Fractionation of sediment phosphorus (P) was conducted to examine the distribution and bioavailability of P fractions in a blood clam Tegillarca granosa-based ecological aquaculture wastewater treatment system. In a laboratory experiment, either a low or high density of clams, or no clams (control), were added to a polypropylene chamber containing aquaculture wastewater and an 8 cm sediment layer. Distribution and bioavailability of inorganic P (Inorg-P) — which included exchangeable P (Ex-P), metal oxide-bound P (NaOH-P), calcium-bound P (HCl-P), redoxsensitive P (BD-P), and detrital P (De-P) — and organic P (Org-P) in the sediment were investigated after 30 d using a sequential extraction procedure (SEDEX). Results showed that T. granosa bioturbation activities markedly changed the contents of P fractions, especially Ex-P, NaOH-P, BD-P, and Org-P (p < 0.05). Total Inorg-P varied from 1.83 to 6.75 μmol g−1, with an average of 4.29 ± 1.37 μmol g−1 among the 3 groups. Org-P ranged from 5.01 to 9.76 μmol g−1 and accounted for 22 to 41% of total P (TP). Despite some variation in contents at different depths, the average proportions of P fractions to TP were, in ascending order, Ex-P, BD-P, NaOH-P, HCl-P, De-P, and Org-P. Inorg-P had the highest proportions (73.83%) of TP. Bioavailable P (Ex-P, NaOH-P, and BD-P) proportions were 61, 58.23, and 44.44%, respectively, relative to the control. The variant contents of the P fractions were most probably due to enhanced organic matter consumption and mineralization, metal oxide dissolutions, and the increased bioavailable P in the bioturbated sediment. This study suggests that T. granosa can modify the concentrations, distribution, and bioavailability of sedimentary P, as well as reduce Org-P. Our study further advances the knowledge on P cycling and provides theoretical assistance for monitoring P in aquatic environments.

中文翻译：

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生态水产养殖废水处理系统中的养分循环：由于 Tegillarca granosa 的生物扰动活动，底栖磷部分的垂直分布

对沉积物磷 (P) 进行分馏以检查 P 组分在基于 Tegillarca granosa 的生态水产养殖废水处理系统中的分布和生物利用度。在实验室实验中，将低密度或高密度的蛤蜊或没有蛤蜊（对照）添加到含有水产养殖废水和 8 厘米沉积层的聚丙烯室中。无机磷（Inorg-P）的分布和生物利用度——包括可交换磷（Ex-P）、金属氧化物结合磷（NaOH-P）、钙结合磷（HCl-P）、氧化还原敏感磷（BD-P） , 和碎屑 P (De-P) - 和有机 P (Org-P) 在 30 d 后使用顺序提取程序 (SEDEX) 进行调查。结果表明，T. granosa 生物扰动活动显着改变了 P 组分的含量，尤其是 Ex-P、NaOH-P、BD-P、和组织-P (p < 0.05)。总 Inorg-P 从 1.83 到 6.75 μmol g-1 不等，3 组之间的平均值为 4.29 ± 1.37 μmol g-1。Org-P 的范围为 5.01 至 9.76 μmol g-1，占总磷 (TP) 的 22% 至 41%。尽管不同深度的含量存在一定差异，但P组分与总磷的平均比例从高到低依次为Ex-P、BD-P、NaOH-P、HCl-P、De-P和Org-P。Inorg-P 的 TP 比例最高 (73.83%)。相对于对照，生物可利用 P（Ex-P、NaOH-P 和 BD-P）的比例分别为 61、58.23 和 44.44%。P 组分的不同含量很可能是由于有机物消耗和矿化增加、金属氧化物溶解以及生物扰动沉积物中生物可利用 P 增加所致。这项研究表明，T. granosa 可以改变浓度、分布、和沉积 P 的生物利用度，以及减少 Org-P。我们的研究进一步推进了 P 循环的知识，并为监测水生环境中的 P 提供了理论帮助。