Julia Howitt

Deployment of DGT units in marine waters to assess the environmental risk from a deep sea tailings outfall

Measurements of total, filterable and DGT-labile concentrations of nine metals (Al, Cd, Cr, Cu, Fe, Pb, Mn, Ni and Zn) have been made at five sites up to 4.2km from a deep sea tailings outfall operated by Lihir Gold Ltd. at Lihir Island, Papua New Guinea. At each site, pairs of DGT units (one containing a 0.4mm and the other a 0.8mm diffusive gel layer) were deployed at three depths (50-70; 105-130; 135-155m) for 4-7 days. Comparison of predicted water column DGT-labile metal concentrations in field deployments showed the 0.8mm DGT units were relatively enriched in metals, with the effect being greatest closer to the outfall for Pb and Mn and least for Fe, Cr, Ni and Zn. The most likely explanation for this is that in addition to simple ion diffusion, kinetic factors associated with ageing or desorption processes govern release of metals from iron and aluminium oxyhydroxide colloids which diffuse through the gels. The thicker gels have a longer residence time over which metals can be released for adsorption. This model explains why enrichment is most pronounced near the outfall; more distant sites have lower colloid concentrations because of the longer time for coagulation to increase particle sizes to the extent they cannot enter the gels. Total and filterable metal (FM) concentrations were frequently below the limits of detection (LOD) achievable by conventional ICP-AES (1-52microgL(-1)) and this limited their usefulness for assessing environmental risk and for metal speciation determination. Because of its pre-concentration step DGT gave metal concentrations above their LODs and these decreased exponentially with distance from the outfall. Concentrations of DGT-labile metal fell below Australian water quality guidelines for protection of 99% of marine organisms within 0.13km of the outfall for Cd, Cr and Ni and below that for protection of 95% of marine organisms within 0.4, 0.7 and 3.6km for lead, zinc and copper, respectively.

Photodegradation, interaction with iron oxides and bioavailability of dissolved organic matter from forested floodplain sources

Photochemical degradation of dissolved organic matter (DOM) can influence food webs by altering the availability of carbon to microbial communities, and may be particularly important following periods of high DOM input (e.g. flooding of forested floodplains). Iron oxides can facilitate these reactions, but their influence on subsequent organic products is poorly understood. Degradation experiments with billabong (= oxbow lake) water and river red gum (Eucalyptus camaldulensis) leaf leachate were conducted to assess the importance of these reactions in floodplain systems. Photochemical degradation of DOM in sunlight-irradiated quartz tubes (with and without amorphous iron oxide) was studied using gas chromatography and UV-visible spectroscopy. Photochemical reactions generated gaseous products and small organic acids. Bioavailability of billabong DOM increased following irradiation, whereas that of leaf leachate was not significantly altered. Fluorescence excitation-emission spectra suggested that the humic component of billabong organic matter was particularly susceptible to degradation, and the source of DOM influenced the changes observed. The addition of amorphous iron oxide increased rates of photochemical degradation of leachate and billabong DOM. The importance of photochemical reactions to aquatic systems will depend on the source of the DOM and its starting bioavailability, whereas inputs of freshly formed iron oxides will accelerate the processes.

Hypoxia, Blackwater and Fish Kills: Experimental Lethal Oxygen Thresholds in Juvenile Predatory Lowland River Fishes

Hypoxia represents a growing threat to biodiversity in freshwater ecosystems. Here, aquatic surface respiration (ASR) and oxygen thresholds required for survival in freshwater and simulated blackwater are evaluated for four lowland river fishes native to the Murray-Darling Basin (MDB), Australia. Juvenile stages of predatory species including golden perch Macquaria ambigua, silver perch Bidyanus bidyanus, Murray cod Maccullochella peelii, and eel-tailed catfish Tandanus tandanus were exposed to experimental conditions of nitrogen-induced hypoxia in freshwater and hypoxic blackwater simulations using dried river red gum Eucalyptus camaldulensis leaf litter. Australias largest freshwater fish, M. peelii, was the most sensitive to hypoxia but given that we evaluated tolerances of juveniles (0.99±0.04 g; mean mass ±SE), the low tolerance of this species could not be attributed to its large maximum attainable body mass (>100,000 g). Concentrations of dissolved oxygen causing 50% mortality (LC50) in freshwater ranged from 0.25±0.06 mg l−1 in T. tandanus to 1.58±0.01 mg l−1 in M. peelii over 48 h at 25–26°C. Logistic models predicted that first mortalities may start at oxygen concentrations ranging from 2.4 mg l−1 to 3.1 mg l−1 in T. tandanus and M. peelii respectively within blackwater simulations. Aquatic surface respiration preceded mortality and this behaviour is documented here for the first time in juveniles of all four species. Despite the natural occurrence of hypoxia and blackwater events in lowland rivers of the MDB, juvenile stages of these large-bodied predators are vulnerable to mortality induced by low oxygen concentration and water chemistry changes associated with the decomposition of organic material. Given the extent of natural flow regime alteration and climate change predictions of rising temperatures and more severe drought and flooding, acute episodes of hypoxia may represent an underappreciated risk to riverine fish communities.

