Comparison of carbon balance in Mediterranean pilot constructed wetlands vegetated with different C4 plant species

Abstract

This study investigates carbon dioxide (CO2) and methane (CH4) emissions and carbon (C) budgets in a horizontal subsurface flow pilot-plant constructed wetland (CW) with beds vegetated with Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty, and Mischantus × giganteus Greef et Deu in the Mediterranean basin (Sicily) during the 1st year of plant growing season. At the end of the vegetative season, M. giganteus showed the higher biomass accumulation (7.4 kg m(-2)) followed by C. zizanioides (5.3 kg m(-2)) and C. papyrus (1.8 kg m(-2)). Significantly higher emissions of CO2 were detected in the summer, while CH4 emissions were maximum during spring. Cumulative CO2 emissions by C. papyrus and C. zizanioides during the monitoring period showed similar trends with final values of about 775 and 1,074 g m(-2), respectively, whereas M. giganteus emitted 3,395 g m(-2). Cumulative CH4 bed emission showed different trends for the three C4 plant species in which total gas release during the study period was for C. papyrus 12.0 g m(-2) and ten times higher for M. giganteus, while C. zizanioides bed showed the greatest CH4 cumulative emission with 240.3 g m(-2). The wastewater organic carbon abatement determined different C flux in the atmosphere. Gas fluxes were influenced both by plant species and monitored months with an average C-emitted-to-C-removed ratio for C. zizanioides, C. papyrus, and M. giganteus of 0.3, 0.5, and 0.9, respectively. The growing season C balances were positive for all vegetated beds with the highest C sequestered in the bed with M. giganteus (4.26 kg m(-2)) followed by C. zizanioides (3.78 kg m(-2)) and C. papyrus (1.89 kg m(-2)). To our knowledge, this is the first paper that presents preliminary results on CO2 and CH4 emissions from CWs vegetated with C4 plant species in Mediterranean basin during vegetative growth.

Domestic Wastewater Depuration Using a Horizontal Subsurface Flow Constructed Wetland and Theoretical Surface Optimization: A Case Study under Dry Mediterranean Climate

“…On the other hand, the climate of the Mediterranean basin, which implies warmer T of the water and, during growing season, the larger and constant growth of the common reed, may justify the high abatement found for this region compared with other European experiences [35]. The abatement process of BOD 5 is mainly carried out by bacterial activity (aerobic and anaerobic) with greenhouse gases production and emission to the atmosphere [41,42], and by the sedimentation and filtration of particulate organic matter [43]. In this respect the assisted aeration during the first year of the study combined within common reed activity was effective [44].…”

Hydroponic systems and water management in aquaponics: a review

“…The complex removal mechanisms in the biofilter and the hydroponic component are similar to those of natural and constructed wetlands. In both, the removal of nutrients and/or pollutants is complex and depends on a variety of mechanisms, including sedimentation, filtration, precipitation, volatilisation, adsorption, plant uptake, and various microbial processes (Wießner et al, 2005;Vymazal, 2007;Wu et al, 2014;Barbera et al, 2015;Maucieri et al, 2014Maucieri et al, , 2016. Lennard and Leonard (2005) compared a reciprocating flood/drain cycle (10 min flood every 70 min) to a constant flow in a hydroponic gravel bed (0.52 m 2 ) plated with lettuce during 21-day cycle.…”

Role of C3 plant species on carbon dioxide and methane emissions in Mediterranean constructed wetland

“…CH4 flux was measured using the static non-stationary chamber technique (Barbera et al, 2014a) three times a month in two microsites in order to replicate the measures. The flux cylindrical chamber, 42 cm high and 20 cm wide, was inserted into the gravel substrate using a permanent ring inserted into the substrate before the beginning of measurements to prevent soil disturbance in each site.…”

“…Only a few studies have been carried out in a Mediterranean environment on GHG emission from pilot-plant CWs (Garcia et al, 2007;Barbera et al, 2014a) or a full-scale CW (Barbera et al, 2014b) vegetated with P. australis or C4 plant species. To our knowledge no studies have focused on GHG emission from CWs vegetated with Arundo donax (C3 species), either in a Mediterranean environment or at other latitudes.…”