Potential of Spartina maritima in restored salt marshes for phytoremediation of metals in a highly polluted estuary.

Sedimentary abiotic environment, and concentration and stock of nine metals were analyzed in vegetation and sediments to evaluate the phytoremediation capacity of restored Spartina maritima prairies in the highly polluted Odiel Marshes (SW Iberian Peninsula). Samples were collected in two 10 -m long rows parallel to the tidal line at two sediments depths (0-2 cm and 2-20 cm). Metal concentrations were measured by inductively coupled plasma spectroscopy. Iron, aluminum, copper, and zinc were the most concentrated metals. Every metal, except nickel, showed higher concentration in the root zone than at the sediment surface, with values as high as ca. 70 g Fe kg(-1). The highest metal concentrations in S. maritima tissues were recorded in its roots (maximum for iron in Spartina roots: 4160.2 +/- 945.3 mg kg(-1)). Concentrations of aluminum and iron in leaves and roots were higher than in superficial sediments. Rhizosediments showed higher concentrations of every metal than plant tissues, except for nickel. Sediment metal stock in the first 20 cm deep was ca. 170.89 t ha(-1). Restored S. maritima prairies, with relative cover of 62 +/- 6%, accumulated ca. 22 kg metals ha(-1). Our results show S. maritima to be an useful biotool for phytoremediation projects in European salt marshes.

Ecotypic variations in phosphoenolpyruvate carboxylase activity of the cordgrass Spartina densiflora throughout its latitudinal distribution range.

This study compared the specific activity of phosphoenolpyruvate carboxylase (PEPC) of Spartina densiflora Brongn., collected from four populations along its latitudinal distribution range. Spartina densiflora is a halophyte with C(4) photosynthesis that has a very wide latitudinal distribution, from Patagonia to the southwest Iberian Peninsula. The basis of intraspecific differences in PEPC activity were analysed by recording the phosphorylation state and amount of the enzyme, comparing leaf anatomy and evaluating leaf gas exchange. S. densiflora individuals from Patagonia had 60% higher PEPC specific activity than plants from the other three populations due to higher levels of PEPC protein that coincided with lower activation mediated by phosphorylation, yielding similar net photosynthesis rate (c. 29 micromol CO(2)xm(-2)xs(-1)). Patagonian plants had a higher area of photosynthetic mesophyll relative to total chlorophyll than plants from north Argentina and the southwest Iberian Peninsula. Ecotypic differentiation in PEPC activity and leaf anatomy were found, distinguishing a higher-latitude ecotype from lower-latitude populations. The higher PEPC protein levels of the Patagonian ecotype seemed to be a response to lower light activation level of the enzyme, as judged by the low PEPC phosphorylation state.