A rapid method for the simultaneous quantification of the major tocopherols, carotenoids, free and esterified sterols in canola (Brassica napus) oil using normal phase liquid chromatography

A normal phase high performance liquid chromatography (HPLC) method was developed to simultaneously quantify several prominent bioactive compounds in canola oil vis. α-tocopherol, γ-tocopherol, δ-tocopherol, β-carotene, lutein, β-sitosterol, campesterol and brassicasterol. The use of sequential diode array detection (DAD) and tandem mass spectrometry (MS/MS) allowed direct injection of oils, diluted in hexane without derivatisation or saponification, greatly reducing sample preparation time, and permitting the quantification of both free sterols and intact sterol esters. Further advantages over existing methods included increased analytical selectivity, and a chromatographic run time substantially less than other reported normal phase methods. The HPLC-DAD-MS/MS method was applied to freshly extracted canola oil samples as well as commercially available canola, palm fruit, sunflower and olive oils.

Urban stormwater inputs to an adapted coastal wetland: role in water treatment and impacts on wetland biota.

The Lake Pertobe wetland system is a semi-natural wetland that has been modified primarily for recreational use. However, this lake system receives stormwater from much of the central business district of Warrnambool City (Victoria, Australia) and serves as a buffer zone between the stormwater system and the Merri River and Merri Marine Sanctuary. This work considers the impact of stormwater inputs on Lake Pertobe and the effectiveness of the lake in protecting the associated marine sanctuary. Sediment contaminants (including heavy metals and polycyclic aromatic hydrocarbons (PAHs)) and water quality parameters within the lake, groundwater and stormwater system were measured. Water quality parameters were highly variable between stormwater drains and rain events. Suspended solids rapidly settled along open drains and shortly after entering the lake. Groundwater inputs increased both salinity and dissolved nitrogen in some stormwater drains. Some evidence of bioaccumulation of metals in the food chain was identified and sediment concentrations of several PAHs were very high. The lake acted as a sink for PAHs and some metals and reductions in Escherichia coli, biological oxygen demand and total phosphorus were observed, affording some protection to the associated marine sanctuary. Nutrient retention was inadequate overall and it was identified that managing the lake primarily as a recreational facility impacted on the effectiveness of stormwater treatment in the system.

Pore Mn2+ dynamics of the rhizosphere of flooded and non-flooded rice during a long wet and drying phase in two rice growing soils

Flooded rice soils produce elevated concentrations of soluble manganous manganese (Mn(2+)) that could be potentially toxic to subsequent crops. To provide insight into how soil pore Mn(2+) changes its concentration in a rice and post rice drying soil, we used an artificial microcosm system to follow Mn(2+) concentrations in two different soil types (red sodosol and grey vertosol) and under two irrigation regimes (flooded and saturated). Soil pore water was collected from four different depths of soil (2.5 cm, 7.5 cm, 15 cm and 25 cm) and Mn(2+) concentrations were analysed during and after the rice phase over a one year cycle. Mn(2+) increased with the advancement of anaerobic conditions at all soil depths, but the concentration was higher in flooded soil compared to saturated soil. Initially, the highest concentration of Mn(2+) was found at a depth of 7.5 cm, while at the later stage of rice growth, more Mn(2+) was found in the deepest sampling depth (25 cm). Plants grown in saturated soils showed a delay in flowering of approximately 3 weeks compared to flooded cultures. Moreover, plants grown in flooded soil produced more tillers and leaf area than those grown in saturated soil. Peak concentrations of soil Mn(2+) were associated with the reproductive stage of rice growth. Mn(2+) concentrations decreased after drainage of water. In post rice soils, Mn(2+) remained elevated for some time (lag phase), and then rapidly declined. Regression analysis revealed that the process of oxidation of Mn(2+) to Mn(4+) following water drainage decreased with soil depth.

The presence of licit and illicit drugs in police stations and their implications for workplace drug testing

The presence of licit and illicit drug residues on surfaces was studied in 10 police stations and a central drug evidence store in New South Wales, Australia, with the results compared to similar surfaces in four public buildings (to establish a community baseline). The results of almost 850 workplace surface swabs were also compared to the outcome of drug analysis in urine and hair samples volunteered by police officers. Surfaces were swabbed with alcohol and the swabs were extracted and analysed by LC-MS/MS. Low level concentrations of the more commonly used drugs were detected at four public sites and one restricted access police office facility. Surface swabs taken in 10 city and country police stations yielded positive results for a broader suite of drugs than at background sites however 75-93% of the positive drug results detected in police stations were below 40ng, which is only slightly greater than the largest background result measured in the current study. This study indicates that contamination issues are more likely to be focussed in higher risk areas in police stations, such as counters and balances in charge areas, and surfaces within drug safes although front reception counters also returned surface contamination. All 64 urine samples collected in this study were negative, while only 2 of the 11 hair samples collected from donors resulted in trace concentrations for cocaine, but not its metabolite benzoylecgonine. Positive hair samples were only obtained from police donors in very high risk jobs, indicating that the exposure risk is low. Minor changes to the materials used as work surfaces, and some procedural changes in police stations and large evidence stores are suggested to decrease the likelihood of drugs contaminating work surfaces, thereby reducing the potential exposure of police officers to drugs in the workplace.

