Comparison of Four Carbapenemase Detection Methods for blaKPC-2 Variants

Rural communities often rely on groundwater for potable water supply. In this study, untreated groundwater samples from 28 shallow groundwater wells in Finland (&#x003C;10 m deep and mostly supplying untreated groundwater to &#x003C;200 users in rural areas) were assessed for physicochemical water quality, stable water isotopes, microbial water quality indicators, host-specific microbial source tracking (MST) markers, and bacterial community composition, activity, and diversity (using amplicon sequencing of the 16S rRNA gene and 16S rRNA). Indications of surface water intrusion were identified in five wells, and these indications were found to be negatively correlated, overall, with bacterial alpha diversity (based on amplicon sequencing of the 16S rRNA gene). High levels of turbidity, heterotrophs, and iron compromised water quality in two wells, with values up to 2.98 nephelometric turbidity units (NTU), 16,000 CFU/ml, and 2,300&#x2009;&#x03BC;g/liter, respectively. Coliform bacteria and general fecal indicator <italic>Bacteroidales</italic> bacteria (GenBac3) were detected in 14 and 10 wells, respectively (albeit mostly at low levels), and correlations were identified between microbial, physicochemical, and environmental parameters, which may indicate impacts from nearby land use (e.g., agriculture, surface water, road salt used for deicing). Our results show that although water quality was generally adequate in most of the studied wells, the continued safe use of these wells should not be taken for granted.</p> <p><bold>IMPORTANCE</bold> Standard physicochemical water quality analyses and microbial indicator analyses leave much of the (largely uncultured) complexity of groundwater microbial communities unexplored. This study combined these standard methods with additional analyses of stable water isotopes, bacterial community data, and environmental data about the surrounding areas to investigate the associations between physicochemical and microbial properties of 28 shallow groundwater wells in Finland. We detected impaired groundwater quality in some wells, identified potential land use impacts, and revealed indications of surface water intrusion which were negatively correlated with bacterial alpha diversity. The potential influence of surface water intrusion on groundwater wells and their bacterial communities is of particular interest and warrants further investigation because surface water intrusion has previously been linked to groundwater contamination, which is the primary cause of waterborne outbreaks in the Nordic region and one of the major causes in the United States and Canada. IMPORTANCE Standard physicochemical water quality analyses and microbial indicator analyses leave much of the (largely uncultured) complexity of groundwater microbial communities unexplored. This study combined these standard methods with additional analyses of stable water isotopes, bacterial community data, and environmental data about the surrounding areas to investigate the associations between physicochemical and microbial properties of 28 shallow groundwater wells in Finland. We detected impaired groundwater quality in some wells, identified potential land use impacts, and revealed indications of surface water intrusion which were negatively correlated with bacterial alpha diversity. The potential influence of surface water intrusion on groundwater wells and their bacterial communities is of particular interest and warrants further investigation because surface water intrusion has previously been linked to groundwater contamination, which is the primary cause of waterborne outbreaks in the Nordic region and one of the major causes in the United States and Canada.

Double diffusion, shear instabilities, and heat impacts of a Pacific Summer Water intrusion in the Beaufort Sea

Pacific Summer Water eddies and intrusions transport heat and salt from boundary regions into the western Arctic basin. Here we examine concurrent effects of lateral stirring and vertical mixing using microstructure data collected within a Pacific Summer Water intrusion with a length scale of ∼20 km. This intrusion was characterized by complex thermohaline structure in which warm Pacific Summer Water interleaved in alternating layers of O(1 m) thickness with cooler water, due to lateral stirring and intrusive processes. Along interfaces between warm/salty and cold/fresh water masses, the density ratio was favorable to double-diffusive processes. The rate of dissipation of turbulent kinetic energy (ε) was elevated along the interleaving surfaces, with values up to 3×10−8 W kg−1 compared to background ε of less than 10−9 W kg−1. Based on the distribution of ε as a function of density ratio Rρ , we conclude that double-diffusive convection is largely responsible for the elevated ε observed over the survey. The lateral processes that created the layered thermohaline structure resulted in vertical thermohaline gradients susceptible to double-diffusive convection, resulting in upward vertical heat fluxes. Bulk vertical heat fluxes above the intrusion are estimated in the range of 0.2-1 W m−2, with the localized flux above the uppermost warm layer elevated to 2- 10 W m−2. Lateral fluxes are much larger, estimated between 1000-5000 W m−2, and set an overall decay rate for the intrusion of 1-5 years.

