Assessment of soil and groundwater impacts by treated urban wastewater reuse. A case study: application in a golf course (Girona, Spain)

Starting in July 2000, treated wastewater of urban origin has been used for the "Serres de Pals" golf course irrigation (Girona, Spain). To evaluate if the soil and the aquifer underneath are affected by the utilization of this type of water, samples have been taken along a period of several months from the wastewater treatment plant, the stabilization lagoon, groundwater and soil profiles. Analyses have been performed for total coliforms and aerobic bacteria, soil water pressure and soil water content as well as chemical analyses of the irrigation water, aquifer and water of the vadose zone. Soil profiles taken at several times during the study indicate the absence of coliforms except for a short period during summer. In the vadose zone an increase of more than 1000 mg kg(-1) of NaO(2) in the top 60 cm of soil was observed while Cl(-) concentration in the aquifer reached up to 1200 mg l(-1) ten months after starting the irrigation.     

Messung der Infiltrationsgeschwindigkeit von Oberflächenwasser mit Hilfe des natürlichen Isotops Radon-222

Owing to its different concentrations in groundwater and river water, the naturally occuring isotope radon-222 can be used as a natural tacer to determine the residence time of freshly infiltrated water and the infiltration velocity. In the study area, predominant correlation was found between the radon activity concentration of groundwater and the lithologic structure of the aquifer. Misinterpretation of low radon activity concentration measured near surface waters due to geological inhomogeneities can result in false assumptions about groundwater flow paths. The infiltration of river water into the adjacent aquifer during a flood wave was also ascertained by measuring radon activity concentration. Further the residence time of infiltrated water was determined at a sampling point installed beneath the river Elbe and infiltration velocity was calculated.     

Sulfamethoxazole contamination of a deep phreatic aquifer

Groundwater samples were obtained from the water table region of a phreatic aquifer (unsaturated zone depth up to 28 m) under land irrigated with wastewater effluents for about 5 decades and a relatively deep pumping well (109 m), used as a drinking water source till 2007, located downstream (1300 m) of wastewater effluent and sludge infiltration facilities. Sulfamethoxazole (SMX) concentrations in secondary effluents varied between 90 and 150 ng/L. SMX was extracted using SPE and was analyzed by HPLC-MS/MS. SMX (maximum concentration of 37 ng/L) was detected in the water table region, in two monitoring wells, after an unsaturated zone transport period of about 16 years. The maximum SMX concentration detected in the pumping well was of 20 ng/L. These results question wastewater effluent disposal strategies including the suitability of irrigation with effluents on the replenishment area of an aquifer supplying drinking water.     

Qualitative hydrological and land-use planning tool for the Israel Coastal aquifer

Due to a variety of past and present land-usages on the aquifer ground surface, appropriate groundwater management should consider anthropogenic activities on the ground surface and the potential of unsaturated zone media to convey water and pollutants to the aquifer. The objective of this paper is to present an approach which generates guidelines and recommendations which can lead to sustainable development. This method assesses the lithological characteristics of the aquifer's vadose zone, indicating potential rechargeability, while weighting factors leading to potential groundwater pollution resulting from some land-use. Recommendations regarding land-use planning and aquifer recharge can then provide a qualitative ecological tool towards sustainable groundwater management. Owing to its location, its critical significance to the country's fresh water supply, and its available field data, Israel's Coastal aquifer is employed here as the study area for implementation of this approach.     

Fate of nine recycled water trace organic contaminants and metal(loid)s during managed aquifer recharge into a anaerobic aquifer: Column studies

