The production of engineered nanomaterials is an emerging and rapidly expanding industry. It exploits the capacity for materials to be manufactured to present particular properties distinct from the bulk material, through tailoring of the particle size and surface functionality. This ability to fine tune particle properties at the nanoscale is responsible for the explosion in uses of engineered nanomaterials in industries as diverse as cosmetics and medicine, to “green” technologies and manufacturing. However, this increased reactivity at the nanoscale, defined as having at least one dimension < 100 nm in size, is also responsible for the increasing concern over their environmental safety. Material flows of engineered nanoparticles into the aquatic environment have been identified throughout their production, use and disposal, putting these ecosystems at potential risk of contamination. In particular, sediments are a likely sink of engineered nanomaterials in the aquatic environment due to their propensity to destabilise and settle out of suspension in natural freshwaters. An emerging body of literature has demonstrated toxicity of nanomaterials to aquatic species. In this thesis, the case is presented for using bioaccumulation as a first indicator of risk to aquatic organisms exposed to engineered nanomaterials. Using the sediment dwelling freshwater worm, Lumbriculus variegatus, this work investigates the factors which govern the bioaccumulation of cerium oxide and silver nanomaterials. It is hypothesised that the fate of these materials in sediments will be determined by their core composition, primary particle size and surface coating. A novel approach is presented to measure two biologically relevant fate parameters (persistence of particles and dissolved species in the sediment pore waters) and how particle properties affect the distribution of the nanomaterials between these phases of the sediment. This provides the context within which to interpret biological exposures assessing both the extent of uptake and how they are accumulated, whether through dietary uptake or across the skin. Understanding this route to uptake is important as the mechanism of toxicity may depend upon the point of contact of a material at the nano-bio interface. For example, a nanoparticle which comes into contact with biological material in the gut may exert a different effect upon an organism than one which is translocated directly across the skin. It is demonstrated that sediment properties determine the fate of engineered nano cerium oxide and silver to a greater extent than stabilising surfactants, with the majority of particles aggregating or associating with the solid constituents of the sediment > 200 nm in size. The dissolved fraction of the metal present in the pore waters was a better predictor of bioavailability than the persistence of particulate material < 200 nm in size, with partially soluble nanosilver being more available than insoluble cerium oxide. The route to metal nanoparticle uptake also differed with particle core, with electrostatically stabilised citrate and sterically stabilised polyethylene glycol (PEG) coated ceria available only through dietary uptake, whilst citrate and PEG coated silver was accumulated through transdermal uptake. Dynamic changes in the fate of silver nanoparticles were also observed for sterically stabilised polyvinylpyrrolidone (PVP) coated silver, resulting in the emergence of a colloidal pore water fraction of silver after 3 months aging in sediments. However, this colloidal silver was still not considered accumulated, indicating that low molecular weight species of silver, dissolving from the particle surface either during the exposure or upon contact with the worms’ surfaces was responsible for uptake of silver from the sediments. In conclusion, this work contributes towards our understanding of the factors which determine both the route and extent of biological uptake of engineered nanomaterials. It presents a novel combination of methods which allow for understanding bioaccumulation of these materials in the context of their fate and behaviour within sediments.

No description available.

