| 摘要: |
| 为探究深水型水源水库沉积物磷的释放潜能及其影响因素以及对比南水进京后密云水库内源磷的变化，本文以密云水库为研究对象，选择代表性点位采集沉积物及上覆水样品，采用改进的连续分级提取方法研究沉积物磷的赋存形态，并进一步通过室内模拟实验研究沉积物-水界面磷交换特征及其对环境因子的响应。结果表明：库区沉积物总磷（TP）含量在533.1 ~ 2650.9 mg/kg之间，具有较高的空间异质性。相比2013年南水入库前的研究，库区沉积物磷含量有上升的趋势。根据上覆水与间隙水之间的总磷浓度梯度，可判断出库区沉积物总体表现为源，释放磷到水体中。库区沉积物无机磷含量表现为：钙磷（Ca-Pi）> 铁铝磷（Fe/Al-Pi）> 潜在活性无机磷（PA-Pi）> 弱吸附态无机磷（WA-Pi）；有机磷含量表现为：中等活性有机磷（MA-Po）> 非活性有机磷（NANaOH-Po）> 潜在活性有机磷（PA-Po）> 弱吸附态有机磷（WA-Po）；在各形态磷中，Ca-Pi含量最高，占无机磷的72.36%，占总磷42.52%，但其释放风险较低；Fe/Al-Pi、MA-Po含量仅次于Ca-Pi，在诸多环境生物条件的影响下可以进一步向水中释放，可被认为是密云水库沉积物磷释放的主要来源。密云水库沉积物-水界面磷交换通量为0.014 ~ 0.022 mg·m-2·h-1，潮河库区整体交换通量高于白河库区；较国内其他研究较多的湖库，密云水库沉积物磷交换通量较低，但其沉积物TP含量相对较高。在环境因子模拟实验中，密云水库沉积物-水界面磷的交换与上覆水PO43-浓度、温度、pH及生物活动有着密切关系。通过实地测量，密云水库上覆水PO43-浓度较低，在沉积物-水界面浓度梯度的促进下，沉积物仍有着较高的磷释放潜力；库区水深较浅的区域沉积物磷释放在夏季更容易受温度升高的影响；现存条件下沉积物-水界面处pH对磷的释放影响较小；生物活动影响下磷呈明显的释放趋势，应加强对密云水库藻类、微生物及底栖生物种群数量的关注。 |
| 关键词: 磷 沉积物-水界面 赋存特征 交换通量 环境因子 |
| DOI： |
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| 基金项目:北京市自然科学基金委员会-北京市教育委员会联合资助项目 |
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| Characteristics of phosphorus exchange at sediment-water interface and its response to environmental factors in Miyun Reservoir* |
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Zhang Xuerui, Guo Yiwei, Wang Xiaoyan, Ning Chenkun
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College of Resource Environment and Tourism,Capital Normal University
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| Abstract: |
| Miyun Reservoir is a typical deep-water drinking water source reservoir in northern China. In order to explore the release potential of phosphorus in sediments of deep-water source reservoirs and its influencing factors, and to compare the changes of endogenous phosphorus in Miyun Reservoir after the south water enters Beijing, this paper takes Miyun Reservoir as the research object, selects representative points to collect sediments and overlying water samples, and uses the improved continuous grading extraction method to study the occurrence form composition of phosphorus in sediments, and further studies the phosphorus exchange characteristics of sediment-water interface and its response to environmental factors through indoor simulation experiments. The results showed that the total phosphorus (TP) content of sediments in the reservoir area ranged from 533.1 to 2650.9 mg/kg, with high spatial heterogeneity. Compared with previous studies, the phosphorus content of sediments in the reservoir area has an upward trend. According to the distribution of total phosphorus concentration between overlying water and interstitial water, sediment is the source of internal phosphorus load. The content of inorganic phosphorus in the sediments of the reservoir area was as follows: calcium phosphorus (Ca-Pi) > iron aluminum phosphorus (Fe/Al-Pi) > potential active inorganic phosphorus (PA-Pi) > weakly adsorbed inorganic phosphorus (WA-Pi); the content of organic phosphorus was as follows: moderately active organic phosphorus (MA-Po) > inactive organic phosphorus (NANaOH-Po) > potentially active organic phosphorus (PA-Po) > weakly adsorbed organic phosphorus (WA-Po). Among all forms of phosphorus, Ca-Pi had the highest content, accounting for 72.36% of inorganic phosphorus and 42.52% of total phosphorus, but its release risk was low. The content of Fe/Al-Pi and MA-Po is second only to Ca-Pi, and can be further released into water under the influence of many environmental biological conditions, which can be considered as the main source of phosphorus release from sediments in Miyun Reservoir. The phosphorus exchange flux at the sediment-water interface of Miyun Reservoir was 0.014 ~ 0.022 mg·m-2·h-1, and the overall exchange flux in Chaohe zone was higher than that in Baihe zone. Compared with other lakes and reservoirs in China, the sediment phosphorus exchange flux of Miyun Reservoir is lower, but the sediment TP content is relatively higher. In the experiment of environmental factors, the exchange of phosphorus at the sediment-water interface of Miyun Reservoir is closely related to the concentration of PO43- in the overlying water, temperature, pH and biological activities. Through field measurement, the concentration of PO43- in the overlying water of Miyun Reservoir is low, and the sediment still has high phosphorus release potential under the promotion of sediment-water interface concentration gradient. The phosphorus release from sediments in shallower water areas is more susceptible to temperature rise in summer. Under the existing conditions, the pH at the sediment-water interface has little effect on the release of phosphorus. Phosphorus showed a significant release trend under the influence of biological activities, and attention should be paid to the number of algae, microorganisms and benthic organisms in Miyun Reservoir. |
| Key words: phosphorus sediment-water interface occurrence characteristics exchange flux environmental factor |
