Article (refereed) -postprint Atmospheric Deposition of Phosphorus to Land and Freshwater 4 5 E Tipping,* A

24 We compiled published and newly-obtained data on the directly-measured atmospheric 25 deposition of total phosphorus (TP), filtered total phosphorus (FTP), and inorganic 26 phosphorus (PO4-P) to open land, lakes, and marine coasts. The resulting global data 27 base includes data for c. 250 sites, covering the period 1954 to 2012. Most (82%) of the 28 measurement locations are in Europe and North America, with 44 in Africa, Asia, 29 Oceania, and South-Central America. The deposition rates are log-normally distributed, 30 and for the whole data set the geometric mean deposition rates are 0.027, 0.019 and 31 0.14 g m a for TP, FTP and PO4-P respectively. At smaller scales there is little 32 systematic spatial variation, except for high deposition rates at some sites in Germany, 33 likely due to local agricultural sources. In cases for which PO4-P was determined as well 34 as one of the other forms of P, strong parallels between logarithmic values were found. 35 Based on the directly-measured deposition rates to land, and published estimates of P 36 deposition to the oceans, we estimate a total annual transfer of P to and from the 37 atmosphere of 3.7 Tg. However, much of the phosphorus in larger particles (principally 38 primary biological aerosol particles) is probably redeposited near to its origin, so that 39 long-range transport, important for tropical forests, large areas of peatland and the 40 oceans, mainly involves fine dust from deserts and soils, as described by the simulations 41 of Mahowald et al. (Global Biogeochemical Cycles 22, GB4026, 2008). We suggest that 42 local release to the atmosphere and subsequent deposition bring about a pseudo43 diffusive redistribution of P in the landscape, with P-poor ecosystems, for example 44 ombrotrophic peatlands and oligotrophic lakes, gaining at the expense of P-rich ones. 45 Simple calculations suggest that atmospheric transport could bring about significant local 46 redistribution of P among terrestrial ecosystems. Although most atmospherically 47 transported P is natural in origin, local transfers from fertilised farmland to P-poor 48 ecosystems may be significant, and this requires further research. 49