From: Prof. Bruce Webb To: Subject: Rivers-List: IAHS Symposium S4 Maastricht Date: 16 May 2000 15:01 Dear Rivers-list Members May I draw your attention to the forthcoming Symposium (S4) on 'Hydrogeochemical and transport processes with emphasis on aquifer characteristics and reactivity' which is being held during the 6th Scientific Assembly of IAHS, 18 – 27 July, 2001, Maastricht, The Netherlands. If you are interested in participating in this meeting, please note that the deadline for submitting abstracts has now been extended to 15 June, 2000. These should be sent to the meeting Covenor: Dr Jasper Griffioen, The Netherlands Institute of Applied Geoscience TNO, PO Box 6012, 2600 JA Delft,The Netherlands tel.: +31 15 2696820; fax: +31 15 2564800 e-mail: j.griffioen@nitg.tno.nl Details of the topics being covered at this meeting are listed below, while information about the Scientific Assembly is available on the IAHS website: http://www.wlu.ca/~wwwiahs/news67/maast.htm Many Thanks Bruce Webb (Co-convenor S4) S4 Hydrogeochemical and transport processes with emphasis on aquifer characteristics and reactivity Leading Commission: ICGW Co-operation of: ICWQ, ICT, ICCE The subsurface of densely populated countries is increasingly being used for many new activities (infrastructural) in addition to more traditional applications, such as groundwater abstraction. For drinking water supply, infiltration systems are implemented that introduce surface water of varying quality into deeper aquifers. In situ remediation is becoming more popular in which the natural attenuation of soil and groundwater pollution depends on the (bacterial and chemical) characteristics of the aquifer material. In all of these developments, changes in groundwater quality have to be predicted in a more intensely utilised subsurface hydrological system. This session also will assess the data requirements and availability to not only assess the impact of human activities but to predict future impacts at a range of spatial scales. S4.1 Aquifer characteristics and hydrogeochemical reactivity Information is needed not only about the pre-existing and new water quality for the prediction of changes in groundwater quality, but also about the biogeochemical reactivity of the porous medium. Increasingly, porous media are being sampled for the determination of biogeochemical characteristics. However, the physical heterogeneity of the subsurface complicates the estimation of these characteristics. Specific sampling and analytical strategies are needed to obtain a representative estimate of the aquifer ‘reactivity’. Also, the characteristics at the measurement scale (point scale) have to be scaled up for local and regional studies, whether or not using simulation models. Papers are welcomed that address sampling strategy of aquifer materials, determination of reactivity, and upscaling especially of biogeochemical aquifer-material characteristics. Papers addressing the issues of data requirements and data availability also are welcomed. S4.2 Characterisation and prediction of groundwater contamination Human activities have resulted in contamination of regional groundwater and surface water resources. The magnitude of source contamination are associated with exploration and refinement of natural resources, agricultural activities, waste dumps or industrial and military complexes. Groundwater contamination is the resultant of physical mass transfer and flow processes together with biogeochemical reactions. Processes such as dissolution from NAPL’s and biogeochemical degradation need often be considered as kinetically controlled. Characterisation of such kinetic processes is needed to determine the present extent of contamination and future behaviour of the contaminant. Determination of the fate of contaminants at the contaminated sites requires the application of a diverse array of characterisation and prediction techniques. Contributions are welcomed regarding field characterisation, laboratory characterisation and mathematical modelling techniques. S4.3 Dynamics of microbially mediated hydrogeochemical processes in aquifers Many redox reactions in the subsurface are microbially mediated and other reactions as well. Degradation of organic contaminants is not a one-step process, but a sequence of redox processes. Disturbance of the redox system also induces other chemical processes. The rate of these microbially mediated reactions is the result of a complex interplay between amongst others mass transfer into biofilms, availability of reductants and oxidants, and competition among (groups of) bacteria. Many process parameters and variables are involved in describing this complex interplay. Proper description of the complex interplay depends on the time and space scale of interest; less mechanistic descriptions are allowed at increasing scale. Studies that deal with validation of conceptual and mathematical models at the field scale are welcomed together with studies about the interplay between hydrological and biogeochemical processes. S4.4 Process concepts behind in-situ remediation The threat of contaminated groundwater to human and ecosystem health necessitates remediation of sites. Conventional "pump and treat" technologies are, in general, economically unfeasible due to the extent of the contamination. Remediation of regional scale contamination is often done by water treatment at groundwater pumping locations, i.e., end-of-pipe techniques. Remediation of (local-scale) contamination, therefore, requires the implementation of innovative technologies. The potential costs of remediation have increased the emphasis on developing passive, low maintenance remedial measures. The potentials and limitations of innovative techniques need to be realised for successful implementation in the field. Papers are welcomed that deal with the process concepts behind in-situ remediation techniques and which also address data needs and availability. **************************************************************** Professor Bruce Webb Professor of Physical Geography School of Geography and Archaeology Department of Geography University of Exeter Amory Building Rennes Drive EXETER EX4 4RJ UK E-mail: B.W.Webb@exeter.ac.uk Telephone: 01392 263334 (+44 1392 263334 from outside UK) Fax: 01392 263342 (+44 1392 263342 from outside UK) *****************************************************************