Evaluation of microbial indicators for the determination of bacterial groundwater contamination sources

Several different Microbial source tracking methods (MSTs) can be used to distinguish human from animal fecal contamination in water; In this study, experiments were carried out to test the effectiveness and reliability of three bacteria based approaches (the fecal coliforms to fecal streptococci ratio, antibiotic-resistant Clostridium perfringens, and human bifidobacteria) in a simulated groundwater micro-environment. The methods were evaluated in three phases: initially, the specificity of each indicator was validated on groundwater samples affected by known pollution source; then the variation of performance with time of each method was determined, and finally, the die-off coefficients for pure species of Clostridium perfringens and Bifidobacterium adolescentis were measured. The results indicate that only the determination of human bifidobacteria concentration can be considered reliable in distinguishing human from animal pollution in groundwater at the conditions applied. Nevertheless, human bifidobacteria were detectable only for two weeks after the contamination event. This study also shows that antibiotic resistant Clostridium perfringens detected using the Shahidi-Ferguson medium is not source specific, whereas it confirms that this species can be useful for timing general fecal contamination events.     

Evolution of invertase activity in honey over two years

Invertase activity is a good parameter for evaluating honey freshness. Invertase activity evolution was determined on 57 fresh, unheated, commercially purchased Galician (northwestern Spain) floral honey samples. All honeys were stored in darkness at room temperature for up 24 months and analyzed each 6 months so as to determine the invertase activity evolution tendency for the first time. Invertase activity analysis was carried out according to Siegenthaler's method and in a simple assay, the latter showing a good precision (coefficient of variation between 0.35 and 0.66%). Initial invertase activity mean value was 163.9 (48.4-251.0) micromol of 4-nitrophenyl-alpha-D-glucopyranoside hydrolyzed/kg of honey/min. After application of the SPSS statistical package, the values of invertase activity showed five types of temporal behavior: exponential (56% of samples), linear (25% of samples), logarithmic (11% of samples), inverse (5% of samples), and quadratic (3% of samples). Linear regression equations were used to predict the invertase activity at 6, 12, 18, and 24 months from the initial Galician honeys' invertase activities; no statistical differences were found between experimental data and the activities calculated from the linear regression equations.     

Evaluation of the sulphur status of some soils from Portugal

Total S, extractable SO₄, and SO₄^? retention capacity were determined in a range of soils covering the dominant soil groups in Portugal which are expected to show S deficiency. Total S was relatively low (83–435 mg S kg^?1) in all soils and KH₂PO₄^? extractable SO₄ was, in general, low for plant growth, ranging from 0.9 to 32.2 mg S kg^?1. SO₄^? retention capacity ranged from ?33.1 to 64.7 mg S kg^?1 and was negative in many (14 out of 20) of the soils. Most of the soils are expected to be S deficient and show extensive leaching of SO₄. Other selected soil properties that may affect the chemistry of SO₄ were determined. A highly significant simple correlation was obtained between SO₄ adsorbed and extractable Al by the Mehra and Jackson method (CDB-Al) (r = 0.74; P < 0.001). A multiple regression which included silt improved the correlation of SO₄ adsorbed with CDB-Al (r = 0.79; P < 0.001).     

Studies of precipitation contamination levels over the north-western forests of Russia subject to emissions from the two nickel smelters

The results of investigations carried out in the forests of Kola peninsula subject to long-term air pollution by the nickel industrial enterprises are presented. Samples of rainwater from the open sites, from under the coniferous (pine) trees crowns and of the stemflow were collected at various distances from the emission sources. The highest levels in pollution of rainwater are detected over the area adjacent to the smelters. Researches of contamination of the precipitation in the vicinity of the two nickel enterprises of Kola peninsula show that concentrations of pollutants vary significantly (up to an order of magnitude) depending upon the meteorological conditions. The area of impact on forests of Kola peninsula is restricted by the radius of 30–40 km from the emission sources.     

