Three decades of changes in water environment of a large freshwater Lake and its relationship with socio-economic indicators

Tai Lake (Ch: Taihu) has attracted international attention forcyanobacteria blooms. However, the drivers of cultural eutrophication, especially long-term socio-economic indicators have been little researched. The results of research demonstrate how socio-economic development affected quality of water and how it has been improved by anthropogenic activities. This study described variability in indicators of water quality in Tai Lakeand investigated thedrivers. Significant relationships existed between concentrations of annual mean total nitrogen (TN), total phosphorous (TP), chemical oxygen demand (COD) and biological oxygen demand (BOD), and population, per capital gross domestic production (GDP) and sewage discharge (p?<?0.05). However, mechanisms causing change varied among TN, TP, COD and BOD. Before 2000, the main contributors to increases in concentrations of TN were human population, GDP and volumes of domestic sewage discharges. After 2000, discharges of industrial sewage become the primary contributor. After 1998, the regressions of annual mean TN, TP and COD on per capital GDP, population and domestic sewage discharge were reversed compared to the former period. Since 1999, an apparent inverted U-shaped relationship between environmental pollution and economic development has developed, which indicated that actions taken by governments have markedly improved quality of water in Tai Lake. The statistical relationship between BOD and per capital GDP didn’t conform to the Kuznet curve. The U-shaped Kuznet curve may offer hope for the future that with significant environmental investments a high GDP can be reached and maintained without degradation of the environment, especially through appropriate management of industrial sewage discharge.     

Co-regulatory role of Microcystis colony cell volume and compactness in buoyancy during the growth stage

The buoyancy of Microcystis colonies determines the occurrence and dominance of bloom on the water surface. Besides the cell density regulation and the formation of larger size aggregates, increases in cell volume per colony (V_cell) and the colony’s compactness (i.e., volume ratio of cells to the colony, VR) may promote Microcystis colony buoyancy. Yet only a few studies have studied the relationship between the internal structure variation of colonies and their buoyancy, and the co-regulatory role of V_cell and VR of Microcystis colonies in the floating velocity (FV) remains largely unexplored. In the present study, we optimized a method for measuring the compactness of Microcystis colonies based on the linear relationship between total V_cell and chlorophyll a. Different relationships between the VRs and FVs were observed with different colony size and V_cell range groups. Both field and laboratory experiments showed that FV/(D₅₀, median diameter)² had a significant linear relationship with VR, indicating that the cell density and extracellular polysaccharides were unchanged over a short time period and could be estimated via the slope and intercept of a fitted line. We also constructed a functional relationship between FV, VR, and V_cell and found that high VR and V_cell can promote Microcystis buoyancy. This means that increasing cell compactness or V_cell may be an active regulation strategy for Microcystis colonies to promote buoyancy. Therefore, quantifying the internal structure of Microcystis colonies is strongly recommended for the assessment of Microcystis bloom development and their management.

Graphical abstract

     

五氟苄基羟胺衍生与GC/MS联用分析大气中的单羰基化合物和多羰基化合物

利用涂布五氟苄基羟胺（PFBHA）的Tenax-TA作为固体吸附剂,采取主动采样的方式采集大气中羰基化合物,再经溶剂洗脱和氮吹浓缩后用气相色谱/质谱（GC/MS）分析,成功检测到14种单羰基化合物和2种二羰基化合物（乙二醛与甲基乙二醛）.研究表明：在吸附剂的装载量为50mg的前提下,当衍生剂的涂布量为260nmol,采集流速为50mL·min^-1时,采集效果最佳.羰基化合物的检测限、平行样的相对标准偏差和样品的加标回收率范围分别为0.54～3.83ng·m^-3、1.0%～14.2%、89.2%～113.8%.该方法在实际大气样品中合适的采样时间为0.5～8.0h.利用此法对上海市宝山区大气中羰基化合物进行了检测,成功检测到16种羰基化合物,且具有明显的日变化趋势.     