ABSTRACT Sipuncula is a group of unsegmented, coelomate, bilaterally symmetrical and wormlike marine deposit-feeding benthic macro-invertebrates. They are abundant along the intertidal habitats and around 150 species have been recorded worldwide. Sipunculans likely accumulate many anthropogenic contaminants by feeding on the contaminated sediments or benthos, and since they are edible marine species and have long been used in Southwest Pacific cuisine, these contaminants may transfer into the food chain and affect the public health of humans.Trace elements and PAHs are the most common contaminants that appear in the coastal areas worldwide. These contaminants lead to losses in oceanic yield and may hazardous effects on health when they enter the food chain. The previous studies of sipunculans along the coast of Taiwan were mostly focused on the taxonomy and distribution of the species living on the hard -ground habitat (rubble), one of the purposes of this study is aiming at the sipunculans on the seagrass beds and wetland soft-ground habitat for species diversity, population dynamic and ecological related research. Among 10 native sipunculans species, Sipunculus nudus is the dominant species living at the segrass bed and wetland in Taiwan. Siangshan wetland locates at the area of industrial pollution and S. nudus here is a species with aquatic economy, but is known limitedly of its population and environmental physiology. Therefore, the other purpose of this research is to investigate the S. nudus population in this wetland and analyze the trace elements: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) and the organic pollutants: PAHs, in order to understand the bioaccumulation of S. nudus in the above two types of soft-substrate regarding the pollutants. The main results of this study are as follows: (1) This study represents a pioneering investigation in Taiwan regarding the species diversity of sipunculans on the seagrass meadow soft-ground sediment, which describes the species and their morphological characteristics. A total of 42 specimens 10 sipunculan species belonging to 3 families were identified. (2) It is the first time that S. nudus is realized as the dominant species in these soft habitats. Because of its cultivation potential, its population dynamics and reproductive cycle in Siangshan wetland were studied. The population size of S. nudus in this area is 0.965¡Ó 0.46 ind.m-2 and the sex ratio is around 1:1; the reproductive period is from April to September in the year with the peak reproductive period from May to August; the body length of matured individual is over 11cm. (3) This is the first report in Taiwan on the trace elements in sipunculan and their surrounding sediments. The bioaccumulation characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) were analyzed and compared in two sipunculan species, S. nudus and Siphonosoma vastum, which were collected from seagrass beds and wetlands in Taiwan. Both sipunculans in the these soft habitats had a high Cu bioaccumulation mechanism. Multivariate analysis, principle component analysis, and partial least squares for discriminant analysis of trace element levels and bioaccumulation factors were used to distinguish the element distributions that corresponded to the two habitats (seagrass beds and wetlands). Different levels of certain trace elements in these two sipunculan species may result not only from the environmental factors of various habitats but also from the accumulation characteristics of various species. The As, Cd, Cr, Cu, Hg, and Zn concentrations were markedly lower in sipunculan than in other invertebrates from the adjacent polluted regions. (4) This is the first report on the accumulation situation of PAHs in different body tissues (tentacle, nephridium, intestine, and muscle) of S. nudus in Taiwan. It was found that the smaller individuals had higher amount of PAHs with higher percentage of low-ring PAHs and they were mostly concentrated in the nephridium. This study provides the bioaccumulation pattern of PAH in the tentacle, nephridium, intestine, and muscle of S. nudus. The logKow and logBAF parameters show that S. nudus may excrete or decompose high-ring PAHs via biotransformation. By comparing the t-PAH of S. nudus with that of the surrounding substrate and invertebrates along the coasts of other countries, the t-PAH content in the muscle of S. nudus is lower than the sediment and the invertebrates. As a result, I suggest removing the internal organs and utilizing the muscle portion as good to reduce the uptake and accumulation of PAHs from the sipunculans.

This pioneering investigation focused on the mercury bioaccumulation relationship of bats and insects. Identifying biomarkers that can be extrapolated to humans is necessary. Radio-transmitter-fitted bats were tracked to identify five of their preferred feeding sites within and outside the Cornwall Area of Concern. Bats, insects and guano were collected from the five sites. High THg levels in bats (N= 80) were noted among species and locations but these levels were not correlated with insects. Some individual Myotis lucifugus and Eptesicus fuscus bats had concentrations (10 - 12 ppm and 15 - 26 ppm) that exceeded those from previous studies (7.6 ppm and 1.5 ppm) (Hickey et al., 2001). One-way ANOVA and t-test (two-tailed) established statistical significance among caddisflies by location (p= 0.0013), insect taxa (p <0.001), bat species (p =0.001) and Eptesicus fuscus by location (p= 0.004). Caddisflies were sampled for MeHg (> 50% Hg was MeHg).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 63-77). Also available via the Internet.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2011. / World wide urban rivers are the most utilised and degraded. A variety of everyday sources of metal pollution exist that is entrenched in the modern way of life. Lately there has been a tremendous growth in the establishment and development of human settlements, both formal and informal in the Cape Town area. The surroundings of the Kuils River are not excluded from this. There are various communities in close proximity to the Kuils River. Due to this, more industries are also being established. This has caused an increased production of potential environmental pollutants, including metals. The aim of the study was firstly, to identify potential sources of metal pollution along the entire length of the Kuils River, in order to identify sampling sites. Secondly, to identify the metals contaminating the water and sediment of the Kuils River. Thirdly, to determine the bioaccumulation of metals in freshwater snails (Physa ecuta). Four sampling sites were identified along the Kuils River. Freshwater snails (P. acuta), sediment and water were collected every 2 months for a period of one year. The following metals were investigated: Aluminium (AI), Cadmium (Cd) Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Nickel (Ni.) and Zinc (Zn). Samples were digested with 55% nitric acid. The Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) were used for metal analyses. The results were statistically analysed by means of ANOVA on ranks using the Sigmastat statistical package. Results revealed that most metals found in water, sediment and snails had significantly higher concentrations at site 1. This is possibly due to input from the surrounding urban area and nearly agricultural activities. Water concentrations of AI, Cu, Mn and Zn were higher than the DWAF (1996) guidelines. Sediment was mostly contaminated with AI, Fe, Pb and Zn, while the snails contained significant levels of Cu, Fe, Mn and Zn. Further investigations involving toxicity testing should be conducted to determine the toxicity of these metals to (Physa acuta).

