The spectral characteristics of dissolved organic matter from sediments in Lake Baiyangdian,North China

Dissolved organic matter (DOM) extracted from sediment samples in Lake Baiyangdian was investigated using UV -Vis absorption and fluorescence spectroscopy. Two parameters, the ratios of absorbance and dissolved organic carbon at 254° nm (SUVA₂₅₄) and the integral area from 240° nm to 400° nm (A_{240 -400}), were used to assess the molecular weight and aromaticity of DOM. The surface sediments showed a relatively low aromaticity of DOM due to the impact of environmental pollution. Synchronous fluorescence spectra showed an extremely high fraction of the protein-like region (PLR). Parallel factor analysis (PARAFAC) of excitation -emission matrix spectra revealed four fluorescent components occurring in sediment DOM: two humic-like (C1 and C2) components and two protein-like (C3 and C4) components. The PARAFAC-PCA displayed three PCA factors (factors 1, 2 and 3) which accounted for 48.250%, 25.927% and 25.391%, respectively, of the variance in fluorescent component. The humic-like components 1 and 2 concurrently showed positive factor 1 loadings. Factor 2 was mainly explained by the tryptophan-like component C3. A non-humic component 4, having a low factor loading in the other two factors, showed an extremely high factor 3 loading. The EEM -PARAFAC-PCA showed varying contributions of terrestrial versus autochthonous DOM sources in lake sediments.     

荧光光谱技术在废水溶解有机物研究中的应用进展

分析废水中特征污染物质的组成、性质、来源等对于水污染控制、应急事故处理、环境质量责任认定等具有重要的意义和价值。荧光光谱技术利用物质的荧光特性,构建物质的特征光谱图,并以此分析物质特性,可用于分析废水中腐殖质、氨基酸、荧光增白剂、木质素、多环芳烃等多种有机污染物质。文章从荧光光谱技术的原理出发,主要对三维荧光光谱技术和同步荧光光谱技术在研究废水溶解有机物特征组成物质中的应用及环境因子对其影响进行了综述,并对该技术的发展前景进行展望,以期为废水溶解有机物特征组成物质提供完善可靠的分析方法。     

城市水体有机污染类型的三维荧光光谱分析法

运用三维荧光光谱技术对深圳市4种水体的有机污染类型进行了分析研究。实验结果表明,深圳市甲水库主要表现为内源污染;深圳市乙水库主要表现为外源污染;大沙河和校园池塘既有内源污染又有外源污染。有机污染的程度由高到低依次为:大沙河、校园池塘、甲水库、乙水库。     

Wastewater fingerprinting by UV-visible and synchronous fluorescence spectroscopy.

Municipal wastewater samples have been collected in three different types of community and fingerprinted by optical methods combining UV-visible spectrometry, synchronous fluorescence spectrometry and turbidity. Correlations, whose slope depends on the sampling location, were obtained between absorbance at 254 nm and the synchronous fluorescence intensity of peaks P1 (I366/316), P2 (I430/380) and P3 (I520/470). The corresponding correlation coefficients are larger than 0.75. Although related to urine as ammonia, the fluorescence intensity of P1 does not exhibit a strong correlation with this substance (correlation coefficient of approximately 0.6). All the measured parameters exhibit diurnal variation patterns related to human activities.     

Chromium adsorption on surface activated biochar made from tannery liming sludge: A waste-to-wealth approach

In a beamhouse, liming plays a key role in the removal of hair/wool and epidermis, but problems are created when waste liming sludge is discharged to the environment. The treatment of tannery wastewater is another major challenge to the industry. In this study, thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium (Cr) from the tannery wastewater. The thermally activated biochars (B500, B550, B600, and B650) were prepared at different temperatures from the liming sludge. Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and scanning electron microscopy analyses. The related functional groups (C–H, O–H, C–N, and =C–O) and chromium adsorption capacity were determined according to the surface morphology, element contents (C, O, Ca, Na, Al, Mg, and Si), surface area (5.8–9.2 m²/g), pore size (5.22–5.53 nm), and particle size (652–1 034 nm) of the experimental biochars. The biochar originated at 600°C from the tannery liming sludge (B600) had a greater surface area with a chromium adsorption capacity of 99.8% in comparison to B500, B550, and B650 biochars. This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.     

Propagation of uncertainty in diffuse pollution into water quality predictions: application to the River Dender in Flanders, Belgium.

