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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  ARSENIC 
  AND 
  CALCIUM 
  

  

  The 
  arsenic 
  in 
  the 
  sea 
  exists 
  apparently 
  in 
  organic 
  form 
  and, 
  like 
  

   iodine, 
  is 
  concentrated 
  in 
  animals 
  and 
  plants. 
  The 
  lobster 
  has 
  40-50 
  

   parts 
  per 
  1 
  million 
  and 
  Laminaria 
  twice 
  as 
  much. 
  

  

  There 
  are 
  many 
  points 
  of 
  interest 
  connected 
  with 
  the 
  calcium 
  in 
  the 
  

   sea 
  ; 
  in 
  fresh 
  water 
  it 
  is 
  the 
  most 
  abundant 
  of 
  the 
  three 
  cations 
  — 
  cal- 
  

   cium, 
  magnesium, 
  and 
  sodium; 
  in 
  sea 
  water 
  it 
  is 
  the 
  least 
  abundant 
  

   as 
  all 
  the 
  time 
  animals 
  and 
  plants 
  are 
  removing 
  it, 
  a 
  fact 
  to 
  which 
  the 
  

   white 
  cliffs 
  of 
  Dover 
  bear 
  abundant 
  testimony. 
  It 
  is 
  related 
  to 
  the 
  

   carbon 
  dioxide 
  content 
  of 
  the 
  oceans 
  which 
  is 
  some 
  15 
  to 
  30 
  times 
  the 
  

   amount 
  present 
  in 
  the 
  atmosphere, 
  and 
  it 
  may 
  be 
  well 
  that 
  the 
  carbon 
  

   dioxide 
  content 
  of 
  the 
  air 
  is 
  regulated 
  by 
  the 
  oceans 
  acting 
  as 
  a 
  reser- 
  

   voir. 
  There 
  is 
  a 
  continual 
  exchange 
  between 
  the 
  air 
  and 
  the 
  surface 
  

   of 
  the 
  sea 
  which, 
  among 
  other 
  things, 
  controls 
  the 
  acidity 
  of 
  the 
  sea 
  

   water 
  to 
  which 
  much 
  of 
  the 
  life 
  of 
  the 
  ocean 
  is 
  acutely 
  sensitive. 
  

   Further, 
  in 
  the 
  sea, 
  as 
  on 
  land, 
  plants 
  use 
  carbon 
  dioxide 
  as 
  the 
  basic 
  

   source 
  of 
  carbon 
  for 
  the 
  building 
  up 
  of 
  organic 
  compounds. 
  

  

  When 
  the 
  carbon 
  dioxide 
  in 
  solution 
  in 
  sea 
  water 
  is 
  reduced, 
  the 
  

   conditions 
  are 
  favorable 
  for 
  the 
  deposition 
  of 
  calcium 
  carbonate. 
  The 
  

   building 
  of 
  shells 
  by 
  animals 
  which 
  live 
  on 
  the 
  sea 
  bottom 
  and 
  of 
  the 
  

   smallest 
  Protozoa 
  is 
  an 
  interesting 
  subject. 
  It 
  accounts 
  for 
  an 
  an- 
  

   nual 
  deposition 
  of 
  1,400 
  million 
  tons 
  of 
  calcium. 
  Shells 
  are 
  of 
  two 
  

   classes, 
  those 
  containing 
  calcium 
  carbonate 
  alone 
  or 
  with 
  magnesium 
  

   carbonate, 
  and 
  those 
  containing 
  calcium 
  phosphate. 
  As 
  yet 
  we 
  have 
  

   no 
  clue 
  to 
  the 
  reactions 
  involved 
  in 
  building 
  shells. 
  One 
  minor 
  point 
  

   is 
  that 
  in 
  tropical 
  waters 
  the 
  percentage 
  of 
  magnesium 
  carbonate 
  is 
  

   higher. 
  

  

  The 
  relative 
  abundance 
  of 
  the 
  alkaline 
  earths 
  in 
  the 
  sea 
  in 
  the 
  order 
  

   calcium, 
  strontium, 
  barium, 
  is 
  about 
  4000 
  : 
  100 
  : 
  1. 
  The 
  temperature 
  of 
  

   the 
  water 
  may 
  also 
  have 
  an 
  effect 
  on 
  the 
  presence 
  of 
  strontium 
  in- 
  

   stead 
  of, 
  or 
  together 
  with, 
  calcium 
  in 
  shells. 
  In 
  very 
  cold 
  waters 
  

   strontium 
  may 
  replace 
  calcium 
  and 
  there 
  is 
  a 
  report 
  of 
  a 
  radiolarian 
  

   from 
  the 
  Antarctic 
  whose 
  shell 
  is 
  composed 
  almost 
  entirely 
  of 
  stron- 
  

   tium 
  carbonate. 
  In 
  other 
  shells 
  both 
  are 
  present 
  in 
  much 
  the 
  same 
  

   proportion 
  as 
  that 
  in 
  which 
  they 
  occur 
  in 
  sea 
  water. 
  

  

  The 
  sea 
  is 
  the 
  greatest 
  potential 
  source 
  of 
  raw 
  materials. 
  It 
  con- 
  

   tains 
  traces 
  of 
  every 
  element 
  ready 
  to 
  hand 
  so 
  that 
  marine 
  plants 
  or 
  

   animals 
  can 
  adapt 
  them 
  to 
  their 
  purpose. 
  There 
  is 
  true 
  symbiosis 
  be- 
  

   tween 
  animal, 
  vegetable, 
  and 
  mineral. 
  Our 
  approach 
  to 
  this 
  subject 
  

   has 
  been 
  from 
  the 
  mineral 
  aspect, 
  to 
  ascertain 
  what 
  minerals 
  can 
  be 
  

   economically 
  won 
  from 
  the 
  sea 
  in 
  competition 
  with 
  land 
  sources 
  of 
  

   the 
  same 
  materials 
  deposited 
  in 
  bygone 
  geologic 
  ages. 
  The 
  sea 
  gives 
  

   us 
  a 
  great 
  quantity 
  of 
  food 
  in 
  fish 
  of 
  all 
  kinds. 
  The 
  study 
  of 
  these 
  is 
  

  

  