Within the Tejo Estuary, non-indigenous species (NIS) Spartina patens colonizes the upper middle marsh competing with the native Halimione portulacoides for space and resources. Due to the very different root system and metabolism between both species, this invasion can have significant biogeochemical implications, namely in terms of metal speciation and availability. In the present study, we evaluate the biogeochemical modifications in terms of metal speciation introduced by the colonization of the NIS S. patens. Total metals Cu, Zn, Pb and As within the rhizosediment varied between the two study species but was generally higher in the rhizosediment of H. portulacoides. These differences could be attributed to the higher organic content and smaller sand fraction found in the rhizosediment of H. portulacoides. Zinc was found to have highest concentration (H. portulacoides 126.22 mg g⁻¹, S. patens 68.35 mg g⁻¹) in the rhizosediments while Cu and As were least concentrated metals. Considering the bioavailable fractions (F1 + F2) Cu, Zn and As were more readily available in the sediment beneath NIS S. patens than in H. portulacoides and Pb presented no significance (p = 0.835). Overall, H. portulacoides rhizosediments had higher total metal concentration, whilst the rhizosediments of NIS S. patens presented a higher percentage of bioavailable metals. Thus, the bioinvasion and expansion of NIS S. patens may have implications for metal biogeochemistry and the natural remediation capacity of salt marshes in estuaries along the Mediterranean and North-eastern Atlantic coasts, as well as ensuing biodiversity and potential trophic web contamination consequences.

在Tejo河口内，非本土物种（Spartina patens）栖息在中部沼泽上游，与当地的Halimione portulacoides争夺空间和资源。由于两个物种之间的根系和代谢差异很大，这种入侵可能会产生重大的生物地球化学影响，即在金属形态和可利用性方面。在本研究中，我们根据NIS S. patens的定殖引入的金属形态评估生物地球化学修饰。在这两个研究物种中，根状茎沉积物中的总金属Cu，Zn，Pb和As有所不同，但一般在马齿。的根茎沉积中较高。这些差异可以归因于马齿。的根状沉积物中较高的有机物含量和较小的砂分数。锌被发现具有最高浓度（H. portulacoides 126.22毫克克^-1，S.藓68.35毫克克^-1）在rhizosediments而Cu和As是最不浓缩金属。考虑到生物可利用的部分（F1 + F2），铜，锌和砷比普通马齿H更容易在NIS S. patens下的沉积物中获得，Pb则无意义（p = 0.835）。总体而言，H. portulacoides rhizosediments有较高的总金属浓度，而NIS的rhizosedimentsS. patens呈现出更高的生物利用度金属百分比。因此，NIS S. patens的生物入侵和扩展可能对金属生物地球化学和盐沼在地中海和东北大西洋沿岸的河口的自然修复能力以及随之而来的生物多样性和潜在的营养网污染后果产生影响。