Arsenic in the Pak Pa-Nang River Basin, Thailand

The Pak Pa-Nang River Basin is located in southern Thailand. Its environmental degradation has been arising because its catchment is mineralized with substantial deposits of tin forming part of the SE Asian Tin Belt, with the presence of arsenopyrite gives rise to high arsenic concentrations, mobilized during past mining activity. Suitable techniques have been developed, for the extraction of arsenic species in a variety of environmental and biological samples. Trypsin and cellulase enzymatic extraction procedures were used to extract arsenic species from fish and plant samples, respectively. Arsenic species in sediments were determined following 1 M H3P04 extraction in an open focused microwave system. An anion-exchange HPLC system employing a step elution, with sulphate and phosphate solution as the mobile phase coupled with ICP-MS was used for separation and detection of the important arsenic species, e.g. AsB, DMA, MMA, and inorganic arsenic in fish and plant samples. And species of AsIII, AsV, MMA and DMA were determined in sediment samples. A nitric acid microwave digestion procedure, followed by carrier gas nitrogen addition (N2)-ICP-MS analysis, to overcome argon chloride (40Ar35Cl+) interference, was used to measure total arsenic. Validation for these procedures was carried out using certified reference materials and real samples, mussel, cockle, green seaweed, brown seaweed and sediment collected from the Tamar Estuary, UK. Fish samples from the Pak Pa-Nang Estuary showed a range for total arsenic concentration, up to 17 µg gˉ¹ dry mass. The highest total arsenic found in plant samples was 189 µg gˉ¹ (dry mass), in the root of rice plants. The major species of arsenic in all fish samples was AsB, together with smaller quantities of DMA and, more importantly, inorganic arsenic. The major species found in plant was MMA, together with inorganic arsenic at various levels, ranging from minor to trace, dependent upon the part of the plant. Total concentrations of arsenic in the sediments covered a range up to 285 µg gˉ¹, and showed a steep decreasing concentration gradient downstream from the upper mined areas to the estuary. AsV was the major species found in the sediment samples with smaller quantities of AsIII and MMA. The presence of the more toxic inorganic forms of arsenic in water, sediments and biota samples has implications for human health, particularly as they are readily 'available'. Considering the dynamic conditions found in the river basin between the dry and wet (monsoon) season, the supply of these highly toxic arsenic species to humans and environment is likely to continue. This may be for many years, particularly when the levels of arsenic stored in river sediments are considered. Higher rainfall could remobilize arsenic from the various main and intermediate sources and could be carried on SPM, especially on fine particulate matter, to the Pak Pa-Nang Estuary and also the Gulf of Thailand. From this study, the implications of arsenic transport within the water management system for the Pak Pa-Nang River Basin are highlighted

IMPACT OF METAL MINING ON THE WATER QUALITY IN THE TAMAR CATCHMENT

This study discusses the effects of past mining activities on sediment and water quality in streams and rivers in the Tamar catchment. High trace element concentrations, both in water and sediments, were observed in streams and rivers draining areas associated with abandoned mine sites. Maximum concentrations were observed in the Gunnislake/Calstock mining district, where intense metalliferous mining took place during the 19th century. Mine waste from abandoned mine sites in this area contained up to 6.3% arsenopyrite, 5.8% pyrite, 0.3% chalcopyrite and 24% scorodite. As a result, high concentrations of trace elements of up to 180000 mg kg‾¹ As, 6500 mg kg‾¹ Cu were determined in these wastes. Sequential extraction of the mine waste revealed that in most cases, the oxidisable fraction accounted for large proportions of mobile species, followed by the reducible fraction. The exchangeable fraction was relatively low, except for Cu in samples from fine grained waste heaps, in which significant amounts of secondary minerals, such as Fe oxides/oxyhydroxides and Fe-As-O minerals were observed, suggesting trace elements had the tendency to be retained and recycled within the fine grained waste heaps. The Fe oxides/oxyhydroxides can contain up to 12% As and Fe-As-O minerals can contain up to 25% As and 6% Cu, indicating that the As and Cu associated with Fe oxide phases represent their reducible fraction. The coarse grained waste heaps, with higher permeability and low cohesion characteristics, had a higher potential to produce acid leachate and were more susceptible to erosion than the fine grained waste heaps. Contaminants from abandoned mine sites entered aquatic systems within the catchment, as shown by the high concentrations of trace elements (up to 25000 mg kg‾¹ As, 28000 mg kg‾¹ ' Cu, 32000 mg kg‾¹ Mn, 9200 mg kg‾¹ Pb and 2700 mg kg‾¹ Zn) observed in sediments in water channels draining these mine sites. Some streams and adits draining abandoned mine sites carried acidic waters with pH values frequently below pH 4. Dissolved concentrations up to 560 μg L‾¹ As, 7600 μg L‾¹ Cu, 3800 μg L‾¹ Fe, 5700 μg L‾¹ Mn, 170 pg L‾¹ Pb and 2500 μg L‾¹ Zn, and particulate concentrations up to 1600 μg UI As, 7900 μg L‾¹ Fe, 290 pg U' Ni, 11 pg U' Pb and 91 μg L-¹ Zn were observed in channels draining abandoned mine sites. In total, the annual flux of trace elements from 25 studied streams and adits input ca. 13,000 kg Fe, 4300 kg Mn, 4200 kg Cu, 3600 kg Zn, 1400 kg As, 400 kg Ni, 350 kg Co, 43 kg Pb, and 6.6 kg Cd into the Tamar estuary. Seven important point sources of metals to the River Tamar were identified. The mass balance calculation revealed that over 50% of trace elements were not accounted for by the studied point sources, suggesting an importance of diffuse sources. The inputs of solid and dissolved contaminants from the intensive mining district affect the water and sediment quality of the Tamar estuary, an important ecosystem in southwest England. This work has provided important information on the relative importance of point and diffuse sources, ‾which is essential in the formulation of effective catchment management strategie