Water quality changes associated with the passage of aerobic reverse osmosis (RO) treated recycled water through a deep anaerobic pyritic aquifer system was evaluated in sediment-filled laboratory columns as part of a managed aquifer recharge (MAR) strategy. The fate of nine recycled water trace organic compounds along with potential negative water quality changes such as the release of metal(loid)s were investigated in large-scale columns over a period of 12 months.The anaerobic geochemical conditions provided a suitable environment for denitrification, and rapid (half-life <1-25 days) degradation of the endocrine disrupting compounds (bisphenol A, 17β-estradiol, 17α-ethynylestradiol), and iodipamide. However, pharmaceuticals (carbamazepine and oxazepam), disinfection by-products (N-nitrosodimethylamine, N-nitrosomorpholine) and iohexol did not degrade rapidly (half-life > 100 days).High retardation coefficients (R) determined for many of the trace organics (R 13 to 67) would increase aquifer residence time and be beneficial for many of the slow degrading compounds. However, for the trace organics with low R values (1.1-2.6) and slow degradation rates (half-life > 100 days), such as N-nitrosodimethylamine, N-nitrosomorpholine and iohexol, substantial biodegradation during aquifer passage may not occur and additional investigations are required.Only minor transient increases in some metal(loid) concentrations were observed, as a result of either pyrite oxidation, mineral dissolution or pH induced metal desorption, followed by metal re-sorption downgradient in the oxygen depleted zone.     

云冈石窟入渗水的形成和运移

在云冈石窟地区,大气降水的入渗不仅是地下水的补给来源,也是洞窟石壁表面水分的来源之一。夏季强降雨和春季融雪是研究区入渗水产生的重要途径。石窟山体包气带厚,入渗水需要经过多层介质才能补给地下水,以石窟围岩中发育的2组优势垂直裂隙为主要运移通道。采用多种方法进行综合分析,估算出降水入渗系数为2.6%～5.4%,平均入渗强度为10～20mm/a。     

Fate of trace organics during rapid infiltration of primary wastewater at Fort Devens, Massachusetts

Transport and fate of trace organics were studied during rapid infiltration of primary wastewater at a land application facility in Fort Devens, Massachusetts. A preliminary sampling trip was made to compare trace organic concentrations in the infiltrating wastewater and in ground water samples from three monitoring wells around the site. Trace organic concentrations were reduced by the rapid infiltration process. However, significant concentrations of specific compounds could be detected in ground water down-gradient of the site.Therefore, a field study was undertaken to determine the primary region where trace organics were removed in the system. Teflon monitoring wells were installed at a depth of 1.2 m in one of the basins at the site prior to flooding. Flooding was initiated and samples of the raw wastewater, the wastewater entering the basin, the infiltrate at 1.2-m depth and the ground water down-gradient of the site were analyzed for six compounds selected for the study.Results from replicate samples during the 6-day flooding period demonstrated that most of the removal for the six compounds occurred in the top meter of the soil, although concentrations of each compound increased substantially in the basin infiltrate from two of the sample points after the fourth day of flooding. No removal of p-dichlorobenzene, p-(I,1,3,3-tetramethylbutyl)phenol and 2-(methylthio)benzothiazole was apparent in the aquifer itself, as indicated by relatively high concentrations of these compounds in the contaminated monitoring well down-gradient of the site.These data indicate that trace organic concentrations in primary effluent can be reduced by rapid infiltration and that most of the removal occurs in the top meter of the soil during the early phase of the flooding cycle. This removal capability can rapidly diminish, however, and result in ground water contamination by trace organics above background levels.     

Modelling vadose zone moisture dynamics in shallow water table settings with the Integrated Hydrologic Model: field-scale testing and application

Reproducing the moisture retention behaviour of the vadose zone in shallow water table settings, especially for the near-surface water table aquifer of the Florida coastal plain, provides unique challenges for integrated hydrological models. A comprehensive distributed parameter model, the Integrated Hydrologic Model (IHM), is developed based on deterministic and physically based soil and vegetative properties. The theory and vertical behaviour of IHM is examined through comparisons with data collected at a study site in west-central Florida. The objectives of this exploration are to test a model of the vertical processes controlling water table behaviour, and to also investigate model parameter effects and offer recommendations for improvements and parameterization for regional model application. Rigorous testing is performed to better understand the robustness and/or the limitations of the methodology of the IHM for vadose zones. Simulation results indicate that IHM is capable of providing reasonable predictions of infiltration, depth to water table (DTWT) elevation response, evapotranspiration (ET) distributions from the upper, lower soil and water table while incorporating field-scale variability of soil and land cover properties.     

