deletions | additions       diff --git a/Fungal_weathering_in_the_lab__.md b/Fungal_weathering_in_the_lab__.md  index c339ed6..8ce4cbd 100644  --- a/Fungal_weathering_in_the_lab__.md  +++ b/Fungal_weathering_in_the_lab__.md 
...
In addition, wood decomposing fungi produce large amounts of oxalic acids when degrading wood \citep{Dutton_1996}, which may have secondary effects on phosphorous release from the soil \citep{Fransson_2004}.    It is not clear if organic acid release and acidification is a primary mechanism to release nutrients from soil minerals, or a secondary effect related to the way microorganisms are growing in the soil.  \citet{van_Scholl_2006a} studied organic acid production in relation to nutrient availabily for several mycorrhizal fungi growing in vitro or in symbiosis with a host tree.  Protons are exuded in response to uptake of positively charged ions regardless of if minerals are present or not, and exudation of organic acids can occur in response to many different factors such as pathogenesis and detoxification of heavy metals \cite{Dutton_1996}.  Furthermore, concentrations of organic acids in soil solution \citep{van_Hees_2000} seldom reach levels that have significant effects on mineral dissolution \citep{chadwick_changing_1999}.