The uncertainty of water quality predictions caused by uncertainty in the inputs related to emissions of diffuse pollution is analysed. An uncertainty analysis of the effects of diffuse pollution is essential to compare the cost and benefits of measures to lower those emissions. We focus on diffuse nitrate pollution due to fertiliser use. Using an efficient Monte Carlo method and Latin Hypercube sampling, the contribution to the overall uncertainty by each of the inputs is calculated. The modelling environment is ESWAT, an extension of SWAT, which allows for integral modelling of the water quantity and quality processes in river basins. The diffuse pollution sources are assessed by considering crop and soil processes. The crop simulations include growth, uptake of water and nutrients and several land management practices. The in-stream water quality model is based on QUAL2E. The spatial variability of the terrain strongly affects the non-point source pollution processes. The methodology is applied to the Dender basin in Belgium. Eight inputs have significant influence on the time that the nitrate content in the river is higher than 3 mg/l. The uncertainty analysis indicated wide uncertainty bounds (95% percentile bounds differ up to +/-50% from the average NO3 predictions).     

Stormflow-dominated loads of faecal pollution from an intensively dairy-farmed catchment

Rainstorms can flush large amounts of faecal pollution from land sources into water bodies, threatening, particularly, contact recreation and bivalve shellfish harvest. We quantified the faecal pollution loads of stormflows in the Toenepi Stream, draining a catchment in intensive dairy-farming (Waikato Region, New Zealand). In this stream, as is typical, E. coli concentration peaks well ahead of flow on storm flow hydrographs, which complicates calculation of loads. However, stormflow E. coli concentration correlates with turbidity in the Toenepi Stream, so we used a continuously-recording turbidimeter to estimate 'continuous' E. coli concentrations and thence E. coli fluxes (cfu/s) and loads (cfu). E. coli was measured on 25 out of the 30 (83%) of storm events occurring in the Toenepi Stream in a 12-month period, using an automatic sampler sampling every 2 hrs over stormflow hydrographs for microbial analysis (within 48 hr). E. coli (cfu) yield on individual events tended to increase systematically with event size. The sum of storm-flow exports (occurring 24% of total time) amounted to 95% of the total annual E. coli export from the Toenepi Catchment. The stream exported about 6% of the (expected) total E. coli production in cattle faeces within the catchment.     

Monitoring of COD as an organic indicator in waste water and treated effluent by fluorescence excitation-emission (FEEM) matrix characterization.

The fluorescence excitation-emission matrices (FEEM) of domestic waste water, treated effluent of a waste water treatment plant and receiving river water were analyzed to select wavelengths for the monitoring of organic contents as COD. Excitation/emission wavelengths of 220/350 nm and 270/350 nm for protein-like fluorescence and 240/450 nm and 340/450 nm for humic-like fluorescence were suggested as fluorescence peak emitting wavelength pairs, respectively. Without any pre-treatment, the protein-like fluorescence peaks showed better correlation between COD values and fluorescence intensities than the humic-like fluorescence peaks. No enhanced correlation was observed by removing the suspended solids from the samples using filtration. However, statistical multiple regression methods, using the fluorescence intensities from each peak and the light scattering intensity at 633 nm as variables, resulted in an enhanced correlation, with r2 > 0.9 for the measured and predicted COD values.     

A New Approach for Aquifer Vulnerability Assessment: the Case Study of Campania Plain

We are going to propose a new method for aquifer vulnerability assessment, named Susceptibility Index-Contamination Degree (SICODE). Starting from the assumption that soil chemistry impacts on infiltration water quality, geochemical tool such as the soil contamination degree index (CD) was combined with hydrogeological parameters in order to enhance previous well-known index (DRASTIC, Susceptibility Index). The study has been carried out at the Campania Plain (CP) aquifer, which mostly supplies the drinking water distribution system of Napoli (Southern Italy). The survey area extends from Mt. Vesuvius to the metropolitan area of Napoli and it can be considered an interesting field laboratory in order to test hydro-geochemical methods and models since both diffuse anthropogenic pollution and natural contamination sources (e.g. interaction processes between groundwater and rock) coexist. Three models have been compared. Our results have showed that DRASTIC is not the best model to be applied to urbanized environments since it does not account for the anthropogenic influence. Susceptibility Index (SI), which incorporates land use parameter, has showed a more detailed map of vulnerability degree and it better answers the local variability of human pressure. However, the proposed SICODE method completely meets the geochemical fingerprint of soil. Sensitivity analysis has revealed a high variability of the parameters due to the local heterogeneity of the analyzed system conditions. A comparison between the groundwater nitrates distribution and the predicted vulnerability has showed that. SICODE gave more accurate predictions than the other ones. This study has provided the evidence that combining hydrogeological and geochemical tools may enhance aquifer vulnerability assessment.

