金鱼(Carassius auratus L.)对水中游离态铅的吸收积累及鳃分泌粘液的自身保护作用

研究了金鱼在铅暴露实验中的铅吸收过程及鱼鳃分泌物的自身保护作用，水相Ｐｂ＾２＋的鳃吸收机理以及分泌粘液对铅的络作用。结果表明，金鱼因铅暴露导致粘液分泌量增加。结合到鳃上的铅与水相Ｐｂ＾２＋活度关系可用Ｌａｎｇｍｕｉｒ吸附等温式表述。

Uptake and accumulation of free lead by goldfish (Carassius auratus L.) and effect of gill mucus on the processes

Uptake of lead by goldfish (Carassius auratus L.) and the effect of mucus on the uptake were studied. The mechanisms of lead uptake are discussed. It was demonstrated that the quantity of mucus released from the fish gill increased with the increasing in lead concentration in water and exposure duration. The mucus is capable of binding metals. Lead accumulated in gill was positively proportional to the lead level in water at low concentration (total lead less than 0.6mg/L). The plot of gill lead against water lead leveled off with increased lead concentration. A Langmuir isotherm can fit the observed data well and the saturated sorption capacity was calculated as 0.9424 mmol/kg (dry wt.). The binding cooperativity (H_n) is very close to unit (1.012) indicating independent binding to the sites with unique apparent affinity. On average, the number of binding sites on the gill of each fish (96.0 mg,wet wt.) was estimated to be 1.62×10^-5 mmol with a conditional binding constant (log K_Pb-gill) of 4.8. A significant linear relation of lead concentrations between gill and blood was observed during the 10-day experiment, suggesting that the free lead in water is first bound on fish gill, then migrate across branchial epithelium to blood via passive diffusion or carrier transport.