Sustainable and integrated water resources management on watersheds facing industrial pollutions and urbanization: a comparative study between Lot River (France) and Danshuei River (Taiwan) – TWIN RIVERS 2011

Since May 2012, hydrobiogeochemical monitoring has conducted by the French teams in the Lot watershed - mainly in three sites: (1) in the Upstream Lot River System at Livinhac, before the confluence with the small polluted watershed; (2) in the Decazeville watershed: the small industrial polluted watershed at its outlet (the Joany site); (3) in the downstream Lot River System at Temple (outlet of the watershed);
Parallel monitoring are carried out by the French and Taiwanese colleagues to characterize the water quality of the Danshui River System at Taiwan. The parameters monitored are similar on both sites: water discharges, Suspended Particulate Matter, metals, nutrients and carbon, chlorophyll and persistent organic contaminants. The transplantation of filter feeding bivalves (Corbicula fluminea) was performed over a period of 20 days in the fall of 2012 on 5 sites in the Riou Mort and Lot Rivers, along the polymetallic pollution gradient. For biofilms, two experiments were conducted: in the spring and fall 2012. After in situ colonization time on six sites over a period of 20-25 days, biofilms were analyzed (density, biomass, Cd bioaccumulation). A parallel experiment was conducted in the laboratory. Diatom Eolimna minima (a metal-tolerant freshwater diatom with a high abundance on the most contaminated sites) were grown in batches and exposed to 3 Cd concentration levels (0, 10 and 100 µg/L). Samples were collected at 7 and 14 days to determine cell growth, bioaccumulation of Cd and mitochondrial gene expression, response to oxidative stress response, photosystems I and II. The Asconit activities consist in performing a bibliographic synthesis on existing studies on the Lot and Danshui Rivers and produce a report for the partners of this projects and stakeholders.

Dissolved Cd concentrations in the Lot River showed a strong seasonal variability (with low value during spring and summer) suggesting a pumping by phytoplankton. The dissolved and particulate Cd concentrations in the Riou Mort increased between 2009 and early 2013 showing that the effect of rehabilitation works carried out on the industrial site is not even noticeable. The intercomparisons of biogeochemical measurements between France and Taiwan highlighted that Taiwanese colleagues did not distinguish between dissolved and particulate forms; the exchange protocol has been used to characterize dissolved and particulate forms of metals in some river samples collected in the Danshui River.
A significant accumulation of Cd is always observed in bivalves transplanted to the Joany site in the Riou Mort River, followed by another site on the Decazeville watershed (on the Riou-Viou River), then Bouillac (Lot, just after the confluence with the Riou Mort), and finally Livinhac (upstream lot) and the Decazeville city (Riou Mort before the industrial waste dumps). At the cellular and molecular level, the effects on bivalves are still present with high metallothionein production and generation of oxidative stress on the most contaminated sites.
The seasonal effect is evident on the density of diatoms with greater colonization of diatoms at the Decazeville city during spring and fall, and conversely higher densities at Joany site in fall compared to spring in connection with an absence grazing by consumers of biofilms in autumn than in spring. Concerning bioaccumulation, metal concentrations (Cd and Zn) are still higher with 118 µg Cd/g dw in the spring and 249 µg Cd/g dw in the fall and the amount of adsorbed metal still well above the metal absorbed. The composition of diatom communities in biofilms shows a distribution of different species depending on the level of contamination of sites.

After (i) the intercomparisons of analytical methodologies to characterize water quality and (ii) the analyze of preliminary biogeochemical results conducted on both sites (Lot and Danshui Rivers), two sampling campaigns, with a high spatial resolution monitoring, will be performed to characterize the biogeochemistry of water using the same protocols. The identification of factors controlling the metal concentrations (e.g. Cd and As) in the Lot River will soon be supplemented by modeling using neural networks by Taiwanese colleagues.
In situ transplantations of Corbicila fluminea are currently tested in Taiwan on the Danshui Rivers in order to try to develop similar approaches than those developed in France. However difficulties are encountered, essentially due to the hurricanes that regularly prevent the maintenance of cages in rivers. New tests will be carried out at the approach of the dry season.
Concerning biofilms, experimental approaches are ongoing and are subject to methodological tests despite difficult weather conditions (rainy season with episodes of typhoons) as observed for Corbicula fluminea. The cages equipped with glass slides were immersed in the rivers studied by the team of Prof. Rita Yam. The arrival of the dry season should facilitate extended exposure in rivers.