     

Health Risk Assessment of Nitrate Contamination in Groundwater: A Case Study of an Agricultural Area in Northeast China

High levels of nitrates in groundwater pose a risk to human health. In this study, we selected areas with typical agricultural nitrate pollution in northeast China as study sites. We then collected groundwater samples for nitrate nitrogen content analysis using the Four Step method developed by the United State Environmental Protection Agency (USEPA) in conjunction with the non-carcinogens health risk model (R?=?CDI/RfD) to determine the health risk associated with nitrate pollution of groundwater. The reference value of nitrates in drinking water was set at 10 mg/L (measured as nitrogen) and the intake reference dose of nitrate was set at 1.6 mg?kg^?1?d^?1 based on the EPA’s IRIS(Integrated Risk Information System). The water intake reference values were set at 2.3 L/d and 1.5 L/d based on the EPA values and actual values observed in the study area. The average exposure time was the ED (exposure duration)?×?365d/a. Weights refer to the 2002 national urban and rural average weight of residents of different genders and different ages. Health hazard index calculation was based on the above information, and the index less than 1 is acceptable (U.S. EPA’s Risk Assessment Guide). Health risk assessment maps were then drawn by Arcgis software. The results indicated that agricultural sewage irrigation areas in the study area showed strong health risks, but that those of the city were relatively small. Moreover, the results indicated that children’s health risks are greater than those of adults.     

地下水硝酸盐污染的研究进展

综述了地下水硝酸盐的迁移转化机理、地下水硝酸盐来源、地下水硝酸去除和地下水中硝酸盐污染的风险评估几个方面的研究进展,并提出了存在的问题和将来值得重视的研究方向。     

Liquid core waveguide with fiber optic coupling for remote pollution monitoring in the deep ultraviolet

A new combination of silica fibres, highly transparent in the ultraviolet (UV) and showing long term stability, combined with a teflon-coated liquid-core waveguide (LCW) is presented for remote sensing in the deep UV, for monitoring one of the major pollutants, nitrates, in water, but with potentially wider applicability. The arrangement exhibits low spectral loss in the range between wavelengths of 200 nm and 400 nm and can be used for analytical investigations to determine small concentrations of such impurities in water. The operation of the optical system to achieve guidance of UV light below a wavelength of 250 nm for fibre optic sensors is discussed. With an optical pathlength of 203 mm, nitrate concentrations as low as 22 μg/l could be detected.     

Characterisation of the recalcitrant organic compounds in leachates formed during the anaerobic biodegradation of waste

This study investigates the use of UV absorption and fluorescence spectroscopy to assess the early development of recalcitrant organic compounds in leachates formed during the anaerobic biodegradation of municipal solid waste. Biochemical methane potential tests were carried out on fresh waste (FW) and composted waste (CW) over a period of 150 days and leachates produced from the degradation of two wastes were analysed for humic-like (H-L) and fulvic-like (F-L) structures by UV spectroscopy and fluorescence excitation-emission-matrix analyses. During anaerobic biodegradation, the synthesis and utilization of H-L and F-L structures in the leachates over time was indicative of the generation of the recalcitrant organic compounds. The results obtained from UV absorption and fluorescence spectroscopy suggested that CW leachates resulted in a higher concentration and more condensed form of recalcitrant H-L and F-L molecules than FW leachates. These findings demonstrate how fluorescence and UV absorption spectroscopy can be used as an indicator for monitoring the evolution of recalcitrant organic compounds (H-L and F-L substances) in leachates formed at different stages of waste biodegradation.     

Catchment-scale fluorescence water quality determination.

Chemical water quality determinants and river water fluorescence were determined on the River Tyne, northeast England. Statistically significant relationships between nitrate (r = 0.87), phosphate (r = 0.80), ammonia (r = 0.70), biochemical oxygen demand (BOD) (r = 0.85) and dissolved oxygen (r = -0.65) and tryptophan-like fluorescence intensity were observed. The strongest correlations are between tryptophan-like intensity and nitrate and phosphate, which in the Tyne catchment derive predominantly from point and diffuse source sewage inputs. The correlation between BOD and the tryptophan-like fluorescence intensity suggests that this fluorescence centre is related to the bioavailable or fluorescence intensity and ammonia concentration and dissolved oxygen. The weaker correlation with ammonia is due to good ammonia treatment within the wastewater treatment plants within the catchment, and that with dissolved oxygen due to the natural aeration of the river such that this is not a good indicator of water quality. Mean annual tryptophan-like fluorescence intensity, measured by both bench and portable spectrometers, agrees well with the General Water Quality Assessment as determined by the England and Wales environmental regulators, the Environment Agency.     

Assessing the cost of groundwater pollution: the case of diffuse agricultural pollution in the Upper Rhine valley aquifer.

This paper presents an assessment of the costs of diffuse groundwater pollution by nitrates and pesticides for the industrial and the drinking water sectors in the Upper Rhine valley, France. Pollution costs which occurred between 1988 and 2002 are described and assessed using the avoidance cost method. Geo-statistical methods (kriging) are then used to construct three scenarios of nitrate concentration evolution. The economic consequences of each scenario are then assessed. The estimates obtained are compared with the results of a contingent valuation study carried out in the same study area ten years earlier.     

