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A high-resolution, multi-proxy approach is utilized on mm- to cm-scale laminated coastal salt pond sediments from St. John, U.S. Virgin Islands, to determine: (1) the sedimentological signature of depositional events/processes, (2) link this sedimentological signature with known depositional events/processes in the historical (past ~100 years) record; and, (3) project back into the recent geologic past (past ~1400 years) to investigate the natural variability of depositional events/processes. High-resolution, short-lived radioisotope geochronology (210Pb, 137Cs, 7Be) combined with high-resolution elemental scanning techniques (scanning XRF and scanning LA-ICP-MS) allows for the direct comparison of well-preserved salt pond deposits to historical records of depositional events (e.g., runoff/rainfall, tropical cyclones, tsunamis) to identify the sedimentary signature of each type of event. There is a robust sedimentary record of terrigenous sediment runoff linked to the frequency of rainfall events that exceed a threshold of ~12 mm/day (minimum to mobilize and transport sediment) for study sites. This is manifested in the sedimentary record as increases in terrigenous indicator elements (%Al, %Fe, %Ti, %Si), which agree well with rainfall records over the past ~50 years. Variability in the sedimentary record over the past ~100 years reflects decadal-scale fluctuations between periods of increased frequency of rainfall events, and decreased frequency of rainfall events. Dm-scale variability in terrigenous indicator elements over the past ~1400 years represents the natural system variability on a decadal–centennial scale, and provides a high-resolution, long-term baseline of natural variability of rainfall/runoff events. A period of increased terrigenous sediment delivery during the 1700s and 1800s likely indicates increased erosion in response to anthropogenic activities associated with the island’s plantation era, and perhaps increased frequency of rainfall events.

A high-resolution, multi-proxy approach is utilized on mm- to cm-scale laminated coastal salt pond sediments from St. John, U.S. Virgin Islands, to determine: (1) the sedimentological signature of depositional events/processes, (2) link this sedimentological signature with known depositional events/processes in the historical (past ~100 years) record; and, (3) project back into the recent geologic past (past ~1400 years) to investigate the natural variability of depositional events/processes. High-resolution, short-lived radioisotope geochronology (210Pb, 137Cs, 7Be) combined with high-resolution elemental scanning techniques (scanning XRF and scanning LA-ICP-MS) allows for the direct comparison of well-preserved salt pond deposits to historical records of depositional events (e.g., runoff/rainfall, tropical cyclones, tsunamis) to identify the sedimentary signature of each type of event. There is a robust sedimentary record of terrigenous sediment runoff linked to the frequency of rainfall events that exceed a threshold of ~12 mm/day (minimum to mobilize and transport sediment) for study sites. This is manifested in the sedimentary record as increases in terrigenous indicator elements (%Al, %Fe, %Ti, %Si), which agree well with rainfall records over the past ~50 years. Variability in the sedimentary record over the past ~100 years reflects decadal-scale fluctuations between periods of increased frequency of rainfall events, and decreased frequency of rainfall events. Dm-scale variability in terrigenous indicator elements over the past ~1400 years represents the natural system variability on a decadal–centennial scale, and provides a high-resolution, long-term baseline of natural variability of rainfall/runoff events. A period of increased terrigenous sediment delivery during the 1700s and 1800s likely indicates increased erosion in response to anthropogenic activities associated with the island’s plantation era, and perhaps increased frequency of rainfall events.

Characterisation of the concentrations and potential health risks of chemicals in recycled water is important if this source of water is to be safely used to supplement drinking water sources. This research was conducted to: (i) determine the concentration of volatile organic compounds (VOCs) in secondary treated effluent (STE) and, post-reverse osmosis (RO) treatment and to; (ii) assess the health risk associated with VOCs for indirect potable reuse (IPR). Samples were examined pre and post-RO in one full-scale and one pilot plant in Perth, Western Australia. Risk quotients (RQ) were estimated by expressing the maximum and median concentration as a function of the health value. Of 61 VOCs analysed over a period of three years, twenty one (21) were detected in STE, with 1,4-dichlorobenzene (94%); tetrachloroethene (88%); carbon disulfide (81%) and; chloromethane (58%) most commonly detected. Median concentrations for these compounds in STE ranged from 0.81 μg/L for 1,4-dichlorobenzene to 0.02 μg/L for carbon disulphide. After RO, twenty six (26) VOCs were detected, of which 1,4-dichlorobenzene (89%); acrylonitrile (83%) chloromethane (63%) and carbon disulfide (40%) were the more frequently detected. RQ(max) were all below health values in the STE and after RO. Median removal efficiency for RO was variable, ranging from −77% (dichlorodifluoromethane) to 91.2% (tetrachloroethene).The results indicate that despite the detection of VOCs in STE and after RO, their human health impact in IPR is negligible due to the low concentrations detected. The results indicate that 1,4-dichlorobenzene is a potential treatment chemical indicator for assessment of VOCs in IPR using RO treatment.

