AQI time series prediction based on a hybrid data decomposition and echo state networks

Environmental Science and Pollution Research - A hybrid AQI time series prediction model is proposed based on EWT-SE-VMD secondary decomposition, ICA (imperialist competitive algorithm) feature...     

基于总量及有效态的铜陵矿区农田土壤重金属生态风险评价

于铜陵矿区采集147个农田土壤样品,分析土壤样品中Cd、Cu、Pb、Zn 4种重金属总量和有效态含量,探讨该地区农田土壤重金属的污染现状、潜在生态风险和来源,并基于不同类型农田土壤有效态重金属的风险评价提出农作物种植建议。结果表明:铜陵矿区农田土壤重金属平均值普遍高于铜陵市土壤背景值,局部地区潜在生态风险极大;4种重金属元素的单项潜在生态危害指数依次为CdCuPbZn,铜陵矿区农田土壤重金属的潜在生态风险程度为中等,Cd为最主要的潜在生态危害因子;基于有效态重金属对不同类型农田土壤进行潜在生态风险评价,春季农田土壤的综合潜在生态危害指数排序为油菜地蔬菜地麦地,秋季农田土壤的综合潜在生态危害指数排序为稻田蔬菜地。基于上述结果,建议在重金属污染程度较高的区域实施小麦-蔬菜轮作,而在蔬菜种植中选择对重金属吸收能力较低的种类或品种。     

An improved trend vegetation analysis for non-stationary NDVI time series based on wavelet transform

Environmental Science and Pollution Research - The aim of this paper is to improve trend analysis for non-stationary Normalized Difference Vegetation Index (NDVI) time series (TS) over different...     

Unsupervised monitoring of vegetation in a surface coal mining region based on NDVI time series

Environmental Science and Pollution Research - Surface coal mining causes vegetation disturbance while providing an energy source. Thus, much attention is given to monitoring the vegetation of...     

Effectiveness of cascading time series models based on meteorological factors in improving health risk prediction

Environmental Science and Pollution Research - Meteorological factors, which are periodic and regular in a long run, have an unignorable impact on human health. Accurate health risk prediction...     

Time series analyses of global change data

The hypothesis that statistical analyses of historical time series data can be used to separate the influences of natural variations from anthropogenic sources on global climate change is tested. Point, regional, national, and global temperature data are analyzed. Trend analyses for the period 1901-1987 suggest mean annual temperatures increased (in degrees C per century) globally at the rate of about 0.5, in the USA at about 0.3, in the south-western USA desert region at about 1.2, and at the Walnut Gulch Experimental Watershed in south-eastern Arizona at about 0.8. However, the rates of temperature change are not constant but vary within the 87-year period. Serial correlation and spectral density analysis of the temperature time series showed weak periodicities at various frequencies. The only common periodicity among the temperature series is an apparent cycle of about 43 years. The temperature time series were correlated with the Wolf sunspot index, atmospheric CO(2) concentrations interpolated from the Siple ice core data, and atmospheric CO(2) concentration data from Mauna Loa measurements. Correlation analysis of temperature data with concurrent data on atmospheric CO(2) concentrations and the Wolf sunspot index support previously reported significant correlation over the 1901-1987 period. Correlation analysis between temperature, atmospheric CO(2) concentration, and the Wolf sunspot index for the shorter period, 1958-1987, when continuous Mauna Loa CO(2) data are available, suggest significant correlation between global warming and atmospheric CO(2) concentrations but no significant correlation between global warming and the Wolf sunspot index. This may be because the Wolf sunspot index apparently increased from 1901 until about 1960 and then decreased thereafter, while global warming apparently continued to increase through 1987. Correlation of sunspot activity with global warming may be spurious but additional analyses are required to test this hypothesis. Given the inconclusive correlation between temperature and solar activity, the significant intercorrelation between time, temperature, and atmospheric CO(2) concentrations, and the suggestion of weak periodicity in the temperature data, additional research is needed to separate the anthropogenic component from the natural variability in temperature when assessing local, regional, and global warming trends.     

