Abstract: In the upper, middle, and lower shoals of Jiuduansha shoal at Yangztse River estuary, an investigation was made on the content, distribution pattern, and cycling characteristics of nutrient elements N, P and K in invading species Spartina alterniflora wetland ecosystem. The results showed that among the S. alterniflora wetland ecosystems in the three shoals, the contents of soil total N, P, and K had relatively small differences, but those of soil available N, P, and K had larger differences. The total K content in soil profile was far higher than the contents of total N and P, with the order of total K>total N>total P. Soil available nutrient contents in the three shoals were in the order of available K > available N > available P. Soil available N, P, and K had different spatial distribution patterns from soil total N, P, and K, and their vertical differentiation in the profile was more obvious than that of soil total N, P, and K. The contents of N, P, and K at different soil depths in the same shoals or at the same soil depths in different shoals were different, and the difference of total N was obviously larger than that of total P and K. The plant K content was the highest, followed by N, and P. The return of nutrient elements in the wetland ecosystem was far greater than their reserve, and the absorption coefficient was in the order of N>P>K. There existed obvious differences in the utilization coefficient and cycling coefficient of N, P, and K among the three shoals of Jiuduansha shoal. The P in the upper shoal and the K in the middle and lower shoals had the highest utilization coefficient; while the K in the upper shoal, P in the middle shoal, and N in the lower shoal had the highest cycling coefficient.

Key words: Ecoremediation, Chlorophyll-a, Size-fractionation