云南省典型咖啡产区稀土元素的地球化学特征及环境意义OA

To investigate the geochemical behavior of rare earth elements and ensure ecological safety,a total of 120 surface soil sam-ples were collected from coffee plantations at different altitudes and cultivation durations in Yunnan Province.Using geochemical anal-ysis methods,the content,fractionation characteristics,and environmental significance of rare earth elements in soils from typical cof-fee-producing areas were systematically studied.The results showed that the average of total rare earth element content in soil samples from each coffee-producing areas was higher than the national background value of rare earth elements(163.86 mg/kg),and also ex-ceeded the upper continental crust(UCC)value(150.68 mg/kg).The anomaly values of Ce(δCe)and Eu(δEu)in soils from different coffee-producing areas were significantly different.The δCe ranged from 0.74 to 1.87,with an average value of 1.08.Normal δCe values accounted for 61.98%of the total samples,and no marked positive anomaly was observed.δEu ranged from 0.42 to 0.82,with an aver-age of 0.56,showing a depletion trend.The ratio of light rare earth elements to heavy rare earth elements(LREE/HREE)in the study area ranged from 7.30 to 15.87,with an average of 10.67,indicating that light rare earth elements were relatively more enriched com-pared to heavy rare earth elements.There was a generally strong positive correlation among rare earth elements,while most rare earth elements showed weak negative correlations with organic matter.Light rare earth elements exhibited weak positive correlations with pH,whereas most heavy rare earth elements showed weak negative correlations with pH.Most rare earth elements had weak negative correlations or no correlation with Ca,and most rare earth elements showed no correlation with K or N.The altitude gradient had a sig-nificant control effect on the fractionation of rare earth elements,and there were obvious elevation differentiation characteristics.