Comparison of pollution indices for the assessment of heavy metal in Brisbane River sediment☆
Graphical abstract
Introduction
Globally, disproportionately large human populations live near waterways and they extensively modify riparian zones, resulting in significant threat to water quality and river health. Worldwide deterioration of water quality arises from both natural and anthropogenic processes including soil erosion, mining, agricultural, industrial, transportation and energy production related activities (Chung et al., 2015, Li et al., 2014). These activities generate pollutants such as heavy metals, which eventually find their way into rivers and streams through weathering, disposal of effluents, runoff and leachates, as well as atmospheric deposition (Mucha et al., 2003). After their introduction into the aquatic ecosystem, most metals are attached to fine-grained particulates and, as a result of settling, accumulate in bottom sediments (Farkas et al., 2007), where they may cause adverse biological effects even though water quality criteria are not exceeded (NRC, 1989, Bibi et al., 2007). Heavy metals are ubiquitous environmental pollutants, which are persistent, non-biodegradable, toxic and bio-accumulative in the aquatic ecosystem (Arnason and Fletcher, 2003, Li et al., 2014). They have drawn wide attention due to their negative effects on human and ecosystem health (Brady et al., 2014a). Consequently, their concentrations, distribution, fate, impact and sources in the environment have attracted global interest and these are areas of ongoing research (Iqbal and Shah, 2014, Brady et al., 2014a, Brady et al., 2014b Sekabira et al., 2012, Singovszka et al., 2015, Vaezi et al., 2015).
The accumulation of metals in the sediment poses a long term threat to water bodies and other parts of the environment. Therefore, there is a need for sediment quality indicators to assess the risks of contamination and toxicity posed by metals in the aquatic environment. This has led to the development of many sediment quality indicators such as contamination factor, enrichment factor, index of geo-accumulation (I-geo), (modified) degree of contamination (Cd or mCd), (modified) pollution index (PI or MPI) and sediment quality guidelines (Muller, 1969, Tomlinson et al., 1980, Qingjie et al., 2008, Brady et al., 2015, Vidal and Bay, 2005). However, these sediment quality indicators either define a qualitative threshold or focus on ecological risk assessment of a single metal. Yet heavy metal pollution in the environment generally occurs in the form of complex mixtures. The synergistic effects of metal pollution rather than an individual metal effect may be of greater concern. The potential adverse risks due to hazardous chemicals (such as heavy metals) in the same medium can be assumed to be cumulative in worse case scenarios (Neff et al., 2005). Consequently, the potential ecological risk index (RI) developed by Hakanson (1980), which evaluates the combined pollution risk of an aquatic system through a toxic-response factor is well suited for assessing ecological risk posed by heavy metals in the environment. Nonetheless, RI is computed using a simple contamination factor. This could possibly introduce error in the assessment of risk pose by a complex environment like an estuary where sedimentation with significant input from creeks is a common occurrence (Brady et al., 2015). Contamination factor does not take the lithogenic and sedimentary inputs of the element of interest into account. In contrast, enrichment factor, which can normalise the impact of terrestrial sedimentary inputs, could provide more useful information and offer a more realistic estimate of the real ecological risk.
The area under study, the Brisbane River estuary, is the largest and most highly urbanised river system in south east of Queensland. The river catchment supports a large population (in excess of one million) and is currently experiencing rapid population growth (ABS, 2015). The catchment is characterised by sub-tropical weather with discrete wet summer (November to May) and dry winter (April to October) seasons (Eyre et al., 1998). The area is also categorised by a physio-geographic stratification along a hydrological gradient from lower to upper catchment, varying urbanization and distinct land uses. Historically, the river has received large amounts of treated sewage effluent with the lower reaches receiving effluent from eight wastewater treatment plants. The area is tidal and flood prone with eleven (11) major floods recorded since 1840. Elevated concentrations of metals in the sediment have been documented (Cox and Preda, 2005, Mackey and Mackay, 1996, Mackey et al., 1992). However, there is lack of information on the quality of the sediment after the recent significant floods in January 2011 and 2013.
The aim of the study was to use sediment quality indicators, including contamination factor, enrichment factor, index of geo-accumulation, modified degree of contamination, modified pollution index, Australian New Zealand sediment quality guidelines and potential ecological risk index to assess the ecological state of the river sediment. This will provide a tool for key stakeholders, including catchment managers, government, and the public in relation to action to protect aquatic biota and wildlife. Also, we propose a modified potential ecological risk index (MRI) which uses enrichment factor instead of contamination factor. This should account for the non-conservative sediment behaviour and natural variations in the sediment resulting in proper identification of anthropogenic contamination. Moreover, the generic outcomes of this study are expected to provide essential guidance for monitoring and regulation of heavy metals in urban waterways worldwide.
