缓释氧复合材料不同投加方式对沉积物-水界面污染物迁移的影响

为改善湖泊沉积物-水界面生境，开发了一种可原位供氧同时削减内源氮释放的缓释氧材料。发现以m（CaO₂）:m（白土）:m（水泥）=2:1:1制备的缓释氧材料具有较好的释氧和pH缓冲能力。通过模拟实验比较缓释氧材料不同投加方式（表层投加和泥内投加）对释氧和沉积物中污染物释放的影响。结果表明:1）表层投加缓释氧材料使得上覆水中DO浓度和pH值明显升高，而在泥内投加可以使pH值维持在7.5以内，同时DO浓度缓慢增加，延长了释氧周期；2）缓释氧材料对沉积物中NH₄+-N释放有显著的抑制作用，且表层投加方式明显高于泥内投加，以空白组作参比，静态培养31 d后，泥内加入缓释氧材料对NH₄+-N的抑制率为53.4%，而表层投加对NH₄+-N的抑制率达到81.1%，投加释氧材料有利于提高上覆水DO水平，促进硝化细菌的生长，从而抑制NH₄+-N的释放；3）缓释氧材料有利于微生物生长，促进了微生物腐殖化作用，从而对沉积物中类陆源腐植酸的释放略有促进，而对类酪氨酸蛋白释放略有抑制；4）缓释氧材料可促进沉积物中Fe/Al-P向Ca-P转化，对DIP的释放略有抑制，但由于pH增加导致沉积物中DOC以及重金属As和Cr的释放略有增加。

EFFECTS OF DIFFERENT DOSING METHODS OF SLOW-RELEASE OXYGEN COMPOSITE MATERIALS ON THE MIGRATION OF POLLUTANTS AT THE SEDIMENT-WATER INTERFACE

In order to improve the lake sediment-water interface habitat, a slow-release oxygen material that can supply oxygen in situ and reduce the release of endogenous nitrogen was developed. The slow-release oxygen material prepared with CaO₂:white clay:cement=2:1:1 (mass ratio) had good oxygen release and pH buffering capability. The simulation experiment compared the effects of different dosing methods of slow-release oxygen materials (surface dosing and in-mud dosing) on the release of oxygen and the release of pollutants in the sediments. The results showed that:1) the DO concentration and pH value of the overlying water were significantly increased by surface dosing, and in-mud dosing could maintain the pH value within 7.5, while the DO concentration increased slowly, prolonging the oxygen release period; 2) slow-release oxygen materials had a significant inhibitory effect on release of NH₄+-N in the sediment, and surface dosing was significantly effective than in-mud dosing. Taking the blank group as the reference, after 31 days of static culture, the inhibition rate of NH₄+-N by adding slow-release oxygen material into the mud was 53.4%, and that of the surface dosing was 81.1%. Adding oxygen-releasing materials increased the level of DO in the overlying water and promoted the growth of nitrifying bacteria, thereby inhibiting the release of NH₄+-N; 3) slow-release oxygen materials were beneficial to microorganisms growth which promoted the humification of microorganisms, thereby slightly promoted the release of terrestrial-like humic acids in the sediments, while slightly inhibited the release of tyrosine-like proteins; 4) slow-release oxygen materials could promote the conversion of Fe/Al-P to Ca-P in the sediment which slightly inhibited the release of DIP, but the release of DOC and arsenic and chromium in the sediment increased slightly, due to the increase of pH.