Risks Associated with the Use of Chemical Amendments in Aquaculture Pond

Management

Claude E. BoydDepartment of Fisheries and Allied Aquacultures

Auburn University, Alabama 36849 USA

and

Laurence MassautFundación CENAIM-ESPOL

Guayaquil, Ecuador

Three types of risks were evaluated:

Environmental (ES)

Food safety (FS)

Handling (HS)

Four levels were assigned to each type of risk:

No risk = 0 Medium risk = 2

Low risk = 1 High risk = 3

Common nitrogen fertilizer compounds.

Compound Application rate Risk level and type

Urea (H2NCONH2)

5-10 kg/ha at 1-4 wk intervals

HS = 1; explosive, irritant, possible mutagen.ES = 1; if spilled, eutrophication, ammonia toxicity, acidity.FS = 0; none.

Ammonium sulfate ((NH4)2SO4)

10-20 kg/ha at 1-4 wk intervals

HS = 1; explosive, irritant, avoid inhalation.ES = 1; if spilled, eutrophication, ammonia toxicity, acidity.FS = 0; none.

Ammonium nitrate (NH4NO3)

5-10 kg/ha at 1-4 wk intervals

HS = 1; explosive, irritant, avoid inhalation.ES = 1; if spilled, eutrophication, ammonia toxicity, acidity,FS = 0; none.

Sodium nitrate (NaNO3), potassium nitrate (KNO3), and calcium nitrate (Ca(NO3)2)

20-30 kg/haAt 1-4 wk intervals

HS = 1; explosive, prolonged KNO3 exposure may produce anemia, irritant.ES = 1; if spilled, eutrophication, ammonia toxicity.FS = 0; none.

Common phosphorus fertilizer compounds.

Compound Application rate Risk level and type

Triple superphospahte (Ca(H2PO4)2)

5-10 kg/ha at 1-4 wk intervals

HS = 0; none.ES = 1; if spilled, eutrophication.FS = 0; none.

Mono- and di-ammonium phosphate (NH4H2PO4 and (NH4)2HPO4)

5-10 kg/ha at 1-4 wk intervals

HS = 1; irritant, monoammonium phosphate is explosive.ES = 1; if spilled, eutrophicationFS = 0; none.

Phosphoric acid (H3PO4)

5-10 kg/ha at 1-4 wk intervals

HS = 1; irritant.ES = 1; if spilled, acidity, toxicity, and eutrophication.FS = 0; none.

Other fertilizer materials.

Compound Application rate Risk level and type

Potassium chloride or muriate of potash (KCl)

1-2 kg/ha at 1-4 wk intervals

100-500 kg/ha in inland shrimp

ponds

HS = 1; irritant.ES = 1; if spilled, eutrophication.FS = 0; none.

Sodium silicate (Na2SiO3)

1-5 kg/ha at 2 wk intervals

HS = 0; none.ES = 0; noneFS = 0; none.

Manure, grass and human wastes

100-500 kg dry wt/ha/wk

HS = 0; none.ES = 1; potential oxygen depletion, eutrophication.FS = 1; disease transmission to humans, heavy metal contamination

Other fertilizer materials.

Compound Application rate Risk level and type

Trace and secondary element mixes (contains various compounds of Fe, Zn, Cu, B, and Mo)

50-100 g/ha permonth

HS = 0; none.ES = 1; if spilled, metal toxicity.FS = 0; none.

Fertilizer enhancers (e.g., humate)

10-100 kg/ha per month

HS = 0; none.ES = 0; none.FS = 0; none.

Mixed fertilizers 25-100 kg/ha per month

HS = 0; none.ES = 1; if spilled, eutrophication.FS = 0; none.

Potassium magnesium sulfate

500-1,000 kg/ha in inland shrimp

ponds

HS = 1; irritant.ES = 1; if spilled, eutrophication.FS = 0; none.

Common liming materials.

Compound Application rate Risk level and type

Agricultural limestone (CaCO3 or CaCO3MgCO3)

1-5 tons/ha annually

HS = 0; none.ES = 0; none.FS = 0; none.

Burnt lime (CaO or CaOMgO)

0.5-1 tons/ha annually

HS = 1; strong caustic, irritant.ES = 1; if spilled, high pH.FS = 0; none.

Hydrated lime (Ca(OH)2 or Ca(OH)2Mg(OH)2)

0.5-1 tons/ha annually

HS = 1; caustic, irritant.ES = 1; if spilled, high pH.FS = 0; none.

Common oxidants.

Compound Application rate Risk level and type

Potassium permanganate (KMnO4)

2-8 mg/L HS = 1; explosive if in contact with organic substances, irritantES = 1; if spilled, toxicity.FS = 0; none.

Hydrogen peroxide (H2O2) or calcium peroxide (CaO2)

Up to 100 kg/ha HS = 1; H2O2 concentrated form is irritant.ES = 1; if spilled, toxicity.FS = 0; none.