Risk assessment of environmental chemicals

This article is a summary from eleven important symposia. In these meetings, critical facts were discussed which are the necessary basis for the important legislation about toxic substances in Europe, in the U.S.A. and in Japan. This review article should also be of some help to the readers of “Chemosphere” for direct contacts with the experts mentioned. It is therefore an informative and coordinative survey, in which chemical and ecotoxicological details are largely omited.     

Impact of uranium mines closure and abandonment on groundwater quality

The aim of the study is to assess the evolving mine water quality of closed uranium mines (abandoned between 1958 and 1992) in the Czech Republic. This paper focuses on the changes in mine water quality over time and spatial variability. In 2010, systematic monitoring of mine water quality was performed at all available locations of previous uranium exploitation. Gravity flow discharges (mine adits, uncontrolled discharges) or shafts (in dynamic state or stagnating) were sampled. Since the quality of mine water results from multiple conditions—geology, type of sample, sampling depth, time since mine flooding, an assessment of mine water quality evolution was done taking into account all these conditions. Multivariate analyses were applied in order to identify the groups of samples based on their similarity. Evaluation of hydrogeochemical equilibrium and evolution of mine waters was done using the Geochemist’s Workbench and PHREEQC software. The sampling proved that uranium concentrations in mine waters did not predominantly exceed 0.45 mg/L. In case of discharges from old adits abandoned more than 40 years ago, uranium concentrations were below the MCL of US Environmental Protection Agency for uranium in drinking water (0.03 mg/L). Higher concentrations, up to 1.23 mg/L of U, were found only at active dewatered mines. Activity concentration of ²²⁶Ra varied from 0.03 up to 1.85 Bq/L except for two sites with increased background values due to rock formation (granites). Radium has a typically increasing trend after mine abandonment with a large variability. Concerning metals in mine water, Al, Co and Ni exceeded legislative limits on two sites with low pH waters. The mine water quality changes with a focus on uranium mobility were described from recently dewatered mines to shafts with water level maintained in order to prevent outflows to surface water and finally to stagnating shafts and discharges of mine water from old adits. The results were in good agreement with published experience on mine water stratification, its disturbance by pumping or natural water decant and the “first flush” phenomenon after mine flooding.     

A time series analysis of aerosol composition measurements

Time sequence measurements of the elemental composition of aerosols, on an hourly to fewhourly basis, may be analyzed statistically for chemical associations which are characteristic of sources before modification of these associations during transport through the atmosphere. If correlations between elemental abundances are computed in the measured data set, high serial correlations in the series can introduce a bias. Therefore, Box-Jenkins techniques are used to obtain the residual series as an estimate of the sequence of independent “shocks” for each element. It is argued that, due to the mixing effects of atmospheric factors, these shocks are the appropriate random variables for investigating the elemental associations within a data set of time sequence aerosol composition measurements. Examples from measurements at different locations in Florida of the concentrations of nine elements, every 2 h for about two weeks, are used to illustrate the method. In particular it is shown that principal component analysis of the residuals gives rise to different interpretations than analysis of the observed series.     

生活垃圾填埋场对地下水污染的风险评价——以北京北天堂垃圾填埋场为例

以国外生活垃圾填埋场对地下水污染的风险评价方法为基础,建立了综合考虑含水层脆弱性及生活垃圾填埋场自身性质的地下水污染风险评价方法,并以北京北天堂垃圾填埋场为例.评价了当地4个生活垃圾填埋场对地下水污染的风险级别.结果表明,生活垃圾填埋场对地下水污染的风险取决于场地规模、防护情况等自身相关参数以及场地所处位置的含水层脆弱...     

