Dr Dirk Erler

RESEARCH INTERESTS

Dirk Erler is an isotope geochemist whose research focusses on the cycling of nitrogen through aquatic systems, in particular tropical sediment and groundwater systems. He is currently involved in a number of projects that aim to quantify the pathways of N cycling using natural abundance measurements and stable isotope addition experiments. His key research interests are:

1) Quantifying the production pathways of N in the subterranean estuaries of permeable carbonate sand islands. Here we use stable isotope additions to whole aquifers to determine the types of processes that transform land derived N. In addition we are using natural abundance isotopes of nitrate (15N and 18O) and ammonium (15N) to determine the dominant mechanisms for the release of N from sediment to water. These processes are being included in mechanistic models that help describe subterranean estuary systems.

2) Determining the presence and extent of anammox and DNRA in tropical sediments. Recently we discovered that Great Barrier Reef sediments contain hotspots of anammox activity. We have also found anammox in wetland sediments. DNRA, which conserves N within systems is also a largely understudied process and we have been measuring this process in tropical sediments.

3) Understanding the pathways for the production and consumption of gaseous nitrogen (di-nitrogen and nitrous oxide) in permeable sediment systems. Gaseous N production is the principal pathway for permanent loss of N from aquatic systems. However gaseous N loss also includes the production of nitrous oxide, a potent greenhouse gas. The production pathways of nitrous oxide are still poorly understood in tropical systems and this particular project involves the use of cavity ring down spectroscopy to determine isotopomer configurations of nitrous oxide which will help identify the major production pathways. As well as nitrous oxide, we are also studying the balance between di-nitrogen production (denitrification) and uptake (fixation) in tropical sediments using concentration and isotope measurements.

4) Evaluating the effectiveness of on-site effluent treatment systems in tropical developing countries. This work involves the construction and monitoring of effluent treatment systems that are suited for use in developing island nations. We collaborate closely with a number of pacific island nations to improve the quality of their groundwater. Part of this research involves the testing of wetland treatment systems for the removal of pollutants.

5) Using the 15N signature of corals as a record of past oceanic N conditions. This latest research is part of an effort to understand coral reef N cycling both now and in the past. Collaborating with national and international researchers we are measuring the 15N component of the intracrystalline organic material trapped within coral growth bands. This may be useful as a proxy of past oceanic N cycling and may also help determine how corals function in nutrient poor environments.

Dirk Erler is using some of the latest techniques to conduct his research. These include the measurement of 15N and 18O in nitrate using the denitrifier method, measurement of organic N (dissolved organic N, coral organic N) using a combination of digestion and denitrifier methods, use of hypobromite oxidation/ azide method for measurement of 15N in ammonium, the use of membrane inlet MS for measurement of di-nitrogen concentration and isotope signature, and most recently the use of cavity ring down approaches to measure isotopes and concentrations of nitrous oxide.

MAJOR RESEARCH GRANTS

ARC Linkage

$607,000 (LP100200732) "Resolving nitrogen and phosphorus transformations along subterranean estuary-sediment/water interface continuums in carbonate sands" 2010 to 2013. CI 3 of 3.

ARC LIEF

-$250,000 (LIEF LE120100156) A high precision, automated system for studying greenhouse gas cycling in coastal environments. 2012. CI 1 of 5.

-$240,000 (LE130100153) "A liquid chromatography/ gas bench: isotope ratio mass spectrometer for new and novel carbon and nitrogen research in coastal systems" 2013. CI 4 of 5

-$170,000 (LE100100013) "Eddy Correlation Lander Array" 2010. CI 6 of 12.

Other Category 1 Grants

- $225,000 Improving environmental and human health in the Pacific Islands through better onsite wastewater management. Australian Research Development Award (AUSAID). 2008. CI 2 of 3.

- $84,410 "Are groundwater inputs driving de-oxygenation, acidification and eutrophication." Herman Slade Foundation. 2009 to 2012. CI 3 of 3.

Non Category 1 Grants

-$96,000 "Monitoring and evaluation of onsite wastewater treatment systems in Cook Islands" (IWRM) 2011 CI 1 of 3

-$39,000 "Monitoring and evaluation of onsite wastewater treatment systems in Tonga" (IWRM) 2011 CI 1 of 3

-$39,000 "Monitoring and evaluation of onsite wastewater treatment systems in Nauru" (IWRM) 2011 CI 1 of 3

- $35,000 "Evaluating the efficiency of the "eco-trench" onsite wastewater treatment systems " NZAid 2010 CI 1 of 2

PUBLICATIONS

In Press/Accepted/Revision Requested

Erler , D. V., Trott, L. A., Alongi, D. M. and Eyre B. D. Denitrification, anammox and nitrate reduction in the sediments of the Southern Great Barrier Reef Lagoon. Marine Ecology Progress Series (accepted July 2012) JIF=2.63; (ERA Rank A).

