Effect of altitude on the stable carbon and oxygen isotopic compositions of land snails at the margin of the East Asian monsoon

摘要: Abstract The carbon and oxygen isotopic composition of land snail shells (δ13Cshell δ18Oshell) has been used to reconstruct paleoenvironmental changes worldwide. Adding the limited calibration information available for monsoon marginal regions, we present δ13C δ18O results modern snails, plants soils, collected from Helan Mountains, in North China, spanning an altitudinal gradient 1733–2851 m a.s.l. Linear regression analysis show that δ13Cshell is positively correlated with altitude on both slopes, similar rates variation; contrast, δ18Oshell negatively western but this effect absent eastern slopes. variations integrated signals living vegetation flux absorbed atmospheric CO2 attributed metabolic are likely responsible above 2000 m a.s.l., while type and/or carbonate ingestion by snails may be important inducing positive shift below determined rainwater fractionation processes between shell body water, controlled temperature alpine environment. In addition, evaporative enrichment fluid or environmental water prior exerts influence δ18Oshell. Notably, study region respond more sensitively climate than core area. rate change response precipitation −0.87‰/°C +2.76‰/100 mm, corresponding slopes +0.41‰/°C −1.29‰/100 mm. Our expand range application as climatic indicators, emphasize differences sensitivity these proxies margin areas. isotope environment adjacent locations (i.e. different slopes) mountainous terrain need considered future studies.