Natural perchlorate (ClO4 -) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4 - compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4 - in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4 - to the more well-studied atmospherically deposited anions NO3 - and Cl- as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4 - is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10-1 to 106 μg/kg. Generally, the ClO4 - concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3 - and ClO4 - co-occur at molar ratios (NO3 -/ClO4 -) that vary between ~104 and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4 - reduction, as indicated in part by NO3 - isotope data. In contrast, much larger ranges of Cl-/ClO4 - and Cl-/NO3 - ratios indicate Cl- varies independently from both ClO4 - and NO3 -. The general lack of correlation between Cl- and ClO4 - or NO3 - implies that Cl- is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a NO3 -/ClO4 - molar ratio ~103. The relative enrichment in ClO4 - compared to Cl- or NO3 - and unique isotopic composition of Atacama ClO4 - may reflect either additional in-situ production mechanism(s) or higher relative atmospheric production rates in that specific region or in the geological past. Elevated concentrations of ClO4 - reported on the surface of Mars, and its enrichment with respect to Cl- and NO3 -, could reveal important clues regarding the climatic, hydrologic, and potentially biologic evolution of that planet. Given the highly conserved ratio of NO3 -/ClO4 - in non-biologically active areas on Earth, it may be possible to use alterations of this ratio as a biomarker on Mars and for interpreting major anion cycles and processes on both Mars and Earth, particularly with respect to the less-conserved NO3 - pool terrestrially.