Areal identification of groundwater nitrate contamination sources in periurban areas

Background, Aims and Scope  The purpose of this study is to verify a method for groundwater contamination risk assessment in urban and periurban areas using Geographic Information Systems (GIS). The method is based on agricultural hazard evaluation. In urban and periurban areas, the problem of dealing with NO₃ concentrations mainly entails identifying nitrate sources from the excessive use of fertilizers, or leaks from the sewage network and old septic systems. Residential areas coexisting with farming, and high and increasing nitrate concentrations, were identified in a densely inhabited area (>2 million inhabitants in about 1,000 km²) with an alluvial aquifer, located in southern Italy. Methods  First of all, comparison between the Contamination Vulnerability Map and the distribution of NO₃ concentrations highlights anomalous areas with low or moderate vulnerability in spite of the diffuse nitrate contamination of the aquifer. Assuming the agricultural origin of the nitrates, the hazard is calculated using the ANHI (Agricultural Nitrate Hazard Index), a parametric index which assesses the potential hazard of nitrate contamination originating from agriculture on a regional scale (Padovani and Trevisan 2002). The ANHI integrates two categories of parameters: the hazard factors (HF), which represent all farming activities that cause, or might cause, an impact on soil quality in terms of nitrate (use of fertilizers, application of livestock and poultry manure, food industry wastewater and urban sludge), and the control factors (CF) which adapt the hazard factors to the characteristics of the site (geographical location, climatic conditions and agronomic practices). Organization, processing and mapping are performed using a Geographical Information System (GIS: ILWIS 3.3 and ARCGIS 9.1). Results  The ANHI Map is obtained by multiplying the hazard factors (HF) and the control factors (CF), and dividing the resulting values into 6 classes. Finally, the Potential risk Map (R) is obtained by coupling the potential hazard of nitrate pollution (ANHI) and the aquifer Contamination Vulnerability Map. Discussion  By using spatial statistics, the Potential Agricultural Nitrate Contamination Risk Map and the Nitrate content of the aquifer correlation can be correlated. Where areas with low correlation in the Land Use Map are in the ‘urban areas and artificial land’ class, the source of the groundwater nitrate is not necessarily related to intensive farming and livestock. Conclusions  The Potential Agricultural Nitrate Contamination Risk Map in urban and periurban environments indicates the relationship between the high nitrate values and land use, giving useful information about the source of nitrate in groundwater. Recommendations and Perspectives  Based on this study, we formulate a hypothesis on the source of groundwater nitrate which should be verified on several case studies using nitrogen isotope techniques.     

Soil contamination in the impact zone of mining enterprises in the Bashkir Transural region

The results of long-term studies of the contents of bulk forms of metals (Cu, Zn, Fe, Ni, Pb, Mn, Co, and Cd) and their mobile compounds in soils of background and human-disturbed areas within the Krasnoural’sk–Sibai–Gai copper–zinc and Baimak–Buribai mixed copper mineralization zones in the Bashkir Transural region are discussed. It is shown that soils of the region are characterized by abnormally high natural total contents of heavy metals (HMs) typomorphic for ore mineralization: Cu, Zn, and Fe for the Sibai province and Cu, Zn, and Ni for the Baimak province. In the case of a shallow depth of the ores, the concentrations of HMs in the soils are close to or higher than the tentative permissible concentration values. The concentrations of mobile HM compounds in soils of background areas and their percentage in the total HM content strongly vary from year to year in dependence on weather conditions, position in the soil catenas, species composition of vegetation, and distance from the source of technogenic contamination. The high natural variability in the content of mobile HM compounds in soils complicates the reliable determination of the regional geochemical background and necessitates annual estimation of background parameters for the purposes of the ecological monitoring of soils. The bulk content of Cu and Zn content in soils near mining enterprises exceeds the regional geochemical background values by 2–12 times and the tentative permissible concentrations of these metals by 2–4 times. Anthropogenic contamination results in a sharp rise in the content of mobile HM compounds in soils. Their highest concentrations exceed the maximum permissible concentrations by 26 times for Cu, 18 times for Zn, and 2 times for Pb. Soil contamination in the impact zone of mining enterprises is extremely dangerous or dangerous. However, because of the high temporal variability in the migration and accumulation of HMs in the soils, the recent decline in the ore mining activities, and the construction of purification facilities, no definite temporal trends in the contents of HMs in the soils have been found in the studied region for the period from 1998 to 2015.     

