摘要:
为探究4-壬基酚对入侵水华蓝藻拟柱胞藻的影响,对不同浓度(0.00、0.05、0.10、0.50、1.00、2.00 mg·L-1)4-壬基酚处理96 h后的拟柱胞藻叶绿素a、抗氧化酶和光合作用进行测定。结果表明,4-壬基酚对拟柱胞藻96 h半数效应浓度(96 h-EC50)为0.457 mg·L-1。高浓度处理(>0.50 mg·L-1)时,拟柱胞藻叶绿素a含量、最大光合效率(Fv/Fm)、光合效率(α)、最大相对电子传递速率(rETRmax)、半饱和光强(Ik)、RC/Cs0、ET0/RC、ΦP0、ΦE0、ψ0和Sm/t(Fm)均显著下降被显著抑制,而光合系统Ⅱ中ABS/RC、DI0/RC和TR0/RC均显著增加,同时超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性随着浓度增加明显上升。而低浓度处理下(<0.10 mg·L-1),拟柱胞藻的叶绿素a含量、光合效率、最大相对电子传递速率和半饱和光强增加。这些结果表明高浓度4-壬基酚处理下,拟柱胞藻的叶绿素合成受阻,光合色素减少,光合反应中心结构受损,QA-大量累积,光合效率下降,抑制藻细胞的光合作用,导致了拟柱胞藻生长受到阻碍,而低浓度壬基酚处理下,则可能表现出低剂量毒物兴奋效应。
Abstract:
To explore the effect of 4-nonylphenol on the planktonic cyanobacterium Cylindrospermopsis raciborskii, chlorophyll a, antioxidative enzymes activities and photosynthetic characteristic parameters were investigated after 96 h treatments of 0.00, 0.05, 0.10, 0.50, 1.00 and 2.00 mg·L-1 4-nonylphenol. The results showed that the 96 h-EC50 values (effective concentration inducing 50% of growth inhibition after 96 h) of 4-nonylphenol in C. raciborskii was 0.457 mg·L-1. Chlorophyll a content, the maximum photochemical efficiency of PSⅡ in the dark (Fv/Fm), photosynthetic efficiency (α), the maximum relative electron transfer rate (rETRmax) and saturating light levels (Ik), RC/Cs0, ET0/RC, ΦP0, ΦE0, ψ0 and Sm/t(Fm) were significantly suppressed (P<0.05), while a significant in-crease was found in ABS/RC, DI0/RC and TR0/RC when C. raciborskii was treated at the high concentrations (>0.50 mg·L-1). In addition, the activities of superoxide dismutase (SOD) and catalase (CAT) were significantly increased as the 4-nonylphenol concentration increased. However, chl a, α, rETRmax and Ik showed significant in- creases when C. raciborskii was exposed to low concentrations of 4-nonylphenol (< 0.10 mg·L-1). Therefore, these results indicated that the growth of C. raciborskii inhibited by high concentrations of 4-nonylphenol may be related to the blockage of chlorophyll synthesis, reduce of photosynthetic pigment, damage of PSⅡ reaction center structure, large accumulation of QA- and decrease of photosynthetic efficiency. Cylindrospermopsis raciborskii might show a "hormesis" at the low concentrations of 4-nonylphenol.
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