Comparison of total and faecal coliforms as faecal indicator in eutrophicated surface water.

The aim of this study was to evaluate the use of total coliforms (TC) and faecal coliforms (FC) using a membrane filtration method for precise monitoring of faecal pollution in Korean surface water. The samples were collected in Korea from both main rivers and their tributaries. Presumptive TC * FC were enumerated. The ratios of presumptive FC to TC were not constant, but varied widely, and TC were difficult to enumerate because of overgrowth by background colonies. For FC this was not the case. Seven hundred and three purified strains of presumptive TC * FC and their background colonies were biotyped using API 20E. Among 272 presumptive TC, non-faecal related species, Aeromonas hydrophila dominated (34.6%) and E. coli accounted for only 5.1%. In contrast, E. coli made up 89% of the 209 presumptive FC. Furthermore, of 164 background colonies on Endo Agar LES, 54.9% was A. hydrophila, while background colonies on m-FC Agar were few (58 strains), and despite their atypical colony appearance, most of them were biotyped as enteric bacteria. These results reveal that the detection of FC rather than TC using m-FC Agar is more appropriate for faecal pollution monitoring in eutrophicated surface water located in a temperate region.     

Limnological aspects of humic substances in Chubut River (Patagonia‐Argentina)

Humic Substances (HSs) of the Chubut River (Patagonia‐Argentina) have been investigated, during two consecutive years and different climatic seasons, in order to obtain a first approach at their spatial and temporal distribution, as well as their origin and relation with environmental characteristics. Absorbance at 250 nm and limnological variables were measured and the data processed by different statistical tools. We found that the processes developed in the lower sections of Chubut River are dominated by those produced in the Florentino Ameghino Reservoir. The riverine HSs are present in very low concentrations, have mainly autochthonous origin, exhibit spatial homogeneity and temporal variability similar to nutrients (nitrates and soluble reactive phosphorus). Copyright © 2010 John Wiley & Sons, Ltd.     

Study of the chemical composition of suspended particles in Lake Baikal

Samples of suspended material (solid particles) from Lake Baikal were analysed by using X‐ray fluorescence elemental analysis with the excitation of monochromatized synchrotron radiation (SRXFA, Novosibirsk, Russia) and electron probe X‐ray microanalysis (EPXMA, Antwerp, Belgium). The chemical composition of particles in different depths and basins of the lake is discussed. The chemical composition of the central parts of the lake are stable, but concentrations are higher in the southern basin, which is liable to pollution.     

黄土高原北洛河沉积物生态风险解析

以黄土高原的典型工业污染河流北洛河为研究对象,测定其干支流17个采样点沉积物中的8种重金属(Hg、As、Cd、Cr、Cu、Pb、Ni、Zn)质量分数,结合描述性统计结果对重金属的空间分布特征进行分析。进一步利用地累积指数法、内梅罗综合污染指数法和潜在生态风险指数法分析重金属的污染程度与生态风险,利用PMF模型和相关性分析进行来源解析。结果表明：北洛河上游沉积物中重金属的平均质量分数高于中下游,As、Cd和Zn的均值分别为背景值的1.26、1.28和1.41倍,Zn、Hg、Cd、Pb、As和Cu的变异系数大于30%,为高度变异水平。地累积指数法与内梅罗综合污染指数法显示,北洛河上游B₁处和下游B₁₃处沉积物中重金属污染处于中高水平;潜在生态风险指数法显示,单一元素污染危害程度依次为Cd>Hg>As>Cu>Ni>Pb>Zn>Cr,整体来看,Cd和Hg的潜在生态危害较大,中游B₁₀和下游B₁₃存在中等生态风险,其余点位均为轻微生态风险。来源解析表明,北洛河沉积物中...     

Environmental Benefits and Control of Pollution to Surface Water and Groundwater by Agroforestry Systems: a Review

Agricultural pollution consists a serious concern for environmental protection managers. Among the pollutants, nitrates, phosphoric compounds and organic pesticides from agricultural activities are the most common and hazardous to the environment and human health. Several mitigation techniques have been proposed to control these pollutants from entering aquatic systems. Agroforestry, which is the common cultivation of crops and trees, is one such mitigation technique. In the present study, the efficiency of agroforestry systems in pollutant reduction is reviewed. A search of relevant international literature was conducted using Scopus, Science Direct and Google Scholar search engines, using relevant keyword combinations for agrochemical pollution abatement with trees. More than 2000 results were found and the most relevant were selected and extensively studied, and are summarized here. From the current knowledge, it can be generally seen that tree roots in agroforestry systems are able to reduce nitrogen and phosphorus residues in soils from 20% up to 100%, have the potential to reduce pesticides leaching and runoff in considerable amounts (up to 90% for runoff), and simultaneously they provide additional benefits to the ecosystems including erosion control, improvement of soil quality and positive effects on biodiversity.