Effects of anthropogenic nutrient input on organisms from different trophic levels in Hanfeng Lake: evidence from stable carbon and nitrogen isotope analysis Labile soil organic carbon distribution on influenced by vegetation types along an elevation gradient in west Sichuan, China Effects of biochar amendment on cropland soil bulk density, cation exchange capacity, and particulate organic matter content in the North China Plain. Nitrogen Content in Soil Particulate Fraction and Its Relationship to the Elevation and the Vegetation The composition and change of particulate fatty acids during a diatom bloom in Jiaozhou Bay, China