"14909120-n"^^ . . . "humic acid"@en-us . . . "0"^^ . "114909120"^^ . "humic acid"^^ . "a dark brown humic substance that is soluble in water only at pH values greater than 2; \"the half-life of humic acid is measured in centuries\""@en-us . . . . "114060959"@en-us . "0"^^ . . .