磷石膏浸出液对斑马鱼的急性毒性及氧化应激损伤

以斑马鱼（Danio rerio）为受试鱼种，研究了磷石膏浸出液对水生生物的急性毒性及亚致死浓度下对斑马鱼肝脏、肌肉和鳃中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）和丙二醛（MDA）的影响，以及96 h后肝脏和鳃组织病理变化.结果表明，磷石膏浸出液中总磷、氟化物和Cd、Cr、Pb、Hg浓度超出地表水V类水标准，其对斑马鱼的毒性较强，96 h半数致死浓度（LC₅₀）为6.5%（体积分数）.慢性毒性实验显示，随暴露时间延长，各组织内3种抗氧化酶活性变化趋势不完全一致，但高浓度（0.65%和3.25%）暴露后期（72 h和96 h）几乎均受到显著抑制，其中，SOD对浸出液的敏感性最高；MDA含量变化规律较为一致，随浸出液浓度增加而升高，肝脏、肌肉和鳃中MDA最高含量均出现在72 h，分别是空白对照组的1.8、1.6和2.1倍，至96 h时略有降低，但仍显著高于对照组.各浓度组暴露96 h后，肝细胞窦间隙扩大，肝巨噬细胞增多，细胞核固缩，部分细胞质空泡化，组织水肿；鳃组织出现上皮细胞增生、脱落，鳃丝充血，鳃小片弯曲变形等现象.综上，未加处理的磷石膏浸出液已超出斑马鱼耐受极限，任其排入环境具有潜在的生态风险.

Acute toxicity and oxidative stress damage of phosphogypsum leachate to zebrafish (Danio rerio)

The zebrafish as the test organism was used to study the toxicity of phosphogypsum leachate to aquatic organisms. The changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) in zebrafish liver, muscle and gill tissue and the pathological changes of their liver and gill tissues were measured. The results showed that the concentration of total phosphorus, fluoride, Cd, Cr, Pb, and Hg in the phosphogypsum leachate exceeded the Class V standard for surface water, which exhibited a highly toxic to zebrafish, and its 96-hour median lethal concentration (LC₅₀) was 6.5%. The changing trends of the three antioxidant enzyme activities in each tissue are not completely consistent as the exposure time increased. However, almost all of them were significantly inhibited, and SOD was highest sensitive to phosphogypsum leachate in the high concentration (0.65% and 3.25%) and the later period of exposure (72 h and 96 h). The MDA exhibited a similar change trend that increased with the concentration of the leachate increased. The highest contents of MDA in liver, muscle and gills all appeared at 72 h and their contents were 1.8-, 1.6- and 2.1-time of the blank control group, respectively. The MDA contents decreased slightly at 96 h but they were still significantly higher than that of the control group. The hepatocyte sinusoid space expanded, the liver macrophages increased, the nucleus was pykeptic, some of the cytoplasm was vacuolated, and the tissue was edema after the zebrafish were exposed to different concentrations of leachate for 96 hours. The phenomena of epithelial cells were proliferated and fall off in the gill tissue, gill filaments were congested, and gill pieces were bent and deformed were observed. In summary, the toxicity of the untreated phosphogypsum leachate exceeded the tolerance limit of zebrafish, which will caused a potential ecological risks after the leachate discharge into the environment without taking any measures.