Storage and Preservation of Artificial Sweeteners in Groundwater Samples

Compound‐specific standardized sampling and storage methods are not available for artificial sweeteners found in groundwater. This study aimed to understand: (1) the appropriate length of storage time for samples containing acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC) in simulated groundwater (SGW); (2) conditions of their stability; and (3) which sampling materials are appropriate for sample collection. The evaluated storage conditions included acidification, headspace, exposure to light, and refrigeration; the evaluated sampling materials included steel, stainless steel, aluminum, polyvinyl chloride, polyamide (nylon), polypropylene (PharMed BPT?) tubing, styrene‐ethylene‐butylene co‐polymer (MasterFlex?) tubing, and polytetrafluoroethylene (Teflon?) tubing. All compounds evaluated were stable in storage at 4 °C for 241 d (8 months). Concentrations of artificial sweeteners were consistently within 60% to 120% of original concentrations, except ACE and SAC that were substantially lower under acidified conditions at 25 °C after 241 d. Artificial sweetener concentrations remained nearly constant while in contact with all sampling materials except steel. SEM and TEM images showed oxidation of steel occurred; moreover, removal of all artificial sweetener compounds from aqueous solution had occurred after 289 d. These results suggest artificial sweetener analyses conducted within 14 d of sample collection produce optimal results; however, longer storage times may be acceptable under certain conditions. The results also suggest concentrations of artificial sweeteners in SGW are not affected by contact with typical well casing, sampling, and storage materials, with the exception of steel. The findings from this study will improve the use of artificial sweeteners as tracers in environmental studies.     

Concentrations of Artificial Sweeteners and Their Ratios with Nutrients in Septic System Wastewater

This study reports the first comprehensive data set of characteristic concentrations of four artificial sweeteners: acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC), and their ratios with nutrients, for untreated septic system wastewater. Samples were collected from the tanks of 19 different septic systems from across Ontario, Canada; these had a variety of usages, from single‐family cottages to multiple‐dwelling (campground or resort) facilities and had no additional treatment systems. The artificial sweetener concentrations and their relative proportions were highly variable in some cases, both temporally for several individual tanks and from site‐to‐site. Variability tended to be lower for multiple‐dwelling compared to single‐dwelling systems. This variability likely reflects differing use of artificial sweetener‐containing products. The median concentrations for the complete data set of all four artificial sweeteners (in a range of 10 to 60 μg/L) were of a similar order of magnitude, but slightly higher, than has generally been reported for wastewater treatment plant influent (though these vary substantially globally). Both SUC and ACE provided adequate positive linear relationships for dissolved nitrogen and phosphorus in the septic tanks, while a summation of ACE and SUC concentrations also gave a strong correlation. In contrast, CYC and SAC showed poor linear correlation with these nutrients. These reported ranges for artificial sweetener concentrations and ratios with nutrients may be used in future studies to estimate the contributions of nutrients or other wastewater constituents (e.g., pharmaceuticals, bacteria, and viruses) from domestic septic systems to groundwater, including water supply or irrigation wells, and nearby surface water bodies.     

Artificial Sweeteners in a Large Septic Plume

Four artificial sweeteners, acesulfame, sucralose, cyclamate, and saccharin were detected in a large septic plume at Long Point, Ontario, Canada. The pattern of sweetener detections in the groundwater indicated that they were derived from waste water seepage from a large septic system at the site. Acesulfame was pervasive in the septic plume, whereas the other three sweeteners have been attenuated, probably by microbial degradation.     

Use of an Artificial Sweetener to Identify Sources of Groundwater Nitrate Contamination

