Predicting the impact and duration of persistent and mobile organic compounds in groundwater systems using a contaminant mass discharge approach.

This study investigated methods for predicting the duration and impact on groundwater quality from persistent and mobile organic compounds (PMOCs) at a drinking water well field affected by multiple contaminant sources. The fungicide metabolite N,N-dimethylsulfamide (DMS), which frequently occurs above the Danish groundwater quality criterion (0.1 µg/L), was used as an example. By combining contaminant mass discharge (CMD) estimations, modeling, and groundwater dating, a number of important discoveries were made. The current center of contaminant mass was located near the source area. The CMD at the well field was predicted to peak in 2040, and an effect from the investigated sources on groundwater quality could be expected until the end of the 21st century. A discrepancy in the current CMD at the well field and the estimated arrival time from the studied source area suggested an additional pesticide source, which has not yet been thoroughly investigated. The presence of the unknown source was supported by model simulations, producing an improved mass balance after inclusion of a contaminant source closer to the well field. The approach applied here was capable of predicting the duration and impact of DMS contamination at a well field at catchment scale. It furthermore shows potential for identification and quantification of the contribution from individual sources, and is also applicable for other PMOCs. Predicting the duration of the release and impact of contaminant sources on abstraction wells is highly valuable for water resources management and authorities responsible for contaminant risk assessment, remediation, and long-term planning at water utilities.

Long-term leaching through clayey till of N,N-dimethylsulfamide, a Persistent and Mobile Organic Compound (PMOC).

Environmental pollution with Persistent and Mobile Organic Compounds (PMOC) from anthropogenic activities is an increasing cause for concern. These compounds are readily leached to groundwater aquifers and are likely to resist degradation, putting pressure on groundwater resources. Pesticides can form PMOCs upon degradation in the environment. The PMOC N,N-dimethylsulfamide (DMS) was the most frequently detected pesticide metabolite in Danish drinking water wells in 2020, although the pesticidal use of the last parent compound (tolylfluanid) ended in 2007. This study aimed to improve the understanding of the leaching of the PMOC DMS from clayey tills by combining a review of compound properties, sources and use, comprehensive field observations and numerical flow and solute transport modeling. The modeling explored the mechanisms of DMS retention during vertical transport in clayey till and the fingerprint in the underlying aquifer. The results were supported by detailed field observations at an agricultural site with strawberry production. Porewater samples were collected from clayey till to a depth of 12 m bgs by a custom designed installation method of suction cups. Groundwater sampling (249 samples) was designed to provide vertical concentration profiles at various distances from the presumed sources. The review of properties showed that the parent compounds and intermediates degrade quickly in topsoil, releasing the highly persistent and mobile DMS. We tested the effect of fractures on transport with different hydraulic apertures and a scenario without fractures by numerical modeling. The results showed that the presence of fractures can smooth the breakthrough curve below the clayey till, leading to faster breakthrough, lower maximum concentration, and several decades of prolonged leaching in simulations with the largest aperture (20 µm). The fracture-matrix interaction is a possible explanation for the observed delay of leaching from clayey till. The vertical concentration profiles in groundwater were used for identifying the sources at the field site and testing source strengths. Assigning one point source (200 µg/L) and two diffuse sources (40-50 µg/L) to the model produced vertical concentration profiles that compared well with observed field data in clayey till and the aquifer. All results were integrated into a conceptual model for the environmental fate of PMOCs in soil and groundwater. The findings of this study imply that the presence of fractures in clayey till should be considered in conceptual site models, since they can substantially prolong the leaching of PMOCs to groundwater. The integration of comprehensive field investigations and numerical modeling is key to understand the fate of PMOCs in complex field systems with different source types. Together with widespread occurrences of PMOCs in groundwater systems, the results highlight the need for improved approval procedures for pesticides and biocides which considers their persistent and mobile metabolites.

Increasing market opportunities for renewable energy technologies with innovations in aquifer thermal energy storage.

