绿狐尾藻光合色素组成及氮磷化学计量学特征对外源铵的响应

Responses of photosynthetic pigments composition,nitrogen and phosphorus stoichiometric characteristics of Myriophyllum aquaticum to exogenous ammonium

绿狐尾藻(Myriophyllum aquaticum)对高浓度铵(NH_(4)^(+))具有较高的耐受性,是处理养殖废水的优选植物。探究外源铵对绿狐尾藻光合色素组成及氮(N)、磷(P)化学计量学特征的影响,对提高绿狐尾藻人工湿地系统的处理效率具有重要意义。该研究设置0、0.1、1、5、15、30 mmol·L^(-1)6个NH_(4)^(+)浓度,室内培养21天,测定分析不同铵浓度下绿狐尾藻叶绿素含量、N含量、P含量和N:P的变化特征。结果表明,随外源铵浓度增加,绿狐尾藻的相对茎高和相对生物量先升高后降低,且通过拟合曲线方程发现,外源铵在16.22和12.58 mmol·L^(-1)时,其相对茎高和相对生物量达到最大值。随外源铵浓度的增加,绿狐尾藻叶片叶绿素含量显著降低,而茎中叶绿素含量增加,且叶绿素a含量变化的幅度比叶绿素b大,但对叶绿素a/b影响不显著,仅在5 mmol·L^(-1)处理时茎叶绿素a/b显著下降。随外源铵浓度增加,与CK相比,叶片和茎的N含量分别显著增加了85%-235%和127%-373%,叶片P含量增幅为49%-51%。当外源铵浓度不大于15 mmol·L^(-1)时,叶片和茎的N含量、N:P增加速度较快,且相对茎高和相对生物量增长较快。相关分析表明,叶片N、P含量和N:P与总叶绿素含量呈极显著负相关关系,而在茎中呈显著或极显著正相关关系。综上所述,外源铵浓度在12-16 mmol·L^(-1)范围内时,绿狐尾藻生长良好,生物量更大,N和P的吸收量更高,从而利用其构建的人工湿地可以有效去除污染废水的N、P,达到高效净化水体的目的。

Aims Myriophyllum aquaticum has high tolerance to high concentration of ammonium(NH_(4)^(+))and thus becomes the preferred species for swine wastewater treatment.It is of great significance to explore the effects of exogenous NH_(4)^(+)on the photosynthetic pigment composition and the stoichiometric characteristics of nitrogen(N)and phosphorus(P)of the M.aquaticum for improving the purifying efficiency of artificial wetlands system of M.aquaticum.Methods Six NH_(4)^(+)concentration levels(0,0.1,1,5,15,30 mmol·L^(-1))were set up in this study.After 21 days of indoor cultivation,the contents of chlorophyll,N and P of M.aquaticum were measured to analyze their characteristics of changes.Important findings The results showed that the relative stem height and biomass increased initially and then decreased,which were well fitted by a curve equation.Moreover,the peak of them appeared at 16.22 and 12.58mmol·L^(-1)exogenous NH_(4)^(+),respectively,via fitting non-linear Gaussian equation.With the increase of exogenous NH_(4)^(+)concentrations,the chlorophyll content in the leaves decreased significantly,but increased in the stems.In addition,there was a wide variation of chlorophyll a than chlorophyll b.The chlorophyll a/b did not change significantly among different NH_(4)^(+)treatments,except the value in the stems of 5 mmol·L^(-1)NH_(4)^(+)treatment,which was significantly decreased.With the increase of exogenous NH_(4)^(+)concentrations,the N contents in the leaves and stems were significantly increased by 85%-235%and 127%-373%,respectively,and the P content in the leaves was increased by 49%-51%in comparison to the control(CK).When the concentrations of exogenous NH_(4)^(+)was no more than 15 mmol·L^(-1),the N content and N:P ratio of the leaves and stems increased rapidly,so were relative stem height and relative biomass.Correlation analysis showed that the contents of N and P,and N:P ratio were negatively correlated with total chlorophyll content in the leaves,but positively correlated with total chlorophyll content in the stems.In conclusion,M.aquaticum grew well with larger biomass and higher absorption of N and P,when the concentrations of exogenous NH_(4)^(+)were in the range of 12-16 mmol·L^(-1).Therefore,the constructed wetlands system planted with M.aquaticum can effectively remove N and P from polluted wastewater and achieve the purpose of efficient water purification.