The artificial sweetener acesulfame (ACE) is a potentially useful tracer of waste water contamination in groundwater. In this study, ACE concentrations were measured in waste water and impacted groundwater at 12 septic system sites in Ontario, Canada. All samples of septic tank effluent (n = 37) had ACE >6 µg/L, all samples of groundwater from the proximal plume zones (n = 93) had ACE >1 µg/L and, almost all samples from the distal plume zones had ACE >2 µg/L. Mean mass ratios of total inorganic nitrogen/ACE at the 12 sites ranged from 680 to 3500 for the tank and proximal plume samples. At five sites, decreasing ratio values in the distal zones indicated nitrogen attenuation. These ratios were applied to three aquifers in Canada that are nitrate‐stressed and an urban stream where septic systems are present nearby to estimate the amount of waste water nitrate contamination. At the three aquifer locations that are agricultural, low ACE values (<0.02‐0.15 µg/L) indicated that waste water contributed <15% of the nitrate in most samples. In groundwater discharging to the urban stream, much higher ACE values (0.2‐11 µg/L) indicated that waste water was the likely source of >50% of the nitrate in most samples. This study confirms that ACE is a powerful tracer and demonstrates its use as a diagnostic tool for establishing whether waste water is a significant contributor to groundwater contamination or not.     

Geochemical Assessment of a Subtropical Reservoir: A Case Study in Curitiba,Southern Brazil

Suspended particles and dissolved substances in water provide reactive surfaces, influence metabolic activity and contribute to the net sediment deposition. It therefore plays an important part in the ecology and quality of the water mass. The water quality in reservoirs is crucial and it is naturally maintained by flushing and sedimentation, which continuously remove phosphorus from the water. In some reservoirs, however, these removal processes are countered by recycling of ions which could play a key role to start and/or maintain the eutrophic state. The combination of macro‐, trace‐ and microanalysis techniques can be useful to trace pollution sources through a chemical fingerprint, whether be during an acute environmental disaster or a long‐term release of pollutants. The water quality and total metal content of reservoir sediments were assessed in a reservoir, situated in the capital of the Paraná State, in the South‐Eastern part of Brazil. The goal of this paper was to determine the metal presence in the sediment and metal and ionic speciation in the Green River reservoir water. Water and bed sediment samples, collected from various sites during 2008 and 2009, were investigated using XRF, ICP‐OES, ICP‐MS, XRD and zeta potential measurements. Based on the results, the heavy metal concentration and chemical composition of the suspended matter in the water samples, as well as the sediment's chemical composition will be discussed.     

Effects of water quality on infiltration,runoff and interrill erosion processes during simulated rainfall

This paper discusses the effects of water quality on the hydrological and erosion response of non‐saline, non‐sodic soils during simulated rain experiments. It is well known that rain water quality affects the behaviour of saline soils. In particular, rain simulation experiments cannot be run using tap water if realistic values of infiltration rates and soil erosion are to be found. This paper reports on similar effects for non‐saline, non‐sodic soils. Two soils – a well‐aggregated clay‐rich soil developed on marine silty clay deposits and a soil developed on silt loam – were selected and subjected to a series of simulated rainstorms using demineralized water and tap water. The experiments were conducted in two different laboratories in order to obtain results independent of the tap water quality or the rainfall simulator characteristics. The results indicate that time‐to‐ponding is largely delayed by solute‐rich water (tap water). When tap water is used, infiltration rates are significantly overestimated, i.e. by more than 100 per cent. Interrill erosion rates increase by a factor of 2·5–3 when demineralized water is used. The silty clay soil was more affected by the water quality than the silt loam soil, with respect to infiltration and runoff production. Regarding interrill erosion rates, the two tested soils were similarly affected by the water quality. Therefore, it can be concluded that rainfall simulation experiments with non‐dispersive soils (e.g. non‐saline, non‐sodic) must also be conducted using water with very low electrical conductivity (i.e. less than 30–50 µS cm⁻¹), close to that of distilled water. The use of tap water certainly hampers comparisons and the relative ranking of the hydrological and erosion response of different soils, while parameter values, such as final infiltration rate or time‐to‐ponding, cannot be extrapolated and extended to natural situations. Therefore, the majority of hydrological and erosion models and parameter values measured during rainfall simulations in the past should be used with caution for all types of soils. Copyright © 2001 John Wiley & Sons, Ltd.     

