The use of sedimentary metal data in predictive modelling of estuarine contamination,assessment of environmental condition and pollutant source identification (Narrabeen Lagoon,Sydney, Australia)

Environmental Science and Pollution Research - Narrabeen Lagoon is recognized as an Intermittently Closed and Open Lake or Lagoon (ICOLL) and is the largest coastal lagoon (2.2 km2) in the...     

Effects of prolonged microscopic work on neck and back strain amongst male ENT clinicians and the benefits of a prototype postural support chair

Musculoskeletal pain is a common occupational hazard experienced by surgeons. Ear, nose and throat (ENT) surgeons are predisposed to neck and back pain due to regular prolonged microscopic work. We conducted a prospective pilot study to investigate the effects of sustained microscopic work on the neck and back, its correlation to surgical experience and to assess the benefits of a prototype postural support chair (PSC) amongst 10 male, ENT clinicians. We used a subjective measure of time to fatigue and pain for the neck and back as well as objective readings from a surface electromyogram (sEMG). We found that an increase in surgical experience correlated with the time taken to experience fatigue and pain in the neck and back. This was corroborated by our sEMG findings. The PSC significantly delayed the sensations in the neck and also eliminated the difference seen amongst the varying seniority of clinicians.     

How Climate and Vegetation Influence the fire Regime of the Alaskan Boreal Biome: The Holocene Perspective

We synthesize recent results from lake-sediment studies of Holocene fire-climate-vegetation interactions in Alaskan boreal ecosystems. At the millennial time scale, the most robust feature of these records is an increase in fire occurrence with the establishment of boreal forests dominated by Picea mariana: estimated mean fire-return intervals decreased from ≥300 yrs to as low as ∼80 yrs. This fire-vegetation relationship occurred at all sites in interior Alaska with charcoal-based fire reconstructions, regardless of the specific time of P. mariana arrival during the Holocene. The establishment of P. mariana forests was associated with a regional climatic trend toward cooler/wetter conditions. Because such climatic change should not directly enhance fire occurrence, the increase in fire frequency most likely reflects the influence of highly flammable P. mariana forests, which are more conducive to fire ignition and spread than the preceding vegetation types (tundra, and woodlands/forests dominated by Populus or Picea glauca). Increased lightning associated with altered atmospheric circulation may have also played a role in certain areas where fire frequency increased around 4000 calibrated years before present (BP) without an apparent increase in the abundance of P. mariana. When viewed together, the paleo-fire records reveal that fire histories differed among sites in the same modern fire regime and that the fire regime and plant community similar to those of today became established at different times. Thus the spatial array of regional fire regimes was non-static through the Holocene. However, the patterns and causes of the spatial variation remain largely unknown. Advancing our understanding of climate-fire-vegetation interactions in the Alaskan boreal biome will require a network of charcoal records across various ecoregions, quantitative paleoclimate reconstructions, and improved knowledge of how sedimentary charcoal records fire events. In this paper, charcoal refers to macroscopic (≥180 μm) as opposed to microscopic (< 180 μm) particles unless indicated otherwise. Radiocarbon ages were converted to calibrated years before AD 1950 using the atmospheric calibration data set (Stuiver et al. 1998).     

Towards a better understanding of tetrachloroethene entry pressure in the matrix of Permo-Triassic sandstones

The pressure required for a chlorinated solvent to enter a geological medium can be calculated given knowledge of the characteristic pore size of the medium and the interfacial tension (IFT) and contact angle of the solvent-water-rock system. Using a centrifuge-based method, capillary pressure-saturation curves have been determined for 30 water-saturated samples of Permo-Triassic sandstones for the solvent tetrachloroethene (PCE). These curves have been successfully fitted using the van Genuchten function to determine PCE entry pressure for each of the sandstone samples. A plot of PCE entry pressures against average pore diameter shows a linear relationship in log-log space; however, observed values for PCE entry pressure are significantly lower than would be expected theoretically for a sandstone-PCE-water system. This may be explained either by a decrease in the IFT or an increase in the contact angle. The IFT may decrease during contact with sandstones due to hysteresis effects during imbibition and drainage of fluids, but this is unlikely to be sufficient to account for the low entry pressures observed. Therefore, it is inferred that the low observed PCE entry pressures are due to higher than expected PCE contact angles, and that the average pore-throat surface of the sandstones is more solvent wetting than would be expected. A weak acid extraction indicates the presence of calcite and dolomite in the sandstone cores, and a correlation is observed between carbonate content per unit porosity and a reduction in PCE entry pressure. It is suggested that these mineral phases are responsible for observed wettability changes and a conceptual model is proposed. One consequence of the lower observed entry pressures is that solvents are likely to penetrate deeper into the matrix of water-saturated sandstones than previously expected.     

