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-FIRE WE KNOW  -ACID  Postfire water quality is determined by what is hydrologically exported to streams and lakes. After fire there is an increase of available nutrients in the soil that can leech out, mainly caused by an increase in soil pH which is associated with an increase in exchangeable cations (e.g.Ca2+,Mg2+, and K+, and the anion SO42) in soil \cite{gonzalez-perez_effect_2004}. Micronutrients These ions are easily exported to streams and lakes and studies have shown post-fire peaks in sulphate (SO42-), chloride (Cl-) and base cation concentrations (e.g. Bayley and others, 1992; Carignan and others, 2000; Mast and Clow, 2008; Bladon and others, 2014). If acid anions (NO3-, SO42- and Cl-) dominates over base cations a acidity effect is observed in downstream waters (Bayley and others (1992), Lydersen and others, 2014). This acidification effect is enhanced in areas which have higher concentrations of stored S from acid rain or have a high proportion of peatlands \cite{bayley_effects_1992}. Post-fire acidification can also result in high aluminum concentrations (Lydersen and others, 2014) and possibly other metals  (e.g. Fe, Mn, and Cu)behavouir, although less studied, seem to be less vulnerable to leech out  \cite{certini_effects_2005}. However, a high base cation concentration may counterbalance the acididyt effect (Carignan and others (2000)).  There is also a an increased availability of soulable P in the soil  post-fire but this effect is suggested to be short and little is may be  leeched out \cite{certini_effects_2005}. Soil Nitrogen levels can increase dramatically post-fire (eg Bladon and others (2008) and Carignan and others (2000)). Following fire soil  organic nitrogen is either volatilised or largely converted into inorganic forms (i.e. NH+4 and NO-3) \cite{certini_effects_2005}. Nitrite is mainly formed from NH+4 through nitrification up until months after the fire (Covington and Sackett 1992). Both NH4+–N and NO3–N are available to plants, but witha sparse or  non-existing vegetation cover after a severe fire, these compounds are leached out. Although, ammonium is assumed to be held by the soil because it adsorbed onto negatively charged surfaces of soil particles (Mroz et al.1980), a study observed a NH+4 pulses that lasted over 2 growing seasons (Grogan et al. (2000) ).   Areas which have higher out \cite{smith_wildfire_2011}. Nitrite  concentrationsof stored S from past acid precipitation or have large areas of peatlands in the watershed  may have aggravated losses of S and H+ peak shortly  afterdrought and fire \cite{bayley_effects_1992}.  ----------  A majority of studies also show post-fire peaks in sulphate (SO42-), chloride (Cl-) and/or base cation concentrations (e.g. Bayley and others, 1992; Carignan and others, 2000; Mast and Clow, 2008; Bladon and others, 2014). Again, peaks in these solutes can be attributed to their release via pyrolysis from biomass and soil organic matter, and to  theafter-effects of  firesuch as soil drying and cracking. Soil modifications may be particularly important in organic soils, where elements such as sulphur (S) are stored in reduced forms,  and are therefore susceptible return  to oxidation reference values within 2-3 years (Bladon  and subsequent leaching. The effects of these solute losses on freshwater acidity depend on the relative balance of base cation others (2008)  andacid anion leaching. In the Ontario lakes studied by  Carignan and others (2000), increases in NO3-, SO42- and Cl- were counterbalanced by increases in base cations, and alkalinity and pH were therefore unaffected. However an earlier study (2000)). However, other studies  in the same region by Bayley and others (1992) did find evidence have reported high concentrations  of nitrite up to 5-9 years  post-fire acidification, and a recent study of acid-sensitive lakes in Norway found severe short-term acidification, (auer & Spencer (1998), Mast  and associated high aluminium concentrations, during the immediate post-fire period (Lydersen Clow (2008)  and others, 2014).  ------------------- Mast (2013)).ONLY N. Am.!! Add TURNER ref?  Ammonium is expected to be held by the soil to a higher degree because it adsorbed onto negatively charged surfaces of soil particles (Mroz et al.1980). However, a study observed a NH+4 pulses that lasted over 2 growing seasons (Grogan et al. (2000) ).    LAND USE EFFECTS  Soil modifications may be particularly important in organic soils, where elements such as sulphur (S) are stored in reduced forms, and are therefore susceptible to oxidation and subsequent leaching.  ----  The duration of these effects appear variable: Bladon and others (2008) and Carignan and others (2000) report peak NO3- concentrations in the first year post-fire, returning to reference levels within 2-3 years; Hauer & Spencer (1998), Mast and Clow (2008) and Mast (2013) report elevated NO3- concentrations for periods of 4-5 years after fires at Northwestern US forest catchments; Bayley and others (1992) recorded elevated NO3- for nine years after a fire in Ontario; and Smithwick and others (2005) suggest that modifications to the overall ecosystem N cycle can extend for decades after major fires.   -----  -LOSSES...eg N,P, CATIONS  Fire can also transform organic N to inorganic forms that are available to plants, but with poorly developed post-fire plant communities, this N can be easily exported to streams and lakes (Smith 2011)(  WHAT INFO IS MISSING?  -BEFORE AFTER EXP  -LONG TERM DATA