koverduijn snow chemistry 2

!"#$%"#&'()*+$,-$./ ,01$ 2*,3#((#($4/5$67)*'#/)$%+38'/9$ :4*)+/$!*4/)#*$4/5$;<$=#*485$>,/#($ $ $ 2*#(#/)#5$?+$@#88+$AB#*57'C/$ %"4D)#*$AB#*B'#0$ •  E<F$G$H/)*,573I,/1$(/,0$3"#&'()*+$4/5$#3,8,9+$ •  E<J$G$!"#$3"#&'()* +$,- $(/,0-488$ •  E<E$G$%"#&'()* +$,-$ 3,85K$5*+$(/,0$3,B#*$ •  E<L$G$%"#&'()* +$,-$ 0#)$(/,0$4/5$(/,0M&#8)04)#*$ (+()#&($ •  E<N$G$./,0$3,B#*$/7)*'#/)$O7P#($4/5$#3,(+()#&$ ?759#)($ •  E<Q$G$.7&&4*+$4/5$-7)7*#$*#(#4*3"$/##5($ H/)*,573I,/1$./,0$%"#&'()*+$4/5$ R3,8,9+$ •  ./,0$D84+($4/$'&D,*)4/)$*,8#$'/$ ?',9#,3"#&'348$D*,3#((#($ –  :#8)04)#*$(7DD8'#($/7)*'#/)($),$)#**#()*'48$4/5$ 4S74I3$#3,(+()#&($ –  :4C,*$'/D7)$),$)"#$"+5*,8,9+$,-$34)3"&#/)($ :4'/$*#4(,/($0"+$)"#$3"#&'()*+$,-$ (/,0$"4($?##/$()75'#5$ F<  2,)#/I48$'&D43)$,-$(/,0$&#8)04)#*($,/$)"#$ S748')+$,-$(7*-43#$04)#*($ J<  !,$'/)#*D*#)$)"#$38'&4I3$4/5$D,887I, /$$$$$$ $$$$$ *#3,*5($*#3,*5#5$'/$3,85$5*+$(/,0<$ $ :4'/$)+D#($,-$D*,3#((#($)"4)$'/O7#/3#$ 3"#&'348$3,&D,('I,/$,-$(/,0$4/5$ &#8)04)#*($ F<  !",(#$'/B,8B'/9$"#4)$4/5$&4(($O7P#($)"4)$,337*$ 57*'/9$(7?8'&4I,/$4/5$&#8I/9$ –  2"+('348$D*,D#*I#($)"4)$5#)#*&'/#$3"4/9#$'/$)"#$3"#&'348$ 8,45'/9$,-$(/,0$ J<  !",(#$'/B,8B#5$0')"$3"#&'348$)*4/(-,*&4I,/($ –  A337*$?+$3"#&'348$*#43I,/($ –  T*'(#$-*,&$&'3*,?',8,9'348$43IB')+$ U"4)$"4B#$0#$8#4*/#5$'/$*#3#/)$ 5#345#(V$ •  ./,0$'($/,)$4$D4(('B#$*#(#*B,'*$,-$3"#&'348$ (D#3'#(<$ •  H-$+,7$()75+$)"#$3"#&'348$5+/4&'3($,-$(/,0K$ +,7$&7()$)4W#$'/),$433,7/)$)"#$D"+('348$4/5$ ?',9#,3"#&'348$3"4*43)#*'(I3($,-$)"#$(/,0$ 3,B#*$#/B'*,/&#/)$ !"#$%"#&'()*+$,-$./ ,0-488$ •  !#**#()*'48$4/5$&4*'/#$#&'((',/($*#3+38#5$'/$ 4)&,(D"#*#X$(7?C#3)#5$),$,P'54I,/$4/5$ *#)7*/#5$),$)"#$84/5$4/5$,3#4/($ •  !"'($*#3+38'/9$,337*($'/$)0,$04+(1$ F<  Y+$5'*#3)$Z5*+[$5#D,('I,/$,-$3"#&'348$(D#3'#($),$ (7*-43#($,*\$ J<  Y+$D*#3'D')4I,/$Z(/,0$4/5$*4'/[$ [...]...  cold,  dry   snow  cover   1.  Surface  exchange  at  the snow- ­‐atmosphere   interface   2.   Surface  and  subsurface  chemical  reacIons   3.  Snow  grain  metamorphism  within  the  pack   4.  Basal-­‐exchange  at  the snow- ­‐soil  interface   Dry  deposiIon  and  volaIlizaIon   •  Dry  deposiIon  =  the  direct  deposiIon  of   chemical  species  from  the  atmosphere  to  the   snow  surface...  annual  emissions   •  Extent  to  which snow  cover  influences  gas   emissions  from  soil  varies   •  Can  vary  from  year  to  year   Chemistry  of  Wet Snow  and Snow- ­‐ Meltwater  Systems   •  PercolaIon  of  meltwaters  through  the snow   cover  causes  the  chemical  composiIon  to   change   •  ConcentraIon  and  distribuIon  of  solutes  in   the snow- ­‐meltwater  system  is  controlled...  solutes   1.  Leaching  of  solute  from snow  grains  and  crystals   2.   Meltwater-­‐parIculate  interacIons   3.  Microbiological  acIvity   4.  Basal  processes:  soil-­‐meltwater  interacIons   Leaching  of  solute  from snow  grains   and  crystals   1.  FracIonaIon  occurs   2.   Meltwater  becomes  more  concentrated   3.  Deeper snow  =  higher  snowmelt  concentraIons   4.  Difficult  to...  (parIcularly  organic  species)  directly   from snow  to  the  atmosphere  because  of  their   relaIvely  high  vapor  pressures   Photochemical  reacIons  in  surface   snow  cover   •  Light  may  play  a  key  role  in  the chemistry  of   snow  cover  through  photochemical  reacIons   •  Unequivocal  evidence  is  yet  to  be  obtained   •  These  reacIons  in snow  are  complex  and   difficult  to  disInguish...  nitrogen  during  melt   Take  home  points   •  Snow  is  not  a  passive  reservoir  of  the  chemical  species  scavenged  from  the   atmosphere  during  snowfall   •  Snow- ­‐atmosphere  exchange  by  dry  deposiIon,  volaIlizaIon,  air   movement,  and snow  metamorphism  can  increase  or  decrease  certain   chemical  species  within  the snow  pack   •  Microorganisms  influence  nutrient... Microorganisms  influence  nutrient  concentraIons  during  the  melt  period   •  Strong  gradients  of  CO2  found  in snow  covers  as snow  mediates  gas   emissions  from  the  soil  to  the  atmosphere   •  More  study  needed  to  elucidate  the  relaIonships  between  the chemistry   of snow,  terrestrial  nutrient  cycles,  and  ecology     Basically,  don’t  this  at  home   Or  proceed...  cyclic  movement  between  the   atmosphere  and snow  cover  that  occurs  when  wind   condiIons  are  favorable   •  Thermal  convecIon  –  if  temperature  gradients  increase   to  a  criIcal  threshold  level,  air  movement  may  be   iniIated  in  the snow  cover  by  thermal  convecIon   Basal  exchange  between  soil  and snow   •  Snow  cover  usually  results  in  a  decrease  in  the...  Iming  of  meltwater  runoff  and  its   chemistry   •  InfiltraIng  meltwater  refreezes  if  the  soil  is  sufficiently   cold,  thus  delaying  runoff  of  some  snowmelt     •  As  a  result,  the  availability  of  N  to  both  the  soil  and   stream  runoff  may  be  limited  during  the  iniIal  runoff   period  when  N  concentraIons  are  highest     Snow  cover  nutrient  fluxes  and   ecosystem...  neutralizes  meltwaters   2.   Lower  region  dust  more  efficient  at  neutralizing   3.  Organic  debris  also  found  along  with  dust   4.  Leaching  removes  soluble  organics/other   chemical  species   Microbial  AcIvity   •  Increases  with  increases  in  water  and  solar   radiaIon   •  Meltwater  results  in  photosyntheIc  acIvity  of   algal  populaIons  in  the snow  cover   •  Decreases...   stream  runoff  may  be  limited  during  the  iniIal  runoff   period  when  N  concentraIons  are  highest     Snow  cover  nutrient  fluxes  and   ecosystem  budgets   •  Major  input  arises  in snow  meltwaters  in  spring   •  Major  output  occurs  when  hydrological  export  by  streams   is  greatest  (may  be  at  same  Ime  as  major  input)   •  Annual  input  and  output  generally  small . !"#$%"#&'()*+$,-$./ ,01$ 2* ,3#((#($4/5$67)*'#/)$%+38'/9$ :4*)+/$!*4/)#*$4/5$;<$=#*485$>,/#($ $ $ 2* #(#/)#5$?+$@#88+$AB#*57'C/$ %"4D)#*$AB#*B'#0$ • . :4C,*$'/D7)$),$)"#$"+5*,8,9+$,-$34)3"&#/)($ :4'/$*#4(,/($0"+$)"#$3"#&'()*+$,-$ (/,0$"4($?##/$()75'#5$ F<  2, )#/I48$'&D43)$,-$(/,0$&#8)04)#*($,/$)"#$ S748')+$,-$(7*-43#$04)#*($ J< . !",(#$'/B,8B'/9$"#4)$4/5$&4(($O7P#($)"4)$,337*$ 57*'/9$(7?8'&4I,/$4/5$&#8I/9$ –  2& quot;+('348$D*,D#*I#($)"4)$5#)#*&'/#$3"4/9#$'/$)"#$3"#&'348$ 8,45'/9$,-$(/,0$ J<