Microplastics in wastewater treatment systems and receiving waters

Plastic pollution is a problem of global scale and will increase as synthetic polymers continue to be produced, used, and discarded. Microplastic (MPs, <5 mm in size) pollution is of increasing concern, because this is estimated to account for more than 92% of global plastic counts and expected to present risks to aquatic fauna and humans. Often, MPs are too small to be seen and are unevenly distributed in the environment due to differences in shape, size, and density, rendering them difficult to find and quantify in environmental samples. Hence, adequate quantitative and qualitative assessment of these materials remains scarce, particularly in freshwaters and wastewaters that remain largely unexplored. However, both systems receive and transport different types of anthropogenic waste, including MPs, so warrant further attention for identification of mitigation strategies. The purpose of this research was to fill gaps in knowledge of the role of freshwater rivers and wastewater treatment plants (WWTPs) as transport vectors of MPs to the environment, and generate incisive understanding of the distribution and behaviour of MPs in these systems. These research findings are expected to be relevant to stakeholders and regulators as they can aid in the identification of priority areas for further research, monitoring, and regulation of MP pollution. Therefore, this research focussed on the abundance and distribution of MPs (60-2800 μm) in urban fresh- and wastewater systems in a river whose catchment contains a large city: the River Clyde catchment (4000 km2) in the city of Glasgow, Scotland. First, liquid fractions were sampled at eight treatment stage points within a tertiary WWTP with 184,500 population equivalents and receiving a mix of household and trade effluent. Then, sediment and water samples were collected in the recipient river, the River Clyde, upstream and downstream from the WWTP. In addition, sediment samples were collected from another nearby freshwater river, the River Kelvin, which also drains through Glasgow and the Clyde at its estuary. The overall aim of this research was to assess the extent of MP pollution in these systems and the distribution, transport, and possible fate of primary and secondary types of MPs. Microplastics were separated from their environmental matrix using the widespread protocols of density separation, hydrogen peroxide oxidation of labile organics, and filtration. Particles were identified by visual sorting followed by chemical confirmation of plastics. Microplastics were ubiquitous and present in all water bodies in varying quantities: 161-432 MPs kg-1 in the River Kelvin tributary, <1-13 MPs L-1 in the WWTP, 1-26 MPs kg-1 in River Clyde sediment, and 0-4 MPs 24 L-1 in River Clyde water. The WWTP displayed high efficiency, removing 96% of incoming pieces, with the majority removed by the primary treatment stage. However, at least one fibre was observed in treated effluent and this may represent daily discharges of at least 12 million particles to the River Clyde from this WWTP. Total MP concentrations in sediment and water samples of the recipient river were higher in the most downstream site compared to the upstream point furthest from the effluent pipe. Fibre concentrations were higher in downstream sediment samples that may indicate some retention in rivers by sedimentation processes – this is supported by the high abundance of fibres in River Kelvin sediments. Fragments were abundant in the main river sediments in similar concentrations across upstream and downstream sites, suggesting these are more likely to be introduced from diffuse sources via surface runoff and in-stream transport. The comparable concentrations observed across sampling events for each of these systems suggest a continuous input of MPs from their source to the environment. For further insight into the relative distribution of primary and secondary MPs and their potential sources, it is necessary to confirm material composition of these particles. A subset of specimens extracted from wastewater (5%), Clyde sediment (15%), and Clyde water (56%) were analysed by Fourier transform infrared spectroscopy (FTIR) for this assessment. Secondary MPs especially fibres were predominant, while primary MPs that have received the most media and public attention and prompted plastic and MP strategies, were lowest in concentration. Polypropylene (PP) was the most detected polymer across all analysed particles and was mainly present in the form of fibres and fragments. Polyester and nylon fibres that may be expected in high abundances in wastewater appeared absent in the WWTP in this study, although this was concluded mainly due to size limitations of the characterisation method. However, the PP fibres in wastewater could originate from sanitary products, medical applications, thermal clothing, and construction materials. This is important as fibres are often linked to washing machine effluent and currently little information from alternate sources for this type of MPs exists. In River Clyde sediment, fibres identified as polyethylene terephthalate were observed and concluded to originate mainly from fishing gear, based on combined assessment of chemical and visual properties. Understanding the causes and significance of MP pollution is a new but expanding area of water research. It was important to share these research findings with the community and so this research was published when possible. This thesis is thus constructed from a series of published and unpublished papers