Hyperthermal polyatomic fluorocarbon (FC) deposition upon the diamond (111) surface is simulated and analyzed at several levels of computational theory. Classical molecular dynamics simulations using the reactive empirical bond order (REBO) potential are used to categorize the surface reactions that occur during radical deposition. Molecular dynamics (MD) simulations, using density functional theory (DFT-MD) via the SIESTA method and program, are used to corroborate the findings from the classical simulations and to categorize reactions that occur during cation deposition. Finally, reaction enthalpies are calculated with higher level quantum mechanical methods using a cluster model to verify and refine the predictions from the MD simulations. The multilevel analysis predicts that FC radicals add directly to the diamond (111) surface with the simultaneous formation of HF. In contrast, FC cations preferentially dissociate H from the surface leaving behind a cationic carbon site. Cations and radical species are found to prefer different reaction pathways, which limits the applicability of REBO. Furthermore, the comparison reveals a difference in the predicted reaction probabilities between REBO and DFT which is attributable to the short cut off distance for interaction in the current REBO formulation.

An assessment of potential health impacts of dioxin and dioxin-like compounds in recycled water for indirect potable reuse was conducted. Toxic equivalency factors (TEFs) for 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) congeners have been developed by the World Health Organization to simplify the risk assessment of complex mixtures. Samples of secondary treated wastewater in Perth, Australia were examined pre-and post-tertiary treatment in one full-scale and one pilot water reclamation plant. Risk quotients (RQs) were estimated by expressing the middle-bound toxic equivalent (TEQ) and the upper-bound TEQ concentration in each sampling point as a function of the estimated health target value. The results indicate that reverse osmosis (RO) is able to reduce the concentration of PCDD, PCDF and dioxin-like PCBs and producewater of high quality (RQ after RO=0.15). No increased human health risk from dioxin and dioxin-like compounds is anticipated if highly treated recycled water is used to augment drinking water supplies in Perth. Recommendations for a verification monitoring program are offered.

There are no evidence-based guidelines for the management of accidental faecal releases (AFR) in Australia. A pilot study conducted with public swimming complexes chosen based upon their level of risk during the peak usage periods. Staff who were responsible for water management were involved in the pilot study (n=9 staff members). Data collection was conducted over a four-week period. Each complex had an average of two AFR per week over the past 12 months. It was not uncommon for each complex to have at least one AFR each day over the summer period. In fact, one complex recorded seven AFR in one day in the previous month. The areas most at risk of contamination in each complex were smaller pools (used mainly by toddlers and infants) and hydrotherapy pools. The staff involved in the pilot project indicated their support for the study outcomes as providing a standardised way to effectively and efficiently deal with AFR in public recreational water environments.

There have been numerous reports of swimming pool-associated outbreaks of Cryptosporidiosis and Giardiasis worldwide, including Australia. It is essential to ensure that effective measures are in place to manage faecal contamination incidents, the primary source of contamination of these pathogens in public swimming pools. There are no evidence-based guidelines for the management of faecal contamination incidents (FCI) in public swimming pools in Australia. The aim of the study is to develop, implement and evaluate guidelines to reduce the public health risk associated with Cryptosporidium and Giardia in public swimming pools in Australia. This research is particularly important both nationally and internationally as the endemic of Cryptosporidium and Giardia is increasing significantly. It is estimated that half of all Indigenous children are affected by these pathogens which can cause long-term disability or death. A random sample of public swimming pools from metropolitan, rural and remote Western Australia will be recruited into the study to assess the effectiveness of guidelines to minimize the risk associated with faecal contamination incidents (FCI). This paper will outline the piloting of these guidelines in two public swimming pools during 2004.