温度对浒苔生长及不同氮源吸收特性的影响

Effects of Temperature on the Growth Rate and Nitrogen Uptake of Ulva prolifera

关键词:  浒苔  水温  氮源  生长

Key words:  Ulva prolifera  Temperature  Nitrogen source  Growth

摘要:

为了评估浒苔(Ulva prolifera)对养殖废水的净化效果，本文研究了4个温度水平(22.5℃、25.5℃、28.5℃和31.5℃)和3种氮源(NH4Cl、NaNO2和NaNO3)下，浒苔对工厂化养殖水环境的适应能力及其净化效果。结果显示，96 h内4个温度处理组浒苔对总氨氮(TAN，包括NH4+-N和NH3)的平均吸收速率分别为14.65、14.88、14.48和13.53 μmol/(gh)，144 h内温度各处理组对亚硝态氮(NO2–-N)的平均吸收速率分别为11.28、10.48、9.11和8.38 μmol/(gh)，144 h内各温度处理组对硝态氮(NO3–-N)的平均吸收速率分别为9.41、8.62、8.80和7.35 μmol/(gh)；温度对浒苔的生长速率有极显著的影响(P<0.01)，而氮源对浒苔的生长速率有显著影响(P<0.05)；在相同氮源条件下，浒苔的生长速率随着温度的升高而逐渐降低；在相同温度条件下，氮源为氨氮(NH4+-N)时，浒苔的生长速率大于氮源为NO2–-N和NO3–-N的生长速率；温度和氮源对浒苔叶绿素a的含量影响不显著(P>0.05)，氮源为NH4+-N和NO2–-N时，随着温度的升高，浒苔中叶绿素a的含量均有升高的趋势，而氮源为NO3–-N时，浒苔中叶绿素a的含量呈先降低再升高的趋势；温度和氮源对浒苔中类胡萝卜素的含量均有极显著影响(P<0.01)。随着温度的升高，各处理组浒苔中类胡萝卜素的含量均呈升高的趋势，其中，在28.5℃和31.5℃条件下，NO3–-N处理组浒苔类胡萝卜素的含量明显高于其他各处理组(P<0.05)。研究表明，温度在22.5℃~31.5℃范围内，浒苔可以有效吸收TAN、NO2–-N和NO3–-N等对虾工厂化养殖废水中的营养盐，浒苔对NH4+-N的吸收速率最大，但随着水温的升高，浒苔对NH4+-N、NO2–-N和NO3–-N的吸收速率均呈降低的趋势。

Abstract:

Marine macroalgae is used as a biofilter for aquaculture wastewater treatment. Marine macroalgae is used as a biofilter for aquaculture wastewater treatment. Ulva prolifera was cultivated at four different water temperatures (22.5℃, 25.5℃, 28.5℃, and 31.5℃) with a different inorganic nitrogen source (NH4Cl, NaNO2, and NaNO3) for each temperature to evaluate the purification efficiency of marine macroalgae U. prolifera on wastewater; all measurements were carried out in triplicate. The results show that, in the temperature range 22.5℃~31.5℃, the TAN uptake rates were 14.65, 14.88, 14.48, and 13.53 μmol/(g·h) in 96 h; the nitrite and nitrate uptake rates were 11.28, 10.48, 9.11, and 8.38 μmol/(g·h) and 9.41, 8.62, 8.80, and 7.35 μmol/(g·h) in 144 h, respectively. Both the temperature (P<0.01) and the nitrogen source (P<0.05) had significant effects on the growth rate of U. prolifera. The growth rate decreased as the temperature increased; further, at the same temperature with an ammonium source, U. prolifera showed the largest growth rate, followed by that with nitrite and nitrate sources. For the ammonium and nitrite sources, the content of chlorophyll a (Chl-a) increased with an increase in temperature; however, for the nitrate source, the content of Chl-a decreased first and then increased. Both the temperature and the nitrogen source had a significant effect on the carotenoid content (P<0.01), which increased with an increase in temperature. In the temperature range of 28.5℃~31.5℃, the carotenoid content in the nitrate source were found to be significantly higher than that in the other sources (P<0.05). The temperature and nitrogen source, thus, has a significant influence on the growth rate, Chl-a, and carotenoid content of U. prolifera. Overall, the TAN uptake rate was the highest, followed by the nitrite and nitrate uptake rates. However, the inorganic nitrogen uptake rate decreased as the temperature increased.