Wastewater-nitrogen removal using polylactic acid/starch as carbon source: Optimization of operating parameters using response surface methodology

The use of PLA/starch blends for nitrogen removal was achieved. The influence of different operating parameters on responses was verified using RSM. The conditions for desired responses were successfully optimized simultaneously. Blends material may have a promising application prospect in the future. Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid (PLA)/starch blends as carbon source and carrier for functional bacteria. The exclusive and interactive influences of operating parameters (i.e., temperature, pH, stirring rate, and PLA-to-starch ratio (PLA proportion)) on nitrification (Y₁), denitrification (Y₂), and COD release rates (Y₃) were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous nitrification and denitrification. The carbon release rate of the blends was controllable. The sensitivity of Y₁, Y₂, and Y₃ to different operating parameters also differed. The sequence for each response was as follows: for Y₁, pH>stirring rate>PLA proportion>temperature; for Y₂, pH>PLA proportion>temperature>stirring rate; and for Y₃, stirring rate>pH>PLA proportion>temperature. In this study, the following optimum conditions were observed: temperature, 32.0°C; pH 7.7; stirring rate, 200.0 r·min^-1; and PLA proportion, 0.4. Under these conditions, Y₁, Y₂, and Y₃ were 134.0 μg-N·g-blend^-1·h^-1, 160.9 μg-N·g-blend^-1·h^-1, and 7.6 × 10³ μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.     

基于我国物种毒性数据的多溴联苯醚预测无效应浓度分析

采用多溴联苯醚(PBDEs)对我国广泛分布生物物种的生态毒性数据,根据欧盟现有化学物质风险评价技术指导文件,对不同环境介质中PBDEs预测无效应浓度(PNEC)进行了推导。结果表明:我国淡水环境PBDEs(四溴、五溴、八溴)的PNEC水分别为50μg·L~(-1)、0.53μg·L~(-1)、0.017μg·L~(-1)。沉积物环境PBDEs(四溴、五溴、八溴和十溴)的PNEC沉积物分别为823.35 mg·kg~(-1)wt、1.55 mg·kg~(-1)dw、12.72 mg·kg~(-1)dw、38.41 mg·kg~(-1)dw。土壤环境PBDEs(四溴、五溴、八溴和十溴)的PNEC土壤分别为668.3mg·kg~(-1)wt、0.38 mg·kg~(-1)dw、147 mg·kg~(-1)dw、98 mg·kg~(-1)dw。次生毒性PBDEs(五溴、八溴和十溴)的PNEC经口分别为0.3~0.7 mg·kg~(-1)、0.56 mg·kg~(-1)、2 500 mg·kg~(-1)。该数值期为我国PBDEs的环境风险评价提供科学基础。     

云南山区野生牛肝菌中重金属汞和镉来源分析及食用安全评估

分析重金属在"环境-牛肝菌-人体"系统中的迁移、富集规律,为牛肝菌重金属污染防治及食用安全评价提供依据。采用ICP-AES法测定云南野生牛肝菌及其生长土壤中Cd和Hg含量,分析牛肝菌对重金属的富集特征及牛肝菌的重金属含量与土壤的联系,推测云南野生牛肝菌中重金属Cd和Hg的来源;根据FAO/WHO规定的每周Cd或Hg的允许摄入量(provisional tolerable weekly intake,PTWI)评估牛肝菌的重金属暴露风险。结果显示,(1)不同种类、产地牛肝菌中Hg和Cd含量具有差异,菌盖中Hg、Cd的含量分别在0.92~16.00 mg·kg~(-1)dw,4.97~24.07 mg·kg~(-1)dw之间,菌柄的Hg、Cd含量分别介于0.46~8.2mg·kg~(-1)dw和2.11~22.08 mg·kg~(-1)dw之间。同一种牛肝菌菌盖中Hg或Cd的含量均高于菌柄(Q(C/S)1),表明牛肝菌菌盖对Hg和Cd的富集能力强于菌柄。(2)牛肝菌菌盖和菌柄对Hg的富集系数(bioaccumulation factor,BCF)分别在1.72~19.12和1.30~6.40之间,菌盖、菌柄的Hg含量均高于相应生长土壤的含量,其中采自楚雄永仁县的铜色牛肝菌菌盖的Hg含量是土壤的19.12倍,表明牛肝菌中的Hg不仅来自土壤,根据山地"Hg诱捕效应"及云南大气Hg升高的相关报道,可以推测云南野生牛肝菌中的Hg主要来源于大气沉降。(3)牛肝菌菌盖、菌柄对Cd的富集系数分别在0.16~1.82和0.07~1.67之间,多数牛肝菌的Cd含量低于土壤含量,表明牛肝菌中的Cd主要来自生长土壤。(4)假设成年人(60 kg)毎周食用300 g新鲜牛肝菌则多数牛肝菌菌盖、菌柄的Hg摄入量低于PTWI(Hg)标准,Hg的暴露风险较低(假设未通过其他途径摄入Hg);食用300 g黑粉孢牛肝菌菌盖或菌柄摄入的Cd达到0.722 mg和0.662 mg,超过PTWI(Cd)标准,食用有Cd暴露风险。     

