The sources and distributions ofterrigenous organic matter （OM） were investigated in a small tropical estu- ary in the Hainan Island, South China. Plants, suspended particulate matter （SPM）, and surface sediments ...The sources and distributions ofterrigenous organic matter （OM） were investigated in a small tropical estu- ary in the Hainan Island, South China. Plants, suspended particulate matter （SPM）, and surface sediments samples in the estuary and coast were collected. Bulk properties [organic carbon （OC%）, total nitrogen （TN%）, stable carbon isotope （613C） and grain size] and lignin phenol concentrations were measured. OC% of mangrove plants was （43.44-2.1） %, which is similar to the values reported for mangrove plants in other re- gions. OC% of sediment samples ranged from 0.07% to 1.42%, and theywere related to the sediment texture. Lignin phenols in the sediment ranged from 5.16 rag/100 mg OC in the uppermost station to 0.51 mg/100 mg OC in the coast. The molar ratio of organic carbon to total nitrogen （C/N） （~7） and 613C （^-31.1 ~ 10-a） of riverine SPM revealed that the major OM sources of riverine SPM were aquatic OM （phytoplankton and/or bacteria）. Moreover, the lower lignin concentration （AS） and higher （Ad/A1）v of lignin phenols suggest that terrestrial OM in riverine SPM were mainly from soil. Furthermore, C/N ratio, 6 ~a C and lignin phenols reveal that mangrove plants were the predominant OM sources of mangrove surface sediment. Based on the 61aC and lignin phenols, it can be concluded that the major OM sources in estuarine and coastal surface sedi- ments were marine phytoplankton, riverine SPM and mangrove surface sediment. In addition, the higher （Ad/A1）v of lignin phenols in those coastal sediments indicate that seagrass might be a potential OM source in coastal sediments, however, the lower （Ad/A1）v in the estuarine sediments in turn suggests that seagrass could not be transported to the mangrove fringed region. A three-end-member model which is based on lignin concentrations and 6 I3C was applied to evaluate the contribution of mangroves to the organic matter preserved in the surface sediments. Around the mangrove fringed region, mangrove could contribute more than 50% to the sedimentary OM, and this value is much higher than riverine OM. Nevertheless, mangrove OM could not be efficiently transported to the coastal region. Our study suggests that mangrove forest is an important OM source in this small estuary.展开更多
Phase space reconstruction is the first step of recognizing the chaotic time series.On the basis of differential entropy ratio method,the embedding dimension opt m and time delay t are optimal for the state space reco...Phase space reconstruction is the first step of recognizing the chaotic time series.On the basis of differential entropy ratio method,the embedding dimension opt m and time delay t are optimal for the state space reconstruction could be determined.But they are not the optimal parameters accepted for prediction.This study proposes an improved method based on the differential entropy ratio and Radial Basis Function(RBF)neural network to estimate the embedding dimension m and the time delay t,which have both optimal characteristics of the state space reconstruction and the prediction.Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively,and both the prediction accuracy and prediction length are improved greatly.展开更多
基金the International Collaborative Program of China under contract No.2007DFB20380(Sino-Germany LANCET Program)the National Natural Science Foundation of China under contract Nos41021064and41076052
文摘The sources and distributions ofterrigenous organic matter （OM） were investigated in a small tropical estu- ary in the Hainan Island, South China. Plants, suspended particulate matter （SPM）, and surface sediments samples in the estuary and coast were collected. Bulk properties [organic carbon （OC%）, total nitrogen （TN%）, stable carbon isotope （613C） and grain size] and lignin phenol concentrations were measured. OC% of mangrove plants was （43.44-2.1） %, which is similar to the values reported for mangrove plants in other re- gions. OC% of sediment samples ranged from 0.07% to 1.42%, and theywere related to the sediment texture. Lignin phenols in the sediment ranged from 5.16 rag/100 mg OC in the uppermost station to 0.51 mg/100 mg OC in the coast. The molar ratio of organic carbon to total nitrogen （C/N） （~7） and 613C （^-31.1 ~ 10-a） of riverine SPM revealed that the major OM sources of riverine SPM were aquatic OM （phytoplankton and/or bacteria）. Moreover, the lower lignin concentration （AS） and higher （Ad/A1）v of lignin phenols suggest that terrestrial OM in riverine SPM were mainly from soil. Furthermore, C/N ratio, 6 ~a C and lignin phenols reveal that mangrove plants were the predominant OM sources of mangrove surface sediment. Based on the 61aC and lignin phenols, it can be concluded that the major OM sources in estuarine and coastal surface sedi- ments were marine phytoplankton, riverine SPM and mangrove surface sediment. In addition, the higher （Ad/A1）v of lignin phenols in those coastal sediments indicate that seagrass might be a potential OM source in coastal sediments, however, the lower （Ad/A1）v in the estuarine sediments in turn suggests that seagrass could not be transported to the mangrove fringed region. A three-end-member model which is based on lignin concentrations and 6 I3C was applied to evaluate the contribution of mangroves to the organic matter preserved in the surface sediments. Around the mangrove fringed region, mangrove could contribute more than 50% to the sedimentary OM, and this value is much higher than riverine OM. Nevertheless, mangrove OM could not be efficiently transported to the coastal region. Our study suggests that mangrove forest is an important OM source in this small estuary.
基金Supported by the Key Program of National Natural Science Foundation of China(Nos.61077071,51075349)Program of National Natural Science Foundation of Hebei Province(Nos.F2011203207,F2010001312)
文摘Phase space reconstruction is the first step of recognizing the chaotic time series.On the basis of differential entropy ratio method,the embedding dimension opt m and time delay t are optimal for the state space reconstruction could be determined.But they are not the optimal parameters accepted for prediction.This study proposes an improved method based on the differential entropy ratio and Radial Basis Function(RBF)neural network to estimate the embedding dimension m and the time delay t,which have both optimal characteristics of the state space reconstruction and the prediction.Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively,and both the prediction accuracy and prediction length are improved greatly.
