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 10⁻¹to 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 ∼10⁴and 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.