Hydrocarbon‐Rich Groundwater above Shale‐Gas Formations: A Karoo Basin Case Study

Horizontal drilling and hydraulic fracturing have enhanced unconventional hydrocarbon recovery but raised environmental concerns related to water quality. Because most basins targeted for shale‐gas development in the USA have histories of both active and legacy petroleum extraction, confusion about the hydrogeological context of naturally occurring methane in shallow aquifers overlying shales remains. The Karoo Basin, located in South Africa, provides a near‐pristine setting to evaluate these processes, without a history of conventional or unconventional energy extraction. We conducted a comprehensive pre‐industrial evaluation of water quality and gas geochemistry in 22 groundwater samples across the Karoo Basin, including dissolved ions, water isotopes, hydrocarbon molecular and isotopic composition, and noble gases. Methane‐rich samples were associated with high‐salinity, NaCl‐type groundwater and elevated levels of ethane, ⁴He, and other noble gases produced by radioactive decay. This endmember displayed less negative δ¹³C‐CH₄ and evidence of mixing between thermogenic natural gases and hydrogenotrophic methane. Atmospheric noble gases in the methane‐rich samples record a history of fractionation during gas‐phase migration from source rocks to shallow aquifers. Conversely, methane‐poor samples have a paucity of ethane and ⁴He, near saturation levels of atmospheric noble gases, and more negative δ¹³C‐CH₄; methane in these samples is biogenic and produced by a mixture of hydrogenotrophic and acetoclastic sources. These geochemical observations are consistent with other basins targeted for unconventional energy extraction in the USA and contribute to a growing data base of naturally occurring methane in shallow aquifers globally, which provide a framework for evaluating environmental concerns related to unconventional energy development (e.g., stray gas).     

Effect of Rigid PVC Bailer Contact on Detection of Pesticides in Water Samples

A field experiment was conducted to examine the effect of short-term (one minute) contact of pesticide-laden water with a polyvinyl chloride (PVC) bailer on quantitative laboratory measurements of seven pesticide concentrations in distilled water samples subsequently decanted from the bailer. Pesticides were tested at two initial concentrations (low. based on current FPA maximum contaminant levels, or MCL: and high, based on a multiple of approximately lour times the MCL). Pesticide species included bromoxynil, diclofop-m, dimethoate. MCPA, methyl parathion, propiconazole, and trifluralin. Dimethoate recoveries were poor for all treatments. For all other pesticides there was no systematic difference between pesticide concentrations measured before and after bailer contact. Effectiveness of bailer decontamination treatments consisting of distilled water rinse alone was related to water solubility (S) for each species. Distilled water samples decanted from a rigid PVC bailer following initial bailer contact with pesticide-spiked water, and after the bailer had been cleaned with a single distilled water rinse, had measured pesticide concentrations of less than 2 percent of the pesticide concentration in the initial pesticide-spiked water, regardless of S. A single distilled water rinse effectively removed all trace of contaminants having S> 500 mg/L. Multiple distilled water rinses, and multiple distilled water rinses followed by 15 bailings of a well, effectively removed all trace of contaminants having S> 50 mg/L. Below threshold S, cleaning effectiveness decreased as a power function of S.     

A preliminary assessment of the spatial sources of contemporary suspended sediment in the Ohio River basin,United States,using water quality data from the NASQAN programme in a source tracing procedure

Reliable information on catchment scale suspended sediment sources is required to inform the design of management strategies for helping abate the numerous environmental issues associated with enhanced sediment mobilization and off‐site loadings. Since sediment fingerprinting techniques avoid many of the logistical constraints associated with using more traditional indirect measurement methods at catchment scale, such approaches have been increasingly reported in the international literature and typically use data sets collected specifically for sediment source apportionment purposes. There remains scope for investigating the potential for using geochemical data sets assembled by routine monitoring programmes to fingerprint sediment provenance. In the United States, routine water quality samples are collected as part of the US Geological Survey's revised National Stream Quality Accounting Network programme. Accordingly, the geochemistry data generated from these samples over a 10‐year period (1996–2006) were used as the basis for a fingerprinting exercise to assess the key tributary sub‐catchment spatial sources of contemporary suspended sediment transported by the Ohio River. Uncertainty associated with the spatial source estimates was quantified using a Monte Carlo approach in conjunction with mass balance modelling. Relative frequency weighted means were used as an alternative way of summarizing the spatial source contributions, thereby avoiding the need to use confidence limits. The results should be interpreted in the context of the routine, but infrequent nature, of the suspended sediment samples used to assemble geochemistry as a basis for the sourcing exercise. Nonetheless, the study demonstrates how routine monitoring samples can be used to provide some preliminary information on sediment provenance in large drainage basins. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel device with macrophytes and bio balls as a rehabilitation tool for small eutrophic urban ponds: a mesocosm approximation