Heating and cooling using aquifer thermal energy storage (ATES) has hardly been applied outside the Netherlands, even though it could make a valuable contribution to the energy transition. The Climate-KIC project "Europe-wide Use of Energy from aquifers" - E-USE(aq) - aimed to pave the way for Europe-wide application of ATES, through the realization and monitoring of six ATES pilot plants across five different EU countries. In a preceding paper, based on preliminary results of E-USE(aq), conclusions were already drawn, demonstrating how the barriers for this form of shallow geothermal energy can be overcome, and sometimes even leveraged as opportunities. Based on final pilot project results, key economic and environmental outcomes are now presented. This paper starts with the analysis of specific technological barriers: unfamiliarity with the subsurface, presumed limited compatibility with existing energy provision systems (especially district heating), energy imbalances and groundwater contamination. The paper then shows how these barriers have been tackled, using improved site investigation and monitoring technologies to map heterogeneous subsoils. In this way ATES can cost-efficiently be included in smart grids and combined with other sources of renewable (especially solar) energy, while at the same time achieving groundwater remediation. A comparative assessment of economic and environmental impacts of the pilots is included, to demonstrate the sustainability of ATES system with different renewables and renewable-based technologies. The paper concludes with an assessment of the market application potential of ATES, including in areas with water scarcity, and a review of climate beneficial impact.

The effect of a compression bandage on the distribution of radiodense contrast medium after palmar digital nerve blocks.

BACKGROUND: Studies have shown proximal diffusion of injected drugs in perineural blocks; such diffusion may affect specificity of the nerve block. OBJECTIVES: To investigate the effect of a compression bandage applied to the pastern region on proximal diffusion of contrast medium injected over the palmar digital nerves. STUDY DESIGN: Experimental study, randomised cross-over design. METHODS: Radiodense contrast medium was injected over the lateral and medial palmar digital nerves of the left front limb of nine mature horses. Each horse was injected on two separate occasions, once with a 5 cm wide compression bandage applied proximal to the injection site and once without. The order of the two treatments was randomised with a wash-out period between treatments of at least 7 days. Radiographs were obtained at 5, 10, 20 and 30 min and distribution of the contrast column assessed. RESULTS: Proximal distribution of the contrast medium was significantly reduced (P<0.01) with compression bandage. Furthermore, the compression bandage inhibited lymphatic drainage of the injected contrast medium. MAIN LIMITATIONS: Clinical effect of the differences in diffusion length was not assessed. CONCLUSIONS: The compression bandage reduced proximal diffusion and lymphatic drainage of contrast material causing it to stay localised around the injection site. Use of compression bandages could thus result in increased specificity of the nerve block and potentially prolong its effect.

Physiological parameters of endurance horses pre- compared to post-race, correlated with performance: a two race study from scandinavia.

Few studies have investigated the physiological parameters of endurance horses in Scandinavia. Hence, this two race study has focused on the effects of endurance racing in terms of equine clinicopathological blood parameters, heart score, and fluid use. Race A involved 15 horses (120 km). Two pre- and one post-race blood samples were taken, body condition score was assessed in triplicate pre-race, and an ECG was used to determine heart score. Race B involved 16 horses (65-120 km). One pre- and two post-race blood samples were taken. For both races, horse data as well as fluid intake estimates and cooling water were noted. Race A showed that blood haematocrit, albumin, sodium, and triglycerides increased significantly with endurance racing, whilst chloride, glucose, iron, and potassium decreased significantly. In race B, blood creatinine, cholesterol, and inorganic phosphate continued to increase significantly during the first post-race sampling period compared to pre-race levels, whilst iron, which decreased significantly during the race, increased significantly over the two post-race sampling periods. It is concluded that whilst no correlation between heart score and speed was observed, a significant correlation exists between experience and changes in blood parameters with endurance racing and between fluid intake and average speed.

Effect of a stent bandage on the likelihood of incisional infection following exploratory coeliotomy for colic in horses: a comparative retrospective study.