Calcium hypochlorite (Ca(OCl)2)

30 mg/L before stocking

HS = 1; irritant, poisonous.ES = 1; formation of trihalomethanes and chlorinated hydrocarbons that are suspected carcinogens, toxic.FS = 0; none.

Sodium, potassium, or calcium nitrate (NaNO3, KNO3, or Ca(NO3)2)

1-5 mg/L HS = 1; explosive, prolonged KNO3 exposure may produce anemia, irritant.ES = 1; if spilled, eutrophication.FS = 0; none.

Common coagulants.

Compound Application rate Risk level and type

Aluminum sulfate (Al2(SO4)314H2O)

15-40 mg/L HS = 1; irritant, acidic.ES = 1; if spilled, acidity and toxicity.FS = 0; none.

Ferric chloride (FeCl3)

15-40 mg/L HS = 1; irritant, acidity.ES = 1; if spilled, acidity and toxicity.FS = 0; none.

Calcium sulfate (CaSO42H2O)

200-500 mg/L HS = 0; none.ES = 0; none.FS = 0; none.

Common osmoregulators.

Compound Application rate Risk level and type

Salt (NaCl) 100-2,000 mg/L HS = 1; irritant.ES = 1; increase in salinity.FS = 0; none.

Calcium sulfate (CaSO42H2O)

100-400 mg/L HS = 0; none.ES = 0; none.FS = 0; none.

Common algicides.

Compound Application rate Risk level and type

Copper sulfate (CuSO45H2O)

0.5-2 mg/L HS = 1; strong irritant.ES = 2; toxicity.FS = 0; none.

Chelated copper compounds

0.2-1 mg/L HS = 0; none.ES = 2; toxicity.FS = 0; none.

Diuron 0.01 mg/L; maximum of nine times/yr

HS = 1; irritant.ES = 2; toxicity.FS = 1; possible residues.

Dyes (food coloring compounds)

1-5 mg/L HS = 0; none.ES = 0; none.FS = 0; none.

Common piscicides.

Compound Application rate Risk level and type

Teaseed cake (active ingredient is sapogenin glycosides)

15 mg/L HS = 0; none.ES = 1; foam strongly, form oil-in-water emulsions and act to protect colloids.FS = 0; none.

Rotenone (C23H22O6) 0.25-2.0 mg/L HS = 1; irritant.ES = 1; toxicity.FS = 0; none.

Lime 1-2 tons/ha HS = 1; caustic, irritant.ES = 1; if spilled, high pH.FS = 0; none.

Common probiotics.

Compound Application rate Risk level and type

Live bacterial inocula (non-pathogenic organisms and usually Bacillus species)

1-2 mg/L at 1 or 2 days to 1 week intervals

HS = 0; none.ES = 0; none.FS = 0; none.

Fermentation products rich in extracellular enzymes

1-2 mg/L at 1 or 2 days to 1 week intervals

HS = 0; none.ES = 0; none.FS = 0; none.

Miscellaneous compounds.

Compound Application rate Risk level and type

Zeolite (aluminosilicate clay) 20-50 kg/ha weekly HS = 0; none.ES = 0; none.FS = 0; none.

Yucca extracts 1-2 mg/L monthly HS = 0; none.ES = 0; none.FS = 0; none.

Bactercides: BKC (alkyldimethyl-benzylammonium chloride), providone, iodine (polyvinylpyrrolidone iodine), glutaraldehyde, formalin

1-10 mg/L HS = 0; none.ES = 1; toxicity.FS = 1; possible residues.

Miscellaneous compounds.

Compound Application rate Risk level and type

Sodium bicarbonate (NaHCO3)

25 mg/L or higher HS = 0; none.ES = 0; none.FS = 0; none.

Iron oxide (FeO) 1 kg m2 HS = 0; noneES = 0; none.FS = 0; none.

KILOL (extracts of grapefruit seed)

HS = 0; none.ES = 0; none.FS = 0; none.

Dipterex (OP insecticide) 1-2 mg/L HS = 2; toxicityES = 2; toxicityFS = 1; possible residue (?)

Substances that could enter aquaculture ponds through contamination.

Compound Risk level and type

Insecticides HS = 2; toxic.ES = 3; bioaccumulative.FS = 3; bioaccumulative.

Pesticides HS = 2; toxic.ES = 3; bioaccumulative.FS = 3; bioaccumulative.

Heavy metals: lead, mercury, arsenic, beryllium, cadmium, chromium, manganese, silver, and zinc

HS = 3; most are toxic to humans if absorbed, some carcinogenic.ES = 3; bioaccumulative.FS = 3; bioaccumulative.

Aluminum, antimony, barium, copper, cyanide, iron, nickel, and selenium

HS = 2; less toxic than above, but high concentrations when absorbed will be toxic.ES = 2; not bioaccumulative.FS = 3; not bioaccumulative.