During the last century, the human-derived impact on freshwater systems has been severe all around the world. Artificial eutrophication has an outstanding relevance in urban aquatic ecosystems and it is recognized as one of the most common problems associated with water deterioration in urban lakes and ponds. Therefore, more studies regarding the trophic interactions and the potential rehabilitation methods should be encouraged. Our aim is to evaluate at a mesocosm scale, a device composed of native aquatic plants, either submerged (SPD) or floating (FPD), including an extra artificial potential refuge (bio balls rolls) for zooplankton as a rehabilitation tool for urban ponds. As regards the impact of the tested devices on water quality variables, FPD provoked a decrease in TP and pH. In turns, SPD maintained the dissolved oxygen concentrations above those registered in FPD. Transparency was significantly higher in the presence of plants at final time. Differences in phytoplankton morpho-functional group diversity and zooplankton functional feeding groups were registered by the end of the experiment. Zooplankton abundance at the artificial refuges was higher than at the water column; a study of the efficiency of the bio balls rolls as potential active/passive refugees is merited.Considering benefits on water quality variables, we suggest that a device combining floating macrophytes plus the bio ball rolls deserves to be further tested at a greater scale in order to be considered as a water rehabilitation tool, including plant harvest.     

Evolution study of a regional groundwater system using hydrochemistry and stable isotopes in Songnen Plain,northeast China

Groundwater is often a critical source of water for municipal, industrial and agricultural uses, especially in arid and semi‐arid environments. Songnen Plain, located in the central part of northeast China, is such a region, it being an important productive base of commodity grain in this country. In the past two decades, groundwater quality in the region, especially salinization, has deteriorated under natural changes and human activities, and has become a crucial factor restricting sustainable eco‐environmental and socio‐economic development. In this paper, The Taoer River catchment, situated in the middle of the region, was selected as the study area for the groundwater quality evolution study using hydrochemistry and stable isotopes to obtain a better understanding of the system. Fifty‐two groundwater samples were collected with systematic design during the low‐water and high‐water periods in 2003. A series of comprehensive quality data interpretations, e.g. statistics, ratios of ions and Piper diagrams, together with stable isotope data, have been used to gain an insight into the spatial and temporal variations and evolution laws of groundwater hydrochemistry. The following main hydrochemical processes were identified as controlling the water quality of the groundwater system: weathering–dissolution, evaporation–condensation, ion‐exchange reactions and groundwater salinization. This latter process, salinization, is the most important process and is caused by the leaching of superficial or near‐surface salts from the saline–alkaline soil into shallow groundwater. Copyright © 2006 John Wiley & Sons, Ltd.     

The Effect of Latex Gloves and Nylon Cord on Ground Water Sample Quality

Eighteen sites in South Carolina under investigation by the Superfund program were sampled to determine ambient ground water quality. Samples from 11 of 15 monitoring wells sampled with a bailer contained either caprolactam or Santowhite® (a registered trademark of the Monsanto Co.) or both organic compounds. A maximum of 540 μg/L of caprolactam and 780 μg/L of Santowhite was observed in the samples from the monitoring wells. None of the samples collected using dedicated submersible pumps at 28 other wells contained either compound.
Caprolactam is used in the manufacturing of nylon cord, and Santowhite is used as an antioxidant in latex gloves. Therefore, it was suspected that the nylon cord used to raise and lower the bailer and the latex gloves that were worn during sampling may have contributed the caprolactam and Santowhite to the sample.
An experiment using pH-adjusted distilled water and private well water revealed that the nylon cord and the latex gloves may contribute contaminants to ground water samples. Research is needed into the potential for caprolactam and Santowhite to interfere with laboratory analyses in addition to the potential for absorption of contaminants by nylon cord. Until additional information is available, alternative materials or sampling techniques should be considered to minimize the potential impact of nylon cord and latex gloves on the quality of bailed samples.     

