Showing papers by "Simon C. Apte published in 2016"

Geochemical controls on aluminium concentrations in coastal waters

Abstract: Environmental context Aluminium may be released into coastal waters in dissolved and particulate forms from urban runoff, industrial discharges and acid sulfate soils. Aquatic organisms may experience toxic effects from exposure to dissolved and particulate aluminium. Therefore, the current study reports the geochemical controls such as speciation, precipitation and adsorption that influence the exposure to these aluminium forms in the field and the laboratory. Abstract A combination of field and laboratory investigations was conducted in order to gain an understanding of aluminium dynamics in coastal seawater environments. Filterable ( 0.025 to <0.45µm) aluminium species were generally minimal, apart from one field sample collected close to a river mouth where aluminium was associated with iron-containing colloids. In seawater (pH 8.15, 22°C) spiked with small increments of aluminium so as not to attain supersaturation, the solubility limit was ~500µgL–1. However, at higher total aluminium concentrations the solution chemistry became highly dynamic. In the presence of aluminium precipitate it was not possible to measure a solubility limit over the 28-day duration of the experiment because the dissolved aluminium concentration varied with both reaction time and precipitate concentration. For instance, when seawater solutions were spiked with 10000µgL–1 of total aluminium, a pulse of dissolved aluminium up to 1250µgL–1 was sustained for several days before decreasing to below 100µgL–1 after 28 days. The initial precipitate appeared to be solely aluminium hydroxide and transformed over time to contain increasing magnesium, consistent with the formation of hydrotalcite (Mg6Al2CO3(OH)16·4H2O), reaching 21% of the precipitate mass after 28 days. Adsorption studies showed that at anticipated suspended particulate concentrations for coastal waters, natural particulate material has a fairly low affinity for dissolved aluminium. The results of the current study highlight the complex chemistry of aluminium in marine waters and the role of precipitation reactions.

Chapter 10 – Global Change

Abstract: Human activities are increasingly altering the composition and integrity of our coastal and marine ecosystems. Land-use changes, increasing coastal urbanization and industrialization, population growth, altered water availability and quality, and climate change are already having a major impact on marine habitats, ecological processes and communities, and the livability of our coastal cities. This chapter focuses on anthropogenic global change which is defined as “the global-scale changes resulting from the impact of human activity on the major processes that regulate the functioning of the biosphere.” Current research emphasis is on multiple stressors and how they may interact to potentially impact marine and estuarine ecosystems over the next 50–100 years. Our understanding of marine ecotoxicology from a multiple stressor perspective has benefited from the development and application of a range of new tools for assessing ecosystem health. Epigenetics, omics, and modeling approaches are just some of the new tools that can assist in assessing responses to global change.

The ecological impacts of submarine tailings placement

Abstract: ELISABETTA B. MORELLO1,2, MICHAEL D.E. HAYWOOD1, DAVID T. BREWER1, SIMON C. APTE3, GERT ASMUND4, Y.T. JOHN KWONG5 & DARREN DENNIS11CSIRO Oceans & Atmosphere, Ecosciences Precinct, 41 Boggo Rd, Dutton Park, QLD 4102, Australia2CNR-National Research Council of Italy, ISMAR-Marine Sciences Institute, Largo Fiera della Pesca 2, Ancona, 60125, ItalyE-mail: Elisabetta.Morello@csiro.au (corresponding author) 3CSIRO Land and Water Flagship, Locked Bag 2007, Kirrawee NSW 2232, Australia4Aarhus University, Department of Bioscience-Arctic Environment, Frederiksborgvej 399, 4000 Roskilde, Denmark5Natural Resources Canada, 555 Booth Street, Ottawa, Ontario, K1A 0G1, CanadaMost of the 2500 industrial-size mines operating around the world dispose of their tailings on land. For technical, spatial, and chemical reasons this is not always feasible, and attention has shifted to submarine tailings placement (STP) and deep-sea tailings placement (DSTP). Marine disposal presents numerous challenges that can have signicant environmental impacts across a range of ecosystems. This review describes the processes at the basis of the disposal rationale and how these can affect its outcome, and outlines the ecological impacts that are associated with or interact with these processes. Mine waste disposal on to the seaoor appears to be poorly understood given the extent of its implementation. The uncertainty surrounding this method extends to our understanding of both biophysical processes and ecological impacts. For example, the potential role of vertically migrating species in transporting mine-disposed trace elements from deeper environments into the shallower surface layers has been largely overlooked, and, similarly, the nature, extent, and impact of secondary plumes that develop off the main tailings current are poorly described and quantied, as is their interaction with migrating biota. Furthermore, the vulnerability of deep-sea environments to human impacts and their potential for recovery remains largely unknown. Given the large degree of uncertainty around the impacts of this practice on a wide range of ecological communities, coupled with the high connectivity of both deep-water and pelagic environments, it is imperative that participating countries, the global scientic community, and managing entities act urgently to bridge these knowledge gaps, improve management practices, and take a more precautionary approach to the implementation of STP and DSTP.