The characteristics of the Waiwhetu artesian aquifer beneath Wellington Harbour including the spatial distribution and causes of submarine spring discharge

<p>This thesis is a study of the sub-harbour Waiwhetu Artesian Aquifer, and in particular the nature and characteristics of artesian leakage from submarine springs. This aquifer is a sheet of gravel and other coarse sediments which continues from the Lower Hutt Valley and extends beneath Wellington Harbour where it varies in thickness from approximately 70m against the Wellington Fault scarp to just over 20m thick against the eastern harbour margin. The water it contains is a valuable resource supplying approximately one third of Wellington's municipal water consumption. At present, there are plans to utilise this artesian water source to a greater extent in the future, to support a greater burden of the region's water requirements. However concerns over possible salt-water intrusion and contamination of the aquifer led to an interest in developing a better understanding of the characteristics of this artesian system, particularly beneath the harbour floor. Harbour floor depressions were selected as likely sources of artesian water leakage based on the presumption that they had been formed by the action of leaking artesian water from beneath. Eleven depression 'zones' were investigated by recording the salinity of the water within the depressions using a portable conductivity/temperature meter. SCUBA diver's observations and bathymetric mapping revealed that depressions ranged in width from 53m to 369m (at the harbour floor) and 12m to 69m (at the depression base), with depths ranging from 13.3m to 31.3m below sea level. Only a few depressions were found to be actively discharging significant amounts of artesian water. SCUBA diver investigations found this leakage to be typically concentrated at a number of small and discrete spring 'vents' located on the base of the active depression. Typical salinities recorded ranged from 28 - 33 ppt within a few centimetres of the discharge vents. Deployment of an S4 current meter in two depressions showed that spring vent discharges vary with the pattern of abstraction from the pumping stations in the Lower Hutt Valley and as a consequence of the tidal cycle. High tides generate a greater load on the underlying aquifer, which in turn compresses the aquifer structure to a greater extent than at low tides, thus 'squeezing' out more water. Almost all of the recorded leakage was found to occur from a cluster of submarine springs within one of the depression zones, roughly 1100 metres from the Hutt River mouth. One other notable area of leakage was found close to Seaview Wharf. No significant leakage was observed or recorded from the two deep depressions south of Somes Island, which had previously been considered to be the major outlet of artesian leakage in the harbour. Lower than normal salinity values were also recorded in the harbour entrance. In this region the aquiclude is hypothesised to peter out, allowing artesian water to escape from the aquifer through a large area of the seabed in the form of widespread leakage as opposed to the concentrated, or discrete, form associated with spring vent discharge. Seismic profiles were used to map the extent of the sub-harbour Waiwhetu Artesian Aquifer and its upper confining aquiclude, the Petone Marine Beds. This work showed that the aquifer gravels extend across the entire harbour area. However, the water-bearing capacity of these deposits was found to be inconsistent. Preferential pathways, present as paleochannels (relic river channels), can be mapped within the aquifer. They concentrate the flow of groundwater through the aquifer and as such supply the submarine spring regions with much higher rates of water flow than the inter-paleochannel areas. The harbour floor depressions are thought to have formed as a consequence of the deformation of aquifer and aquiclude deposits during intense shaking associated with earthquakes leading to the removal of portions of the confining aquiclude. This typically occurs from a combination of raised piezometric pressures as a result of consolidation of the aquifer material during shaking, and from failure of the aquiclude by liquefaction. This rupture of the aquiclude results in the release of large volumes of artesian water through the aquiclude and to the sea. As this flow of water moves upward through the aquiclude, it erodes and transports away the fine sediment that forms this member. The features left behind are the characteristic harbour floor depressions we associate with submarine spring discharge. The abstraction of water from the Waiwhetu Artesian Aquifer (for the Wellington municipal water supply) lowers the piezometric pressure within the aquifer close to the abstraction zone. As such, the relocation of the abstraction focus (during 1980) to three kilometres inland from Petone Foreshore has greatly improved the 'health' of the subharbour aquifer and has similarly reduced the threat of salt-water intrusion. Data gathered during this study implies that while the two deep depressions south of Somes Island are unlikely to be a threat with regard to salt-water intrusion, the cluster of depressions off the Hutt River mouth could be a site of salt-water entry if piezometric pressures in the aquifer beneath them dropped low enough. Spring discharge velocities collected over one spring vent indicate that the presently set minimum piezometric Petone Foreshore level (below which abstraction must cease) needs to be revised.</p>

