The Study About Bioconcentration Ability Of Seashell To Heavy Metal

It is studied for the routine of cumulate and absorb of three heavy metals(Cu, Cd, Pb)by four kinds of seashll (Tegillarca granosa,Ruditapes philippinarum,Sinonovacula constricat canarck,Monodonta labio)in the lab. The bioconcentration of three heavy metals for four kinds of seashll also is studied. Ii is discussed for heavy metal concentration between water quality standard and seashll quality standard. The test is carried out through law-hydrostatic method. The salinity of sea water is 28.5-29.0, pH is 8.1-8.3. [Cu²⁺], [Pb²⁺] and [Cd²⁺] is 0.015mg/L,0.001 mg/L and 0.0001 mg/L in the sea water. The shell length of Tegillarca granosa, Ruditapes philippinarum, Sinonovacula constricat canarck, Monodonta labio is (2.2-3.5)cm, (3.0-3.6)cm, (1.8-2.8)cm and (8.0-12.5)cm, the avoirdupois is (4.8-7.2)g, (6.0-7.8)g, (3.6-5.2)g, (11.0-20)g. The range of [Cu²⁺] is (0.015⁰.115)mg/L , the range of [Pb²⁺] is (0.001⁰.051)mg/L and the range of [Cd²⁺] is (0.0001⁰.050)mg/L in the experiment. It is set 6 group for evry kind heavy metal and every seashell. The seashell is taken out for detect heavy metal with GF-AAS in 0d, 1d, 3d, 5d, 10d , 15d, 20d, 25d and 30d.The test results shows:(1) Four kind of seashell have bioconcentration effect to Cu, Pb and Cd in seawater. The bioconcentration of Tegillarca granosa is obvious when [Cu²⁺]≥0.035mg/L or [Pb²⁺]≥0.0035mg/L. Similarly, the bioconcentration of Ruditapes philippinarum is obvious when [Cu²⁺]≥0.025mg/L or [Pb²⁺]≥0.006mg/L. The bioconcentration of Sinonovacula constricat canarck is obvious when [Cu²⁺]≥0.025mg/L or [Pb²⁺]≥0.011mg/L. The bioconcentration of Monodonta labio is obvious when [Cu²⁺]≥0.035mg/L or [Pb²⁺]≥0.011mg/L. Another, the bioconcentration of four kinds of seashell is obvious to Cd when [Cd²⁺]≥0.050mg/L. The sequence of bioconcentration ability and speed is: Cu>Pb>Cd. The bioconcentration ability of four kind of seashell isn't distinguished.(2)As a whole, the residue of heavy metal in seashell body is increase if the concentration of heavy metal is increase in water. The relation of residue in seashell body with concentration in water is positive correlation. But it is decrease when [Cu²⁺] is (0.025⁰.035)mg/L, [Pb²⁺] is (0.006⁰.011) mg/L,[Cd²⁺] is (0.0026⁰.0051)mg/L. When the seashell is input to seawater which is added heavy metal, the residue of heavy metal in seashell body is higher when the time is longer. But the residue is lower more than some time ago in about 3d. Maybe it is the result of inhibition of seashell. When the concentration of heavy metal is increase, the inhibition is appearing and part of heavy metal is discharged. When the concentration of heavy metal is continue to increase or the time is prolong , The seashell will adapt the environment and the cumulating and absorbing will be in gear with the passage of time.(3)When [Cu²⁺] is (0.035⁰.115)mg/L, uptake rate constant(k1) is 2.70-22.3, extract rate constant(k2) is 0.008-0.126, bioconcentration factor (BCF) is 176.8-854.6,the maximal metal contents in test organism(CAmax) at steady-state is (7.4-53.9)mg/kg. The change of k1 , k2 and BCF is no relation with [Cu²⁺]. Cmax is increase when [Cu²⁺] is increase. When [Pb²⁺] is (0.006⁰.051)mg/L, uptake rate constant(k1) is 1.79-35.5, extract rate constant(k2) is 0.009-0.151, bioconcentration factor (BCF) is 139.4-1429,the maximal metal contents in test organism(CAmax) at steady-state is (2.06-16.5)mg/kg. K1 , k2 and BCF is decrease when [Pb²⁺] is increase.. Cmax is increase when [Pb²⁺] is increase. When [Cd²⁺] is 0.050mg/L, uptake rate constant(k1) is 2.41-7.97, extract rate constant(k2) is 0.044-0.148, bioconcentration factor (BCF) is 55.0-166,the maximal metal contents in test organism(CAmax) at steady-state is (5.69-8.32)mg/kg.(4)The water quality standard and seashll quality standard is not consistency about heavy metal. It is suggested increasing the request about Pb and Cd in water quality standard. It is can be aceepted that decreasing the request about Pb and Cd in seashll quality standard.