Trace Metal Distribution Within Marine and Estuarine Sediments of Western Moreton Bay,Queensland, Australia: Relation to Land Use and Setting

This broad‐scale investigation provides an overview of trace metal concentration and distribution within sediments in the subtropical setting of Moreton Bay on the eastern Australian coast. Samples of sediment in one‐metre long PVC cores were collected from the intertidal zone of the western shoreline of the Bay and within its main estuaries. The material is typically silty sand along the Bay shoreline, becoming more clayey within the estuaries. Downcore pH is typically between 7.0 and 8.0, with layers in some cores of pH 6.0 to 7.0. Locally, pH can fall below 5.0 due to pyrite oxidation or exceed 8.0 due to the presence of shell fragments. A comparison with results of similar studies in other highly populated centres in Australia shows that overall the Moreton Bay area sediments have relatively low metal content. Typically, concentrations are two to three times higher in fine‐grained, estuarine sediments than in sandy material along the Bay shoreline. Compared with Australian and New Zealand Environment and Conservation Council Guidelines for metal concentrations in sediments, the elements most commonly elevated and warranting further assessment are Ni, Hg, Pb, Zn, and occasionally Cd, As and Cr. The highest metal concentrations are found in estuaries, close to more populated or industrialised areas, notably along the Brisbane River. Overall, the distribution of metals in unconsolidated material is controlled by (a) the heavy metal affinity for Fe‐ and Mn‐rich oxidised sediments, (b) grain size, (c) background concentrations in local rocks, and (d) conditions of weathering and deposition. For example, natural elevation of Fe occurs in marine sediments adjacent to areas of Tertiary basalts and this has produced a relative increase in a number of trace metals in those sediments. Typically, trace metals correlate well with Al, and with Fe and Mn oxyhydroxides. The results of this study show that in the western Moreton Bay region, natural controls have the major influence over metal distribution; although urban and industrial inputs exist, for much of the area they are secondary. The main sources of introduced trace metals are presumed to be light industry (such as maritime and port facilities, petroleum refineries and storage, manufacturing and chemical processes), landfills, agriculture and intensive fertilising (for example, golf courses) as well as the composite effect of urban centres. Overall, higher concentrations of metals are closely related to intense development. If specific locations are targeted for focussed sampling, elevated concentrations of metals are likely to be found locally.     

Time for tools: A review on geospatial tools and their role in co-management

The overall goal of this study was to conduct an extensive literature review to characterize how geospatial tools are being applied in co-management contexts globally. This was accomplished through two objectives: (i) to investigate the use and applications of geospatial tools in cases of natural resource co-management; and (ii) to identify benefits and challenges associated with the use of these technologies. A total of 26 articles met the inclusion criteria for review; these encompassed a range of contexts, but were predominantly focused on co-management of fisheries, protected areas, and forests. Case studies were analyzed through the lens of four tool-based categories: participatory mapping, spatial data collection, remote sensing, and modelling. Findings suggest a wide range of applications, demonstrating the versatility of these tools including those used to measure the efficacy of co-management. Frequently cited geospatial tool benefits included identifying space-use patterns, determining the state of resources, capacity building, and monitoring change over time. Challenges with geospatial tools included issues of scale and generalization, data uncertainty, incomplete or poor data, and lack of trust. A primary conclusion from this study is that geospatial tools tend to be used in a participatory fashion, thereby contributing to key elements of co-management such as trust building and knowledge co-production.     

Identifying past agricultural activity through soil phytolith analysis: a case study from the Hawaiian islands

Soil samples from documented archaeological sites and adjacent fields were analyzed for phytolith assemblage in an effort to identify and reconstruct prehistoric and early historic agricultural systems on the Island of Hawaii. The removal of indigenous tree and shrub vegetation, subsequent agricultural activity, and eventual abandonment of the fields can be identified in the areas tested. The applicability of phytolith analysis to archaeological problems is advanced and areas of strength and weakness identified.