Assessing the decoupling of economic growth from environmental impacts in the European Union: A consumption-based approach.

Pursuing a responsible and sustainable development, the United Nations urged to decouple economic growth from environmental impacts. Several European Union (EU) policies have been implemented towards such goal. Although multiple authors have evaluated the decoupling of the economic growth from the resource use or environmental concerns, the environmental assessment mostly focused on pressures rather than impacts, and used single indicators assumed to be a proxy of the overall effects on the environment. Furthermore, no studies were found using a process-based life cycle approach to quantify the environmental impacts of consumption. To solve such research gap, this paper assesses the decoupling in the EU focusing on potential environmental impacts, complementing a production-based approach with two options for accounting for the impacts of consumption. The aim of this paper is to evaluate the decoupling of the economic growth (in terms of Gross Domestic Product) from the environmental impacts due to EU-28 consumption, assessed by means of life cycle assessment (LCA). The decoupling is then assessed in impact terms rather than limited to pressures by using the Environmental Footprint (EF2017) indicators, which allows assessing 16 different impacts. The Consumption Footprint indicator quantified the environmental impacts of EU apparent consumption, including the territorial impacts (Domestic Footprint) and the embodied impacts in both imports and exports (Trade Footprint). The inventory of pressures for the trade component is compiled either with a bottom-up approach (process-based LCA of representative traded goods) or a top-down approach (input-output-based LCA). Methodological aspects influencing the decoupling assessment and the resulting outputs are presented and discussed. According to the results, the environmental impacts of EU-28 consumption showed decoupling during the last decades (2005-2014), between relative to absolute decoupling depending on the inventory modeling approach taken. Some countries showed higher decoupling levels than others displaying a heterogeneous map of EU-28 decoupling, which was led by acidification, particulate matter, land use and eutrophication impacts. Notwithstanding current limitations, the assessment of decoupling using consumption-based environmental indicators is very promising for supporting policy-making towards addressing the actual impacts driven by the EU production and consumption system.

Improving water management in European catfish recirculating aquaculture systems through catfish-lettuce aquaponics.

In the context of climate change and population growth, aquaculture plays an important role for food security, employment and economic development. Intensive recirculating aquaculture systems (RAS) allow to treat and recycle fish effluents to reduce waste concentration in outflow water thereby reducing environmental contamination. RAS sustainability may be further improved using aquaponics, a circular productive system in which RAS wastewater is recovered for crop cultivation and recycled back to the fish tanks. In this study, water metabolism of a catfish RAS was assessed and the opportunity to produce lettuce with the RAS effluent was tested. Crop growth and water consumption in aquaponics were compared to those experienced in hydroponics at three nutrient solution concentration (EC of 1.6, 2.0 and 3.0 dS∙m-1), also considering water- (WUE) and nitrogen- use efficiency (NUE). A scenario for converting the RAS in a catfish-lettuce aquaponic system was, then, proposed. The RAS water balance included an input of 555 L∙day-1, out of which 32 L∙day-1 were lost by evaporation from the tubs whereas 460 L∙day-1 were discarded. The lettuce yield, NUE and WUE in aquaponics were respectively 20.3%, 22.3% and 20.6% lower than those obtained in hydroponics. Best performances in hydroponics were achieved with EC of 2.0 dS m-1. No difference in term of water consumption arose between the treatments, with average water use of 46 mL∙plant-1∙day-1. Considering the current RAS productivity of 329 kg year-1, a 10 m2 raft system hosting 160 lettuces would satisfy the nitrogen filtration demand. Once closed the water loop between the two productive sub-units, the current water input of 532 L∙day-1 could be reduced to the amount needed to replace the water lost by evaporation (50 L∙day-1) and the RAS water output would decrease from 555 to 103 L∙day-1.