Microplastic pollution in the estuarine and river environment of the River Thames, UK

Microplastic pollution is ubiquitous globally and is considered a leading threat to ecosystems. As microplastic studies increase, key areas remain understudied, such as rivers, with new areas and sources of microplastics still being discovered. The overall aim of this thesis is to investigate the abundance of microplastics within the tidal river Thames, UK and identify potential sources of microplastics. In this thesis, I assess the current literature on microplastics, identify potential research gaps within current known knowledge, and show the range of laboratory methods used in studies worldwide to identify and quantify microplastic abundance within the environment. Through surface water samples collected along the river Thames from May 2019 -May 2021, I demonstrate that microplastics are present within the river Thames and vary between sites and samples, as well as identifying potential sources. I highlight how seasonality and rainfall impact microplastic abundance within this river system. During this study, the Covid -19 pandemic occurred, proving a unique sampling opportunity. As a result, this thesis acknowledges that this pandemic may have impacted microplastic abundance and provides valuable information on the short-term impacts of the pandemic on microplastic within this time. Finally, I highlight the effects of the New Year fireworks displays on microplastic abundance within water samples collected from the river Thames at Westminster. This data is novel as it had not previously been noted or identified when this study was published. The data and results presented within this thesis provide valuable information on the abundance, possible sources and accumulation of microplastics along the river Thames that can be used as a baseline for future studies. This data and results can also be used by stakeholders such as the Environment Agency, Thames Water and non-profit organisations to inform possible decisions on the removal of microplastic pollution from the river

Investigation of pharmaceutical residues and polybrominated diphenyl ethers in selected river estuaries and canal in Eastern Cape Province, South Africa

The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa.Thesis (PhD) -- Faculty of Science and Agriculture, 202

Investigation of pharmaceutical residues and polybrominated diphenyl ethers in selected river estuaries and canal in Eastern Cape Province, South Africa

The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa.Thesis (PhD) -- Faculty of Science and Agriculture, 202

Tracing back the source of contamination

From the time a contaminant is detected in an observation well, the question of where and when the contaminant was introduced in the aquifer needs an answer. Many techniques have been proposed to answer this question, but virtually all of them assume that the aquifer and its dynamics are perfectly known. This work discusses a new approach for the simultaneous identification of the contaminant source location and the spatial variability of hydraulic conductivity in an aquifer which has been validated on synthetic and laboratory experiments and which is in the process of being validated on a real aquifer

Sewage sludge as source of activated carbon for the removal of endocrine disrupting chemical in wastewater

Sewage sludge is an unavoidable consequence of wastewater treatment (WWT). Increasing legislation has propagated sludge production whilst limiting disposal options. WWT effluent contains many trace contaminants, one group of significant concern being endocrine disrupting chemicals (EDCs). Their removal is becoming a priority. Sludge is a potentially valuable material which offers opportunities for reuse and valorisation. This research has undertaken an in depth and rigorous study of the optimization of sludge carbonization and activation to produce inorganic-carbonaceous adsorbents akin to activated carbon. The resulting sludge based adsorbents (SBAs) have been comprehensively evaluated for their adsorption of EDCs using bisphenol A (BPA). This data has enabled a fundamental analysis of SBA-EDC adsorption processes and the proposal of an adsorption mechanism. SBA production using various European sludge types was undertaken, to produce high performance SBAs based on surface area (SA) and EDC adsorption. Key research findings were: • SBAs can be produced from most types of municipal sludge, except lime added sludge. • Carbonized or carbonized/steam activated SBAs presented low SA (270_m2/g) and BPA adsorption capacity (87 mg/g) when compared to chemically activated SBAs. • K2CO3 was the best chemical reagent in producing high SA up to 1979 m2/g and BPA adsorption of 714 mg/g. • FeCl3 is a very attractive chemical reagent in giving high BPA adsorption and SBA yield of 119_mg/g and 59.3_%, respectively. • Bisphenol A adsorption fitted well with Langmuir, Freundlich and Temkin equations with the best fit depending on the production conditions (temperature, time, activating reagent). • BPA adsorption by SBAs generally depend on SA and pore volume, with surface chemistry also influencing adsorption, especially for chemically activated SBAs. • The SBAs produced from K2CO3 activation outperformed all commercial activated carbons (CACs); the best SBA outperformed the best CAC by nearly 2-fold indicating the significant potential of SBAs as effective adsorbents for WWT effluents.Open Acces