TiO_2胶体光催化降解罗丹明B染料

TiO2胶体从钛氧有机物水解制备,表征的方法有：X射线衍射光谱（XRD）、激光散射粒径分布、傅立叶变换红外光谱（FT-IR）、X射线光电子谱（XPS）和透射电子显微镜（TEM）。利用罗丹明B染料分子作为探针分子研究TiO2胶体的光催化活性,分析了pH、催化剂用量、外加氧化剂（H2O2）用量及罗丹明B初始浓度对TiO2胶体光催化活性的影响。结果表明：制备的TiO2胶体粒子平均粒径为13.8 nm（激光散法测定）,光催化降解罗丹明B染料的反应属于一级动力学反应,可以用Langmuir-Hinshewood模型加以描述,反应速率常数k1为0.08413 mg/（L.min）,平衡吸附常数k2为1.5305 L/mg;在pH为6,TiO2胶体用量为0.04%,H2O2（含量30%）用量为0.2%（V/V）,光照度为69.6μW/cm2时,5 h后罗丹明B染料的降解率可达到99%以上;相似的条件,0.2%的P25 TiO2粉体光催化处理染料水时,罗丹明B的降解率为90%。纳米TiO2胶体不仅可以提高罗丹明B的光催化降解率,还具有用量少,可有效降低水处理成本的特点。     

环境友好型淋洗剂对重金属污染土壤的修复效果

以广西某废弃铅锌冶炼企业重金属复合污染土壤为对象,采用土柱淋洗的方法,分别将自制的茶皂素、柠檬酸和EDTA 3种淋洗剂进行复合淋洗,并对复合淋洗的最佳配比、淋洗剂添加方式和淋洗时间进行研究,得到对环境友好且淋洗效果好的复合淋洗剂。最后,对淋洗前后土壤中Cu、Pb和Zn的赋存形态进行研究,探讨淋洗机理。研究结果表明,茶皂素和柠檬酸复合时对重金属Cu、Pb、Zn的去除率分别达到了77.00%、52.09%和58.66%,综合考虑淋洗效率以及经济环保等因素,选择将茶皂素和柠檬酸复合进行淋洗。复合淋洗实验结果表明,柠檬酸和茶皂素体积比为3∶1复合方式淋洗30 h,淋洗效果最佳,对重金属Cu、Pb和Zn的去除率分别达到82.77%、65.49%和78.12%。茶皂素和柠檬酸复合淋洗能有效的去除土壤中酸可提取态和有机结合态的重金属,氧化物结合态的Pb和Zn也有较大程度的降低,同时还发现,茶皂素和柠檬酸共同作用对残余态的Pb去除效果也较好,可达到50%以上。从茶籽饼中提取茶皂素与天然有机酸柠檬酸复合淋洗,用于修复污染面积小、污染浓度高且污染比较集中的重金属污染土壤,效果好且对环境友好。     

Assessment and distribution of antimony in soils around three coal mines, Anhui, China

Thirty-three soil samples were collected from the Luling, Liuer, and Zhangji coal mines in the Huaibei and Huainan areas of Anhui Province, China. The samples were analyzed for antimony (Sb) by inductively coupled plasma-optical emission spectrometry (ICP-OES) method. The average Sb content in the 33 samples was 4 mg kg(-1), which is lower than in coals from this region (6.2 mg kg(-1)). More than 75% of the soils sampled showed a significant degree of Sb pollution (enrichment factors [EFs] 5-20). The soils collected near the gob pile and coal preparation plant were higher in Sb content than those collected from residential areas near the mines. The gob pile and tailings from the preparation plant were high in mineral matter content and high in Sb. They are the sources of Sb pollution in surface soils in the vicinity of coal mines. The spatial dispersion of Sb in surface soil in the mine region shows that Sb pollution could reach out as far as 350 m into the local environment conditions. Crops in rice paddies may adsorb some Sb and reduce the Sb content in soils from paddyfields. Vertical distribution of Sb in two soil profiles indicates that Sb is normally relatively immobile in soils.     