Complex mixtures of biologically active pharmaceutical residues continuously enter aquatic environments via wastewater, where it can affect species through preserved human drug targets or cause unexpected effects in non-target species. Benzodiazepines and antihistamines are two highly consumed groups of pharmaceuticals that have been shown to bioconcentrate in aquatic organisms and induce behavioural alterations affecting individual fitness. Few studies have investigated bioaccumulation and possible ecological effects of co-occurring pharmaceuticals in food-webs. The aim of this study was to: 1) quantify and compare species-specific bioconcentration and bioaccumulation, by exposing a tri-trophic system consisting of algae, zooplankton and three-spined sticklebacks to oxazepam (benzodiazepine), fexofenadine (antihistamine) and a mixture of both, and 2) analyse if exposure to these pharmaceuticals induce behavioural alterations in sticklebacks, by using standardized behavioural experiments. Species-specific bioconcentration of both oxazepam and fexofenadine was confirmed (F3,98 = 3.061, p = 0.03) were algae and zooplankton bioconcentrated substantially more pharmaceuticals (~50-1800 μg kg-1) compared to sticklebacks (~0.1-6 μg kg-1). Uptake of oxazepam in both zooplankton and sticklebacks was significantly higher compared to fexofenadine (p &lt; 0.001).  Zooplankton and sticklebacks retained 16 and 0.3%, respectively, of fexofenadine from the consumed contaminated prey. Sticklebacks showed no direct behavioural alterations, but possible direct and indirect cascading effects might occur in co-occurrence with fish species exhibiting pharmaceutical-induced alterations. These findings highlight the importance of including consumption of contaminated prey as an important exposure route, when assessing effects of pharmaceuticals in the environment. Contamination magnitudes and subsequent effects are species-specific and vary depending on type of pharmaceuticals.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, November 2014. / Unable to load abstract.

No description available.

Approximately 10,000 tones of Hg are deposited annually as a result of anthropogenic activities. This increased Hg burden is known to have adverse neurological and reproductive effects on Common loons. A positive correlation between mercury (Hg) and selenium (Se) has been reported to exist in marine mammals and various species of marine and aquatic piscivorous birds. It has been hypothesized that the Hg/Se interactions may involve in the multiple mechanisms of Hg detoxification. This study focused on the suggested Hg/Se complex that forms in association with specific proteins. Specifically, this project focuses on the nature of these interactions in different tissues from wild Common loons (Gavia immer) that have been collected by the Canadian Wildlife Service. The Hg and Se concentrations in the various tissues were quantified using AAS. MALDI-TOF-MS and protein sequencing characterized the nature of the Hg/Se complex binding protein. Among the tissues, the liver had the highest concentrations of Hg and Se followed by kidney; muscle and brain. A strong association between Hg and Se was found in liver, kidney and eggs whereas there was no association in muscle and brain. In contrast brain and muscle had highest percentage of organic Hg suggesting that only inorganic Hg is associated with Se. Two Hg-Se binding protein complexes were found in liver both in the 15,200-15,300 Da range while one such complex in the same weight range was found in kidneys, when sequenced it was found that these proteins were the alpha A chain of Hemoglobin. The protein complex found in eggs was unique and although it was impossible to fully sequence it, it represents an unknown protein. The role of Se in Hg toxicity in eggs warrants further study.