1. Kim Tiam S., Moisset, S., Feurtet-Mazel, A., Mazzella, N., Arini, A., Delmas, F., Morin, S., Daffe, G. and Gonzalez, P. (2013) Development of q-PCR approaches to assess water quality: Effects of cadmium and pesticides on gene expression of diatoms SETAC North America 34th Annual Meeting - Nashville, TN, USA, 17-21 novembre 2013, poster.
2. Chang FJ, Tsai WP, Wang YC, Chen PA, Chang LC, Coynel A., Vachaud G. (2014) Optimal reservoir operation strategy for balancing ecosystem and human needs Hydrology in a Changing World: Environmental and Human Dimensions Proceedings of FRIEND-Water 2014, Hanoi, Vietnam, February 2014 (IAHS Publ. 36X, 2014), oral + proceeding

While today water is still an abundant resource, its future availability is threatened by: increasing demands of a growing population and economic expansion, chemical and microbiological risks, as well as the potential impacts of climate change. The situation now calls for a wise use and a more adequate management and protection of this resource. In Europe, in order to comply with the most recent EU Water Framework Directive, additional efforts are needed to be made to reduce the potential threats on the national water bodies. In Taiwan, where hydrological and geological environments have undergone drastic changes due to urbanization, excessive utilization of steep terrain, major earthquake (1999) and increased number of typhoons and torrential rain events, the Water Resources Agency was created in 2002 with a mission to build a safe, ecological and diverse water environment, and to ensure sufficient quality and sustainable water resources. It is in that context that the proposal intends to carry out integrated studies in two river catchments (Danshuei River, Taiwan; Lot River, France) submitted to severe contamination, to provide strategic managerial decisions for sustainable watershed management at a cross-continental scale. In both cases, the rationale will be to combine different types of approaches (hydrology, geochemistry, ecology, ecotoxicology, genetics) to deepen and diversify our knowledge of these ecosystems, and to involve in the team a group of consultants to ensure the applicability of results and their transfer as management tools to water agencies on both sides. Four research units from Bordeaux (UMR EPOC and CEMAGREF/REBX), Paris (UMR Sisyphe) and Grenoble (UMR LTHE) and one private consulting group (ASCONIT Consultants) will be involved on the French side. On the Taiwanese side, 5 research units from National Taiwan University (NTU), Academia Sinica (SINICA), Hydrotech Research Institute (HRI), Tamkang University (TKU), and Agricultural Engineering Research Center (AERC) and one non-profit senior consultant from Water Resources Agency will be involved. The TWIN RIVERS project will be organized on tasks to address the following points:
- Identification of pollutants, intercomparison of monitoring and analytical techniques
- Impact of pollution on aquatic species
- Exchange and intercomparison of statistical and biological indicators of water quality
- Development of an environmental driven multi-objective optimization model to establish the concepts of sustainable watershed management in close connection with managers (Water Agencies, Regional Water Public Boards…) and stakeholders.
We aim at developing scientific studies between France and Taiwan taking profit of the very strong differences in climate, soils and land-use between the two countries to stimulate research activities on both sides. The first impact of this collaborative work between the two countries will be on water policy. The collaboration will also be based on a “win-win” concept in which each country will benefit of the strengths of the counterpart:
- French partners will benefit of Taiwan partners’ experiences in statistical and neuronal analysis of data for the development of a multi-objective watershed management model.
- Taiwan partners will benefit of French partners’ experiences on biological indicators (diatoms, biofilms) and on joint planning processes promoted by water agencies and Regional Watershed Public Boards (EPTB).
Exploitation of the results obtained in the course of this programme, in terms of knowledge, methods and models, will consist of active collaborations in both studied areas and will be supported by training via research exchanges and by presenting results at national and international conferences and international journals. Finally, this project will provide an excellent opportunity for bilateral student supervision, formation of internationally experienced PhDs (co-supervision France-Taiwan).