Evaluating the hydrogeochemical response of springs using phase-plane plots andsingular spectrum analysis

摘要

An ongoing study is focused on understanding the hydrology and geochemistry ofthree contaminated, perennial, semi-arid zone springs at a high explosives production facility at Los Alamos National Laboratory, in northern New Mexico, USA. Springflow time series were examined using singular spectrum analysis (SSA) to identify the important time-scales affecting flow in the springs. SSA results suggest that springflow has two dominant patterns: a series of low-frequency modes which follow the seasonal and longer-term climate conditions at the site, and a large number of higher frequency modes which display the characteristic 'red noise' spectrum related to local, short-term weather conditions. Phase-plane plots of (delta)(sup 18)O and spring discharge suggest that high flow conditions are dominated by snowmelt and summer monsoon inputs while low flow conditions can be affected by mixing of fast and slow flow components causing wide variations in (delta)(sup 18)O values. The analysis is being used for development of an efficient strategy for sampling design for environmental monitoring of contaminants that respond to multiple time scales.