Risk assessment for atmospheric environmental management: a case study in the Hunter Region of New South Wales,Australia

The theoretical framework of a risk assessment scheme is applied to air quality assessment in a developing region in Australia, the Hunter Valley in the state of New South Wales. It is found that the application of such a scheme high-lights a number of inadequacies in the air quality management. New modeling methodologies are found to be necessary to assess some air quality impacts, as existing knowledge is inadequate. The importance of extensive data bases is underlined as is the need for social surveys to supplement air pollution monitoring when gauging aesthetic effects of air pollutants.A visiting fellow on leave from the School of Australian Environmental Studies, Griffith University, Brisbane, Queensland, Australia.     

Fibrinopeptide a increases after Chorionic villus sampling

Fibrinopeptide levels were measured in 20 women during transcervical chorionic villus sampling (CVS). Fibrinopeptide A, a sensitive indicator of fibrinogen cleavage by thrombin, significantly increased in five subjects, whereas there was no change in Bβ peptide, an indicator of fibrinolysis. The data suggest that modest fibrin formation, uncompensated by fibrinolysis, may be induced in some women by CVS.     

Evaluation of diffusive samplers and photoionisation detectors for measuring very short peak exposures in the workplace

The extent to which very short peak widths, peak frequency, sampling time and post-sampling/pre-capping time impact upon occupational exposure measurements of toluene has been investigated using diffusive tubes. Additionally, the effect of the width of the peak on the estimation of peak maximum concentration and time-weighted average (TWA) concentration from real-time instruments (photoionisation detectors-PIDs) was also studied, and their responses modelled. No clear differences were perceived between diffusive and pumped tube results. Mean biases of -5 to +6% were recorded but no trend could be distinguished with respect to any of the variables examined; the main source of uncertainty was attributed to analytical uncertainty. The diffusive tubes can therefore be used to measure short term transient toluene concentrations (e.g. 5 s duration) over short (15 min) exposure periods. The two slower responding PIDs (t50 = 4 s) underestimated the maximum concentration of short term peaks having durations less than 10 s. The other three PIDs (t50 < or = 2 s) only significantly underestimated the maximum concentration of short term peaks having durations of 2 s and below. Pulse duration appeared to affect the PID's estimation of peak height more than peak area (TWA concentration).     

Natural variability and correlations in the metabolic profile of healthy Eisenia fetida earthworms observed using ¹H NMR metabolomics

¹H NMR metabolomics can be used to assess the sub-lethal toxicity of contaminants to earthworms by identifying alterations in the metabolic profiles of contaminant- exposed earthworms in contrast to those of healthy (control) individuals. In support of this method this study sought to better characterize the baseline metabolic profile of healthy, mature earthworms of the species, Eisenia fetida, which is recommended for both acute and sub-lethal toxicity testing for soil contaminants. Profiles of D₂O-buffer extracted metabolites were determined using ¹H NMR spectroscopy and both inter-individual metabolic variability and pair-wise metabolic correlations were assessed. The control earthworm extracts exhibited low overall inter-individual metabolic variability, with a spectrum-wide median relative standard deviation (%RSD = standard deviation/mean × 100) of 14%, which suggests that the metabolic profile of E. fetida earthworms is well controlled in laboratory conditions and supports further use of this organism in environmental metabolomics research. In addition, strong positive correlations were detected between the levels of maltose, betaine, glycine, and glutamate as well as between the levels of lactate, valine, leucine, alanine, lysine, tyrosine, and phenylalanine which had not previously been reported. Since comparison of pair-wise metabolic correlations between control and treated organisms can reveal changes in the underlying pattern of biochemical relationships between the metabolites, identification of these significant metabolic correlations in control earthworms provides an additional characteristic that may be applied to delineate between control and treated earthworms in future NMR-based metabolomic studies.     

