Dynamic emergy valuation of water hyacinth biomass in wetlands: an ecological approach

•Unit Emergy Values (UEV) for a wetland natural resource were calculated.•Em$/kg values were obtained for lower and upper thresholds for dry and wet years.•Em$/kg values support the decision of the best time of year for extraction.•UEV obtained can support public policies related to new economic activities.

The water hyacinth (Eichhornia spp), characterized by elevated growth rates, is a native aquatic weed in the Pantanal wetland and represents the main species in aquatic floating mats that are carried by the Paraguay River according to the wetland flood pulse dynamics. The floating mats have a role in nutrient cycling to consumers of detritivorous food webs, such as typical fish of the region. Nonetheless there are potentials of using water hyacinth biomass to produce biofuels and biomaterials through biomass conversion techniques like anaerobic digestion and pyrolysis. Biomass growth of water hyacinth was modeled in the floodplain of the Upper Paraguay River basin to identify the underlying dynamics by means of emergy analysis. Emergy modeling has permitted to obtain monthly unit emergy values (UEVs) useful to evaluate the economic feasibility of water hyacinth biomass use in phase with the flood pulse of the Pantanal wetland. This approach can be replicated to other natural or constructed wetlands where the aquatic weeds growth is excessive.