Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom

Surface sediments are closely related to lake black blooms. The dissolved oxygen （DO） distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and ∑H2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 μm. Fe^2＋ concentrations, ∑H2S concentrations, and ∑H2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe^2＋ and ∑H2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms.     

Delayed association of acute particulate matter 2.5 air pollution exposure with loss of complexity in cardiac rhythm dynamics: insight from detrended fluctuation analysis

Environmental Science and Pollution Research - There is a delayed (lag 1 to 2 days) correlation between acute PM 2.5 (particulate matter <?2.5 μm in aerodynamic...     

好氧颗粒污泥自生动态膜生物反应器处理碱减量印染废水

自生动态膜生物反应器(SFDMBR)接种颗粒污泥启动,研究溶解氧浓度和水力停留时间对该反应器处理碱减量印染废水的影响。自生动态膜生物反应器形成稳定的动态膜后,出水浊度小于10 NTU,系统对浊度的去除率在90%以上,溶解氧和水力停留时间对反应器出水浊度基本无影响。系统对废水色度的去除率随着溶解氧浓度的提高和水力停留时间的延长而增加,但是系统对色度的去除效率一般不超过40%。溶解氧浓度由0.3 mg/L逐渐增大至2.4 mg/L,COD的去除率由40%提升至80%,而当溶解氧浓度大于1.0 mg/L后,UV254的去除率达到95%。水力停留时间在8~48 h时,COD去除效率由65%逐渐上升至85%左右;水力停留时间在8~32 h,UV254去除效率为68%~93%,超过32 h后水力停留时间对UV254去除效率的影响已不明显。     

纳米Al_2O_3固定化红平红球菌菌球的制备及其对苯酚的降解

以海藻酸铝为主要包埋材料、纳米Al_2O_3为添加剂,包埋固定红平红球菌,制得纳米Al_2O_3固定化红平红球菌菌球,并将其用于苯酚的降解。表征结果显示:菌球内部包含丰富的菌丝体;内部孔径以中孔居多。实验结果表明:菌球的最优制备方案为0.05 g纳米Al_2O_3加入3 m L海藻酸钠溶液中、海藻酸钠质量分数6%、微生物包埋量0.5 m L/m L(以海藻酸钠溶液计)、Al_2(SO_4)_3质量分数3%;在初始苯酚质量浓度为400 mg/L、反应时间为24h、菌球加入量为8 g/L、反应p H为8.0、反应温度为30℃的条件下,菌球首次使用时可使苯酚完全降解,使用5次后的苯酚降解率仍达93%以上,具有良好的循环使用性。     

长江经济带工业绿色转型与生态文明建设的办同效应研究

测度长江经济带工业绿色转型效率和生态文明建设质量,把脉二者协同效应,对推进长江经济带绿色协同发展具有实践指导作用.在全国视野下,基于2011～2017年省级数据,采用Super-SBM模型测度长江经济带工业绿色转型效率,运用熵权法-Topsis评价模型测度长江经济带生态文明建设质量,构建耦合协调度模型实证研究长江经济带工业绿色转型与生态文明建设的协同效应.结果 表明:长江经济带工业绿色转型效率低于全国平均水平,上中下游地区呈梯度递增空间格局,省际差异显著;长江经济带生态文明建设质量与全国平均水平基本持平,上中下游地区呈"V"型空间格局,省际差异较小;长江经济带各省份工业绿色转型效率与生态文明建设质量的协同系数普遍较低,且呈加剧趋势,主要原因是生态文明建设滞后于工业绿色转型.建议地方政府提高对工业绿色转型与生态文明建设协同发展的重视程度,着力扭转生态文明建设滞后于工业绿色转型的发展态势.特别要加大国土空间和生态环境治理保护力度,推动长江经济带中上游地区农业和工业生态化发展,普及生态文化,完善生态安全治理体系.     

