In situ exposures using caged organisms: a multi-compartment approach to detect aquatic toxicity and bioaccumulation

An in situ toxicity and bioaccumulation assessment approach is described to assess stressor exposure and effects in surface waters (low and high flow), the sediment-water interface, surficial sediments and pore waters (including groundwater upwellings). This approach can be used for exposing species, representing major functional and taxonomic groups. Pimephales promelas, Daphnia magna, Ceriodaphnia dubia, Hyalella azteca, Hyalella sp., Chironomus tentans, Lumbriculus variegatus, Hydra attenuatta, Hexagenia sp. and Baetis tibialis were successfully used to measure effects on survival, growth, feeding, and/or uptake. Stressors identified included chemical toxicants, suspended solids, photo-induced toxicity, indigenous predators, and flow. Responses varied between laboratory and in situ exposures in many cases and were attributed to differing exposure dynamics and sample-processing artifacts. These in situ exposure approaches provide unique assessment information that is complementary to traditional laboratory-based toxicity and bioaccumulation testing and reduce the uncertainties of extrapolating from the laboratory to field responses.     

Effects of beach sand properties, temperature and rainfall on the degradation rates of oil in buried oil/beach sand mixtures

Lysimeters located outdoors have been used to evaluate the decomposition of buried oily beach sand waste (OBS) prepared using Forties light crude oil and sand from different locations around the British coast. The OBS (5% oil by weight) was buried as a 12-cm layer over dune pasture sub-sand and overlain by 20 cm of dune pasture topsoil. Decomposition rates of oil residues averaged 2300 kg ha(-1) in the first year and the pattern of oil decomposition may be represented by a power curve. Oil decomposition was strongly related to the temperature in the OBS layer, but was also significantly affected by rainfall in the previous 12 h. The CO(2) flux at the surface of the treatment lysimeters followed the relationship [log(10) CO(2) (mg C m(-2) h(-1))=0.93+0.058x OBS temp. (degrees C)-0.042x12 h rain (mm)]. There was considerable variation in the rate of oil decomposition in sands collected from different sites. Sand from Askernish supported most microbial activity whilst sand from Tain was relatively inactive. The decomposition process appeared to cease when the sand became saturated with water, i.e. temporarily anaerobic. However, decomposition recommenced when the soil dried out. The fastest rate of decomposition occurred in sand from one of the two sites predicted to have high populations of hydrocarbon-degrading bacteria. Larger particle size and higher Ca content may also be significant factors governing the rate of decomposition.     

Movement of petroleum hydrocarbons in sandy coastal soils

In a field trial, oiled beach sand was buried in a coastal dune system in south Wales. A monitoring programme was designed to assess the rate of leaching of inorganic ions and hydrocarbons from the deposit. Active breakdown of the weathered oil occurred within the oiled beach sand, but hydrocarbons from the original material, or arising as a result of degradation, did not follow the same leaching pattern as inorganic ions; they remained within the original deposit. The results suggest that weathered oil coming ashore from spills at sea can be mixed with sand and buried to degrade in coastal soils, without risk of groundwater contamination by hydrocarbons.     

Elemental and spectroscopic characterization of fractions of an acidic extract of oil sands process water

‘Naphthenic acids’ (NAs) in petroleum produced water and oil sands process water (OSPW), have been implicated in toxicological effects. However, many are not well characterized. A method for fractionation of NAs of an OSPW was used herein and a multi-method characterization of the fractions conducted.     

Monocyclic and monoaromatic naphthenic acids: synthesis and characterisation

Characterisation of the complex mixtures of carboxylic acids (naphthenic acids) occurring in crude oils and in degraded oil sands is environmentally important. Indeed some acids in waters from oil platforms are apparently hormonally active, and the oil sands acids are said to be toxic to a wide range of biota. Previous attempts to identify monocyclic and monoaromatic naphthenic acids have been hampered by the lack of authenticated synthetic reference compounds. Some studies have indicated that acids with ethanoic acid side chains are present in the naphthenic acids mixtures, so in the present study, we synthesised and characterised by mass spectrometry, a range (C_8–14) of monoaromatic and monocyclic ethanoic acids. Using 2-D comprehensive gas chromatography–mass spectrometry, we then compared the retention times and mass spectra of the synthetic acids with those of a commercial naphthenic acids mixture. Some alicyclic and numerous aromatic acids were successfully identified.     

Abundances and variability of tropospheric volatile organic compounds at the South Pole and other Antarctic locations

Multiyear (2000–2006) seasonal measurements of carbon monoxide, hydrocarbons, halogenated species, dimethyl sulfide, carbonyl sulfide and C₁–C₄ alkyl nitrates at the South Pole are presented for the first time. At the South Pole, short-lived species (such as the alkenes) typically were not observed above their limits of detection because of long transit times from source regions. Peak mixing ratios of the longer lived species with anthropogenic sources were measured in late winter (August and September) with decreasing mixing ratios throughout the spring. In comparison, compounds with a strong oceanic source, such as bromoform and methyl iodide, had peak mixing ratios earlier in the winter (June and July) because of decreased oceanic production during the winter months. Dimethyl sulfide (DMS), which is also oceanically emitted but has a short lifetime, was rarely measured above 5 pptv. This is in contrast to high DMS mixing ratios at coastal locations and shows the importance of photochemical removal during transport to the pole. Alkyl nitrate mixing ratios peaked during April and then decreased throughout the winter. The dominant source of the alkyl nitrates in the region is believed to be oceanic emissions rather than photochemical production due to low alkane levels.Sampling of other tropospheric environments via a Twin Otter aircraft included the west coast of the Ross Sea and large stretches of the Antarctic Plateau. In the coastal atmosphere, a vertical gradient was found with the highest mixing ratios of marine emitted compounds at low altitudes. Conversely, for anthropogenically produced species the highest mixing ratios were measured at the highest altitudes, suggesting long-range transport to the continent. Flights flown through the plume of Mount Erebus, an active volcano, revealed that both carbon monoxide and carbonyl sulfide are emitted with an OCS/CO molar ratio of 3.3 × 10^?3 consistent with direct observations by other investigators within the crater rim.     

