| 摘要: |
| 本研究采用化学连续提取法,分析了赣江南昌段表层沉积物磷赋存形态特征及其生物有效性,并通过等温吸附实验探讨了沉积物磷释放风险。结果显示：赣江南昌段表层沉积物总磷(TP)的含量范围为235.21~702.24 mg/kg,平均含量为522.93 mg/kg。TP含量变异系数为36.0%,表明TP含量具有较高的空间异质性。所有采样点位中无机磷(IP)均以闭蓄态磷(Oc-P)为主要赋存形态,各形态无机磷含量特征表现为：Oc-P > 铁结合态磷(Fe-P)> 碎屑钙磷(De-P)> 自生钙磷(ACa-P)> 交换态磷(Ex-P)> 铝结合态磷(Al-P)；有机磷(OP)以残渣态有机磷(Res-Po)为主要赋存形态,按活性划分表现为：非活性有机磷(NOP)> 中活性有机磷(MLOP)> 活性有机磷(LOP)。赣江南昌段沉积物生物有效磷(BAP)含量范围为61.59~218.27 mg/kg,平均含量为145.54 mg/kg,占TP比重为29.57%。与国内其他水体相比,BAP总量及占TP比重均处于较低水平,沉积物内源磷释放风险较低。BAP中Fe-P的平均占比为56.72%,表明赣江沉积物磷潜在释放风险主要来源于Fe-P。采样期间赣江南昌段沉积物磷平衡浓度(EPC0)高于上覆水溶解性活性磷(SRP),磷吸附饱和度(DPS)均低于沉积物磷大量流失的临界值25%,表明此阶段沉积物磷虽作为上覆水的“磷源”,但出现大量释磷的可能性不高。TP、Fe-P和De-P之间均存在显著相关关系(p<0.05),表明外源输入可能是赣江沉积物磷的主要来源。综上分析,赣江表层沉积物总磷及各形态磷含量较低,且生物有效磷占比较低,磷释放风险不高。因此,沉积物作为内源磷释放引起赣江水体富营养化的风险不高,这意味着赣江水体应更多关注外源输入问题。本研究结果为赣江南昌段水环境的科学管理提供了数据支撑和科学依据。 |
| 关键词: 赣江 沉积物 磷形态 生物有效磷 释放风险 |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Characteristics and release risk of phosphorus fractions in sediments from Nanchang section of Ganjiang River |
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Xiang Sulin1, Chu Minghang1, Liu Lizhen2, Zhu Lin2, Wu Yongming2, Liang Peiyu2
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1.School of Civil Engineering and Architecture,East China Jiaotong University;2.Institute of Microbiology,Jiangxi Academy of Sciences
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| Abstract: |
| In this study, the characteristics and bioavailability of phosphorus fractions in surface sediments of Ganjiang River were analyzed by chemical sequential extraction method. The risk of sediment phosphorus release was explored by isothermal adsorption experiments. The results showed that the total phosphorus (TP) content in the surface sediments of the Nanchang section of the Ganjiang River ranged from 235.21 to 702.24 mg/kg, with an average of 522.93 mg/kg. The coefficient of variation of the TP content was 36.0%, which indicated that the TP content had a high degree of spatial heterogeneity. In all the sampling sites, the occluded phosphorus (Oc-P) was the principal storage form of inorganic phosphorus (IP), and the inorganic phosphorus content of each form was characterized as Oc-P > Iron-bound phosphorus (Fe-P) > detrital calcium phosphate (De-P) > authigenic calcium phosphate (ACa-P) > exchangeable phosphorus (Ex-P) > aluminum-bound phosphorus (Al-P). Organic phosphorus (OP) was mainly deposited in the form of residual organic phosphorus (Res-Po), and according to the division of activity, it was as follows: inactive organic phosphorus (NOP) > medium-active organic phosphorus (MLOP) > active organic phosphorus (LOP). The content of bioactive phosphorus (BAP) in the sediment of the Nanchang section of Ganjiang River ranged from 61.59 to 218.27 mg/kg, with an average content of 145.54 mg/kg, and the proportion of BAP in TP ranged from 24.75% to 35.12%, with an average proportion of 29.57%. Compared with other water bodies in China, the total amount of BAP and the proportion of TP were low, and the risk of endogenous sediment release was low. 56.72% of Fe-P in BAP showed that the potential risk of phosphorus release from Ganjiang River sediment mainly came from Fe-P. During the sampling period, the equilibrium phosphorus concentration (EPC0) of the sediments in the Nanchang section of the Ganjiang River was higher than that of the dissolved reactive phosphorus (SRP) of the overlying water. The values of the degree of phosphorus saturation (DPS) were lower than the critical value of 25% for the large amount of phosphorus loss from the sediments, which indicated that although the sediments acted as a "source of phosphorus" for the overlying water at this stage, the possibility of large amounts of phosphorus release was not high. There were significant correlations (p<0.05) between TP, Fe-P, and De-P, indicating that exogenous inputs may be the primary source of phosphorus in Gan River sediments. In summary, the total phosphorus and each form of phosphorus in the surface sediments of the Gan River were low, and the proportion of biologically effective phosphorus was relatively low. Hence, the risk of phosphorus release was not high. Therefore, the risk of eutrophication of the Ganjiang River water body caused by the release of phosphorus from sediments as an endogenous source is low, which means that more attention should be paid to exogenous inputs to the Gan River water body. The results of this study provide data support and theoretical basis for the scientific management of the water environment of the Nanchang section of the Ganjiang River. |
| Key words: Ganjiang River sediment phosphorus fractions bioavailable phosphorus release risk |
