水体悬浮颗粒物对斜生栅藻生理生化及光合活性的影响

Effects of water suspended particulate matter on the physiological and photosynthetic activity of Scenedesmus obliquus

通过研究不同浓度(30、40、50、60、70mg·L)和不同粒径(0～75μm、75～96μm、96～150μm、150～250μm)水体悬浮颗粒物对斜生栅藻(Scenedesmus obliquus)叶绿素a含量、抗氧化系酶活性、脂质过氧化物丙二醛(MDA)含量、可溶性蛋白含量及光合参数变化的影响,探讨了水体悬浮颗粒物对斜生栅藻生理生化及光合活性影响的机制.结果表明,预处理与未处理悬浮颗粒物在一定浓度范围内会促进藻类生长,超过各自临界浓度(预处理为40mg·L-1、未处理为50mg·L-1)后,随着颗粒物浓度的增加会对藻类生长产生抑制现象.未经处理的相同浓度不同粒径颗粒物对斜生栅藻都表现出抑制作用,0～75μm粒径组颗粒物作用下藻体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、MDA和可溶性蛋白质含量等均显著区别于其他粒径组的作用(p<0.05).经过预处理的相同浓度不同粒径颗粒物中,96～150μm粒径组对藻类的生长抑制较其他粒径组明显,且小粒径组颗粒物对藻类体内SOD、CAT、MDA和可溶性蛋白质含量等影响较大.受不同浓度悬浮颗粒物胁迫的斜生栅藻相对电子传递速率随着时间延长在一定程度上降低,但这种抑制作用在藻细胞的耐受范围,藻细胞可以通过自身调节将电子传递速率恢复到正常水平甚至更高以抵抗逆境环境.

In this study, we explored the effects of different concentrations （30, 40, 50, 60, 70 mg·L^-1） and particle sizes （0-75 μm, 75~96 μm, 96~150 μm, 150~250 μm） of the suspended particulate matter on the chlorophyll a content, the antioxidant system activity, malondialdehyde （MDA） content, soluble protein content, and the changes of photosynthetic activity of S. obliquus. The results revealed that treated or untreated suspended particulate matter within a certain concentration range would promote the growth of algae. However, when they exceeded the critical concentrations （40 mg·L-1 for treated suspended particulate matter and 50 mg·L-1 for untreated suspended particulate matter）, the growth of algae was inhibited with the concentration increased. Untreated suspended particulate matter with the same concentration and different sizes showed that all size groups had inhibitory effects on the growth of S. obliquus. Significant differences in physiological and biochemical effects, including the changes of the activities of superoxide dismutase （SOD） and catalase （CAT）, the content of MDA and soluble protein, were observed between the influences of 0~75 μm particle size group and the other particle size groups. For treated suspended particulate matter with the same concentration and different sizes, 96~150 μm particles had more obvious inhibitory effects on the growth of S. obliquus. And the activities of SOD and CAT, the content of MDA and soluble protein of smaller size groups had bigger change. With the induction of different concentrations of suspended particulate matter, the relative electron transport rate of S. obliquus was reduced to a certain extent with time. However, this inhibition effect was in the range of tolerance of the algal cells. The algal cells could therefore recover the electron transport rate to normal or even higher levels to resist adverse environment by self-regulation.