Organic contaminant behavior during rapid infiltration of secondary wastewater at the phoenix 23rd avenue project

Movement of trace organic pollutants during rapid infiltration of secondary wastewater for groundwater recharge was studied at the 23rd Avenue Rapid Infiltration Project in Phoenix, Arizona. Samples of the wastewater applied to the spreading basins and of renovated water taken from monitoring wells were characterized for priority pollutants and other specific organic compounds using gas chromatography/mass spectrometry. The concentrations of organic constituents were affected by volatilization, biodegradation and sorption processes. Nonhalogenated aliphatics and aromatic hydrocarbons exhibited concentration decreases of 50–99% during soil percolation. Halogenated organic compounds were generally removed to a lesser extent. Concentrations of trichloroethylene, tetrachloroethylene, and pentachloroanisole appeared to be significantly higher in the renovated water than in the basin water, reasons for this behavior remain unclear. Many organic contaminants were detected in the groundwater indicating such systems should be designed to localize contamination of the aquifer. Chlorination of the wastewater had no significant effect on concentrations and types of trace organic compounds.     

河南商丘市规划中心城区浅层地下水防污性能评价

在分析商丘市规划中心城区自然地理及水文地质条件的基础上,基于DRASTIC评价方法,本文选取地下水位埋深、含水层岩性、土壤类型、地形坡度、包气带介质类型和含水层富水性6项指标作为评价因子,建立优化改进的评价模型—DASTIY模型,运用层次分析法(AHP)确定权重,并借助MapGIS进行研究区浅层地下水防污性能评价和分区。结果表明,商丘市规划中心城区浅层地下水防污性能整体为差,评价结果可为地方政府制定地下水资源保护及产业布局提供决策依据。     

DRASTIC模型在贵州省毕节地段浅层地下水脆弱性评价中的应用

为了实现贵州省毕节地段地下水系统脆弱性评价的直观展示,选取含水层埋深、含水层补给、含水层介质类型、土壤介质类型、坡度、包气带厚度和渗透系数七项评价因子,采用DRASTIC模型建立了地下水系统脆弱性评价模型,通过模糊层次分析法(FAHP)确定了评价因子的权重,并基于ArcGIS软件对毕节地段地下水资源的各项数据指标进行了矢量化,实现了毕节地段地下水脆弱性等级划分的直观性分布图。评价结果表明,该区域地下水脆弱性较高且分布不均。     

A GIS-based DRASTIC model for assessing aquifer vulnerability in Kakamigahara Heights, Gifu Prefecture, central Japan

Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible resource management and land use planning. This contribution aims at estimating aquifer vulnerability by applying the DRASTIC model as well as utilizing sensitivity analyses to evaluate the relative importance of the model parameters for aquifer vulnerability in Kakamigahara Heights, Gifu Prefecture central Japan. An additional objective is to demonstrate the combined use of the DRASTIC and geographical information system (GIS) as an effective method for groundwater pollution risk assessment. The DRASTIC model uses seven environmental parameters (Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone, and hydraulic Conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability. The western part of the Kakamigahara aquifer was dominated by "High" vulnerability classes while the eastern part was characterized by "Moderate" vulnerability classes. The elevated north-eastern part of the study area displayed "Low" aquifer vulnerability. The integrated vulnerability map shows the high risk imposed on the eastern part of the Kakamigahara aquifer due to the high pollution potential of intensive vegetable cultivation. The more vulnerable western part of the aquifer is, however, under a lower contamination risk. In Kakamigahara Heights, land use seems to be a better predictor of groundwater contamination by nitrate. Net recharge parameter inflicted the largest impact on the intrinsic vulnerability of the aquifer followed by soil media, topography, vadose zone media, and hydraulic conductivity. Sensitivity analyses indicated that the removal of net recharge, soil media and topography causes large variation in vulnerability index. Moreover, net recharge and hydraulic conductivity were found to be more effective in assessing aquifer vulnerability than assumed by the DRASTIC model. The GIS technique has provided efficient environment for analyses and high capabilities of handling large spatial data.     