高产农田土壤硝态氮淋失与地下水污染动态研究

对桓台县区域农田监测研究表明,水肥管理不同的2个监测区域郭家区、李家区高产农田土体内NO_3~--N淋失迁移动态有差异,地下水污染亦不同。春天始土体内NO_3~--N含量趋于持续降低,浅层地下水NO_3~--N含量则持续升高,雨季后地下水中NO_3~--N含量尤剧烈升高,并达年内最高值,表现出农田N肥对地下水的直接污染,这可能与李家区灌溉次数多、土壤质地较轻和地下水位较浅有关。     

Evaluation of the studies on decline of pesticide residues

A specifically designed field trial was carried out in an apple orchard by applying Reldan 50 EC (active ingredient, chlorpyrifos-methyl) according to registered uses in Hungary to study the variability of results derived from supervised field trials. Two types of composite samples (A, size 24; and C, size 12) were taken at days 0, 3, 7, 10, and 14 after application to study the uncertainty of estimated residue values derived from supervised trials. In the case of type A the sampling officer selected the fruits from the specified quadrant of the tree, whereas for type C the fruits were taken from the vicinity of the marked position at consecutive sampling times. An evaluation model applying various formulas for the linearization of the decline curves of pesticide residues was applied, which enabled using the statistics of linear regression for calculating the best fit and confidence intervals for the experimental data. The results indicated that the uncertainty of sampling contributed approximately 84-90% of the combined uncertainty of the results (24-30%). In the decline studies performed simultaneously on the same field, the estimated time required to decrease the initial concentration to half ranged from 0.64 to 4.7 days. Despite the fact that the sample size of type C is half that of type A, both sampling methods provided similar results.     

Simulation of chromium transport in the unsaturated zone for predicting contaminant entries into the groundwater

Heavy metal contaminations in the top‐soil layers can impose serious threats to groundwater quality. A seepage water prognosis of probable future contaminant entries at the groundwater surface has to take into account the emission characteristics of the source zone and the reactive transport of the contaminated leachate through the unsaturated zone. Here, a possible approach is presented, exemplarily for a site contaminated with chromium, encompassing batch elution experiments, unsaturated soil column leaching experiments with flow interruption, soil monolith lysimeter experiments, and numerical modeling of non‐equilibrium solute transport. The prognosis provides a long‐term prediction of Cr concentrations at the groundwater surface. It must be emphasized, that the modeling results are uncertain, because several of the parameters in the simulations can be determined only with significant errors. Additionally, the approach is not applicable routinely for every hazardous waste site. Our study reveals, however, that reactive contaminants can possibly reach the groundwater at hazardous concentrations within very short time.     

海水作景观水引起河道两岸地下水污染研究

利用天津市滨海新区具有较发达的河网和方便的入海通道,将海水引入河道作景观水是改善水环境的措施之一。该文利用垂向二维变密度水流和溶质运移的数值模型,计算了河道中不同海水水位时两岸地下水的溶质污染扩散趋势和范围,并分析了采取暗管向河道底部两侧含水层注水的工程措施对地下水污染的控制作用。结果表明：河道高水位运行时,海水入侵两岸现象明显;低水位时盐分能控制在一定范围内;对于低水位运行并考虑暗管注水,盐分只向河床底部运移,基本不向两岸扩散。     

基于GIS的地下水资源可持续性评价

该文根据区域水资源评价工作的特点和GIS技术强大的空间分析功能,探讨了GIS技术在区域水资源可持续性评价中的可行性,并将其应用到北京市通州区潞城镇地下水资源可持续性评价中。根据GIS技术与动态均衡法的结合,评价得出自1988年以来,潞城镇地下水储量一直处于亏损状态,16年累计亏损1715.577万m³,地下水位平均每年下降0.12 m。表明今后该区域地下水应采取相应措施来缓解地下水的压力。     

Soil contamination in the zone affected by waste products of Tin Ore Processing in the Khabarovsk region

The degree of soil contamination in the impact zone of the Solnechnyi Tin Ore Processing Plant in the Solnechnyi district of the Khabarovsk region was evaluated. It was shown that the air contamination by the waste products of the ore-processing plant is extremely high with respect to the concentrations of toxic dust and heavy metals. The maximum concentrations of these contaminants exceed the background values by 16–80 times. The bulk contents of Pb, Zn, Cu, As, and Hg in the upper soil horizons within the impact zone exceeded the maximum permissible concentrations and the background values by 2–90 times. Abnormally high concentrations of Zn, As, and Pb were observed not only in the surface 10–cm-thick soil layer but also in the underlying (10–20 cm) horizon. The soil contamination transformed the geochemical sequence of heavy metals typical of the background soils (Zn > Pb > As > Cu > Hg) into a new sequence (As > Pb > Cu > Zn > Hg). The statistical data proved that the intensity of the migration of the heavy metals in the soils decreases with a rise in the soil humus content and a drop in the soil acidity. This should be taken into account in the elaboration of soil-protective measures in the investigated region.     