Quantification of licit and illicit drugs on typical police station work surfaces using LC-MS/MS

Licit and illicit drug use is widespread in the community and as a result, drug residues can be transferred onto handles and work surfaces in shared places. Police officers are more likely than members of the public to encounter drug residues while performing their work duties. As a result, sampling and analysis methodology must be developed to assess their work environments to determine which drug residues are present, at what concentration, and how long they may persist on the work surface to attempt to determine whether the residues pose a risk. The following reports a method for determining residues on work surfaces using cotton swabs, solvent extraction and analysis with LC-MS/MS. LC column type, swab extraction time, solvent composition, and analyte suppression were investigated. The reported method is simple, allows high throughput at low cost, simultaneously analyses for 23 licit and illicit drugs and metabolites, and has the scope for inclusion of additional analytes. Additionally, the method could be adapted easily to suit other organic chemicals, such as pesticides. The optimised method was used to investigate the persistence of 23 drugs and metabolites on five different surface types commonly found in police stations, under both dark and illuminated incubation conditions. The results demonstrated that different drugs within a given class can have dramatically different rates of loss, and general predictions cannot be made for other drugs in the same class. Illuminated incubation conditions generally accelerated the loss of drugs on surfaces, either by enhanced volatilisation, photocatalysis, or a combination of both. Only drugs such as amphetamine, methamphetamine and ketamine deviated from this trend because their disappearance from all surfaces under both incubation conditions was so rapid that no real difference was observed.

Work place drug testing of police officers after THC exposure during large volume cannabis seizures

Police officers responsible for the seizure and removal of illegally grown cannabis plants from indoor and outdoor growing operations face the prospect of THC exposure while performing their work duties. As a result, a study investigating the amount of THC on hands and uniforms of officers during raids on cannabis growing houses (CGHs) and forest cannabis plantations (FCPs) and in the air at these sites was conducted. Swabs of gloves/hands, chests, and heads/necks were collected and analysed for THC. Results of hand swabs indicated that officers removing plants from FCPs were exposed to THC concentrations up to 20 times those involved in raids at CGHs, which was mainly associated with the number and size of plants seized. Air samples collected inside cannabis houses showed no detectable THC. Air samples collected inside the cargo area of the storage trucks used during FCP raids indicated that THC can be volatilised when lush plants are compressed by other seized plants loaded on top of them in the truck over a period of several days, allowing composting of plants at the bottom of the load to commence. The elevated temperature and humidity inside the truck may assist the decarboxylation of THCA to THC, as well as increasing the rate of volatilisation of THC. More than 100 urine samples were collected from officers in raids on both CGHs and FCPs and all tested negative for THC. Removal of cannabis plants by officers often resulted in cuts, abrasions and ruptured blisters on exposed skin surfaces, particularly at FCPs. The results in this study suggest that even when small areas of damaged skin are directly exposed to THC by contact transfer, the likelihood of showing a positive THC urine test is low.

Adaptive Management of Environmental Flows: Using Irrigation Infrastructure to Deliver Environmental Benefits During a Large Hypoxic Blackwater Event in the Southern Murray–Darling Basin, Australia

Widespread flooding in south-eastern Australia in 2010 resulted in a hypoxic (low dissolved oxygen, DO) blackwater (high dissolved carbon) event affecting 1800 kilometres of the Murray–Darling Basin. There was concern that prolonged low DO would result in death of aquatic biota. Australian federal and state governments and local stakeholders collaborated to create refuge areas by releasing water with higher DO from irrigation canals via regulating structures (known as ‘irrigation canal escapes’) into rivers in the Edward–Wakool system. To determine if these environmental flows resulted in good environmental outcomes in rivers affected by hypoxic blackwater, we evaluated (1) water chemistry data collected before, during and after the intervention, from river reaches upstream and downstream of the three irrigation canal escapes used to deliver the environmental flows, (2) fish assemblage surveys undertaken before and after the blackwater event, and (3) reports of fish kills from fisheries officers and local citizens. The environmental flows had positive outcomes; mean DO increased by 1–2 mg L−1 for at least 40 km downstream of two escapes, and there were fewer days when DO was below the sub-lethal threshold of 4 mg L−1 and the lethal threshold of 2 mg L−1 at which fish are known to become stressed or die, respectively. There were no fish deaths in reaches receiving environmental flows, whereas fish deaths were reported elsewhere throughout the system. This study demonstrates that adaptive management of environmental flows can occur through collaboration and the timely provision of monitoring results and local knowledge.