沉积物中不同浓度多壁碳纳米管对Cd和BDE-47生态毒性的影响

Impacts of multi-walled carbon nanotubes on ecotoxicity of Cd and BDE-47 in sediments

随着碳纳米管的广泛应用,其将不可避免地进入环境中.由于其具有极好的吸附亲和力和吸附容量,碳纳米管可以充当环境中持久性有毒污染物的载体,从而改变共存污染物的生物有效性和生态毒性.为评价淡水沉积物中不同多壁碳纳米管(MWCNTs)对Cd和BDE-47生态毒性的影响,采用沉积物慢性生物测试研究了不同浓度MWCNTs存在下Cd和BDE-47对铜锈环棱螺肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与Ⅱ相解毒反应的关键酶谷胱甘肽-S-转移酶(GST)以及脂质过氧化损伤指标丙二醛(MDA)的影响.结果表明,沉积物中低浓度MWCNTs(0.5 mg·g^(-1))增强Cd对铜锈环棱螺的氧化胁迫,中、高浓度(5、50 mg·g^(-1))MWCNTs引起Cd对铜锈环棱螺的氧化损伤,MWCNTs的存在显著增强了沉积物中Cd对铜锈环棱螺的毒性,而且具有浓度-效应关系;低浓度MWCNTs不影响BDE-47对铜锈环棱螺的毒性,中、高浓度MWCNTs显著降低BDE-47的毒性,同样具有明显的浓度-效应关系.因此,在评价MWCNTs的潜在环境风险时,不仅考虑MWCNTs自身的毒性,还应当考虑MWCNTs的浓度、共存污染物的种类和MWCNTs与共存污染物之间的相互作用.

With the widespread and increasing usage, carbon nanotubes （CNTs） may inevitably release into the aquatic environment. Due to their excellent adsorption affinity and capacity, CNTs can act as potential carriers of persistent toxic substances （PTS）. Sorption of PTS by CNTs can therefore potentially alter the bioavailability and ecotoxicity of coexisting PTS. This work aimed to evaluate the impacts of multi-walled carbon nanotubes （MWCNTs） with different concentrations in freshwater sediments on ecotoxicity of Cd and 2, 2＇, 4, 4＇-tetrabromodiphenyl ether （BDE-47） by depositfeeding gastropoda Bellamya aeroginosa. The effects of Cd and BDE-47 on superoxide dismutase （ SOD ） （ the key component of antioxidant defense system） , glutathione-S-transferase （GST） （the key enzyme of phase Ⅱ detoxification reaction ） , and lipid peroxidation biomarker malondialdehyde （MDA） in the hepatopancreas of B. aeroginosa following 21 d chronic sediment bioassay were investigated in the presence of MWCNTs with various concentrations. The results shewed that low concentration （0.5 mg.g-1 ） of MWCNTs enhanced oxidative stress of Cd to B. aeroginosa, and relatively high concentration （5, 50 mg. g-1 ） of MWCNTs caused oxidative damage. Hence, the presence of MWCNTs in sediments significantly enhanced the ectoxicity of Cd to B. aeroginosa in concentration-dependent manner. Comparatively, low concentration of MWCNTs had no effects on toxicity of BDE-47, and relatively high concentration of MWCNTs significantly reduced toxicity of BDE-47 in a concentration-dependent manner. When assessing potential environmental risk of MWCNTs, focus should be placed not only on the toxicity of MWCNTs itself, but also on the concentrations of MWCNTs, the category of coexisting contaminants, and interaction between MWCNTs and coexisting contaminants.