The characteristics of the Waiwhetu artesian aquifer beneath Wellington Harbour including the spatial distribution and causes of submarine spring discharge

<p>This thesis is a study of the sub-harbour Waiwhetu Artesian Aquifer, and in particular the nature and characteristics of artesian leakage from submarine springs. This aquifer is a sheet of gravel and other coarse sediments which continues from the Lower Hutt Valley and extends beneath Wellington Harbour where it varies in thickness from approximately 70m against the Wellington Fault scarp to just over 20m thick against the eastern harbour margin. The water it contains is a valuable resource supplying approximately one third of Wellington's municipal water consumption. At present, there are plans to utilise this artesian water source to a greater extent in the future, to support a greater burden of the region's water requirements. However concerns over possible salt-water intrusion and contamination of the aquifer led to an interest in developing a better understanding of the characteristics of this artesian system, particularly beneath the harbour floor. Harbour floor depressions were selected as likely sources of artesian water leakage based on the presumption that they had been formed by the action of leaking artesian water from beneath. Eleven depression 'zones' were investigated by recording the salinity of the water within the depressions using a portable conductivity/temperature meter. SCUBA diver's observations and bathymetric mapping revealed that depressions ranged in width from 53m to 369m (at the harbour floor) and 12m to 69m (at the depression base), with depths ranging from 13.3m to 31.3m below sea level. Only a few depressions were found to be actively discharging significant amounts of artesian water. SCUBA diver investigations found this leakage to be typically concentrated at a number of small and discrete spring 'vents' located on the base of the active depression. Typical salinities recorded ranged from 28 - 33 ppt within a few centimetres of the discharge vents. Deployment of an S4 current meter in two depressions showed that spring vent discharges vary with the pattern of abstraction from the pumping stations in the Lower Hutt Valley and as a consequence of the tidal cycle. High tides generate a greater load on the underlying aquifer, which in turn compresses the aquifer structure to a greater extent than at low tides, thus 'squeezing' out more water. Almost all of the recorded leakage was found to occur from a cluster of submarine springs within one of the depression zones, roughly 1100 metres from the Hutt River mouth. One other notable area of leakage was found close to Seaview Wharf. No significant leakage was observed or recorded from the two deep depressions south of Somes Island, which had previously been considered to be the major outlet of artesian leakage in the harbour. Lower than normal salinity values were also recorded in the harbour entrance. In this region the aquiclude is hypothesised to peter out, allowing artesian water to escape from the aquifer through a large area of the seabed in the form of widespread leakage as opposed to the concentrated, or discrete, form associated with spring vent discharge. Seismic profiles were used to map the extent of the sub-harbour Waiwhetu Artesian Aquifer and its upper confining aquiclude, the Petone Marine Beds. This work showed that the aquifer gravels extend across the entire harbour area. However, the water-bearing capacity of these deposits was found to be inconsistent. Preferential pathways, present as paleochannels (relic river channels), can be mapped within the aquifer. They concentrate the flow of groundwater through the aquifer and as such supply the submarine spring regions with much higher rates of water flow than the inter-paleochannel areas. The harbour floor depressions are thought to have formed as a consequence of the deformation of aquifer and aquiclude deposits during intense shaking associated with earthquakes leading to the removal of portions of the confining aquiclude. This typically occurs from a combination of raised piezometric pressures as a result of consolidation of the aquifer material during shaking, and from failure of the aquiclude by liquefaction. This rupture of the aquiclude results in the release of large volumes of artesian water through the aquiclude and to the sea. As this flow of water moves upward through the aquiclude, it erodes and transports away the fine sediment that forms this member. The features left behind are the characteristic harbour floor depressions we associate with submarine spring discharge. The abstraction of water from the Waiwhetu Artesian Aquifer (for the Wellington municipal water supply) lowers the piezometric pressure within the aquifer close to the abstraction zone. As such, the relocation of the abstraction focus (during 1980) to three kilometres inland from Petone Foreshore has greatly improved the 'health' of the subharbour aquifer and has similarly reduced the threat of salt-water intrusion. Data gathered during this study implies that while the two deep depressions south of Somes Island are unlikely to be a threat with regard to salt-water intrusion, the cluster of depressions off the Hutt River mouth could be a site of salt-water entry if piezometric pressures in the aquifer beneath them dropped low enough. Spring discharge velocities collected over one spring vent indicate that the presently set minimum piezometric Petone Foreshore level (below which abstraction must cease) needs to be revised.</p>

