Nanotoxicity in Aquatic Invertebrates

Due to their unique properties, nanomaterials (NMs) are being incorporated in several applications including consumer products, electronics, pesticides and the pharmaceutical industry. As such, the rapid development and large-scale production of NMs has inspired concerns regarding their environmental health risks. In order to address these concerns, there has been a rapid development in the methods of toxicity testing of NMs, specifically in aquatic organisms. Understanding the unique properties of nanoscale materials has proven to be a particular important aspect of their toxicity. Properties such as surface area, surface coating, surface charge, particle reactivity, aggregation and dissolution may affect cellular uptake, in vivo reactivity and distribution across tissues. The behaviour of NPs is influenced by both the inherent properties of the NP as well as environmental properties (such as temperature, pH, ionic strength, salinity, organic matter). As such, this chapter describes methodologies of NM characterization in exposure media and NM in vivo toxicity experimental procedures under variable environmental conditions (with special emphasis on temperature)

Stripping Voltammetric Measurement of Trace Metal Ions at Screen-printed Carbon and Carbon Paste Electrodes

AbstractScreen-printed carbon electrodes (SPCEs) and carbon paste electrodes (CPEs) were prepared as “mercury-free” electrochemical sensors for the determination of trace metal ions in aqueous solutions. SPCEs were coated with conducting polymer layers of either polyaniline (PANI), or polyaniline-poly(2,2′–dithiodianiline) (PANI-PDTDA). Furthermore, CPEs containing electroactive compounds with reactivity towards metal ions were employed to obtain enhanced selectivity. Optimised experimental conditions for Hg2+, Pb2+, Ni2+ and Cd2+ determination included the supporting electrolyte concentration, deposition potential (Ed) and accumulation time (tacc). Initial results showed linearity in the examined concentration range between 1 × 10-9M and 1 × 10-6M for laboratory prepared solution

Nanotoxicology: A Review

Nanotoxicology represents a new and growing research area in toxicology. It deals with the assessment of the toxicological properties of nanoparticles (NPs) with the intention of determining whether (and to what extent) they pose an environmental or societal threat. Inherent properties of NPs (including size, shape, surface area, surface charge, crystal structure, coating, and solubility/dissolution) as well as environmental factors (such as temperature, pH, ionic strength, salinity, and organic matter) collectively influence NP behavior, fate and transport, and ultimately toxicity. The mechanisms underlying the toxicity of nanomaterials (NMs) have recently been studied extensively. Reactive oxygen species (ROS) toxicity represents one such mechanism. An overproduction of ROS induces oxidative stress, resulting in inability of the cells to maintain normal physiological redox-regulated functions. In the context of this book, this chapter includes topics pertaining to chemical and physical properties of NMs and characterization for proper toxicological evaluation, exposure, and environmental fate and transport, and ecological and genotoxic effects. This chapter reviews the available research pertaining specifically to NMs in the aquatic environment (in plants, aquatic invertebrates, and fish) and their use in biomarker studies

Graphene Oxide–Antimony Nanocomposite Sensor for Analysis of Platinum Group Metals in Roadside Soil Samples

The present study introduced a very sensitive and low-cost analytical procedure based on voltammetry to study platinum group metals in road dust and roadside soil matrices. Cathodic stripping voltammetry in conjunction with a reduced graphene oxide-antimony nanocomposite sensor and ICP-MS analysis were used to analyse roadside soil and dust samples. The results were processed to evaluate possible pollution in order to map the distribution of the PGMs along specific roads in the Stellenbosch area, outside Cape Town. The results revealed that within each site under investigation, Pd was more abundant than Pt and Rh using both voltammetric and spectroscopic methods. The AdDPCSV results obtained showed concentrations for Pd(II) ranging between 0.92 – 4.0 ng kg–1. For Pt (II), the concentrations ranged between 0.84 – 0.99 ng kg–1. For Rh(III), concentrations ranged between 0.42 – 1.21 ng kg–1. The ICP-MS results showed Pd concentrations ranging between 0.01 – 0.34 µg kg–1. For Pt the concentrations ranged between 0.004 – 0.07 µg kg–1. For Rh, concentrations ranged between 0.002 – 0.26 µg kg–1. The analysis showed significant levels of all PGMs in soil and dust samples analysed. Metal concentration in dust and soil followed the trend Pd > Pt > Rh using both voltammetric and spectroscopic technique

Voltammetric Analysis of Platinum Group Metals Using a Bismuth-Silver Bimetallic Nanoparticles Sensor

