Effect of magnesium on charophytes calcification: implications for phosphorus speciation stored in biomass and sediment in Myall Lake (Australia)
Effect of magnesium on charophytes calcification: implications for phosphorus speciation stored in biomass and sediment in Myall Lake (Australia)
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DOI：
10.1007/s10750-009-9846-1
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发表时间：
2009-06
期刊：
影响因子：
2.6
通讯作者：
K. Siong;T. Asaeda
中科院分区：
文献类型：
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作者：
K. Siong;T. Asaeda
我们研究了镁（Mg）对Myall湖（一个盐度为2-3 PSU的浅滨浅湖泊）非钙质沉积物上生长的绿囊植物是否能像生长在淡水富钙硬水（即富钙硬水）钙质沉积物上的绿囊植物一样，作为磷(P)的有效营养库。结果表明，Myall湖水中高Mg降低了苔藓植物的钙化。同样，在自来水中加入镁也产生了同样的效果。抑制方解石形成显著降低了叶绿植物生物量和沉积物中钙结合磷形成的百分比。然而，Myall湖中叶绿植物不能沉淀方解石并不会降低植物床作为磷养分汇的能力。生物量中较大比例的生物可利用性较低的非反应性有机结合P (NaOH-P: 40-65%)，加上植物的分解速度较慢，将导致死亡有机质被掩埋，矿化过程不完全。尤其是绿藻植物菌体的碎屑相对来说更耐矿化。沉积P分馏结果支持了这一机制，其中难熔P和非反应性有机P组分至少占总P的80%。
We examined the effect of magnesium (Mg) on the charophytes calcite (CaCO3) encrustation and assessed whether charophytes, growing on non-calcareous sediments in the Myall Lake, a poorly flushed shallow coastal lake with salinity of 2–3 PSU, could function as an effective nutrient sink for phosphorus (P) in a similar manner to charophytes growing on calcareous sediments of the freshwater calcium (Ca)-rich hardwater, i.e., through the formation of Ca-bound P. Our results showed that high Mg in the Myall Lake water reduced the calcification in charophytes. Likewise, the addition of Mg into the tap water also produced the same effect. The inhibition of the calcite formation decreased significantly the percentage of Ca-bound P formation in the charophyte biomass as well as in the sediment. However, the inability of charophytes in Myall Lake to precipitate calcite does not reduce the plant beds' capability to act as a P nutrient sink. Instead of Ca-bound P, a large percentage of less bioavailable non-reactive organically bound P (NaOH–P: 40–65%) fraction in the biomass, together with the plant’s slow decomposition rate, will lead to burial of dead organic matter and an incomplete mineralization process. In particular, detritus of the charophyte plants’ thalli is relatively more resistant to mineralization. This mechanism was supported by the result of sedimentary P fractionation in which the refractory P and non-reactive organic P fractions accounted for at least 80% of the total P.