极端降水过程对岩口水库入库溪流污染负荷的影响及其对策

以岩口水库小流域为研究对象,通过监测2019年和2020年2次台风降水过程中入库河流氮磷通量变化,解析了极端降水事件对入库河流及下游库区污染负荷的影响,并评估极端降水条件下外源输入对库区水质污染的贡献。结果表明,降水历时和强度存在明显差异的两场暴雨全过程均可划分为4个典型阶段,即局部产流期、全流域产流期、水量消退期和流域恢复期。其中以全流域产流期(第Ⅱ阶段)污染负荷最重,输送了整个阶段50%以上的总磷负荷,且污染负荷的增长倍数与降水强度呈显著正相关。与降水前相比,台风“利奇马”和“黑格比”两场降水过程对下游岩口水库的入库总氮污染负荷分别增加了880 kg 和419 kg,总磷污染负荷分别增加了110 kg 和23 kg,而且增加的总氮以溶解态为主,总磷以颗粒态为主,说明地表径流冲刷导致河流中汇入了大量的面源污染负荷。本研究证实了极端降水事件,尤其是全流域产流阶段的降水会显著加剧流域面源对下游库区的污染贡献,建议采取合理的滞蓄、沉淀和净化等策略对地表径流污染负荷进行削减以降低下游库区水质污染风险。     

Experimental and numerical study of methylparaben decomposition in aqueous solution using the UV/H2O2 process

The present paper aims at presenting a kinetic model that is supposed to result in the decomposition of methylparaben in completely mixed batch reactor (CMBR) using the UV/H₂O₂ process. The proposed model incorporates photochemical, chemical reactions and their constant rates to formulate the overall kinetic rate expressions which are integrated into MATLAB. Thus, the changes in pH values during the process of oxidation are taken into consideration. In addition, the effects of hydrogen peroxide (HP) dosage, as well as the concentration of hydroxyl radicals, are examined. Accordingly, the pseudo-first-order rate constant, its variation as functions of HP concentration, incident UV-light intensity and the limitations of the adopted approach are discussed. In line with that, the authors provided evidence of the validity of the kinetic model through the exposure of previous experimental studies as reported in the literature review then through the evidence of the present experimental data.     

Pilot study on the treatment of low carbon and nitrogen ratio municipal sewage by A1/O2/A3/A4/O5 sludge-membrane coupling process with multi-point inflow

Environmental Science and Pollution Research - A new multi-point inflow pre-anoxic/oxic/anaerobic/anoxic/oxic (A1/O2/A3/A4/O5) sludge-membrane coupling process and pilot plant were developed and...     

The accuracy of plume trajectories forecast using the U.K. Meteorological Office operational forecasting models and their sensitivity to calculation schemes

Studies into the various errors associated with long-range 950 mb trajectories computed using the Meteorological Office numerical weather prediction suite are presented. In the absence of observational data, trajectory error is measured using a verification computed from the model analysed and short-period forecast wind fields. While it is safest to assume that errors determined in this way are the minimum to be expected in relation to “true” trajectories, they nonetheless provide a useful diagnostic of model performance under different synoptic conditions and for trajectory releases at different stages of the forecast. Absolute and directional errors are analysed and the effect of altering the trajectory calculation schemes considered. The possible implications of the results for acid precipitation control strategies are discussed in some detail.     

Decolorization and decomposition of organic pollutants for reactive and disperse dyes using electron beam technology: effect of the concentrations of pollutants and irradiation dose

Dyeing wastewater was known to have strong color and refractory organic pollutants. In this study irradiation alone was used for dyes wastewater treatment. This paper studies the effect of the concentrations of pollutants to its removal at various dosages using electron beam technology. Irradiation was effective in removing the highly colored and refractory organic compounds. The color removal for initial concentrations of 255 CU, 520 CU, 990 CU and 1900 CU treated using irradiation at 0.5kGy were 61%, 48%, 28% and 16%, respectively. However, at the dose of 108kGy and higher, the color removal between 87% and 96% were recorded with no apparent trend. COD removal also reported similar trend but at relatively lower removal percentage. The COD removal at 0.5kGy for initial COD concentrations of 57mg/l and 515mg/l were 10% and 0%, respectively. At irradiation dose of 108kGy, the removal for initial COD concentrations of 57mg/l and 515mg/l were 37% and 13%, respectively. This showed that concentrations of pollutants and dose of irradiation applied to remove color and COD were dependent to each other.     

Source term characterisation using concentration trends and geochemical associations of Pb and Zn in river sediments in the vicinity of a disused mine site: Implications for contaminant metal dispersion processes

River sediment at a disused lead-zinc mine was analysed to provide an understanding of the chemical nature of the source term for contaminated sediment exported from the site. Changes in concentration and geochemical associations of Pb and Zn were measured using aqua regia digestion and the BCR sequential extraction procedure. Sediment in the immediate vicinity of the mine was highly contaminated with Pb (max. c. 11,000 mg kg⁻¹) and Zn (max. c. 30,000 mg kg⁻¹), but these values declined rapidly within 1 km of the mine due to dilution and hydraulic sorting. Lead fractionation changed from being predominantly in the reducible fraction to being in the acetic acid-extractable fraction, whereas Zn was predominantly in the residual fraction. This material is transported as fine sediment in the river system.