Time filter

Source Type

Christchurch, New Zealand

Suggate R.P.,Institute of Geological & Nuclear Sciences | Boyd R.J.,Solid Energy New Zealand
New Zealand Journal of Geology and Geophysics

Vertical rank gradients are inferred from lateral variations of Rank(S r) in successive coal horizons in the Paparoa Group and Brunner Coal Measures in Greymouth Coalfield. The gradients are lowest, c. 3 Rank(S r)/km, in the centre of the coalfield where the lateral rank pattern is simple. In the west, vertical gradients ranging from <4 to >8 Rank(S r)/km result from contrasting Upper Rewanui and Brunner lateral rank patterns. There, it is inferred that warm fluids migrated from more deeply buried coal measures further east and have enhanced Upper Rewanui ranks. For calculating Brunner burial depths, the high western vertical gradients are rejected and a gradient of 4.0 Rank(S r)/km is adopted, as it is also east of the Mt Davy Fault Zone where the gradient is unknown. Brunner burial depths increased from 1.8 km in the far west to 4.3 km in the Mt Davy area, and palaeotemperatures increased eastwards from 90-95°C to 150-155 °C. © 2012 The Royal Society of New Zealand. Source

Tsang D.C.W.,University of Canterbury | Tsang D.C.W.,Hong Kong Polytechnic University | Olds W.E.,University of Canterbury | Weber P.A.,Solid Energy New Zealand | Yip A.C.K.,University of Canterbury

Utilising locally available industrial by-products for in situ metal stabilisation presents a low-cost remediation approach for contaminated soil. This study explored the potential use of inorganic (acid mine drainage (AMD) sludge and zero-valent iron) and carbonaceous materials (green waste compost, manure compost, and lignite) for minimising the environmental risks of As and Cu at a timber treatment site. After 9-month soil incubation, significant sequestration of As and Cu in soil solution was accomplished by AMD sludge, on which adsorption and co-precipitation could take place. The efficacy of AMD sludge was comparable to that of zero-valent iron. There was marginal benefit of adding carbonaceous materials. However, in a moderately aggressive environment (Toxicity Characteristic Leaching Procedure), AMD sludge only suppressed the leachability of As but not Cu. Therefore, the provision of compost and lignite augmented the simultaneous reduction of Cu leachability, probably via surface complexation with oxygen-containing functional groups. Under continuous acid leaching in column experiments, combined application of AMD sludge with compost proved more effective than AMD sludge with lignite. This was possibly attributed to the larger amount of dissolved organic matter with aromatic moieties from lignite, which may enhance Cu and As mobility. Nevertheless, care should be taken to mitigate ecological impact associated with short-term substantial Ca release and continuous release of Al at a moderate level under acid leaching. This study also articulated the engineering implications and provided recommendations for field deployment, material processing, and assessment framework to ensure an environmentally sound application of reactive materials. © 2013 Elsevier Ltd. Source

Tsang D.C.W.,University of Canterbury | Tsang D.C.W.,Hong Kong Polytechnic University | Yip A.C.K.,University of Canterbury | Olds W.E.,University of Canterbury | Weber P.A.,Solid Energy New Zealand
Environmental Science and Pollution Research

In situ metal stabilisation by amendments has been demonstrated as an appealing low-cost remediation strategy for contaminated soil. This study investigated the short-term leaching behaviour and long-term stability of As and Cu in soil amended with coal fly ash and/or green waste compost. Locally abundant inorganic (limestone and bentonite) and carbonaceous (lignite) resources were also studied for comparison. Column leaching experiments revealed that coal fly ash outperformed limestone and bentonite amendments for As stabilisation. It also maintained the As stability under continuous leaching of acidic solution, which was potentially attributed to high-affinity adsorption, co-precipitation, and pozzolanic reaction of coal fly ash. However, Cu leaching in the column experiments could not be mitigated by any of these inorganic amendments, suggesting the need for co-addition of carbonaceous materials that provides strong chelation with oxygen-containing functional groups for Cu stabilisation. Green waste compost suppressed the Cu leaching more effectively than lignite due to the difference in chemical composition and dissolved organic matter. After 9-month soil incubation, coal fly ash was able to minimise the concentrations of As and Cu in the soil solution without the addition of carbonaceous materials. Nevertheless, leachability tests suggested that the provision of green waste compost and lignite augmented the simultaneous reduction of As and Cu leachability in a fairly aggressive leaching environment. These results highlight the importance of assessing stability and remobilisation of sequestered metals under varying environmental conditions for ensuring a plausible and enduring soil stabilisation. © 2014 Springer-Verlag Berlin Heidelberg. Source

Simmler M.,Lincoln University at Christchurch | Simmler M.,ETH Zurich | Ciadamidaro L.,Institute for Natural Resources and Agrobiology | Schulin R.,ETH Zurich | And 5 more authors.
Environmental Science and Technology

Repeated application of Cd-rich phosphate fertilizers can lead to the accumulation of this nonessential element in soil. This can result in increased plant uptake, with possible breaches of food or feed safety standards. We aimed to determine whether lignite (brown coal) can reduce Cd solubility and plant uptake in New Zealand pasture soils. In batch sorption experiments, we tested the capacity of lignite and lignite-soil mixtures to sorb Cd at various soil pH and Cd loadings. Over a pH range of 4-7, Cd sorption by lignite was 1-2 orders of magnitude greater than by a typic immature pallic soil containing 2% carbon. The addition of 5 wt % lignite to a range of soils revealed that lignite addition was most effective in reducing soluble Cd in soils with low pH. In a greenhouse experiment, we tested the effect of lignite on the accumulation of Cd and other elements by perennial ryegrass, Lolium perenne (L.). The addition of just 1 wt % lignite to the aforementioned soil reduced plant Cd uptake by 30%, without adversely affecting biomass or the uptake of essential nutrient elements including copper and zinc. This may be due to preferential binding of Cd to organic sulfur in lignite. © 2013 American Chemical Society. Source

Discover hidden collaborations