REASONS FOR PERFORMING STUDY: Incisional infections are common in horses after colic surgery. There is a clinical impression that the use of a stent bandage reduces the prevalence of such infections. OBJECTIVE: To determine the effect of a stent bandage on the likelihood of incisional infection after ventral midline exploratory coeliotomy. It was hypothesised that the use of a stent bandage would reduce the likelihood of incisional infection. METHODS: Medical records of horses that underwent exploratory coeliotomy for colic between January 2005 and September 2011 were reviewed. Inclusion criteria were animals that had one ventral midline coeliotomy and had survived at least 10 days after surgery. Horses were categorised into 2 groups:no-stent group and stent group. The following data were collected for each case: age, sex, weight, heart rate, packed cell volume, primary lesion, performance of an enterotomy or intestinal resection, surgical classification, use of local antimicrobials, duration of surgery, intra-abdominal administration of sodium carboxymethylcellulose, intravenous administration of lidocaine, surgeon, use of a stent bandage, duration of stent use, and use of a belly band. Factors associated with the outcome measure 'wound infection' vs. 'no wound infection' were analysed using a generalised linear mixed model for logistic regression with surgeon as a random effect. RESULTS: The inclusion criteria were met in 130 horses: 55 were assigned to the no-stent group and 75 to the stent group. In the no-stent group, 12 (21.8%) horses developed incisional infections, whereas only 2 horses (2.7%) in the stent group had incisional infections. In the stent group, no incisional infections were observed during the last 20 months of the study. Statistical analysis showed that only the effect of the use of a stent bandage was significant (P = 0.005). CONCLUSIONS: The prevalence of incisional infections when a stent bandage was used was 2.7%, a finding that compared favourably to information in the literature. Use of a stent bandage significantly reduced the likelihood of incisional infections. POTENTIAL RELEVANCE: A stent bandage would reduce the likelihood of incisional infection in horses undergoing exploratory coeliotomy for colic.

Sporting activity following colic surgery in horses: a retrospective study.

REASONS FOR PERFORMING STUDY: There is a paucity of studies addressing sporting activity and horse owners' satisfaction after horses have undergone colic surgery. OBJECTIVES: To determine 1) survival rate after colic surgery, 2) prevalence of horses returning to, or starting, sporting activities and 3) assess the owners' satisfaction regarding colic surgery. METHODS: Cases that underwent exploratory celiotomy for colic between January 2005 and August 2010 were reviewed. All horses that had one or more celiotomies and were discharged after colic surgery were included in a telephone questionnaire survey. Only horses that survived at least 6 months after colic surgery were included in the sporting activity analysis. Data extracted from the records included case details, intra-operative diagnosis and surgical treatment. Information from a telephone questionnaire included the horses' post surgical details (horse alive or subjected to euthanasia, post operative complications, pre- and post surgical use, return to sporting activity, sporting performance, behavioural changes, management changes and recommendation by owner for colic surgery). A logistic regression model was used for the statistical analysis of post hospitalisation performance and an ordinal regression model used for analysis of post colic complications and of owner's recommendation of surgery. A Kaplan-Meier survival curve was computed to show survival of horses discharged after colic surgery. RESULTS: The survival rates (%) at 6, 12, 24, 36, 48 and 60 months were 95.3, 86.6, 80.9, 76.9, 62.1 and 57.6, respectively. A large majority of horses (86.1%) resumed or started sporting activities after colic surgery. The proportion of horses that the owners believed to achieve the same or better performance after surgery was 83.5%. In 89.9% of the cases, owners stated that they would recommend colic surgery. CONCLUSIONS: Horses discharged after colic surgery had a high long-term survival rate. A high prevalence of horses resumed or started sporting activities with a high proportion of horses at their presurgical performance level. The large majority of owners of discharged horses were satisfied with colic surgery performed on their horses.

Composition of leachate from old landfills in Denmark.

The Danish counties have performed numerous investigations of old landfills. These investigations have been presented in several reports, but no comprehensive summary of the findings has been carried out. The objective of this study was to evaluate the typical composition of leachates from old smaller landfills by a comprehensive review of the investigations carried out by the counties. In total 106 landfills were selected by criteria avoiding dilution effects. A database was constructed using a standard program. Statistical evaluations showed that the leachate concentrations in general decreased with the age of the landfill, and that the leachate concentrations were lower than found in other similar studies.

Lateral gas transport in soil adjacent to an old landfill: factors governing gas migration.

Field experiments investigating lateral gas transport in soil adjacent to an old landfill in Denmark during a one-year period were conducted. A significant seasonal variation, with low concentrations of methane and high concentrations of carbon dioxide in the summer, caused by methane oxidation was observed. There was a good correlation between pressure above the barometric pressure and the methane concentration in the soil, indicating that advective flow was the controlling process. This was confirmed by calculations. Diurnal measurement during a drop in barometric pressure showed that lateral migration of landfill gas was a very dynamic system and the concentrations of LFG at a specific place and depth changed dramatically within a very short time. The experiments showed that change in barometric pressure was an important factor affecting gas migration at the Skellingsted landfill in Denmark.

Lateral gas transport in soil adjacent to an old landfill: factors governing gas migration.