Fate of N-nitrosodimethylamine in recycled water after recharge into anaerobic aquifer

Laboratory and field experiments were undertaken to assess the fate of N-nitrosodimethylamine (NDMA) in aerobic recycled water that was recharged into a deep anaerobic pyritic aquifer, as part of a managed aquifer recharge (MAR) strategy. Laboratory studies demonstrated a high mobility of NDMA in the Leederville aquifer system with a retardation coefficient of 1.1. Anaerobic degradation column and ¹⁴C-NDMA microcosm studies showed that anaerobic conditions of the aquifer provided a suitable environment for the biodegradation of NDMA with first-order kinetics. At microgram per litre concentrations, inhibition of biodegradation was observed with degradation half-lives (260 ± 20 days) up to an order of magnitude greater than at nanogram per litre concentrations (25-150 days), which are more typical of environmental concentrations. No threshold effects were observed at the lower ng L⁻¹ concentrations with NDMA concentrations reduced from 560 ng L⁻¹ to <6 ng L⁻¹ over a 42 day ¹⁴C-NDMA aerobic microcosm experiment.Aerobic ¹⁴C-NDMA microcosm studies were also undertaken to assess potential aerobic degradation, likely to occur close to the recharge bore. These microcosm experiments showed a faster degradation rate than anaerobic microcosms, with a degradation half-life of 8 ± 2 days, after a lag period of approximately 10 days.Results from a MAR field trial recharging the Leederville aquifer with aerobic recycled water showed that NDMA concentrations reduced from 2.5 ± 1.0 ng L⁻¹ to 1.3 ± 0.4 ng L⁻¹ between the recharge bore and a monitoring location 20 m down gradient (an estimated aquifer residence time of 10 days), consistent with data from the aerobic microcosm experiment. Further down gradient, in the anaerobic zone of the aquifer, NDMA degradation could not be assessed, as NDMA concentrations were too close to their analytical detection limit (<1 ng L⁻¹).     

Indicators of coastal groundwater quality changes induced by seawater infiltration

The diminishing public water supply in Greater Beirut induced by various factors since the 1960's reaching its climax during the civil war (1975–1992), led to the drilling of a multitude of private wells in the Cenomanian coastal aquifer. The increasingly high extraction of the groundwater led to progressive changes in the quality of the ground‐water due to seawater infiltration. This problem stimulated some studies directed at detecting and assessing the status and magnitude of the seawater infiltration, but most of them failed to apply any reliable diagnostic indicators designed to detect and to trace any changes in the quality of the groundwater. In contrast, the present study demonstrates the application of certain diagnostic indicators (DI) devised specifically for the detection, progress and trends of seawater infiltration into an aquifer.     

Schutz flussnaher Trinkwasserfassungen bei Flussraum-Aufweitungen in voralpinen Schotterebenen

In alpine and peri-alpine flood plains, rivers can lose water to the ground water (infiltrating conditions), or gain water from it (exfiltrating conditions). Since sediments within these flood plains are highly permeable, drinking water wells near infiltrating rivers are often highly efficient. To reduce flood risks, engineers couple hydraulic flood protection measures with an enhancement of lateral connectivity. Eventually, the residence time of the infiltrating ground water is reduced and the fraction of infiltrated water rises. Floods lead to the breakthrough of freshly infiltrated water. This can lead to groundwater contamination, if the river is loaded with wastewater. Where measures of hydraulic engineering are necessary, drinking-water wells must therefore be protected from contamination. We discuss three cases of contamination risk: i) low risk under exfiltrating conditions or where river and ground water interaction is weak, ii) increased risk during or after hydraulic operations under infiltration conditions; and iii) generally high risk at wells with low residence times and high fractions of infiltration water. We suggest that the risk is reduced when a thick unsaturated zone separates the river from the well (> 10?m), compared to direct water loss through saturated media. For wells at risk, we propose technical protection measures to reduce the danger.     

Use of static Quantitative Microbial Risk Assessment to determine pathogen risks in an unconfined carbonate aquifer used for Managed Aquifer Recharge

