Composting of seaweed waste: Evaluation on the growth of Sarcocornia perennis

Composting represents a suitable and cheap method for handling and processing seaweeds accumulated on the coast. Within this framework, two seaweed composts were prepared, one with Undaria pinnatifida accumulated in spring-summer and other with a mixture of seaweeds accumulated in autumn-winter, both from Central Patagonian beaches. The effect of these two composts was evaluated experimentally as an amendment for the growth of Sarcocornia perennis (chickenclaws), a plant species dominating Patagonian salt marshes. Both composts were applied at 75, 50, and 25% doses with perlite. The analysis of the compost properties (phytotoxicity test, C/N, electrical conductivity, pH, and metal content) allowed characterizing both composts as matures and stables. The growth results showed that both composts allow the growth of S. perennis in all doses tested; however, Undaria compost was better in the stimulation of vegetative growth when applied in dose 50%, followed by 75% of both composts. For these reasons, both composts from seaweed waste accumulated on Patagonian coasts could be used in the growth of S. perennis and potentially other plant species, giving value to the seaweeds that currently are considered a waste that disturb these coasts and are discarded without use.

Comparison of phytoremediation potential capacity of Spartina densiflora and Sarcocornia perennis for metal polluted soils

Phytoremediation is considered the most appropriate technique to restore metal polluted soil, given its low cost, high efficiency and low environmental impact. Spartina densiflora and Sarcocornia perennis are perennial halophytes growing under similar environmental conditions in San Antonio marsh (Patagonia Argentina), therefore it is interesting to compare their phytoremediation potential capacity. To this end, we compared concentrations of Pb, Zn, Cu, and Fe in soils and in below- and above-ground structures of S. perennis and S. densiflora. It was concluded that both species are able to inhabit Pb, Zn, and Cu polluted soils. Although Sarcocornia translocated more metals to the aerial structures than Spartina, both species translocated only when they were growing in soils with low metal concentrations. It seems that the plants translocate only a certain proportion of the metal contained in the soil. These results suggest that both species could be considered candidates to phytostabilize these metals in polluted soils.

Accumulation and distribution of trace metals within soils and the austral cordgrass Spartina densiflora in a Patagonian salt marsh

Concentrations of Cd, Cu, Fe, Pb, and Zn were determined in soils and in below- and above-ground structures of Spartina densiflora in a Patagonian salt marsh (San Antonio, Río Negro, Argentina). Also, the relationship between trace metal concentrations in soils and plants was investigated to improve our knowledge regarding the ability of this plant species to take up and accumulate trace metals from the soil. Our results indicate that, within the studied salt marsh, soil trace metal concentrations follow a decreasing concentration gradient toward the sea. They show moderate pollution and a potentially negative biological effect in one site of the salt marsh. While below-ground structures reflect the soil metal concentration pattern, this is not so evident in above-ground concentrations. Also, S. densiflora is able to absorb a limited amount of metals present in the soil, the soil bioaccumulation factor being lower in sites where soil metal concentration is higher.