Purpose

To better control and manage phosphorus (P) in the aquatic environment of the Qiuxi River, a typical river severely influenced by anthropogenic activities in southwest China, the morphological characteristics and the release potential of P in sediments during different water seasons were determined.

Materials and methods

The overlying water and sediment samples were collected from the Qiuxi River in the normal-water season (NWS), low-water season (LWS), and high-water season (HWS), and physicochemical properties were quantified. Total phosphorus (TP) in sediment and the inorganic phosphorus (P_i) fraction were analyzed using the standard measures technology (SMT) procedure, and organic phosphorus (P_o) was further determined to be labile P_o (LOP), moderately labile P_o (MLOP), or non-labile P_o (NLOP). The release potential of P from the sediments was studied by experiments under simulated conditions.

Results and discussion

The results showed that P pollution in the Qiuxi River was the most serious during the LWS, with mean TP concentrations in the sediment of 854.6 mg kg⁻¹, and the release risk of the sediment P was also highest during this water season. The variation in P concentration was significantly influenced by the discharge of domestic sewage, agricultural diffusion, flow rate, and OM. The concentrations of P fractions varied with water season, but P_i was constantly higher than P_o. HCl-extractable P_i (HCl-P_i) accounted for most of the P in the sediments, which was related to its characteristics and the geographical location of the Qiuxi River. The maximum P release (R_max) was 25.9 mg kg⁻¹ in the LWS and 15.3 mg kg⁻¹ in the HWS, which were positively correlated with the TP (r² = 0.848, p < 0.01) and OM (r² = 0.847, p < 0.01) concentrations in the sediments and explained why the release risk of the sediment P in the LWS was higher than that in the HWS.

Conclusions

Phosphorus pollution and the P release potential in the sediments of the Qiuxi River were most severe in the LWS, so more effective measures to restrain the release of P should be taken during the LWS. Moreover, OM in sediments should be given more attention owing to its significantly positive correlation with the risk of P release.

中文翻译：

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沉积物中磷的季节变化特征和释放潜力-以西南地区典型的扩散源污染河秋溪河为例

目的

为了更好地控制和管理丘溪河水环境中的磷（P），这是一条受到人为活动严重影响的典型河流，确定了不同水季中沉积物中磷的形态特征和释放潜力。

材料和方法

在正常水季节（NWS），低水季节（LWS）和高水季节（HWS）从秋溪河采集上覆水和沉积物样品，并对理化性质进行定量。使用标准测量技术（SMT）程序分析沉积物中的总磷（TP）和无机磷（P _i）组分，并进一步确定有机磷（P _o）为不稳定的P _o（LOP），中等不稳定的P _o（MLOP）或不稳定的P _o（NLOP）。在模拟条件下，通过实验研究了磷从沉积物中的释放潜力。

结果和讨论

结果表明，秋水河中低磷期间磷污染最为严重，沉积物中的总磷浓度为854.6 mg kg ^-1，在此水季节，沉积物P的释放风险也最高。磷浓度的变化受生活污水排放，农业扩散，流速和OM的影响很大。P馏分的浓度随水季节而变化，但P _i始终高于P _o。HCl可萃取的P _i（HCl-P _i）占沉积物中P的大部分，这与它的特征和秋溪河的地理位置有关。最大P释放量（R _max）在LWS中为25.9 mg kg ^-1，在HWS中为15.3 mg kg ^-1，与TP（r ²  = 0.848，p  <0.01）和OM（r ²  = 0.847，p  <0.01）浓度呈正相关解释了为什么低水位沉积物中磷的释放风险高于高水位沉积物中的释放风险。

结论

黄土高原地区丘西河沉积物中的磷污染和磷释放潜力最为严重，因此在黄土高原期间应采取更为有效的措施来抑制磷的释放。此外，由于沉积物中的OM与P释放风险显着正相关，因此应给予更多关注。