Physico-chemical changes in metal-spiked sediments deployed in the field: implications for the interpretation of in situ studies

Manipulative field studies are useful for investigating cause-effect relationships between contamination and benthic community health. However, there are many challenges for creating environmentally relevant exposures and determining what measurements are necessary to correctly interpret the results. This study describes the physical and chemical changes in the properties of metal-spiked marine sediments deployed in four different locations for up to 11 months. The test sediments lost between 20% and 75% of their volume during the deployment period, with the greatest losses occurring at sites affected by strong hydrodynamic activity. More sediment was lost from clean treatments than those spiked with high metal concentrations and corresponded with differential recruitment of infauna to these treatments. In general, a greater proportion of spiked-metals remained at lower energy sites (48-85%) than at higher energy sites (15-48%). The decreased metal concentrations were attributed mostly to the loss of the metal-spiked sediments (through resuspension) and their dilution with sediments depositing from the surrounding environment. A range of recommendations are made for optimising the information gained from field-based studies using metal-spiked sediments. These include the careful documentation of physico-chemical sediment properties pre- and post-deployment, the use of co-located sediment traps and knowledge of site-specific hydrodynamic processes.     

Measuring atmospheric composition change

Scientific findings from the last decades have clearly highlighted the need for a more comprehensive approach to atmospheric change processes. In fact, observation of atmospheric composition variables has been an important activity of atmospheric research that has developed instrumental tools (advanced analytical techniques) and platforms (instrumented passenger aircrafts, ground-based in situ and remote sensing stations, earth observation satellite instruments) providing essential information on the composition of the atmosphere. The variability of the atmospheric system and the extreme complexity of the atmospheric cycles for short-lived gaseous and aerosol species have led to the development of complex models to interpret observations, test our theoretical understanding of atmospheric chemistry and predict future atmospheric composition. The validation of numerical models requires accurate information concerning the variability of atmospheric composition for targeted species via comparison with observations and measurements.In this paper, we provide an overview of recent advances in instrumentation and methodologies for measuring atmospheric composition changes from space, aircraft and the surface as well as recent improvements in laboratory techniques that permitted scientific advance in the field of atmospheric chemistry. Emphasis is given to the most promising and innovative technologies that will become operational in the near future to improve knowledge of atmospheric composition. Our current observation capacity, however, is not satisfactory to understand and predict future atmospheric composition changes, in relation to predicted climate warming. Based on the limitation of the current European observing system, we address the major gaps in a second part of the paper to explain why further developments in current observation strategies are still needed to strengthen and optimise an observing system not only capable of responding to the requirements of atmospheric services but also to newly open scientific questions.     

Accounting for both local aquatic community composition and bioavailability in setting site-specific quality standards for zinc

Recent years have seen considerable improvement in water quality standards (QS) for metals by taking account of the effect of local water chemistry conditions on their bioavailability. We describe preliminary efforts to further refine water quality standards, by taking account of the composition of the local ecological community (the ultimate protection objective) in addition to bioavailability. Relevance of QS to the local ecological community is critical as it is important to minimise instances where quality classification using QS does not reconcile with a quality classification based on an assessment of the composition of the local ecology (e.g. using benthic macroinvertebrate quality assessment metrics such as River InVertebrate Prediction and Classification System (RIVPACS)), particularly where ecology is assessed to be at good or better status, whilst chemical quality is determined to be failing relevant standards. The alternative approach outlined here describes a method to derive a site-specific species sensitivity distribution (SSD) based on the ecological community which is expected to be present at the site in the absence of anthropogenic pressures (reference conditions). The method combines a conventional laboratory ecotoxicity dataset normalised for bioavailability with field measurements of the response of benthic macroinvertebrate abundance to chemical exposure. Site-specific QS_ref are then derived from the 5%ile of this SSD. Using this method, site QS_ref have been derived for zinc in an area impacted by historic mining activities. Application of QS_ref can result in greater agreement between chemical and ecological metrics of environmental quality compared with the use of either conventional (QS_con) or bioavailability-based QS (QS_bio). In addition to zinc, the approach is likely to be applicable to other metals and possibly other types of chemical stressors (e.g. pesticides). However, the methodology for deriving site-specific targets requires additional development and validation before they can be robustly applied during surface water classification.     