Application of Sediment Quality Guidelines in the Assessment and Management of Contaminated Surficial Sediments in Port Jackson (Sydney Harbour), Australia

Sediments in the Port Jackson estuary are polluted by a wide range of toxicants and concentrations are among the highest reported for any major harbor in the world. Sediment quality guidelines (SQGs), developed by the National Oceanographic and Atmospheric Administration (NOAA) in the United States are used to estimate possible adverse biological effects of sedimentary contaminants in Port Jackson to benthic animals. The NOAA guidelines indicate that Pb, Zn, DDD, and DDE are the most likely contaminants to cause adverse biological effects in Port Jackson. On an individual chemical basis, the detrimental effects due to these toxicants may occur over extensive areas of the harbor, i.e., about 40%, 30%, 15% and 50%, respectively. The NOAA SQGs can also be used to estimate the probability of sediment toxicity for contaminant mixtures by determining the number of contaminants exceeding an upper guideline value (effects range medium, or ERM), which predicts probable adverse biological effects. The exceedence approach is used in the current study to estimate the probability of sediment toxicity and to prioritize the harbour in terms of possible adverse effects on sediment-dwelling animals. Approximately 1% of the harbor is mantled with sediment containing more than ten contaminants exceeding their respective ERM concentrations and, based on NOAA data, these sediments have an 80% probability of being toxic. Sediment with six to ten contaminants exceeding their respective ERM guidelines extend over approximately 4% of the harbor and have a 57% probability of toxicity. These areas are located in the landward reaches of embayments in the upper and central harbor in proximity to the most industrialised and urbanized part of the catchment. Sediment in a further 17% of the harbor has between one and five exceedences and has a 32% probability of being toxic. The application of SQGs developed by NOAA has not been tested outside North America, and the validity of using them in Port Jackson has yet to be demonstrated. The screening approach adopted here is to use SQGs to identify contaminants of concern and to determine areas of environmental risk. The practical application and management implications of the results of this investigation are discussed.     

A novel method using sedimentary metals and GIS for measuring anthropogenic change in coastal lake environments

Background, aim and scope  

A new method using sedimentary metals and geographic information system as indicators for assessing temporal and spatial anthropogenic change in estuaries has been applied to a large coastal lake (Lake Macquarie) in New South Wales, Australia.     

Stormwater metal loading to a well-mixed/stratified estuary (Sydney Estuary, Australia) and management implications

Stormwater modelling indicated an average annual discharge from Sydney estuary catchment of 215,300 mL and loadings of 0.8, 0.5, 1.7, 3.2, 1.1, 3.6 and 17.7 tonnes for As, Cd, Cr, Cu, Ni, Pb and Zn, respectively. Priority for remediation should be given to creeks with high-metal loads in the upper and central estuary, as well as discharging to the western shores of Middle Harbour. Managerial strategies need to target dissolved and particulate metal phases to ensure effective remediation. The proportion of metals discharged under low- (<5 mm rainfall/day), medium- (>5 to <50 mm/day) and high-flow conditions (>50 mm/day) was approximately 10%, 60% and 30% of total loading, respectively. Under high-flow conditions the estuary becomes stratified and most metals are exported to the sea, whereas metals discharged during low-flow may be remediated by infiltration. Effective remediation will depend on the extent to which ‘first-flush’ metals associated with medium-flow conditions can be remediated.     

Climate Skepticism in British Newspapers, 2007–2011

Climate skepticism in the UK media has not been a major focus of recent research. This paper aims to help fill the gap by looking at the incidence of skeptical voices in UK newspapers across three periods: 2007, 2009/2010, and 2010/2011. After analyzing more than 3200 articles, it finds that skeptical voices increased their presence markedly across all newspapers and all types of articles in the second period, and maintained a significant presence in many in the third. Uncontested skeptical voices were particularly prevalent in opinion pieces and editorials in right-leaning newspapers in the second. It also finds that skeptical voices or opinions were more likely to be included in pieces written by in-house non-specialist columnists than by environment editors or correspondents. The negative implications of the results for public understanding and the quality of public debate are then explored.     

Abundance of denitrification genes under different peizometer depths in four Irish agricultural groundwater sites

This study examined the relationship between the abundance of bacterial denitrifiers in groundwater at four sites, differing with respect to overlaying land management and peizometer depth. Groundwater was sourced from 36 multilevel piezometers, which were installed to target different groundwater zones: (1) subsoil, (2) subsoil to bedrock interface, and (3) bedrock. The gene copy concentrations (GCCs), as gene copies per liter, for bacterial 16S rRNA genes and the denitrifying functional genes, nirK, nirS, and nosZ, were determined using quantitative polymerase chain reaction assays. The results were related to gaseous nitrogen emissions and to the physicochemical properties of the four sites. Overall, nirK and nirS abundance appeared to show no significant correlation to N₂O production (P?=?0.9989; P?=?0.3188); and no significant correlation was observed between nosZ and excess N₂ concentrations (P?=?0.0793). In the majority of piezometers investigated, the variation of nirK and nirS gene copy concentrations was considered significant (P?<?0.0001). Dissolved organic carbon (DOC) decreased with aquifer depth and ranged from 1.0–4.0 mg l^?1, 0.9–2.4 mg l^?1, and 0.8–2.4 mg l^?1 within piezometers located in the subsoil, subsoil/bedrock interface, and bedrock depths, respectively. The availability of increasing DOC and the depth of the water table were positively correlated with increasing nir and nosZ GCCs (P?=?0.0012). A significant temporal correlation was noted between nirS and piezometer depth (P?<?0.001). Interestingly, the nirK, nirS, and nosZ GCCs varied between piezometer depths within specific sites, while GCCs remained relatively constant from site to site, thus indicating no direct impact of agricultural land management strategies investigated on denitrifier abundance.