Risk assessment and prioritisation of contaminated sites on the catchment scale

Contaminated sites pose a significant threat to groundwater resources worldwide. Due to limited available resources a risk-based prioritisation of the remediation efforts is essential. Existing risk assessment tools are unsuitable for this purpose, because they consider each contaminated site separately and on a local scale, which makes it difficult to compare the impact from different sites. Hence a modelling tool for risk assessment of contaminated sites on the catchment scale has been developed. The CatchRisk screening tool evaluates the risk associated with each site in terms of its ability to contaminate abstracted groundwater in the catchment. The tool considers both the local scale and the catchment scale. At the local scale, a flexible, site specific leaching model that can be adjusted to the actual data availability is used to estimate the mass flux over time from identified sites. At the catchment scale, a transport model that utilises the source flux and a groundwater model covering the catchment is used to estimate the transient impact on the supply well. The CatchRisk model was tested on a groundwater catchment for a waterworks north of Copenhagen, Denmark. Even though data scarcity limited the application of the model, the sites that most likely caused the observed contamination at the waterworks were identified. The method was found to be valuable as a basis for prioritising point sources according to their impact on groundwater quality. The tool can also be used as a framework for testing hypotheses on the origin of contamination in the catchment and for identification of unknown contaminant sources.     

Measurements of fluorocarbons 11 and 12 and model validation: An assessment

Measurements of CFCl₃ (F-11) and CF₂Cl₂ (F-12) are reviewed and analyzed. Observations of temporal and spatial distribution are not yet sufficient to allow precise estimations of the atmospheric lifetimes of F-11 and F-12. The importance of a finite tropospheric lifetime, in regard to future predictions of F-11 and F-12, is emphasized.The lifetime of F-11 may be relatively short, a 10-y lifetime is not ruled out by present analysis. Such a sink would imply the future F-11 level may only be double the present level if production is held constant at 1975 rate. There are larger uncertainties in the estimate of F-12 lifetimes because of fewer data and uncertainty in the release rate data. It is argued that a 10–20 y lifetime for F-12 is not ruled out by observational data.     

Risk assessment of biocides in roof paint

BACKGROUND, AIM AND SCOPE: Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. MATERIALS AND METHODS: A laboratory simulation was used to determine the time dependant leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. RESULTS: Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Südwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. DISCUSSION: The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. CONCLUSIONS: The leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field study. RECOMMENDATIONS AND PERSPECTIVES: The leaching study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.     

Global networking for assessment of impacts of global change on plant pests

Global change encompasses changes in atmospheric composition, climate and climate variability, and land cover and land use. The occurrence of these changes and their interactive effects on biological systems are worldwide; thus, an effective global change research and impact assessment program must be based on international and interdisciplinary research and communication. With this in mind, several collaborative research networks with a focus on global change have been established in the biological sciences. They include the Global Change and Terrestrial Ecosystems (GCTE) Core Project of the International Geosphere-Biosphere Programme (IGBP) which aims to predict the effects of global change on terrestrial ecosystems, including agriculture and production forestry. Because of the importance of plant pests (arthropods, microbial pathogens, weeds) as yield-reducing factors in agriculture and as early indicators of global change, GCTE initiated a network Activity on "Global Change Impacts on Pests, Diseases and Weeds" with the overall goal of developing a predictive capability for impact assessment and adaptation. The network's specific objectives, contributing research projects, initial results and future challenges are discussed.     

Risk assessment of land-use suitability and application to Tangshan City

Risk assessment for suitability is one of the main problems in city landuse planning for disaster prevention. Decision-making strategy using GIS-based Ordered Weighted Averaging (OWA) method is discussed through analysing OWA evaluation procedure. Data of geological disaster in Tangshan City are used to calculate the distances from dangerous areas or safety area to yield evaluation criteria for all disaster factors of land-use suitability.     