Long-term copper partitioning of metal-spiked sediments used in outdoor mesocosms

Understanding the effects of sediment contaminants is pivotal to reducing their impact in aquatic environments. Outdoor mesocosms enable us to decipher the effects of these contaminants in environmentally realistic scenarios, providing a valuable link between laboratory and field experiments. However, because of their scale, mesocosm experiments are often complex to set up and manage. The creation of environmentally realistic conditions, particularly when using artificially contaminated sediment, is one issue. Here, we describe changes in geochemistry over 1.5 years of a sediment spiked with four different concentrations of copper, within a large freshwater mesocosm facility. The spiking procedure included proportional amendments with garden lime to counteract the decreases in pH caused by the copper additions. The majority of copper within the spiked mesocosm sediments partitioned to the particulate phase with low microgram per liter concentrations measured in the pore waters and overlying waters. The minimum partition coefficient following equilibration between pore waters and sediments was 1.5?×?10⁴ L/kg, which is well within the range observed for field-contaminated sediments (1?×?10⁴ to 1?×?10⁶ L/kg). Recommendations are made for the in situ spiking of sediments with metals in large outdoor mesocosms. These include selecting an appropriate sediment type, adjusting the pH, allowing sufficient equilibration time, and regular mixing and monitoring of metal partitioning throughout the experimental period.     

Investigation of insecticide leaching from potted nursery stock and aquatic health benefits of bioretention cells receiving nursery runoff

Tree nurseries and greenhouses within the USDA red imported fire ant (RIFA) quarantine zone are required to incorporate insecticides into their potting media to prevent artificial spread of RIFA. Bifenthrin and fipronil are two common insecticides that are incorporated into potting media. During irrigation and stormwater events, there is potential for insecticides to leach from nursery pots, resulting in the contamination of nearby surface waters. In this study, occurrences of insecticides in simulated nursery runoff were compared with two irrigation strategies and two types of containers in single pot leaching and field runoff simulations. In addition, toxicity of pot leachate to the aquatic invertebrate, Hyallela azteca, was measured, and removal efficiencies of insecticides from bioretention cell media were evaluated. Overhead irrigation resulted in significantly higher concentrations than drip irrigation, and RootMaker® pots allowed more leaching as compared to standard slick-wall pots. However, in all tests, the average concentration of bifenthrin during 15 days of leaching in both pot and field simulations was greater than 200 ng/L; more than 100-fold greater than the LC₅₀ for H. azteca. Toxicity studies confirmed this level of toxicity. Higher amounts of compost, 20 and 40 %, in bioretention cell media resulted in greater percent reduction of both bifenthrin and fipronil. This study determined that management techniques may be able to limit the amount of insecticide that leaches from pots and runs off to receiving water bodies. Specifically, the selection of appropriate pot types, irrigation strategies, or filtering runoff through bioretention cells may reduce contamination loads. Thus, further best management strategies such as the use of bioretention cells are needed in nursery and greenhouse facilities to prevent surface water runoff from transporting toxic insecticides.     

Challenges with tracing the fate and speciation of mine-derived metals in turbid river systems: implications for bioavailability

The fast-flowing and highly turbid Lagaip River (0.5–10 g/L suspended solids) in the central highlands of Papua New Guinea receives mine-derived metal inputs in both dissolved and particulate forms. Nearest the mine, metal concentrations in suspended solids were 360, 9, 90, 740 and 1,300 mg/kg for As, Cd, Cu, Pb and Zn, while dissolved concentrations were 2.7, 0.6, 3.1, 0.1 and 25 μg/L, respectively. This creates a significant metal exposure source for organisms nearer the mine. However, because the Lagaip River is diluted by a large number of tributaries, the extent to which mine-derived metals may affect biota in the lower catchments is uncertain. To improve our understanding of the forms of potentially bioavailable metals entering the lower river system, we studied the partitioning and speciation of metals within the Lagaip River system. Dissolved and particulate metal concentrations decreased rapidly downstream of the mine due to dilution from tributaries. As a portion of the particulate metal concentrations, the more labile dilute acid-extractable forms typically comprised 10–30 % for As and Pb, 50–75 % for Cu and Zn, and 50–100 % for Cd. Only dissolved Cd, Cu and Zn remained elevated relative to the non-mine-impacted tributaries (<0.03, 0.5 and 0.3 μg/L), but the concentrations did not appreciably change with increasing dilution downriver. This indicated that release of Cd, Cu and Zn was likely occurring from the more labile metal phases of the mine-derived particulates. Chelex-labile metal analyses and speciation modelling indicated that dissolved copper and lead were largely non-labile and likely complexed by naturally occurring organic ligands, while dissolved cadmium and zinc were predominantly present in labile forms. The study confirmed that mine-derived particulates may represent a significant source of dissolved metals in the lower river system; however, comparison with water quality guidelines indicates the low concentrations would not adversely affect aquatic life.