Plant contamination by heavy metals in the impact zone of Novocherkassk Power Station in the south of Russia

Journal of Soils and Sediments - The aim of this study is the assessment of Ni, Mn, Cd, Cu, Pb, Cr and Zn accumulation by different herbaceous species and soils on the technogenic areas around...     

Heterogeneity of bacterial populations and pesticide degradation potentials in the unsaturated zone of loamy and sandy soils

Soil microbial processes play an important role in relation to pesticide pollution of groundwater, and may be strongly influenced by hydrological and geochemical properties. The consequences of such heterogeneous environments on bacterial biomass, enzymatic activities, carbon utilisation patterns, and pesticide mineralisation potentials in the unsaturated zone of a sandy loam and a coarse sandy soil profile were studied. In sandy loam soil profiles the number of bacteria decreased from 10⁹ cells g^-1 in the surface layers to about 10⁷ cells g^-1 at 1.5-5 m depth. Simultaneously, the hydrolysis of fluorescein diacetate and arylsulfatase activity decreased to below the detection limit at about 1.5 m depth, and carbon utilisation patterns showed that bacterial populations from surface soil were significantly different from those from 4 m depth. Bacterial biomass and activity in macropore soil tended to be slightly higher than in matrix soil, and the carbon utilisation patterns of bacterial populations extracted from macropore soil and from matrix soil seemed to be different. Maximally 3% of ¹⁴C-labelled mecoprop and isoproturon was mineralised in soil from the 1-1.5 m depth, and less than 1.5% was mineralised in soil from the 3.5-4 m depth. The macropore soil tended to have a higher degradation potential than the matrix soil. The total number of bacteria in the coarse sandy soil profile decreased from about 10⁸ in the plough layer to 10⁷ cells g^-1 at 0.4-2 m. The enzymatic activities and the degradation potentials of ¹⁴C-labelled mecoprop and isoproturon were significantly correlated (r² >0.79) and showed a distinct decrease at about 0.4 m. In addition to the depth variability, a horizontal heterogeneity in this soil was observed as horizons or compartments that differed in colour, i.e. with different chemical composition and concentrations of Fe and organic matter. Counts of viable bacteria and measurements of fluorescein diacetate hydrolysis and arylsulfatase activity confirmed a high variability of microbial biomass and activity in the sandy soil profile.     

Arsenic chemistry in a groundwater aquifer from the Eastern Province of Saudi Arabia

Groundwater samples were collected from shallow aquifers underneath an industrial complex in the Eastern Province of Saudi Arabia. Arsenic (As) concentrations in the groundwater samples varied between 10^?8.6 and 10^?6.8 M (0.18 and 11.14 µg L^?1), with an average of 10^?7.5 M (2.19 μ L^?1). The analysis of variance for the analytical data showed that sampling locations had significantly affected As concentrations in the groundwater samples. Analytical and thermodynamic calculations showed that H₂ASO₄ ^? was the most predominant As species in acidic groundwater samples, and HAsO₄ ^2? was the most abundant species in alkaline groundwater samples. Concentrations of H₃AsO₄° and AsO₄ ^3? were too low to be important in this study. Reduced As chemical forms were also expected to be very low. All the groundwater samples were undersaturated with respect to the thermodynamic solubility isotherms of Ca₃(AsO₄)₂(c), Fe₃(AsO₄)₂(c), and Mn₃(AsO₄)₂(c) minerals. Lack of reliable thermodynamic data for these arsenates could be responsible for differences between the theoretical and measured concentrations of As in the shallow groundwater samples. The general trend in the distribution of HAsO₄ ^2? activities in the groundwater samples was parallel to that of the Ca₃(AsO₄)₂ solubility isotherm but different from those of Fe₃(AsO₄)₂(c), and Mn₃(AsO₄)₂(c). These data suggest that As concentrations in the groundwater samples were probably controlled by the precipitation and dissolution of Ca₃(AsO₄)₂ type mineral. A three step hypothesis for As interactions in groundwater/soil system is proposed that combines both solid phase formation and adsorption of As onto the solid colloidal surfaces. This hypothesis is expected to better represent As behavior in groundwater/soil environment.     

