Real-time instrumentation

Major instrumentation projects

• Development of flow injection instruments for chemical monitoring and mapping
• Biogeochemistry of organic phosphorus compounds

Team members

• Ian McKelvie (Project Leader)

Development of flow injection instruments for chemical monitoring and mapping

This project involves the development of rapid, on-line water quality measurement techniques and compact, portable, multi-parameter flow injection analysis systems. The aim is to deploy these instruments on-site or on-board a research vessel for real-time measurement or spatial mapping of chemical parameters such as phosphate, nitrate, ammonia and silica. A prototype has been produced which is capable of very rapid, sensitive measurements (see picture); this uses only minimal amounts of reagents (mLs) for hundreds of analyses. A related area of research involves the use of controlled release of enzymes from a solid matrix as part of a reagent delivery system. This approach will enable the controlled dispensing of minute volumes of expensive or less stable reagents.

Biogeochemistry of organic phosphorus compounds

This research area is studying the biogeochemistry of nutrient species in aquatic systems, with a particular emphasis on organic phosphorus. Funding has been obtained via two ARC grants: a large ARC grant for a project on Inositol phosphates: their detection and occurrence in the aquatic environment and a small ARC grant for project on Enzymatic determination of phospholipids in the aquatic environment. Both projects are developing and applying sensitive and selective detection techniques for measuring these species in the environment. Prototype multi-parameter portable flow injection monitoring system

Phosphohydrolytic enzymes, such as alkaline phosphatase, phytase and phosphodiesterase, have been investigated as a means to functionally characterise organic phosphorus. These enzyme methods have been coupled with a size exclusion technique to separate high and low molecular mass organic phosphorus species in sediments and soils.

This technique has been used to study the occurrence of inositolhexakisphosphate in sediment pore waters and sediment extracts. Although inositolhexakisphosphate can make up 80% of the total phosphorus content in some soils and sediments, it is insoluble and strongly bound within the sediments, and is therefore effectively biologically unavailable. However, we have recently found that inositol phosphate and other higher molecular weight (MW) organic phosphorus compounds are present in sediment interstitial waters, and are also readily released from sediments at brackish water salinities (>5 ppt). Further research in this area will concentrate on defining the physicochemical conditions that favour organic phosphorus release, and on assessing the bioavailability of this released organic phosphorus.