| 近20年长江中游监利—汉口河段氮、磷负荷时空变化特征分析 |
| 摘要点击 2557 全文点击 604 投稿时间：2023-09-10 修订日期：2023-12-21 |
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| 中文关键词 长江 氮、磷浓度 氮、磷通量 时空变化 水沙 |
| 英文关键词 Yangtze River nitrogen and phosphorus concentrations nitrogen and phosphorus fluxes tempo-spatial variations water and sediment |
| DOI 10.13227/j.hjkx.20240921 |
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| 中文摘要 |
| 氨氮（NH4+-N）和总磷（TP）属于长江流域重点管控污染物. 基于2003~2020年实测水质数据,分析长江中游监利至汉口河段NH4+-N和TP浓度及通量的时空变化,研究水沙因素和支流入汇等对污染物通量变化的影响,结果表明：①近年来干流NH4+-N和TP浓度降低明显,2020年二者较2003年各断面平均减幅为41%和34%；沿程上NH4+-N和TP浓度均先降低后升高. 由支流洞庭湖及汉江入汇的NH4+-N和TP浓度整体低于干流；干流二者多年均值均为0.12 mg·L-1,支流入汇的则为0.11 mg·L-1和0.09 mg·L-1. ②通过上、 下游断面通量差扣除支流入汇贡献后,NH4+-N和TP通量在监利—螺山段沿程损失,在螺山—汉口段沿程增加. 在监利—螺山段,与侧向入流（如洞庭湖）的NH4+-N和TP浓度偏低从而造成该段NH4+-N和TP浓度降低有关,在螺山—汉口段则相反且该段水量、 沙量沿程增加. 整个监利—汉口河段TP通量和水量、 沙量总体增加,而NH4+-N通量显著减少应归因于长江地区以NH4+-N为主的污染物减排政策. ③相关性分析结果表明,NH4+-N通量与NH4+-N浓度的相关性最好,而与流量及与输沙率无明显相关,反映研究段NH4+-N主要受点源控制；TP通量与流量及与输沙率的相关性在高流量时期相对较好,而其与TP浓度的相关程度在低流量时期更高,反映枯水期点源排放对TP贡献较丰水期增大. |
| 英文摘要 |
| Ammonia nitrogen （NH4+-N） and total phosphorus （TP） were the major control pollutants in the Yangtze River Basin. Based on measured data from 2003 to 2020, the temporal and spatial variations in concentrations and fluxes of NH4+-N and TP in the Jianli to Hankou （JL-HK） reach of the Middle Yangtze River were studied, and the impacts of flow-sediment factors, tributary inflows, and others on variations in NH4+-N and TP fluxes were discussed. The results showed that： ① In recent years, NH4+-N and TP concentrations in the mainstream have declined significantly, with annual NH4+-N and TP concentrations at each monitoring station in 2020 averagely decreasing by 41% and 34% compared to those in 2003, respectively. Spatially, NH4+-N and TP concentrations decreased and then increased along the mainstream. NH4+-N and TP concentrations of tributary inflows, which include the Dongting Lake and Han River, were generally lower than that of the mainstream. The multi-year average values of NH4+-N and TP concentrations were both averaged at 0.12 mg·L-1 in the mainstream and were averaged at 0.11 mg·L-1 and 0.09 mg·L-1 in the tributary inflows. ② The flux differences between the upper and lower sections net of tributary confluences showed that NH4+-N and TP fluxes were lost in the Jianli to Luoshan （JL-LS） sub-reach and increased in the Luoshan to Hankou （LS-HK） sub-reach in most years. NH4+-N and TP fluxes decreased in the JL-LS sub-reach, which was related to the lower NH4+-N and TP concentrations in lateral inflows, such as Dongting Lake, and thus lowered the NH4+-N and TP concentrations in the mainstream. The LS-HK sub-reach showed the opposite trends, and the water and sediment loads increased in this sub-reach. Across the whole JL-HK reach, TP flux as well as water and sediment loads were recharged along the reach, whereas NH4+-N flux was reduced greatly, which could be attributed to the pollution abatement conducted in the Yangtze River Basin, which mainly focused on NH4+-N. ③ The correlation analysis results showed that NH4+-N fluxes had the strongest correlation with NH4+-N concentrations but not significantly correlated with discharges and sediment transport rates, indicating that NH4+-N was mainly controlled by point source pollution in the study reach. TP fluxes had higher correlations with discharges and sediment transport rates in high flow level periods, and the correlations between TP fluxes and TP concentrations were better in low flow level periods, reflecting that point source pollution contributed more to TP in dry seasons compared to flood seasons. |
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