2011

Despland, L.M., Clark, M.W., Vancov, T., Erler, D., Aragno, M. 2011. Nutrient and trace-metal removal by bauxsol pellets in wastewater treatment.Environmental Science and Technology 45, 5746-5753. (ERA RAnk *A)

Eyre, B. D., Maher, D., Oakes, J. M., Erler, D. V. and Glasby, T. Differences in benthic metabolism, nutrient fluxes and denitrification in Caulerpa taxifolia communities compared to uninvaded sediment and seagrass (Zostera capricorni). Limnology and Oceanography 56, 1737-1750. JIF = 3.66; (ERA Rank A).

Erler, D. V.; Tait, D.; Eyre, B. D.; Bingham, M., Observations of nitrogen and phosphorus biogeochemistry in a surface flow constructed wetland. Science of the total environment 2011, 409, 5359-5367. JIF= 3.19. (ERA Rank A)

Santos, I.R.; Glud, R.N., Maher, D., Erler, D., Eyre. B.D. Diel coral reef acidification driven by porewater advection in permeable carbonate sands, Heron Island, Great Barrier Reef. Geophysical Research Letters, in press, doi:10.1029/2010GL046053 (ERA Rank A*)

2010

Santos, I.R.; Erler, D.; Tait, D.; Eyre, B.D. 2010. Breathing of a coral cay: Tracing tidally driven seawater recirculation in permeable coral reef sediments. Journal of Geophysical Research, 115: C12010. JIF=3.082. (ERA Rank A*)

Erler, D. V. and Eyre, B. D. 2010. Combining Natural Abundance Stable Isotope Signatures and Stable Isotope Tracer Experiments to Quantify Nitrogen Dynamics in a Constructed Wetland. Journal of Environmental Quality 39, 2191-2199. JIF =2.10 (ERA Rank A)

Erler, D. V., Eyre, B. D. and Davison, L. 2010 Temporal and spatial variability in the processing of nitrogen in a constructed wetland: a whole system stable isotope addition experiment. Limnology and Oceanography 55(3), 1172â€"1187. DOI:10.4319/lo.2010.55.3.1172 JIF = 3.66 (ERA Rank A)

2008

Erler, D. V., B. D. Eyre, and L. Davison. 2008. The contribution of anammox and denitrification to sediment N2 production in a surface flow constructed wetland. Environmental Science & Technology 42: 9144-9150

2007

Erler, D. V., P. Songsangjinda, T. Keawtawee, and K. Chaiyakam. 2007. Nitrogen dynamics in the settlement ponds of a small-scale recirculating shrimp farm (Penaeus monodon) in rural Thailand. Aquaculture International 15: 55-66..

2005

Erler, D. V., P. Songsangjinda, T. Keawtawee, and K. Chaiyakam. 2005. Preliminary investigation into the effect of carbon addition on growth, water quality and nutrient dynamics in zero-exchange shrimp (Penaeus monodon) culture systems. Asian Fisheries Science 18: 195-204.

2004

Erler, D., P. Pollard, P. Duncan, and W. Knibb. 2004a. Treatment of shrimp farm effluent with omnivorous finfish and artificial substrates. Aquaculture Research 35: 816-827.

Erler, D., P. C. Pollard, and W. Knibb. 2004b. Effects of secondary crops on bacterial growth and nitrogen removal in shrimp farm effluent treatment systems. Aquaculture Engineering 30: 103-114.

Conference Proceedings

Erler, D., Pollard, P.C., Burke, M.J., Knibb, W., 2000. Biological remediation of aquaculture waste: a combined finfish, artificial substrate treatment system. In: Kumar, M. (Ed.), Proceedings of the National Workshop on Wastewater Treatment and Integrated Aquaculture. South Australian Research and Development Centre, South Australia, Henley Beach, S.A. (Australia), pp. 93-107.

Reports

Erler, D. and Willett, D. 2008. Tracing the flow of Nitrogen in heterotrophic 'floc' based integrated aquaculture systems. DPI&F Final Report #2008/10.

Palmer, P.J., Bell, G., Burke, M., Erler, D., Knibb, W., Lobergeiger, R., Morrison, C., Pledger, B., Rutherford, B., Willett, D. 2004. Wastewater Remediation Options for Prawn Farmers. Final report to Aquaculture Industry Development Initiative 2002-2004. Report #QO04018.

Willett, D., Erler, D., Knibb W. Biological remediation of nutrient rich irrigation water in the Burdekin region (2003). Final report to the South Burdekin Water Board, DPI&F report #2003-1.

Palmer, P.J., Erler, D., Burke, M., Lobegeiger, R.L., Morrison, C., Bell, W., Knibb, W., 2003. Growing banana prawns, Penaeus merguiensis, in prawn farm settlement ponds to utilise and help remove waste nutrients. NHT Final Report, project #717757/BNE5129.

Palmer, P.J., Erler, D., Morrison, C., Rutherford, B., Knibb, W., 2003. Nutrient levels in experimental tanks supplied with prawn pond effluent: the effect of artificial substrate and different densities of the banana prawn, Penaeus merguiensis. NHT Final Report Attachment, project #717757/BNE5129.

Updated: 14 May 2013