College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, China.
Key Laboratory of Pollution Control and Resource Recycling of Fujian Province, Fujian Normal University, Fuzhou, 350007, China.
Environ Sci Pollut Res Int. 2018 Dec;25(35):35365-35375. doi: 10.1007/s11356-018-3447-3. Epub 2018 Oct 20.
In coastal wetland ecosystems, most phosphorus (P) accumulates in the sediments and becomes a major pollutant causing eutrophication by recycling to the water column in estuary areas, especially exotic plant invasions will change the nutrient cycling. In this study, a large wetland invaded by exotic species Spartina alterniflora for over 15 years was selected to study the sediment P fractionation and its retention for different plant invasion periods. The samples were collected from east to west in September and the sediment P was fractionated into total P (TP), inorganic P (IP), iron/aluminum-bound P (Fe/Al-P), calcium-bound P (Ca-P), and organic P (OP). Additionally, the effect of the invasion period on the wetland P fractionation based on space-time reciprocal principle was investigated. For different S. alterniflora invasion periods, the average TP concentration was 675.37 mg kg with a range of 160.33-1071 mg kg. The IP concentration was in the range of 107.33-813.33 mg kg (accounting for 54.4-79.5% of TP), of which Fe/Al-P and Ca-P represented up to 99.4%. In addition, the P retention (R) was within 41.67-329.67 mg kg. We also found that TP, IP, Fe/Al-P, Ca-P, OP, and R in sediments were negatively correlated with pH (p < 0.05), and were also significantly positively correlated (p < 0.01) with water content and electrical conductivity. There were positive correlations between the various forms of P in the sediments (p < 0.01). However, the most important finding was that invasion time of S. alterniflora had a direct effect on the P speciation and three stages were determined. In the first stage, S. alterniflora mainly consumed the OP of the sediment. In the second stage, S. alterniflora showed great vitality and biological immobilization led to the transforming of IP to OP. In the third stage, all P fractions greatly decreased to values even lower than for the bare beach which indicated that S. alterniflora growth had begun to degenerate. These three stages well explained the P seemingly contradictory increases and decreases apparent in previous studies and provide important information for understanding the effect of S. alterniflora invasion.
在滨海湿地生态系统中，大部分磷（P）积累在沉积物中，并通过在河口地区向水柱中循环成为主要的污染物，导致富营养化，特别是外来植物的入侵会改变养分循环。本研究选择了一个被外来物种互花米草入侵超过 15 年的大型湿地，研究了不同植物入侵时期的沉积物磷分馏及其保留情况。在 9 月，从东到西采集样品，并将沉积物 P 分为总磷（TP）、无机磷（IP）、铁/铝结合磷（Fe/Al-P）、钙结合磷（Ca-P）和有机磷（OP）。此外，还根据时空互反原理研究了入侵时期对湿地磷分馏的影响。对于不同的互花米草入侵时期，TP 浓度的平均值为 675.37mgkg，范围为 160.33-1071mgkg。IP 浓度范围为 107.33-813.33mgkg（占 TP 的 54.4-79.5%），其中 Fe/Al-P 和 Ca-P 占比高达 99.4%。此外，P 保留量（R）在 41.67-329.67mgkg 之间。我们还发现，沉积物中的 TP、IP、Fe/Al-P、Ca-P、OP 和 R 与 pH 值呈负相关（p<0.05），并且与含水量和电导率呈显著正相关（p<0.01）。沉积物中各种形态的 P 之间存在正相关关系（p<0.01）。然而，最重要的发现是互花米草的入侵时间对磷形态有直接影响，并确定了三个阶段。在第一阶段，互花米草主要消耗沉积物中的 OP。在第二阶段，互花米草表现出强大的活力，生物固定作用导致 IP 向 OP 的转化。在第三阶段，所有磷分数都大大降低，甚至低于裸滩的值，这表明互花米草的生长已经开始退化。这三个阶段很好地解释了先前研究中磷似乎矛盾的增加和减少现象，并为理解互花米草入侵的影响提供了重要信息。