Arsenic Removal from Natural Groundwater Using Cupric Oxide

Groundwater is a main source of drinking water for some rural areas. People in these rural areas are potentially at risk from elevated levels of arsenic (As) due to a lack of water treatment facilities. The objectives of this study were to (1) measure As concentrations in approximately 50 groundwater samples from rural domestic wells in the western United States, (2) explore the potential of cupric oxide (CuO) particles in removal of As from groundwater samples under natural conditions (i.e., without adding competing anions and adjusting the pH or oxidation state), and (3) determine the effects of As removal on the chemistry of groundwater samples. Forty‐six groundwater well samples from rural domestic areas were tested in this study. More than 50% of these samples exceeded the U.S. Environmental Protection Agency Maximum Contaminant Limit (US EPA MCL) of 10 µg/L for As. CuO particles effectively removed As from groundwater samples across a wide range of pH (7.11 and 8.95) and concentrations of competing anions including phosphate (<0.05 to 3.06 mg/L), silica (<1 to 54.5 mg/L), and sulfate (1.3 to 735 mg/L). Removal of As showed minor effects on the chemistry of groundwater samples, therefore most of the water quality parameters remained within the US EPA MCLs. Overall, results of this study could help develop a simple one‐step process to remove As from groundwater.     

乌鲁木齐地区水汞空白值较高原因分析

从蒸馏水的制备过程及乌鲁木齐10号泉的化学成份等方面入手，通过分析认为乌鲁木齐水汞空白值较高的原因是：①在蒸馏水的制备过程中自来水中汞富集到蒸馏水中；②乌鲁木齐10号泉水中含有较高的S^2-，使10号泉水汞测值偏低。另外，还探讨了如何利用水汞空白值来处理水汞资料，从而提高水汞观测资料的质量及其在地震分析预报中的作用。     

Detecting Virus‐Like Particles from the Umgeni River,South Africa

It is important to consider viruses in water quality because of their incidence as causal agents for diarrhoeal disease, and due to their characteristics, which allow them to survive in changing environmental conditions indefinitely. This study assessed the viral quality of the Umgeni River in South Africa seasonally. A two‐step tangential flow filtration process was setup to remove the bacteria and to concentrate the virus populations from large volume water samples. The concentrated water samples contained up to 659 and 550 pfu/mL of somatic and F‐RNA coliphages, respectively. Several virus families including Adenoviridae, Herpesviridae, Orthomyxoviridae, Picornaviridae, Poxviridae and Reoviridae were found in the river based on the morphologies examined under transmission electron microscopy. All concentrated water samples produced substantial cytopathic effects on the Vero, HEK 293, Hela and A549 cell lines. These results indicate the potential of viruses in the water samples especially from the lower catchment areas of the Umgeni River to infect human hosts throughout the year. The present study highlights the importance of routine environmental surveillance of human enteric viruses in water sources. This can contribute to a better understanding of the actual burden of disease on those who might be using the water directly without treatment.

     

Using a topographic index to distribute variable source area runoff predicted with the SCS curve‐number equation

Because the traditional Soil Conservation Service curve‐number (SCS‐CN) approach continues to be used ubiquitously in water quality models, new application methods are needed that are consistent with variable source area (VSA) hydrological processes in the landscape. We developed and tested a distributed approach for applying the traditional SCS‐CN equation to watersheds where VSA hydrology is a dominant process. Predicting the location of source areas is important for watershed planning because restricting potentially polluting activities from runoff source areas is fundamental to controlling non‐point‐source pollution. The method presented here used the traditional SCS‐CN approach to predict runoff volume and spatial extent of saturated areas and a topographic index, like that used in TOPMODEL, to distribute runoff source areas through watersheds. The resulting distributed CN–VSA method was applied to two subwatersheds of the Delaware basin in the Catskill Mountains region of New York State and one watershed in south‐eastern Australia to produce runoff‐probability maps. Observed saturated area locations in the watersheds agreed with the distributed CN–VSA method. Results showed good agreement with those obtained from the previously validated soil moisture routing (SMR) model. When compared with the traditional SCS‐CN method, the distributed CN–VSA method predicted a similar total volume of runoff, but vastly different locations of runoff generation. Thus, the distributed CN–VSA approach provides a physically based method that is simple enough to be incorporated into water quality models, and other tools that currently use the traditional SCS–CN method, while still adhering to the principles of VSA hydrology. Copyright © 2004 John Wiley & Sons, Ltd.     