Evaluation of metal and microbial contamination in botanical supplements

The sale of botanical dietary supplements in the United States is on the rise. However, limited studies have been conducted on the safety of these supplements. There are reports on the presence of undesired metals in some of the botanical dietary supplements. In this study, echinacea, garlic, ginkgo, ginseng, grape seed extract, kava kava, saw palmetto, and St. John's wort supplements manufactured by Nature's Way, Meijer, GNC, Nutrilite, Solaray, Sundown and Natrol, have been analyzed for lead, mercury, cadmium, arsenic, uranium, chromium, vanadium, copper, zinc, molybdenum, palladium, tin, antimony, thallium, and tungsten using inductively coupled plasma mass spectrometry. All samples were devoid of mercury contamination. Results indicated that the botanical supplements analyzed did not contain unacceptable concentrations of these metals. These supplements were also evaluated for microbial contamination, and most samples analyzed showed the presence of bacteria or fungi or both. Microbes were not counted nor were microbial counts determined in these samples.     

A detailed reconstruction of changes in the factors and parameters of soil erosion over the past 250 years in the forest zone of European Russia (Moscow region)

Accelerated soil erosion is a major threat to soil, and there are great variations in the rate of soil erosion over time due to natural and human-induced factors. The temperate forest zone of Russia is characterized by complex stages of land-use history (i.e. active urbanization, agricultural development, land abandonment, etc.). We have for the first time estimated the rates of soil erosion by the WaTEM/SEDEM model (rainfall erosion) and by a regional model (snowmelt erosion) over the past 250 years (from 1780 to 2019) for a 100-km² study site in the Moscow region of Russia. The calculations were made on the basis of a detailed historical reconstruction of the following factors: the location of the arable land, crop rotation, the rain erosivity factor, and the maximum snow water equivalent. The area of arable land has decreased more than 3.5-fold over the past 250 years. At the end of the 20th century, the rates of gross erosion had declined more than 5.5-fold (from 28 × 10³ to 5 × 10³ t?ha^?1?yr^?1) in comparison with the end of the 18th century. Changes in the boundaries of arable land and also the relief features had led to a significant intra-slope accumulation of sediments. As a result of sediment redeposition within the arable land, the variation in net soil erosion was significantly lower than the variation in gross soil erosion. The changes in arable land area and in crop composition are the factors that have to the greatest extent determined the changes in soil erosion in this territory.     

Land use change and gully formation over the last 200 years in a hilly catchment

Gully erosion can be widely observed on cultivated hillslopes in Hungary. Loose sediments covering two thirds of the total area of the country are prone to gully erosion.A detailed study of gully formation was carried out in the Rakaca catchment (58 km²), northeastern Hungary. The objectives include (1) a detailed survey of the present gullies, (2) an explanation of differences in gully distribution within the catchment, (3) clarification of the role of influencing factors like slope gradient, vegetation cover and soil type and (4) a study of changes of gully distribution and development in time over the last 200 years based on the comparison of topographic maps.The present gully distribution was first surveyed by applying 1:10 000 topographic maps and aerial photographs. The total length of the network is 70.9 km, i.e. 1.22 km/km². Distribution inhomogeneities within the catchment can well be explained by differences in slope gradient and vegetation cover.The rate of increase of the gully length per unit area (1 km²) calculated for different time periods shows the following trends: (1) until 1860, when more than 50% of the catchment was forested, it was 5 m year⁻¹ km⁻²; (2) between 1860 and 1920, when forest area dropped to almost 25% and agricultural land use was extended to slopes steeper than 25%, it still remained at roughly 5 m year⁻¹ km⁻²; (3) after 1920, with 24–25% forest cover and with the extension of farming activity to the steepest slopes, it reached 10 m year⁻¹ km⁻².It could be shown that gully erosion on cultivated slopes leads to the development of gully systems in 50–60 years even if slope gradient is below 12%.To prevent further development of gully systems, it is suggested that at least 30% of the area should be forested and slopes steeper than 17% should not be cultivated at all.