A human health risk assessment of rare earth elements in soil and vegetables from a mining area in Fujian Province,Southeast China

Contaminated food through dietary intake has become the main potential risk impacts on human health. This study investigated concentrations of rare earth elements (REEs) in soil, vegetables, human hair and blood, and assessed human health risk through vegetables consumption in the vicinity of a large-scale mining area located in Hetian Town of Changting County, Fujian Province, Southeast China. The results of the study included the following mean concentrations for total and bio-available REEs of 242.92 ± 68.98 (135.85–327.56) μg g⁻¹ and 118.59 ± 38.49 (57.89–158.96) μg g⁻¹ dry weight (dw) in agricultural soil, respectively, and total REEs of 3.58 ± 5.28 (0.07–64.42) μg g⁻¹ dw in vegetable samples. Concentrations of total REEs in blood and hair collected from the local residents ranged from 424.76 to 1274.80 μg L⁻¹ with an average of 689.74 ± 254.25 μg L⁻¹ and from 0.06 to 1.59 μg g⁻¹ with an average of 0.48 ± 0.59 μg g⁻¹ of the study, respectively. In addition, a significant correlation was observed between REEs in blood and corresponding soil samples (R² = 0.6556, p < 0.05), however there was no correlation between REEs in hair and corresponding soils (p > 0.05). Mean concentrations of REEs of 2.85 (0.59–10.24) μg L⁻¹ in well water from the local households was 53-fold than that in the drinking water of Fuzhou city (0.054 μg L⁻¹). The health risk assessment indicated that vegetable consumption would not result in exceeding the safe values of estimate daily intake (EDI) REEs (100−110 μg kg⁻¹ d⁻¹) for adults and children, but attention should be paid to monitoring human beings health in such rare earth mining areas due to long-term exposure to high dose REEs from food consumptions.     

Dechlorination of hexachlorobenzene using lead–iron bimetallic particles

Synthesized lead–iron (Pb/Fe) bimetallic particles were applied to dechlorinate hexachlorobenzene (HCB) under various conditions (e.g. bimetal amount, initial pH value, reaction temperature, and reaction duration). The results showed that adding Pb onto Fe benefited the dechlorination of HCB and the bimetal with 1.4% Pb content performed best. The degradation rate decreased regularly as the initial pH value of the aqueous increased from 1.9 to 11.1 except for pH 7.0 where the fastest dechlorination rate emerged. The dechlorination could be enhanced by increasing the amount of Pb/Fe or the reaction temperature. The dechlorination ratio of HCB within 15 min increased from 24.3% to 81.3% when Pb/Fe amount increased from 0.1 g to 0.8 g. The dechlorination followed pseudo-first-order kinetics, and the dechlorination rate constants were 0.0027, 0.0064, 0.0157, and 0.0321 min^?1 at 25, 50, 70, and 85 °C, respectively, and the activation energy (E_a) of the dechlorination by Pb/Fe was 37.86 kJ mol^?1.     

人工浮床技术开发与应用研究进展

人工浮床作为一种新型的生态修复技术,主要依靠植物、微生物和水生动物的共同作用实现对水体的净化,具有不占用土地、不消耗能源、成本低、管理简单等优点,在地表水修复和污水净化中得到了越来越多的应用.然而,受植物生长速度和温度的影响,其在应用中仍存在净化能力差、适用范围有限等缺陷.优势植物筛选与植物刈割、微生物强化技术和水生动物强化法等途径可以在一定程度上解决这些问题.人工浮床中植物、微生物和水生动物在污染物去除中的耦合过程、微生物活性及影响因素和人工浮床的设计、构建及日常管理标准的制定等研究尚不深入,是限制人工浮床技术进一步推广的主要因素,也是未来研究的重点和难点.     