Nonlinear structure‐enhancing filtering using plane‐wave prediction*

Attenuation of random noise and enhancement of structural continuity can significantly improve the quality of seismic interpretation. We present a new technique, which aims at reducing random noise while protecting structural information. The technique is based on combining structure prediction with either similarity‐mean filtering or lower‐upper‐middle filtering. We use structure prediction to form a structural prediction of seismic traces from neighbouring traces. We apply a non‐linear similarity‐mean filter or an lower‐upper‐middle filter to select best samples from different predictions. In comparison with other common filters, such as mean or median, the additional parameters of the non‐linear filters allow us to better control the balance between eliminating random noise and protecting structural information. Numerical tests using synthetic and field data show the effectiveness of the proposed structure‐enhancing filters.     

Effects of the sea floor topography on the 1D inversion of time‐domain marine controlled source electromagnetic data

Time‐domain marine controlled source electromagnetic methods have been used successfully for the detection of resistive targets such as hydrocarbons, gas hydrate, or marine groundwater aquifers. As the application of time‐domain marine controlled source electromagnetic methods increases, surveys in areas with a strong seabed topography are inevitable. In these cases, an important question is whether bathymetry information should be included in the interpretation of the measured electromagnetic field or not. Since multi‐dimensional inversion is still not common in time‐domain marine controlled source electromagnetic methods, bathymetry effects on the 1D inversion of single‐offset and multi‐offset joint inversions of time‐domain controlled source electromagnetic methods data are investigated. We firstly used an adaptive finite element algorithm to calculate the time‐domain controlled source electromagnetic methods responses of 2D resistivity models with seafloor topography. Then, 1D inversions are applied on the synthetic data derived from marine resistivity models, including the topography in order to study the possible topography effects on the 1D interpretation. To evaluate the effects of topography with various steepness, the slope angle of the seabed topography is varied in the synthetic modelling studies for deep water (air interaction is absent or very weak) and shallow water (air interaction is dominant), respectively. Several different patterns of measuring configurations are considered, such as the systems adopting nodal receivers and the bottom‐towed system. According to the modelling results for deep water when air interaction is absent, the 2D topography can distort the measured electric field. The distortion of the data increases gradually with the enlarging of the topography's slope angle. In our test, depending on the configuration, the seabed topography does not affect the 1D interpretation significantly if the slope angle is less or around 10°. However, if the slope angle increases to 30° or more, it is possible that significant artificial layers occur in inversion results and lead to a wrong interpretation. In a shallow water environment with seabed topography, where the air interaction dominates, it is possible to uncover the true subsurface resistivity structure if the water depth for the 1D inversion is properly chosen. In our synthetic modelling, this scheme can always present a satisfactory data fit in the 1D inversion if only one offset is used in the inversion process. However, the determination of the optimal water depth for a multi‐offset joint inversion is challenging due to the various air interaction for different offsets.     

Small-scale spatial variation of benthic algal assemblages in a peat bog

Spatial patterns on a very small scale (10 cm), and the effect of artificial barriers on the composition of phytobenthic algal assemblages along two transects within different microhabitat types were investigated. Samples were taken in a peat bog along linear transects on a scale of 10 cm, and water chemistry was examined. The distribution of algae along both transects was influenced by both spatial distance and environmental conditions in similar proportions. Differences in species composition in various parts of the transects were observed, but this pattern was primarily related to the abundance of species, rather than to their presence/absence in samples. Similarity in species composition correlated with spatial distance and environmental parameters in both microhabitat types. I concluded that, given a homogenous environment on a small scale, spatial distribution of algae is affected by both the environmental conditions of the microhabitats and their dispersal limitations. Moreover, an artificial barrier constituted an obstruction for water and nutrient flow, as well as algal migration, and had an impact on species composition.