This study dealt with the development of a bismuth-silver bimetallic nanosensor for differential pulse adsorptive stripping voltammetry of platinum group metals (PGMs) in environmental samples. The nanosensor was fabricated by drop coating a thin bismuth-silver bimetallic film onto the active area of the screen-printed carbon electrodes. Optimization parameters such as pH, dimethylglyoxime (DMG) concentration, deposition potential and deposition time, stability test and interferences were also studied. In 0.2 M acetate buffer (pH = 4.7) solution and DMG as the chelating agent, the reduction signal for PGMs ranged from 0.2 to 1.0 ng L−1. In the study of possible interferences, the results have shown that Ni(II), Co(II), Fe(III), Na+, SO42−, and PO43− do not interfere with Pd(II), Pt(II), and Rh(III) in the presence of DMG with sodium acetate buffer as the supporting electrolyte solution. The limit of detection for Pd(II), Pt(II), and Rh(III) was found to be 0.07, 0.06 and 0.2 ng L−1, respectively. Good precision for the sensor application was obtained with a reproducibility of 7.58% for Pd(II), 6.31% for Pt(II), and 5.37% for Rh(III) (n = 10)

Optimisation of Parameters for Spectroscopic Analysis of Rare Earth Elements in Sediment Samples

The rapid demand for rare earth elements (REEs) in recent years due to increased use in various technological applications, agriculture, etc. has led to increased pollution and prevalence of REEs in the environment. Therefore, monitoring for REEs in the aquatic environment has become essential including the risk assessment to aquatic organisms. Since direct determination of REEs in sediment samples prove difficult at times, due to low concentrations available and complex matric effects, separation and enrichment steps are sometimes used. In this work, various REEs were determined employing wet acid digestion and lithium metaborate fusion in our optimised analytical technique. A comparison of the two analytical techniques was also made. The results obtained from the optimised ICP-OES radial view technique were in 5% agreement with the ICP-MS results from the same samples. The accuracy of the method was checked with the geological reference material GRE-03 and found to be in reasonable agreement. We demonstrated that there is a consistent relationship between the signals of the REEs and nebuliser gas flow rates, plasma power and pump speed. The detection limits for all the REEs ranged from 0.06 mg L-1 Yb to 2.5 mg L-1 Sm using the ICP-OES fusion technique

Intelligent and Biosensors

The use of intelligent sensors have revolutionized the way in which we gather data from the world around us, how we extract useful information from that data, and the manner in which we use the newly obtained information for various operations and decision making. This book is an attempt to highlight the current research in the field of Intelligent and Biosensors, thereby describing state-of-the-art techniques in the field and emerging new technologies, also showcasing some examples and applications

Phytostabilization of metals by indigenous riparian vegetation

Given the increasing pressure of man-made activities on riparian zones, the capacity of the riparian vegetation along the Upper Olifants River, South Africa, to phytoextract and phytostabilize aluminium (Al), manganese (Mn) and iron (Fe) from the soil was investigated. The aim of the study was to gain better understanding of the capacity of indigenous vegetation in riparian zones to immobilize metals in the soil, thereby improving river water quality and ecosystem services. Seven commonly-occurring pollution-tolerant riparian plant species were evaluated to establish their potential as bioaccumulators for Fe, Al and Mn. Species included: Cyperus haspan, Schoenoplectus corymbosus, Typha capensis, Phragmites australis, Cynodon dactylon, Cyperus marginatus and Juncus effusus, which were sampled in five riparian areas in the Upper Olifants catchment. The bioconcentration factor (BCF) for Mn was > 1 for all species investigated with a maximum of 5 for Typha capensis, which also showed the highest accumulation of Al (10.26) and Fe (7.03). The remaining species presented with Al and Fe BCF between 0.11 and 2.00, with minimal transfer from root to shoot. When measured against an ideal hypothetical buffer zone, the buffer zones under investigation varied between intact and severely compromised. Intact riparian zones showed elevated metal concentrations in the soil, yet significantly lower concentrations in the river water compared to areas with insufficient vegetative cover. A polluted riparian area overgrown by P. australis effectively phytoextracted 204 960 g/m2 Al, 204 400 g/m2 Fe and 27 887 g/m2 Mn. The two indigenous Cyperus spp. were not ideal for metal immobilization with low bioaccumulation and transfer factors as well as low biomass. High biomass and Al, Fe and Mn phytostabilizing species: P. australis, T. capensis, S. corymbosus and J. effusus, should be considered in the rehabilitation of South African buffer areas

Value Stream Mapping as a Supporting Management Tool to Identify the Flow of Industrial Waste: A Case Study

The Value Stream Mapping (VSM) method was applied to a case study in the iron and steel industry in Southern Africa as a supporting management tool to identify, demonstrate, and evaluate industrial waste and comprised of three steps. The first step included collecting and verifying waste generation and flow data as the VSM data input step. The second step comprises three phases: mapping waste generation and fractions and horizontal and vertical performance analysis. The third step is comprised of actual and future state maps compilation. Following the first year of implementation, waste was reduced by 28%, and waste removal cost by 45%. Implementing the VSM method demonstrated cost savings and reduced waste flow within the study’s first year. The initial waste generation reduction target of 5% per annum was exceeded. The VSM method application proved to be a practical method for the iron and steel industry to visualize and analyze waste flows, identify opportunities and challenges in waste management operations, reduce waste, promote lean manufacturing, and achieve an environmentally responsible zero-waste environment