Analysis of air quality characteristics of Beijing–Tianjin–Hebei and its surrounding air pollution transport channel cities in China

Beijing–Tianjin–Hebei(BTH) and its surrounding areas are very important to air pollution control in China.To analyze the characteristics of BTH and its surrounding areas of China,we collected 5,641,440 air quality data from 161 air monitoring stations and 37,123,000 continuous monitoring data from air polluting enterprises in BTH and surrounding cities to establish an indicator system for urban air quality portraits.The results showed that particulate matter with aerodynamic diameters of 2.5 μm(PM_(2.5)),particulate matter with aerodynamic diameters of 10 μm(PM_(10)) and SO_2 improved significantly in 31 cities from2015 to 2018,but ozone deteriorated.Air quality in BTH and the surrounding areas showed obvious seasonal characteristics,among which PM_(2.5),PM_(10),SO_2,and NO_2 showed a "U" type distribution from January to December,while O_3 had an "inverted U" distribution.The hourly changes in air quality revealed that peaks of PM_(2.5),PM_(10) and NO_2 appeared from 8:00 to 10:00,while those for O_3 appeared at 15:00–16:00.The exposure characteristics of the 31 cities showed that six districts in Beijing had the highest air quality population exposure,and that exposure levels in Zhengzhou,Puyang,Anyang,Jincheng were higher than the average of the 31 investigated cities.Additionally,multiple linear regression revealed a negative correlation between meteorological factors(especially wind and precipitation) and air quality,while a positive correlation existed between industrial pollution emissions and air quality in most of BTH and its surrounding cities.     

生物阳极型MFC对磺胺喹噁啉的降解性能研究

磺胺喹噁啉（Sulfaquinoxaline,SQX）作为一种磺胺类抗生素,广泛用于禽畜球虫病防治,易在环境中残留从而造成环境污染,对其降解研究较少.本研究通过微生物燃料电池（Microbial fuel cells,MFCs）,以10 mg·L^-1 SQX和乙酸钠为底物研究SQX降解特性、电化学性能、产物生物毒性及菌群结构.结果表明,SQX降解率随着乙酸钠浓度的升高先增大后减小,其中SQX与TOC在10 d内最大降解率分别为87.1%和94.0%;MFC体系的最大功率密度和输出电压分别为309.8 mW·m^-2和0.702 V;大肠杆菌和青海弧菌Q67毒性实验结果表明,SQX经MFC处理后可有效降低生物毒性;通过LC-TOF/MS分析,SQX生物降解过程中的主要中间产物,推测出羟基化反应、磺酰胺键断裂、吡嗪环C-N键断裂、水解反应、分子重排等降解路径;微生物群落分析表明,MFC阳极体系中Terrimonas、Aquamicrobium、Thiobacillus等菌属与SQX生物降解相关.     

Achieving air pollutant emission reduction targets with minimum abatement costs: An enterprise-level allocation method with constraints of fairness and feasibility

• Quantification of efficiency and fairness of abatement allocation are optimized. • Allocation results are refined to the different abatement measures of enterprises. • Optimized allocation results reduce abatement costs and tap the abatement space. • Abatement suggestions are given to enterprises with different abatement quotas. For achieving air pollutant emission reduction targets, total pollutant amount control is being continuously promoted in China. However, the traditional pattern of pollutant emission reduction allocation regardless of economic cost often results in unreasonable emission reduction pathways, and industrial enterprises as the main implementers have to pay excessively high costs. Therefore, this study adopted economic efficiency as its main consideration, used specific emission reduction measures (ERMs) of industrial enterprises as minimum allocation units, and constructed an enterprise-level pollutant emission reduction allocation (EPERA) model with minimization of the total abatement cost (TAC) as the objective function, and fairness and feasibility as constraints for emission reduction allocation. Taking City M in China as an example, the EPERA model was used to construct a Pareto optimal frontier and obtain the optimal trade-off result. Results showed that under basic and strict emission reduction regulations, the TAC of the optimal trade-off point was reduced by 46.40% and 45.77%, respectively, in comparison with that achieved when only considering fairness, and the Gini coefficient was 0.26 and 0.31, respectively. The abatement target was attained with controllable cost and relatively fair and reasonable allocation. In addition, enterprises allocated different emission reduction quotas under different ERMs had specific characteristics that required targeted optimization of technology and equipment to enable them to achieve optimal emission reduction effects for the same abatement cost.     

Two-Dimensional Numerical Modeling of Flow Pattern and Bed Topography in Channel Bend

Environmental Modeling & Assessment - An improved two-dimensional (2D) depth-averaged model for hydrodynamic, sediment transport, and morphological adjustment is proposed in an orthogonal...