Determination of Flow Characteristics of Ohashi River through 3-D Hydrodynamic Model under Simplified and Detailed Bathymetric Conditions

The Ohashi River is a narrow water stream that connects two brackish lakes in Japan. Intermittent saline water intrusion often occurs in Lake Shinji from Lake Nakaumi through Ohashi River. In this study, two approaches were discussed to reproduce the hydrodynamic conditions of a morphologically complex river. In the first approach, the river sinuosity was straightened. The straightening of the river resulted in a higher flow velocity and water flux coefficient due to the reduction in the flow path and the resistance, and this approach was found to be appropriate for the reproduction of the flow velocity. However, the river shape was visually quite different from the actual river morphology. In the second approach, the prime focus was given to the shape and bathymetry to quantitively reproduce the flowrate of the saline water intrusion. This approach resulted in an underestimation of the flow velocity, which was compensated by increasing the cross-sectional area of the river. A slower flow velocity causes up to a 3-h time lag for the water mass to pass through the Ohashi River, which in principle should affect the temporal variations of the water temperature and salinity. Fortunately, as the typical time scale for water temperature and salinity fluctuations in the Ohashi River is a few days, a 3-h time lag did not cause any problems.

A study of salt water intrusion in the Kallada river, south west coast of Kerala, India

Munroe Island in Kollam District of Kerala is a typical backwater village situated at the confluence of the Ashtamudi backwater and the Kallada river system. It is an amalgamation of eight small islands with a total area of 13.4 sq. km. Salinity intrusion has been a serious threat in the downstream areas of Kallada river for more than one and half decades, affecting the groundwater quality of Munroe Island. The present study focuses on the seasonal variation in physico-chemical characteristics of the underground water system of Munroe island and Kallada river with special reference to saline water intrusion. Physico-chemical analysis of ground water revealed that samples were unsuitable for drinking due to higher content of Na, Ca, and K. Microbiological analysis of island groundwater showed the presence of coliform and E-coli bacteria above the permissible limit. Results indicated a significant correlation between salinity and major anions viz., Cl− and SO42 and cations viz., Mg, Na, Ca, and K of both river surface and island groundwater. In the present study it is clearly evident the occurrence of salt water intrusion in Kallada river from Ashtamudy lake and the its severity become higher during premonsoon season. The results also indicated that the salinity increase in kallada river has a negative impact on island ground water quality. The paper also suggest suitable management strategies for overcoming the salt water intrusion thereby upgrading island sustainability.