Field experiments investigating lateral gas transport in soil adjacent to an old landfill in Denmark during a one-year period were conducted. A significant seasonal variation, with low concentrations of methane and high concentrations of carbon dioxide in the summer, caused by methane oxidation was observed. There was a good correlation between pressure above the barometric pressure and the methane concentration in the soil, indicating that advective flow was the controlling process. This was confirmed by calculations. Diurnal measurement during a drop in barometric pressure showed that lateral migration of landfill gas was a very dynamic system and the concentrations of LFG at a specific place and depth changed dramatically within a very short time. The experiments showed that change in barometric pressure was an important factor affecting gas migration at the Skellingsted landfill in Denmark.

Macroporous silicon electrical sensor for DNA hybridization detection.

Macroporous silicon (pore diameter 1-2 microm) was used in an electrical sensor for real time, label free detection of DNA hybridization. Electrical contacts were made exclusively on the back side of the substrate, which allowed complete exposure of the porous layer to DNA. Hybridization of a DNA probe with its complementary sequence produced a reduction in the impedance and a shift in the phase angle resulting from a change in dielectric constant inside the porous matrix and a modification of the depletion layer width in the crystalline silicon structure. The effect of the DNA charge on the response was corroborated using peptide nucleic acid (PNA), an uncharged analog of DNA. The sensitivity and selectivity of the device were characterized and the sensing properties of the porous layer alone were investigated using self-supporting macroporous silicon membranes.

Lateral gas transport in soil adjacent to an old landfill: factors governing emissions and methane oxidation.

Field investigations of lateral gas transport and subsequent emissions in soil adjacent to an old landfill in Denmark were conducted during a 1-year period. A significant seasonal variation in the emissions with high carbon dioxide and low methane fluxes in the summer (May to October) was observed. This was attributed to methane oxidation. Diurnal measurements during a drop in barometric pressure showed that the fluxes of landfill gas changed dramatically within a very short time. The concentrations and the soil moisture content in the upper part of the soil profile had significant influence on the fluxes, as did the distance from the landfill border, temperature, barometric pressure and the pressure gradient. Statistical analyses proved that soil moisture described the largest part of the variation. No methane is emitted during the summer. Calculations and isotope analyses showed that very high fractions of the laterally migrating methane were oxidised.

Lateral gas transport in soil adjacent to an old landfill: factors governing emissions and methane oxidation.

Field investigations of lateral gas transport and subsequent emissions in soil adjacent to an old landfill in Denmark have been conducted during a one-year period. A significant seasonal variation in the emissions with high carbon dioxide and low methane fluxes in the summer (May to October) was observed. This was attributed to methane oxidation. Diumal measurements during a drop in barometric pressure showed that the fluxes of landfill gas changed dramatically within a very short time. The concentrations and the soil moisture content in the upper part of the soil profile had significant influence on the fluxes, as did the distance from the landfill border, temperature, barometric pressure and the pressure gradient. Statistical analyses proved that soil moisture described the largest part of the variation. No methane at all emitted during the summer. Calculations and isotope analyses showed that very high fractions of the laterally migrating methane were oxidised.

MnSOD expression is increased in metastatic gastric cancer.

BACKGROUND: Manganese superoxide dismutase (MnSOD) catalyzes the scavenging of superoxide radicals in order to protect cells from the damage caused by reactive oxygen species. Previous studies implicate MnSOD in cancer progression, but its role in gastric cancer metastasis is poorly understood. MATERIALS AND METHODS: To determine whether MnSOD expression correlates with gastric cancer metastasis, we compared immunostaining for MnSOD in the primary tumors of gastric cancer patients with (n = 15) and without (n = 9) nodal metastases. These patients were matched for risk factors associated with gastric cancer metastasis, such as tumor site, depth, and grade. MnSOD expression was scored positive (increased) if MnSOD staining of tumor cells was more intense than MnSOD staining in corresponding normal gastric epithelial cells. Statistical analyses were via chi(2) test and Fisher's exact test. RESULTS: MnSOD expression was increased in 14 of the 15 (93%) metastatic tumors, compared to only 4 of the 9 (44%) nonmetastatic tumors (P = 0.015). There was no significant difference in staining when the two groups were compared based on tumor grade (P = 0.70) or depth of tumor cell invasion (T stage) (P = 0.22). CONCLUSIONS: MnSOD expression is upregulated in the primary tumors of gastric cancer patients with lymph node metastases. This finding supports an involvement of MnSOD and possibly the reactive oxygen status of the gastric tumor microenvironment in gastric cancer metastasis.