Section snippets
Sample collection
The study was conducted in 2014–2015 to cover the different land-use types and various urbanization levels of the river. Twenty two sites spanning Latitude 27°32′20.81″S to 27°22′39.37″S and Longitude 152°51′1.55″E to 153° 9′40.86″E were sampled (Fig. 1). The sites can be grouped into four physio-geographical strata namely: rural (SP1-SP3, which is mostly forestland), residential (SP4-SP12, moderately to highly residential, park and bushlands), commercial (SP13-SP18, highly urbanised,
Analytical performance of the method of analysis
The performance of the LA-ICP-MS method had been detailed in Duodu et al. (2015). However, due to the initial poor recovery of Cr, a simple excel equation was developed from the average Cr concentration of PACS-2 using GBW07312, MESS-3 and STSD-1 as calibration standards. This gave Cr recovery of 100.3%. Table 3 gives the measured against certified values of some metals in PACS-2 employing GBW07312, MESS-3 and STSD-1 as calibration standards. There was good agreement between the measured and
Conclusion
The concentrations of major and trace metals (determined with LA-ICP-MS) in Brisbane River sediment are presented in this study. The distribution characteristics show that most of the metals analysed were fairly stable across the sampling sites and between sampling periods. The variation patterns of elements in the sediment were found to be strongly dependent on their sources. Three sources of metals: marine sand intrusion, mixed lithogenic and sand intrusion as well as transport-related
Acknowledgement
The authors are thankful to Queensland University of Technology and Ghana Atomic Energy Commission for providing scholarship and study leave, respectively, for Godfred Odame Duodu to undertake this study. Our sincere gratitude goes to the Institute of Future Environments (QUT), which operates the Central Analytical Research Facility where the data reported in this paper was derived. Access to CARF is supported by generous funding from the Science and Engineering Faculty (QUT). Lastly, we
References (59)
- et al.
Reliability of subtidal sediments as “geochemical recorders” of pollution input: San Simón Bay (Ría de Vigo, NW Spain)
Estuar. Coast. Shelf Sci.
(2006) - et al.
A 40+ year record of Cd, Hg, Pb, and U deposition in sediments of Patroon Reservoir, Albany County, NY, USA
Environ. Pollut.
(2003) - et al.
Enrichment, distribution and sources of heavy metals in the sediments of Deception Bay, Queensland, Australia
Mar. Pollut. Bull.
(2014) - et al.
Temporal trends and bioavailability assessment of heavy metals in the sediments of Deception Bay, Queensland, Australia
Mar. Pollut. Bull.
(2014) - et al.
Nano silver and nano zinc-oxide in surface waters – exposure estimation for Europe at high spatial and temporal resolution
Environ. Pollut.
(2015) - et al.
Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry
Anal. Chim. Acta
(2015) - et al.
A suspended sediment budget for the modified Subtropical Brisbane River estuary, Australia
Estuar. Coast. Shelf Sci.
(1998) - et al.
Assessment of the environmental significance of heavy metal pollution in surficial sediments of the River Po
Chemosphere
(2007) - et al.
Atmospheric deposition as a source of heavy metals in urban stormwater
Atmos. Environ.
(2013) An ecological risk index for aquatic pollution control.A sedimentological approach
Water Res.
(1980)
Impacts of dredging on dry season suspended sediment concentration in the Brisbane River estuary, Queensland, Australia
Estuar. Coast. Shelf Sci.
Spatial distribution of heavy metals in urban soils of Naples city (Italy)
Environ. Pollut.
A review of soil heavy metal pollution from mines in China: pollution and health risk assessment
Sci. Total Environ.
Application of principal component analysis for the estimation of source of heavy metal contamination in surface sediments from the Rybnik reservoir
Chemosphere
Spatial distribution of acid-volatile sulphide concentration and metal bioavailability in mangrove sediments from the Brisbane River, Australia
Environ. Pollut.
Nutrient levels and heavy metals in mangrove sediments from the Brisbane River, Australia
Mar. Pollut. Bull.
Metal contamination of estuarine intertidal sediments of Moreton Bay, Australia
Mar. Pollut. Bull.
Macrobenthic community in the Douro estuary: relations with trace metals and natural sediment characteristics
Environ. Pollut.
Emission factors for heavy metals from diesel and petrol used in European vehicles
Atmos. Environ.
Calculating pollution indices by heavy metals in ecological geochemistry assessment and a case study in parks of Beijing
J. China Univ. Geosci.
Geochemistry of major and trace elements in sediments of the Ria de Vigo (NW Spain): an assessment of metal pollution
Mar. Pollut. Bull.
Geochemical speciation, anthropogenic contamination, risk assessment and source identification of selected metals in freshwater sediments—a case study from Mangla Lake, Pakistan
Environ. Nanotechnol. Monit. Manag.
Influence of soil properties on the effect of silver nanomaterials on microbial activity in five soils
Environ. Pollut.
Top-/bottom-soil ratios and enrichment factors: What do they really show?
Appl. Geochem.
Assessment of spatial distribution and potential ecological risk of the heavy metals in relation to granulometric contents of Veeranam lake sediments, India
Ecotoxicol. Environ. Saf.
The role of Mn2+-rich hydrous manganese oxide in the accumulation of arsenic in lake sediments
Water Res.
Emissions of fuel metals content from a diesel vehicle engine
Atmos. Environ.
Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The Guidelines, No. 4, Vol. 1, Chapters 1–7
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This paper has been recommended for acceptance by Prof. W. Wen-Xiong.