Study On The Bioconcentration And Elimination Of Cd In Mytilus Edulis

Aquatic products including Mytilus edulis were heavily polluted with heavy metals and those heavy metals were difficult to be removed and so on. To resolve those problems, Hairtail was taken as research object, and it was made as proteolytic peptides, and then was chelated with metallic elements. Cd in different tissues of Mytilus edulis was messured by feeding Mytilus edulis with those chelations, to find a new way which is effective, economical and environmental to remove the heavy metals. And healthy sea food would be beneficial to people’s health.This paper included several following parts.1. The paper took Mytilus edulis as the research object, and studied the acute toxicity test of Cd to Mytilus edulis and the change regularity of Cd in visceral mass, anterior adductor muscle, posterior adductor muscle, mantle and gill of Mytilus edulis. Results as follows:（1） LC50, 6.9586 mg/L; 95%CI, 1.8201-26.6024 mg/L; LC0, 0.0696 mg/L.（2） Enrichment: The concentration of Cd in different tissues of Mytilus edulis was enlarge with higher concentration of Cd in sea water and prolonger time and the concentrations of Cd in visceral mass, anterior adductor muscle, posterior adductor muscle, mantle and gill of Mytilus edulis were 109.62, 11.391, 15.323, 19.509, 63.672 mg/L. The value of k was higher at fist, lower in middle and higher at last. The value of BCF was lower while the concentration of Cd was higher in the sea water. The value of k and BCF have the same law in different tissues, which is that visceral mass>gill>posterior adductor muscle>mantle>anterior adductor muscle. The relationship between Cd enrichment and time was appropriate for the model of Harris.（3） Deprivation: The concentration of Cd in different tissues of Mytilus edulis did not obviously reduce（P>0.05）, which indicated that Mytilus edulis’ s ability of removing Cd was very weak and Mytilus edulis was the net accumulated biological.2. The paper took Hairtail as the research object, and studied the best hydrolysis conditions of Papain for Hairtail and the best Chelating conditions of enzymatic hydrolysate with metallic elements, and then enough PH-Fe²⁺ , PH-Zn²⁺ , PH-Ca²⁺ and PH-Mg²⁺ would be made. Results as follows:（1） The best hydrolysis conditions: 6 h, p H6.5, 45℃, 20000 u/g enzymatic activity. Under the best condition, the degree of hydrolysis got up to 71.3%.（2） The best Chelating conditions: 30℃, p H7.0, 30 min. Under this condition, the rates of chelation for PH-Fe²⁺ , PH-Zn²⁺ , PH-Ca²⁺ and PH-Mg²⁺ were 68.9%、65.7%、63.2%�'� 42.3% respectively.3. The paper took Mytilus edulis as the research object, and studied the removal law of Cd in visceral mass, anterior adductor muscle, posterior adductor muscle, mantle and gill of Mytilus edulis with PH-Fe²⁺ , PH-Zn²⁺ , PH-Ca²⁺ and PH-Mg²⁺ feeding Mytilus edulis. Results as follows:（1） Cd concentrations in anterior adductor muscle, gill, posterior adductor muscle, mantle, and visceral mass of mussel after 5 days of Cd（0.32 mg/L） exposure were 11.391, 15.323, 63.672, 19.509, and 109.62 μg/g, respectively.（2） After 8 days of depuration period, 5 mg/L of PH-Fe²⁺ , PH-Zn²⁺ , and PH-Ca²⁺ showed no significant（P>0.05） effect on Cd concentrations in mussel tissues. However, while significances（P<0.05） were observed in 20 mg/L of PH-Fe²⁺ , PH-Zn²⁺ , and PH-Ca²⁺ treated groups. The Cd concentrations in anterior adductor muscle, gill, mantle, posterior adductor muscle, and visceral mass were significantly（P<0.05） decreased by 29.56³5.83%, 27.51³3.62%, 31.59⁴0.34%, 25.83³1.28%, and 33.62³3.97%, respectively. Nevertheless, the variables of Cd concentrations in tissues treated with 5²0 mg/L PH-Mg²⁺ showed no significant（P>0.05） differences compared with the control during the whole period.（3） For these reasons, PH-Fe²⁺ , PH-Zn²⁺ , and PH-Ca²⁺ can be recommended as a depuration agent in mussel feed to decrease the Cd concentrations in tissues.