苯并(a)芘神经毒性研究进展

苯并(a)芘(BaP)是一种广泛存在于环境中的多环芳烃,具有致癌、致畸、致突变性。目前BaP的神经毒性研究零散而不深入,本文主要总结分析了BaP的神经毒性表现,简要介绍了BaP诱发神经毒性呈现的剂量-效应关系,进一步系统阐述了目前研究中发现的可能分子机制,包括BaP诱导神经递质及其代谢物含量的改变,相关DNA及蛋白质的损伤,抗氧化系统及线粒体的改变等,以期为进一步研究提供参考。     

Improving simulations of sulfate aerosols during winter haze over Northern China: the impacts of heterogeneous oxidation by NO<Subscript>2</Subscript>

We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are–0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s^–1). At the Beijing station, sulfur dioxide (SO₂) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO₂ emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO₂ emissions and incorporating heterogeneous oxidation of dissolved SO₂ by nitrogen dioxide (NO₂) on sulfate formation during winter haze. The results suggest that doubling SO₂ emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO₂ by NO₂ substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO₂ to sulfate conversion in the HetS (heterogeneous oxidation by NO₂) case reduces SO₂ concentrations, it is still largely overestimated by the model, indicating the overestimations of SO₂ concentrations in the North China Plain (NCP) are mostly due to errors in SO₂ emission inventory.

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Improving simulations of sulfate aerosols during winter haze over Northern China: the impacts of heterogeneous oxidation by NO2

Incorporating the missing heterogeneous oxidation of S(IV) by NO₂ into the WRF-Chem model. Sulfate production is not sensitive to increase in SO₂ emission. The newly added reaction reproduces sulfate concentrations well during winter haze. We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are -0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s⁻¹). At the Beijing station, sulfur dioxide (SO₂) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO₂ emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO₂ emissions and incorporating heterogeneous oxidation of dissolved SO₂ by nitrogen dioxide (NO₂) on sulfate formation during winter haze. The results suggest that doubling SO₂ emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO₂ by NO₂ substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO₂ to sulfate conversion in the HetS (heterogeneous oxidation by NO₂) case reduces SO₂ concentrations, it is still largely overestimated by the model, indicating the overestimations of SO₂ concentrations in the North China Plain (NCP) are mostly due to errors in SO₂ emission inventory.     

加速溶剂同时萃取和净化-气相色谱-三重四极杆串联质谱测定土壤和沉积物中8种多溴联苯醚

建立了土壤和沉积物中8种多溴联苯醚(PBDEs,BDE-28、BDE-47、BDE-99、BDE-100、BDE-153、BDE-154、BDE-183和BDE-209)加速溶剂同时萃取和净化-气相色谱-三重四极杆串联质谱(ASE-GC-MS-MS)的分析方法。通过优化加速溶剂萃取与弗罗里硅土在线净化和串联质谱多反应监测模式的条件,较好地去除基质干扰,并提高了三重四极杆串联质谱定性的准确性及定量的灵敏性。该方法采用改进的色谱柱能同时分析包括高溴代联苯醚BDE-209在内的8种PBDEs,其浓度范围为1～100 ng/mL(BDE-209为10～1 000 ng/mL),线性良好,线性回归系数均大于0.997。方法检出限为0.004～0.1 ng/g,方法回收率为75%～110%,方法精密度为2.4%～15.6%。适于批量处理土壤和沉积物中含有多组分痕量PBDEs的样品。     

沈阳臭氧污染时空分布特征及变化趋势

以沈阳2013—2015年臭氧(O_3)监测数据为基础,从地域差异及时间变化上分析了沈阳O_3浓度变化特征。结果表明:沈阳城市外围O_3浓度高于城市中心;O_3浓度变化具有明显季节特征,夏季O_3浓度最高,冬季最低;O_3浓度日变化呈单峰分布,谷值出现在06:00,峰值出现在14:00;O_3浓度出现明显"周末效应",周末白天O_3浓度高于工作日O_3浓度,夜间差异不大。     

固相萃取-气相色谱法测定水中硝基氯苯类化合物

建立固相萃取-气相色谱法测定水中15种硝基氯苯类化合物的方法。选用HLB柱为固相萃取柱,选用环己烷∶丙酮(3∶1,V∶V)混合溶剂作洗脱剂,得到方法检出限为0.011～0.040μg/L。空白水样加标回收率为73.6%～119%,相对标准偏差为6.1%～13.9%,精密度和准确度良好。对成分不复杂的实际水样进行测定,加标回收率为64.1%～118%,相对标准偏差为5.8%～15.6%,该方法能够基本满足成分不复杂的环境水体中痕量硝基氯苯类化合物的测定。