Key issues in the conservation of the Australian coastal archaeological record: natural and human impacts

Australia has an extensive coastline extending over 60,000 km through diverse tropical and temperate environments. Indigenous archaeological sites are found along this coastline from the time of earliest settlement at least 50,000 years ago. However, Pleistocene sites are rare owing largely to the destructive impacts of sea-level change associated with the end of the last ice age around 10,000 years ago. After this sites are more numerous but there is variability around the coastline due to the impact of a range of both natural and human factors. Here we focus on six key issues impacting on the development and conservation of coastal archaeological deposits: sea-levels, climate change, cyclones, storms, tsunamis and contemporary human impacts. A number of examples of these impacts are discussed from across Australia. Managing and monitoring of sites has been limited in Australia and geoindicators are discussed as a means of developing a long-term measurement of continuing impacts.     

The Nutrient Status of Some Graminaceous Species in Britain. 1. Molinia Caerulea (L.) Moench

Above-ground biomass biomass of Molinia caerulea from 36 sites throughout Britain was analysed for concentrations of elements (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn and Na), with matching analyses of soil nutrients, together with pH and LOI. Between-year and seasonal variation in the nutrients was also studied at one of the sites. the grass was found on acid sites ranging between pH 3.1 and 5.8. the soil humus content varied widely, and there were significant correlations between that and elements (N, P, K, Ca, Mg and Na) in the soil. Concentrations of calcium, magnesium, zinc and manganese in the plant material were significantly correlated with extractable levels in the soils. Between year variation in the plant nutrient concentrations at one site was of a similar order to variation between the sites. Generally there was less variation in nitrogen, phosphorus and potassium tissue levels than in calcium, magnesium, zinc and copper. Iron and sodium were the most variable. Tissue concentrations of nitrogen, phosphorus, potassium and copper declined throughout the growing season, whereas magnesium, calcium and iron built up until August/September after which a decline set in as the leaves senesced. the results are discussed in relation to the importance of standardizing the time of sampling, in comparison with concentrations of tissue levels in other plants and the growth strategy of this deciduous grass.     

Performance of Greater Sage-Grouse Models for Conservation Assessment in the Interior Columbia Basin, U.S.A.

Abstract: Valid modeling of habitats and populations of Greater Sage-Grouse ( Centrocercus urophasianus) is a critical management need because of increasing concern about population viability. Consequently, we evaluated the performance of two models designed to assess landscape conditions for Greater Sage-Grouse across 13.6 million ha of sagebrush steppe in the interior Columbia Basin and adjacent portions of the Great Basin of the western United States (referred to as the basin). The first model, the environmental index model, predicted conditions at the scale of the subwatershed (mean size of approximately 7800 ha) based on inputs of habitat density, habitat quality, and effects of human disturbance. Predictions ranged on a continuous scale from 0 for lowest environmental index to 2 for optimal environmental index. The second model, the population outcome model, predicted the composite, range-wide conditions for sage grouse based on the contribution of environmental index values from all subwatersheds and measures of range extent and connectivity. Population outcomes were expressed as five classes (A through E) that represented a gradient from continuous, well-distributed populations (outcome A) to sparse, highly isolated populations with a high likelihood of extirpation (outcome E). To evaluate performance, we predicted environmental index values and population outcome classes in areas currently occupied by sage grouse versus areas where extirpation has occurred. Our a priori expectations were that models should predict substantially worse environmental conditions ( lower environmental index) and a substantially higher probability of extirpation ( lower population outcome class) in extirpated areas. Results for both models met these expectations. For example, a population outcome of class E was predicted for extirpated areas, as opposed to class C for occupied areas. These results suggest that our models provided reliable landscape predictions for the conditions tested. This finding is important for conservation planning in the basin, where the models were used to evaluate management of federal lands for sage grouse.     

A guide to representing variability and uncertainty in biodiversity indicators

Biodiversity indicators are used to inform decisions and measure progress toward global targets, such as the United Nations Sustainable Development Goals. Indicators aggregate and simplify complex information, so underlying information influencing its reliability and interpretation (e.g., variability in data and uncertainty in indicator values) can be lost. Communicating uncertainty is necessary to ensure robust decisions and limit misinterpretations of trends, yet variability and uncertainty are rarely quantified in biodiversity indicators. We developed a guide to representing uncertainty and variability in biodiversity indicators. We considered the key purposes of biodiversity indicators and commonly used methods for representing uncertainty (standard error, bootstrap resampling, and jackknife resampling) and variability (quantiles, standard deviation, median absolute deviation, and mean absolute deviation) with intervals. Using 3 high-profile biodiversity indicators (Red List Index, Living Planet Index, and Ocean Health Index), we tested the use, suitability, and interpretation of each interval method based on the formulation and data types underpinning the indicators. The methods revealed vastly different information; indicator formula and data distribution affected the suitability of each interval method. Because the data underpinning each indicator were not normally distributed, methods relying on normality or symmetrical spread were unsuitable. Quantiles, bootstrapping, and jackknifing provided useful information about the underlying variability and uncertainty. We built a decision tree to inform selection of the appropriate interval method to represent uncertainty or variation in biodiversity indicators, depending on data type and objectives. Our guide supports transparent and effective communication of biodiversity indicator trends to facilitate accurate interpretation by decision makers.