative treatment methods for wastewater. Microorganism produces EPS (extracellular polymer substrates) and it is also known as microbial or bioflocculants. Microbial flocculants have been widely studied for its capacity for flocculation, removal of dyes, metals and toxic chemicals. This article discusses the bioflocculants and its potential to treat the wastewater. Keywords: Wastewater, EPS, bioflocculants, heavy metal, toxic chemicals

This research reports the results of some heavy metal content (Zn, Pb,Cd, Ni and Co) in Mushin area of Lagos - State using the moss plant Barbulaindica (Hook) spreng.var.indica as bioindicator. The samples of the Moss plant were collected randomly from September to November, 2016 at ten different locations at Mushin area between 2 to 2.5 metres high from unplastered buildings in Lagos state and analysed for their heavy metal contents as at the time of sampling. The samples were properly cleaned from all the debris then weighed and digested with a mixture of HN03 and H2O2 for 35 min. The concentrations of the five heavy metals were determined using Atomic Absorption Spectrophotometer (AAS). Results of the analysis, shows that the average concentration of the heavy metals at Mushin are: Zn 23.477mg/l,53.9%; Pb 4.240mg/l,9.74%; Cd 0.195mg/l,0.45%; Ni 4.418mg/l, 10.15% and Co 11.191mg/l,25.71%. The most abundant pollutant heavy metal was Zn in all the sites while the least abundant was Cd. Levels of some of the heavy metals were present in concentrations greater than WHO (2001) threshold limiting values. The most polluted site is Olorunshogo 11.809mg/l while the least polluted is Shoremekun 1.2765mg/l. The sequence of bioaccumulation and distribution follows the pattern: Zn > Co > Ni > Pb > Cd. The concentrations of heavy metals obtained exceeded the recommended limits of the Federal Ministry of Environment (FME), European communities (EC) and United Nations Environmental Programme (UNEP) permissible level for heavy metals in the atmosphere which suggests that the study area is polluted with heavy metals. There is a significant high level of each heavy metal in the atmosphere of Mushin areas (Pvalue< 0.05). Keywords: Anthropogenic, bioaccumulation, bioindicator, concentrations, pollution, spectrophotometer

Recent developments on BODIPY based chemosensors for the detection of group IIB metal ions