1. PRELIMINARY INVESTIGATION ON ARSENIC FRACTIONATION IN SOIL FROM OGOSTA RIVER FLOODPLAIN USING A SEVEN-STEP EXTRACTION PROCEDURE. Authors: LACRIMIOARA SENILA, ZORNITSA CHOLAKOVA, VASSILKA MLADENOV, MARIUS ROMAN, ERIKA LEVEI, TSVETAN KOTSEV, MARIN SENILA.