Laser-induced breakdown spectroscopy application in environmental monitoring of water quality: a review

Water quality monitoring is a critical part of environmental management and protection, and to be able to qualitatively and quantitatively determine contamination and impurity levels in water is especially important. Compared to the currently available water quality monitoring methods and techniques, laser-induced breakdown spectroscopy (LIBS) has several advantages, including no need for sample pre-preparation, fast and easy operation, and chemical free during the process. Therefore, it is of great importance to understand the fundamentals of aqueous LIBS analysis and effectively apply this technique to environmental monitoring. This article reviews the research conducted on LIBS analysis for liquid samples, and the article content includes LIBS theory, history and applications, quantitative analysis of metallic species in liquids, LIBS signal enhancement methods and data processing, characteristics of plasma generated by laser in water, and the factors affecting accuracy of analysis results. Although there have been many research works focusing on aqueous LIBS analysis, detection limit and stability of this technique still need to be improved to satisfy the requirements of environmental monitoring standard. In addition, determination of nonmetallic species in liquid by LIBS is equally important and needs immediate attention from the community. This comprehensive review will assist the readers to better understand the aqueous LIBS technique and help to identify current research needs for environmental monitoring of water quality.     

投菌水解（酸化）—生物接触氧化—混凝法处理酵母生产废水

研究了采用投菌水解（酸化）－生物接触氧化－浊凝化处理酵母生产废水。试验结果表明,进水浓度控制在ＣＯＤＣｒ值５０００ｍｇ／Ｌ左右,生化系统可取得较高的处理效率;生经处理出水再以碱式 化铝为混凝剂,聚丙烯酰胺为助凝剂进行混凝处理,其出水ＣＯＤＣｒ值可控制在２００ｍｇ／Ｌ以下,并且可部分回流使用。     

Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils

A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 μg kg^?1 range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.     

Spatial, temporal, and speciation variations of heavy metals in sediments of Nan'ao Island, a representative mariculture base in Guangdong coast, China

Heavy metals in sediments from Baisha Bay, Nan'ao Island, one of Guangdong Province's largest mariculture bases in Southern China, were investigated. The results display that the concentrations of 6 heavy metals from surface sediments were 0.040-0.220 (Cd), 24.22-39.61 (Pb), 25.30-42.66 (Cr), 10.83-19.54 (Ni), 15.06-39.24 (Cu) and 55.12-141.73 mg kg(-1) (Zn), respectively. The highest concentrations and the greatest increasing rates of heavy metals were found in a sediment core in a fish cage culture area due to receiving sewage discharge, uneaten fish bait, and boat gasoline combustion. Cd was preferentially associated with the acid-soluble fraction and Pb mainly with the reducible fraction in surface sediments. Meanwhile, Cd and Pb displayed greatest labile fractions, indicating anthropogenic origin. A principal component analysis (PCA) revealed three groupings (Cd; Cr, Ni and Cu; Pb and Zn) that mainly result from different distributions of the metals in the various fractions. The ecological risk of the polluted sediments stemmed mainly from Cd, and from Pb and Cu to a lesser degree. It is suggested that the density of fish-stocking be controlled, periodic movement of rafts (cages) be introduced, and the total numbers of net-cages and human activities in the mariculture zones be restricted. in order to facilitate the recovery of the polluted sediment.     

Natural and anthropogenic factors affecting the shallow groundwater quality in a typical irrigation area with reclaimed water,North China Plain

In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO₃ type in grass land to Ca·Na-Cl (+NO₃) type and Na (Ca)-Cl (+NO₃+SO₄) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO₃) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area.     

壳聚糖接枝共聚物的合成及应用研究

在N2保护下,以浓度为0.8 mmol/L硝酸铈铵为引发剂,控制壳聚糖(CTS)和丙烯酰胺(AM)质量比为mCTS∶mAM=1∶6,于50℃下接枝共聚反应3 h,得改性的壳聚糖衍生物(CAM).用IR对产物进行表征.通过对废水的处理,研究了共聚产物在絮凝、COD去除、脱色上的应用.结果表明:CAM的絮凝效果好于聚丙烯酰胺和壳聚糖,CAM对COD的去除率达到84.7%,并有较好的脱色效果.     

典型SSRIs类抗抑郁药对鱼类的毒性效应研究进展

选择性血清素再摄取抑制剂(selective serotonin reuptake inhibitors,SSRIs)是一类在临床上具有良好治疗效果的抗抑郁药物,由于使用量巨大,在水环境中频繁被检出,其潜在生态毒性效应引起人们的广泛关注.鱼类作为水生脊椎动物,具有和人类相似的神经调控系统,更易受到水体中残留的SSRIs...     

优势菌处理印染废水的工艺及脱色机理研究

采用不完全厌氧－好氧工艺处理印染废水,工程运行前在水解池中投入了主要用于脱色的优势菌群,经３年多的运行,系统的脱色率均稳定在９０％以上。从池中取菌进行分离鉴定,并进行各单株菌脱色能力实验,对其中具有最佳脱色能力的菌株进行偶氮染料活性黑ＫＮＢ的脱色产物的化学分析,从而探讨水解池中染料的脱色机理。结果发现：分离到的１０株菌对试验染料有较好脱色效果,高效液相色谱检测发现产物只有苯胺类物质的存在。该菌的脱色作用主要是破坏了染料的发色基团——偶氮双键。     

高锰酸钾预氧化后地表水中三氯甲烷生成量的预测模型研究

在饮用水处理中,适当地采用高锰钾预氧化可以降低水中的三氯甲烷生成量。本文研究了影响三氯甲烷生成量的因素,如反应时间,反应温度等,并以这些影响因素为参数通过一元线性回归等数学方法,建立了各影响因素下三氯甲烷生成量折了模型和综合预测模型。     

氯代苯及氯代酚类优先污染物好氧生物降解动力学的研究

利用测定微生物呼吸耗氧量的方法,对氯代苯及氯代酚类中的７种优先污染物,用经它们分别驯化的活性污泥对其好氧生物降解动力学进行了研究。