Efficiency of three halophyte species in removing nutrients from saline water: a pilot study

H J De Lange,M P C P Paulissen

doi:10.1007/s11273-016-9489-8

Abstract

Saline wetlands may be well suited for purifying contaminated water from saline agriculture and aquaculture or from freshwater-based agriculture in areas subject to increased salinity. However, case studies on the nutrient removal efficiency of halophyte species are scarce, especially for temperate regions. Here we tested the nutrient removal efficiency and ability to store nutrients in aboveground and belowground biomass of three halophyte species, Aster tripolium, Bolboschoenus maritimus subsp. compactus, and Spartina anglica, in a greenhouse microcosm experiment at two salinity levels. Nutrient removal from water differed among the species: Spartina had the highest nitrogen removal, Bolboschoenus and Spartina had the highest phosphorus removal. The species also differed in the allocation of the nutrient uptake. Bolboschoenus had the highest absolute uptake of nitrogen and phosphorus in shoots, whereas Spartina had the highest uptake of nitrogen and phosphorus in roots. The applicability of these three species in constructed saline wetlands depends on the local salinity and water regime.

Highlights

Many constructed wetlands are designed to purify contaminated freshwater (e.g. Verhoeven and Meuleman 1999; Kadlec and Wallace 2009)
Bolboschoenus had the highest absolute uptake of N and P in shoots, whereas Spartina had the highest uptake of N and P in roots
Salinity of the treatment water was not a significant factor, except for nutrient uptake in Bolboschoenus which was higher at low salinity

Summary

Introduction

Many constructed wetlands are designed to purify contaminated freshwater (e.g. Verhoeven and Meuleman 1999; Kadlec and Wallace 2009). Examples of full-scale constructed wetlands in temperate regions purifying contaminated saline water from aquaculture sources are only recently becoming available Buhmann and Papenbrock 2013; De Lange et al 2013) Such saline constructed wetlands may help to prevent unwanted loading of vulnerable estuaries or coastal waters with nutrients, organic pollutants and/or pathogens from both point and diffuse sources. Salinity pressure is increasing in many low-lying coastal areas worldwide due to climate change and sea level rise (e.g. Rozema and Flowers 2008). In this perspective, saline treatment wetlands can be considered a logical and sustainable adaptation measure, with various additional advantages such as providing a semi-natural transition zone between intensively used agricultural areas and adjacent natural estuarine and coastal areas (Roncken et al 2011). The rehabilitation and/or enhancement of existing salt marshes will provide other essential ecosystem services, such as the stabilisation of fine sediments, providing a protective buffer between land and sea, and providing a habitat to a diversity of terrestrial and marine fauna (Laegdsgaard 2006)

Methods

Results

Conclusion