5" day - Central Institute of Brackishwater Aquaculture

(C) B.derMda
The rare of oxidation of pyritic mmerial is rtrongly uulysed by microbes.
Oxidation rates of pyritic clump hve bem reduced kmpcmily by the use of
bctericidcr to kill caulpic mi&. In Munl ccoaymm pht grvwch ir Itcavil)
depndmt on inhmm roil mkrobLl pnraw. Hens. hacricidn highly specific to
Ihe oxidation of pyrites should be 4.
3. NeufnlhHoa
Chemiul neumlisation of =id by calcite, dolomite, magnesiu and slaked lime
can be followed. Slaked lime may uua pH to overshoot, which may cnux problems.
Chemical neutraliwtion of acid has limited bmefiu, beclux acid is rcgularl)
transported into the pond there by depleting the mutnlising agent. Although the soil
an be limed, il will nM maurrlly b+ dl itr potential acidity. Soil tcxnuc and
mvcnm my hve M influsncc on ltml~ RIM. In clayey wil. mixing lime with
wil is dlmcult. Thc aha masrl.11 wui for narrmllntim of wid m Rlor prerr
muds. fcrtilisen, rice hull, ash etc. Bm this is very expensive.
4. Oxldatlon and Inching
As the neuaalisation of the ASS is too ditlicuh or expensive. m alternate
nntcsy I# to allw the masrW to oxidbe dslikntaly md to kach out the oxidation
products. This Is only rscammardcd tor GOM tattud unds md gravels, which are
relatively highly permeable to air md water md which contain relatively ~nall
mounts of pyrite. The time required for complete oxidation and leaching cannot be
predicted since it depends an prevailing climatic conditions such as rainfall.
fempnture and wind speed as well u the site and shape of the heap to be oxidid.
5. Removal of pyritic materiab
It haa been propoaed that some acid sulphate matcrinls or potential acid sulphate
mmrialr un k maled by removal of pyrita 'mn the dimmc. 7his pmpoul which
lnvolws fhe hydnullc repntion md m o d of pyrhe using hydro clone& relies on
the Irt thet pyrlta hu a mwh larger pMiob donrfy thm camon roll forming
minerals like q w . Thus tha sqmmtcd pyrite would be placed under anserobtc
conditions below the water surface.
2.5 Reclmmafbn ofacld srlph.te pod db
ASS formation in existlng ponds can be avoided by following cwmt pond
pmpurtion. Excessive twninp o m of pond baaom lhould be avoided slnce this will
expose sim of pamtial wid soil to bscome rhul md pmbiem soil. The most
beneficial bul expensive method of using ASS Tor qusculturr is to employ plastic
linm presently u& in SE Asia. psrriculuty in Mdaylu and Indonesia. However.
the procedure for rapid rnlullltim of ponds with acid sulphate soils is as follows:
P In rhe wly put of he Qy SCWOIL Qy he pond md hrrow thoroughly. Fill
with bncldrhwaw. M- tbe pH of tbc M*r fkqumtfy. Thc pH will
dmpR~ntbuof-(7m9)mbobv4. OaGsfhepHpHsabil~