Managed Aquifer Recharge (MAR) is becoming a mechanism used for recycling treated wastewater and captured urban stormwater and is being used as a treatment barrier to remove contaminants such as pathogens from the recharged water. There is still a need, however, to demonstrate the effectiveness of MAR to reduce any residual risk of pathogens in the recovered water. A MAR research site recharging secondary treated wastewater in an unconfined carbonate aquifer was used in conjunction with a static Quantitative Microbial Risk Assessment (QMRA) to assess the microbial pathogen risk in the recovered water following infiltration and aquifer passage. The research involved undertaking a detailed hydrogeological assessment of the aquifer at the MAR site and determining the decay rates of reference pathogens from an in-situ decay study. These variables along with literature data were then used in the static QMRA which demonstrated that the recovered water at this site did not meet the Australian Guidelines for recycled water when used for differing private green space irrigation scenarios. The results also confirmed the importance of obtaining local hydrogeological data as local heterogeneity can influence of residence time in the aquifer which, in turn, influences the outcomes. The research demonstrated that a static QMRA can be used to determine the residual risk from pathogens in recovered water and showed that it can be a valuable tool in the preliminary design and operation of MAR systems and the incorporation of complementary engineered treatment processes to ensure that there is acceptable health risk from the recovered water.     

VLDA模型及其在潜水脆弱性评价中的应用——以新疆焉耆县平原区为例

在地下水脆弱性评价的GOD法和DRASTIC模型的基础上,提出了VLDA模型,其中V为包气带岩性(1ithology of vadose zone)、L为土地利用方式(pattern of land use)、D为地下水埋深(groundwater depth)、A为含水层特征(aquifer characterist...     

Caffeine as an indicator for the quantification of untreated wastewater in karst systems

Contamination from untreated wastewater leakage and related bacterial contamination poses a threat to drinking water quality. However, a quantification of the magnitude of leakage is difficult. The objective of this work is to provide a highly sensitive methodology for the estimation of the mass of untreated wastewater entering karst aquifers with rapid recharge. For this purpose a balance approach is adapted. It is based on the mass flow of caffeine in spring water, the load of caffeine in untreated wastewater and the daily water consumption per person in a spring catchment area. Caffeine is a source-specific indicator for wastewater, consumed and discharged in quantities allowing detection in a karst spring. The methodology was applied to estimate the amount of leaking and infiltrating wastewater to a well investigated karst aquifer on a daily basis. The calculated mean volume of untreated wastewater entering the aquifer was found to be 2.2 ± 0.5 m³ d⁻¹ (undiluted wastewater). It corresponds to approximately 0.4% of the total amount of wastewater within the spring catchment.     

Linearity and reversibility of iodide adsorption on sediments from Hanford, Washington under water saturated conditions

A series of adsorption and desorption experiments were completed to determine the linearity and reversibility of iodide adsorption onto sediment at the Hanford Site in southeastern Washington. Adsorption experiments conducted with Hanford formation sediment and groundwater spiked with dissolved (125)I (as an analog tracer for (129)I) indicated that iodide adsorption was very low (0.2 mL/g) at pH 7.5 and could be represented by a linear isotherm up to a total concentration of 100 mg/L dissolved iodide. The results of desorption experiments revealed that up to 60% of adsorbed iodide was readily desorbed after 14 days by iodide-free groundwater. Because iodide adsorption was considered to be partially reversible, even though small amount of initial iodide is retarded by adsorption at mineral-water interfaces, the weak adsorption affinity results in release of iodide when iodide-free pore waters and uncontaminated groundwaters contact the contaminated sediments in the vadose zone and aquifer systems.     

Überwachung der Auswirkungen von Flussaufweitungen auf das Grundwasser mittels Radon

The restoration of the perialpine river Töss in a floodplain of northern Switzerland (Linsental) included the removal of bank reinforcements and tracer studies in the river and in oberservation wells of the adjacent alluvial groundwater. The river water is continuously recharging the aquifer system and the groundwater is used extensively as drinking water. Radon activity concentrations of freshly infiltrated groundwater are interpreted as radon groundwater age between the river and a well. A first flood after the restoration operations resulted in a widening of the river bed and in a reduction of the flow distance to the wells. Sixteen days after a second flood, the results of radon measurements were compared with those from before the restoration. The radon age of the groundwater between the river and the wells decreased, probably as a result of the reduction of the flow distances. Concentrations of autochthonous and coliform bacteria increased after the restoration operation and even more one day after the first flood. Thus the findings on the bacteria corroborate the interpretation of the radon concentrations. The restoration has not yet reduced the quality of the groundwater, which is pumped for drinking water. The study is contributing to the solution of land-use conflicts between river restoration and the supply of drinking water from the alluvial groundwater.