PM2.5　and　TSP　samples　were　collected　at　Lake　Daihai,　a　rural　high-mountain　area　in　China,　in　four　seasons　during　2005-2007.　Organic　carbon　(OC),　elemental　carbon　(EC),　char-EC,　and　soot-EC　were　analyzed　using　the　thermal/optical　reflectance　(TOR)　method　with　different　temperature　plateaus　and　oxidation　atmospheres.　TC,　OC,　EC,　and　char-EC　concentrations　of　TSP　and　PM2.5　showed　seasonal　variations　with　the　highest　concentrations　in　winter　and　the　lowest　in　Summer,　while　soot-EC　reveals　a　little　different　variation,　with　the　highest　concentration　in　spring,　indicating　different　source　contributions　from　other　parameters.　OC/EC　correlations　were　weaker　at　Daihai　than　those　from　urban　areas.　Although　little　differences　existed　in　TSP　and　PM2.5,　average　OC/EC　ratios　varied　seasonally　and　ranged　from　similar　to　9.0　in　winter　to　similar　to　5.0　in　spring.　Char-/soot-EC　ratios　showed　similar　pattern,　with　the　highest　average　ratios　(＞　3.0)　in　winter,　consistent　with　the　contributions　from　residential　biomass　burning　and　coal　combustion.　Back　trajectories　related　the　highest　carbon　concentrations　with　the　southeasterly　air　masses　and　the　lowest　carbon　levels　with　northward　flows.　(c)　2007　Elsevier　Ltd.　All　rights　reserved.