羊粪生物炭对水体中诺氟沙星的吸附特性

以羊粪为原料分别在350、450、550、650℃条件下制备生物炭,通过元素分析、BET-N_2、电镜扫描及FTIR表征了不同热解温度下羊粪生物炭的结构特征,并采用序批实验研究了pH、生物炭投加量、热解温度、初始浓度等因素对羊粪生物炭吸附水体中诺氟沙星(NOR)的影响及吸附机制.结果表明,随着热解温度的升高,生物炭的比表面积、总孔容、平均孔径增大,芳香性和稳定性也有所提高.羊粪生物炭吸附NOR的最佳初始pH为6.0,吸附在180 min左右达到平衡,采用准二级动力学模型能更好地拟合动力学数据(R~20.96),吸附速率由表面吸附和颗粒内扩散共同控制.等温吸附拟合发现,Langmuir模型能较好地描述NOR在羊粪生物炭上的吸附行为(R~20.93),吸附过程均为有利吸附,且可能与氢键和π-π键作用密切相关,4种热解温度下生物炭的吸附能力大小为:650℃550℃450℃350℃.吸附过程中ΔGθ0、ΔHθ0、ΔSθ0,表明羊粪生物炭对NOR的吸附是自发、吸热及熵增加的过程.650℃和550℃条件下制备的羊粪生物炭可作为水体中NOR的优势吸附材料.     

绿洲土Pb-Zn复合胁迫下重金属形态特征和生物有效性

通过对Pb-Zn复合胁迫下干旱区绿洲土壤中油菜种植进行盆栽试验模拟,探讨了重金属复合污染对油菜生长的影响及其各形态之间的转化规律和生物有效性.结果表明,低浓度Pb、Zn处理下,油菜生长得到促进,茎叶生长优势大于根系.随着外源重金属的投加,土壤中Pb、Zn主要赋存形态较对照均由紧结合态向松结合态转化,重金属生物有效性提升;可交换态Pb、碳酸盐结合态Zn分别是油菜不同部位吸收Pb、Zn的主要贡献形态.油菜在低浓度胁迫水平对Pb、Zn的富集能力和转移能力强于高浓度胁迫水平,且油菜对Pb、Zn的富集、迁移系数均随土壤中对应元素或共存元素生物有效态含量的增大而减小.所有处理中,油菜茎叶中的Pb含量均超出了食品安全限量指标,建议在此类土壤种植叶菜类蔬菜前进行相关指标检测.     

草原生态环境监测数据建库方法初探

该文系统地介绍了草原生态环境监测数据库的一般方法，在建立图像，图形，多媒体及数据子库的前提下，同时提出了宏观遥感监测数据与地面定位监测数据的结合方式，可操作性较强。     

哈尔滨市环境空气质量评价与经济增长关系研究

以PM10、SO2和NO2作为空气质量的评价对象,采用空气综合污染指数法研究了哈尔滨市2001年到2015年的环境空气质量变化趋势.以空气综合污染指数作为因变量,哈尔滨市人均GDP作为自变量,来探讨哈尔滨环境空气质量与经济增长之间的关系.得出2001年到2015年期间,哈尔滨环境空气质量呈现先变好又变差再变好的趋势,哈尔滨环境空气质量与经济增长之间呈现近似三次方函数关系,且部分呈现到"U"型曲线关系.     

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The fate of nitrogen and iron species

•Bacterially-mediated coupled N and Fe processes examined in incubation experiments. •NO₃⁻ reduction was considerably inhibited as initial Fe/N ratio increased. •The maximum production of N₂ occurred at an initial Fe/N molar ratio of 6. •Fe minerals produced at Fe/N ratios of 1–2 were mainly easily reducible oxides. The Fe/N ratio is an important control on nitrate-reducing Fe(II) oxidation processes that occur both in the aquatic environment and in wastewater treatment systems. The response of nitrate reduction, Fe oxidation, and mineral production to different initial Fe/N molar ratios in the presence of Paracoccus denitrificans was investigated in 132 h incubation experiments. A decrease in the nitrate reduction rate at 12 h occurred as the Fe/N ratio increased. Accumulated nitrite concentration at Fe/N ratios of 2–10 peaked at 12–84 h, and then decreased continuously to less than 0.1 mmol/L at the end of incubation. N₂O emission was promoted by high Fe/N ratios. Maximum production of N₂ occurred at a Fe/N ratio of 6, in parallel with the highest mole proportion of N₂ resulting from the reduction of nitrate (81.2%). XRD analysis and sequential extraction demonstrated that the main Fe minerals obtained from Fe(II) oxidation were easily reducible oxides such as ferrihydrite (at Fe/N ratios of 1–2), and easily reducible oxides and reducible oxides (at Fe/N ratios of 3–10). The results suggest that Fe/N ratio potentially plays a critical role in regulating N₂, N₂O emissions and Fe mineral formation in nitrate-reducing Fe(II) oxidation processes.