Land classification and change intensity analysis in a coastal watershed of Southeast China

The aim of this study is to improve the understanding of land changes in the Jiulong River watershed, a coastal watershed of Southeast China. We developed a stratified classification methodology for land mapping, which combines linear stretching, an Iterative Self-Organizing Data Analysis (ISODATA) clustering algorithm, and spatial reclassification. The stratified classification for 2002 generated less overall error than an unstratified classification. The stratified classifications were then used to examine temporal differences at 1986, 1996, 2002, 2007 and 2010. Intensity Analysis was applied to analyze land changes at three levels: time interval, category, and transition. Results showed that land use transformation has been accelerating. Woodland's gains and losses were dormant while the gains and losses of Agriculture, Orchard, Built-up and Bare land were active during all time intervals. Water's losses were active and stationary. The transitions from Agriculture, Orchard, and Water to Built-up were systematically targeting and stationary, while the transition from Woodland to Built-up was systematically avoiding and stationary. ? 2014 by the authors; licensee MDPI, Basel, Switzerland

Comparative embryotoxicity of phenanthrene and alkyl-phenanthrene to marine medaka (Oryzias melastigma)

Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are the predominant form of PAHs in oil, comprising 85-95% of total PAHs. However, little attention has been paid to these chemicals in ecological risk assessment of marine oil spill. A comparative study of the toxic effects of phenanthrene and retene (7-isopropyl-1-methylphenanthrene, an alkyl-phenanthrene) on the early life stage of marine medaka (Oryzias melastigma) was conducted. Results showed that retene was significantly more toxic than phenanthrene, and marine medaka could be more sensitive to retene than some freshwater fishes. Retene had a higher excretion rate than phenanthrene during the larvae stage. Both of compounds resulted in developmental malformation of marine medaka embryos, with phenanthrene affecting on peripheral vascular system and yolk sac, while retene affecting on cardiac tissues. The toxicity of phenanthrene might be mainly related to its anesthetic effects, and that of retene might be related to the CYP1A-mediated toxicity of its metabolites. ? 2014 Elsevier Ltd

Detecting the dynamic linkage between landscape characteristics and water quality in a subtropical coastal watershed, southeast China

Geospatial analysis and statistical analysis are coupled in this study to determine the dynamic linkage between landscape characteristics and water quality for the years 1996, 2002, and 2007 in a subtropical coastal watershed of Southeast China. The landscape characteristics include Percent of Built (%BL), Percent of Agriculture, Percent of Natural, Patch Density and Shannon's Diversity Index (SHDI), with water quality expressed in terms of COD Mn and NH4 +-N. The %BL was consistently positively correlated with NH4 +-N and CODMn at time three points. SHDI is significantly positively correlated with COD Mn in 2002. The relationship between NH4 +-N, CODMn and landscape variables in the wet precipitation year 2007 is stronger, with R2 = 0.892, than that in the dry precipitation years 1996 and 2002, which had R2 values of 0.712 and 0.455, respectively. Two empirical regression models constructed in this study proved more suitable for predicting CODMn than for predicting NH4 +-N concentration in the unmonitored watersheds that do not have wastewater treatment plants. The calibrated regression equations have a better predictive ability over space within the wet precipitation year of 2007 than over time during the dry precipitation years from 1996 to 2002. Results show clearly that climatic variability influences the linkage of water quality-landscape characteristics and the fit of empirical regression models. ? 2011 Springer Science+Business Media, LLC

Analysis on linkage between farm landscape and water quality in Jiulong River watershed

Correlation analysis was performed to explore the relationships between CODMn, NH4+-N, TP and farm landscape in the Jiulong River watershed. Linear regressions between water quality and farm land percents were also processed in flood season, dry season and average season. The results showed that the total proportion of farm lands located in the slopes less than 15 degrees and greater than 25 degrees were positively correlated with CODMn, NH4+-N and TP concentrations in the water. Contagion index (CONTAG) of farm lands was positively correlated with TP concentrations, and Shannon Diversity Index (SHDI) of farm lands was negatively correlated with TP concentrations. The determinate coefficients were 0.565 and-0.527, respectively. Water eutrophication was susceptible to farm land pollutions in flood season and dry season. The farm lands located in the slopes less than 15 degrees took up 74.3% in the 100 m-width riparian buffer. The farm lands located in the riparian buffer and in the deep slopes played a crucial role in water quality management, especially the non-point source pollution control in the Jiulong River watershed