采用数值风洞模型对热电厂烟塔合一大气污染扩散的研究

随着城市的快速建设,城市建筑的高度和体量不断增加,同时大气污染源的排放方式和排放状态也与从前发生了很大的变化,特别是热电厂采用烟塔合一排放方式的出现,对常规应用的稳态远距离以统计学为基础理论的高斯大气预测方法提出了挑战。目前国内外广泛使用的大气污染物预测模式——德国模式在烟塔合一排放方式的预测上存在着许多关键性问题,如大风下洗条件下,冷却塔附近空腔区的大小和范围、空腔区污染物最高地面浓度等无法给出准确的预测结果。为准确预测烟塔合一排放方式的大气污染物扩散情况,采用一种新的大气污染物扩散的预测模式——数值风洞模型进行模拟预测研究,预测结果表明,在烟塔合一排放方式下,大气污染物最高地面浓度随风速增加而增加,同时在冷却塔下风向存在负压区,污染物在该区域高浓度聚集。且在夏季6.0m/s风速下,冷却塔下风向最高地面浓度出现峰值,属于最不利的气象条件。数值风洞模型可利用图形化手段实现对空腔区产生、变化、破碎至再生成的全过程描述,从而建立了一种大气污染预测的重要手段。     

无机陶瓷膜处理油田采出水

针对陶瓷膜在油田采出水处理过程中操作参数的选择及污染机理进行了研究。通过现场实验,分析了不同的操作参数对膜通量的影响,陶瓷膜对含油量及悬浮物的去除效果,膜阻力组成及膜污染清洗方法。实验结果表明,在确定出水水质达到低渗透油田注水水质A1级标准条件下,陶瓷膜过滤最佳操作条件为:跨膜压差0.16 MPa、温度50℃、膜面流速5.0 m/s。同时发现,NaOH和HNO3联合清洗有助于恢复膜通量。     

臭氧催化氧化工艺深度处理印染废水

采用正交实验对催化剂NiO/γ-A12O3的制备条件进行优化,并探讨臭氧催化氧化法对于印染废水的深度处理效能.结果表明,最优的催化剂制备条件为:浸渍液浓度为3％、浸渍时间为4h、灼烧温度为450℃、灼烧时间为3h.臭氧催化氧化反应15 min时,COD浓度由84.22 mg/L降低至50.00 mg/L以下;氨氮浓度由10.88 mg/L降低至5.01 mg/L;色度去除率达到69％,明显高于单纯臭氧氧化的反应效率.     

A2O工艺好氧末段溶解氧变化对脱氮除磷影响

采用连续流A2O工艺处理实际的生活污水,研究好氧末段在不同溶解氧(DO)浓度条件下对污泥沉降性能、系统脱氮除磷的影响,同时考察了DO对污泥硝化活性、厌氧释磷速率和反硝化脱氮速率的影响.结果表明,随着末段溶解氧的提高,污泥容积指数SVI从140降至100左右,后又升高到120～170;系统的硝化效果提高,氨氮的去除率从6...     

电化学工艺处理有机废水的研究进展

综述了目前国内外学者在二维电极和三维电极的开发和改进方面的研究成果,指出了电化学氧化技术和电极材料的主要研究方向和发展趋势.提出为解决电化学水处理技术中提高电催化效率和延长电极寿命的问题,当前研究的主要方向应集中在阳极材料、反应器结构和处理工艺方面.     

页岩对污泥氨气挥发的抑制作用

氨气是城市污水污泥产生的恶臭气体之一,控制或抑制其产生是资源化利用甚至处置过程中至关重要的.通过改进氨气测量方法定量分析外掺页岩对污泥氨气挥发的抑制作用和机理,实验研究了页岩掺量、陈放形式以及环境温度对污泥氨气挥发浓度的影响.结果表明,外掺页岩对污泥氨气挥发具有明显的抑制作用,随温度升高、陈放时间延长抑制效果有所减弱但仍具有明显作用;页岩对污泥氨气挥发的抑制作用主要为对氨气的吸附作用.