Risk assessment of boron in glass wool insulation

Background, aim and scope  Glass wools are man-made vitreous fibres, which consist principally of sodium, calcium and magnesium silicates, but may contain smaller amounts of other elements, including boron. The boron contents originate from the use of borates in the glass melting process as a glass former and a flux agent. During the production and application of glass wool insulation products, workers may legally be exposed to glass fibre up to the occupational limit value, commonly of 1 fibre/cm³. However, in practice, the fibre exposure will be at least ten times lower. Boron is a non-metallic element widely distributed in nature, where it occurs as boric acid, borates and borosilicates. Humans are mainly exposed to boron via vegetarian food and drinking water, mineral supplements and various consumer products. Boron is an essential element for plant growth, but the essentiality for humans is not proven, although intakes of trace amounts of the element seem to be useful for bone health and proper brain function; higher concentrations of boron, however, may be toxic. In relation to the European Union legislation on dangerous substances, an EU Expert Group has recommended classifying boric acid and borates with risk phrases for reproductive toxicity. The aim of this paper is to assess whether the new EU hazard classification of boron compounds should imply that glass wool products used for building insulation in the future should be labelled, “may impair fertility and cause harm to the unborn child”, because of the low boron content. Materials and methods  Boron intakes are estimated in a worst-case occupational situation with human exposure to glass wool fibres at the occupational limit of 1 fibre/cm³ by calculation of the mass of the amount of fibres inhaled during an 8-h work day. Fibres are supposed to be cylinders of glass with a length of 30 μm, an average diameter of 1.5–2 μm and containing either 1.5% or 3.5% boron. As a worst-case scenario, the density of the fibres is set to 2,700 kg/m³. The inhalation rate of the individuals at moderate work load was set to 2 m³/h. A worst-case scenario also corresponds to 100% retention and to 100% solubility of the retained fibres in the lungs. Results  With the normal boron content of 1.5% in glass wool fibres for building insulation, the extra daily occupational boron intake/uptake will be 0.03–0.06 mg B for 5 days a week. For more uncommon glass wool with maximum boron content of 3.5%, the worst-case daily boron intake/uptake will be 0.08–0.16 mg B. The main boron exposure in the general population is from vegetarian food, and the average daily dietary intake with food is estimated to 1.2–1.5 mg B/day. In addition, significant intakes may come with drinking water, especially from mineral water. In some instances, exposure from mineral supplements, cosmetics and other consumer products may be significant. For example, individuals taking mineral supplements, e.g. for bodybuilding, may have an additional intake to that of 1–10 mg/day. During the years, various organisations have recommended safe intake values for boron. Recently, the Scientific Panel on Dietetic Products, Nutrition and Allergies of the European Food Safety Authority (EFSA) has established the ‘Tolerable Upper Intake Level’ (UL) for the intake of boron (boric acid and borates) at 0.16 mg B/kg body weight per day or about 10 mg B/day for an adult. Discussion  The calculated, worst-case exposure scenario during an 8-h work day will result in an extra daily boron intake that only corresponds to about 10% of the average daily adult boron intakes through food and drinks of about 1.5 mg. The inter-individual variations in boron intakes from foods, water and supplements will be much greater than an eventual, very worst-case, additional intake of boron from inhalation of glass wool fibres. In addition, the combined intakes are far lower than the ‘Tolerable Upper Intake Level’ of 10 mg B/day for a person weighing 60 kg, as recommended by the European Food Safety Agency. The potential boron intake from inhalation of glass wool fibres is also much lower than boron intakes by workers in the boron industry, who at the present occupational limit value will be exposed to 50 mg of boron 5 days a week, or 100 times more than the worst case for glass wool fibres. Furthermore, in practice, exposure levels will mostly be ten to 100 times lower than the occupational limit used here as a worst case. Conclusions  The estimated boron intake from inhalation of glass wool fibres in occupational settings will be insignificant and without any health risks, even in the case of non-compliance with the occupational limit value. Any proposal requiring hazard labels on commercial glass wool products for building insulation, because of the boron content, is not supported by the present scientific knowledge. Recommendations and perspectives  The European Commission should ensure that the new EU hazard classification of boron compounds is not applied to commercial glass wool products for building insulation having a low content of boron.     

Autocorrelation and univariate time series modelling for grass fluoride and airborne fluoride concentrations

The dependence of observed fluoride levels-grass, gaseous air and particulate air-on previous levels was investigated in the field situation. Autocorrelation was found in grass fluoride observations, and to a lesser extent was present in both gaseous and particulate airborne fluorides. Univariate time series models were obtained which accounted for 56-66% of total variation in grass fluoride, 31% in gaseous airborne and 26% in particulate airborne fluorides. The large amount of variation unexplained by the models was thought to be due to the influence of environmental and meteorological factors not included in the models, and random variation due to day-to-day and plot-to-plot variation.     

Experimental assessment and validation of quantification methods for cellulose content in municipal wastewater and sludge

Environmental Science and Pollution Research - Cellulose, mostly in the form of toilet paper, forms a major component of the particulates in raw municipal wastewater, which could lead to...