外来种互花米草对江苏省潮间带生物地球化学过程的影响研究

Spartina alterniflora Loisel, a species vegetating in intertidal flats along the eastern coast of the United States, was introduced in China almost 30 years ago and has become an urgent topic due to its invasiveness in the coastal zone of China. The impacts of this alien species S. alterniflora on intertidal ecosystem processes in the Jiangsu coastland were investigated by comparing the sediment nutrient availability and trace element concentration characteristics in a mud flat and those of a four-year old Spartina salt marsh that had earlier been a mudflat. At each study site, fifteen plots were sampled in different seasons to determine the sediment characteristics along the tidal flats. The results suggested that Spartina salt marsh sediments had significantly higher total N, available P, and water content, but lower pH and bulk density than mudflat sediments. Sediment salinity, water content, total N, organic C, and available P decreased along a seaward gradient in the Spartina salt marsh and increased with vegetation biomass. Furthermore, the concentrations of trace elements and some metal elements in the sediment were higher under Spartina although these increases were not significant. Also, in the Spartina marsh, some heavy metals were concentrated in the surface layer of the sediment. The Spartina salt marsh in this study was only four years old; therefore, it is suggested that further study of this allen species on a longer time frame in the Jiangsu coastland should be carried out.

Effect of an alien species Spartina alterniflora Loisel on biogeochemical processes of intertidal ecosystem in the Jiangsu coastal region, China

The leaching characteristics of a garden soil may be greatly affected by application of poultry and livestock manures from intensive farming.Packed soil columns of a garden soil(CK)and the soils after respectively receiving 2% pig manure (PM),chicken manure(CM),and commercial organic manure(OM)were leached with 0.05 mol L-1 Ca(NO3)2 and 0.01 mol L-1 EDTA solutions.The leachate EC(electric conductivity)values gradually increased at the beginning and then reached a stable value when the soil columns were leached with 0.05 mol L-1 Ca(NO3)2 solution.The leachate EC values showed a peak-shape when leached with 0.01 mol L-1 EDTA solution.In all the soil columns,the pH values of the leachates decreased with increase of displacement volumes when the Ca(NO3)2 solution was used.The total amounts of Cu and Zn eluted from the four soil columns were significantly correlated with the extracted soil Cu and Zn concentrations by 1.0 mol L-1 NH4NO3,but were not correlated with the leachate dissolved organic carbon(DOC)contents.The Zn concentration in the leachate of the PM-treated soil column with 0.05 mol L-1 Ca(NO3)2 solution was above the Quality Standard III for Ground Water of China(GB/T 14848-93,Zn ＜ 1.0 mg L-1).When compared with 0.05 mol L-1 Ca(NO3)2,the EDTA solution significantly accelerated Cu and Zn elutions in the manure-treated columns.This suggested that applying poultry and livestock manures from intensive farming to farmland might pose a threat to the groundwater quality.