Collected Surface Water Research Articles

Bacterial biogeography in the coastal waters of northern Zhejiang, East China Sea is highly controlled by spatially structured environmental gradients.

The underlying mechanisms of microbial community assembly in connective coastal environments are unclear. The coastal water area of northern Zhejiang, East China Sea, is a complex marine ecosystem with multiple environmental gradients, where the distributions and determinants of bacterioplankton communities remain unclear. We collected surface water samples from 95 sites across eight zones in this area for investigating bacterial community with 16S rRNA gene high-throughput sequencing. Bacterial alpha-diversity exhibits strong associations with water chemical parameters and latitude, with 75.5% of variation explained by suspended particle. The composition of dominant phyla can group the sampling sites into four bacterial provinces, and most key discriminant phyla and families/genera of each province strongly associate with specific environmental features, suggesting that local environmental conditions shape the biogeographic provincialism of bacterial taxa. At a broader and finer phylogenetic scale, bacterial beta-diversity is dominantly explained by the shared variation of environmental and spatial factors (63.3%); meanwhile, the environmental determinants of bacterial β-diversity generally exhibit spatially structured patterns, suggesting that bacterial assembly in surface water is highly controlled by spatially structured environmental gradients in this area. This study provides evidence for the unique biogeographic pattern of bacterioplankton communities at an entire scale of this marine ecosystem.

UJI pH DAN KARAKTER FISIK KUALITAS AIR DI PEMUKIMAN PABRIK KELAPA SAWIT (PKS) NAGA SAKTI TAPUNG HILIR

Water is the source of life for all living beings on this earth. Some sources of water for daily needs comes from shallow wells, artesian wells, springs, surface water and rain water collection. The Naga Sakti cottage settlements is one of the settlements adjacent to the Palm Oil Mill (POM) in the district of Lower Tapung Riau Kampar district, and the location of settlements in the area of oil palm plantations. Water produced from wells on the settlement sometimes colored and taste. therefore necessary to test the water pH and physical to determine whether the water in the wells meet the Ministry of Health of the Republic of Indonesia Number: 416/MENKES/PER/IX/1990 about water quality requirements with a pH test and physical parameters that include viscosity, Total Dissolved solids (TDS), Density, conductivity, Oxidation Reduction Potential (ORP), resistivity, salinity, and taste test. Water quality testing was conducted at a radius of 4 km to 8 km from the MCC. From the results of the pH test has been done, there are three that are close to the standard radius PERMENKES ie a radius of 4, 5 and 6 miles. As for the 8 km radius pH values far below the standard Permenkes at pH test. Then to test all the physical radius PERMENKES already meet the standards , in the form of test viscosity, density, ORP, TDS, salinity, conductivity, resistivit , and flavor .

Implementation of an Eulerian Metod of Determination of Surface Water Collection Efficiency for Atmospheric Icing Problems

Implementation of an Eulerian Metod of Determination of Surface Water Collection Efficiency for Atmospheric Icing Problems

Heavy metal contamination, sources, and pollution assessment of surface water in the Tianshan Mountains of China.

In order to gain insight into heavy metal contamination occurring in the surface water of the Tianshan Mountains in northwest China, we collected surface water samples from there, tested heavy metals Pb, Ni, Cd, Co, Hg, As, Cu, Mn, Zn, and Cr, and then we analyzed the data using typical analysis, multivariate statistical, and pollution index methods. Results showed that (1) the order of the average values of the ten kinds of heavy metals in all the water samples was as follows: Zn > Mn > Cu > Co > Ni > Pb > Cr > As > Hg > Cd. The maximum variation coefficients of Zn and Pb were 138.96 and 145.86 %, respectively, indicating that these heavy metal concentrations varied largely between different sampling locations. (2) Research showed the average concentrations of Pb, Cd, As, Cu, Zn, and Cr were all within the national surface water standard of class IV and those of As, Cu, Mn, and Cr were all within the range of the Drinking Water Guidelines from the WHO, indicating the surface water of the Tianshan Mountains is clean. (3) Multivariate statistical analysis showed that Cu, Cd, Mn, Hg, Zn, and Pb have close correlations, and they mainly came from artificial sources; while Ni, As, Co, Cu, and Cr mainly came from natural sources. The results of correlation analysis, principal component analysis, and cluster analysis are consistent. (4) Pollution evaluation showed the values of comprehensive pollution index (WQI) of ten kinds of heavy metals in three sections were all lower than 2, suggesting the low levels of pollution, while the over-limit ratios of Pb and Zn in water samples of the middle Urumqi-Akesu section, As in the western Zhaosu-Tekesi section, and Pb, Hg, and Zn in the eastern Balikun-Yiwu section were all above 10 %. This research shows that recent economic development of the Tianshan Mountains has negatively influenced the heavy metal concentrations in the surface water, although the concentrations of the ten kinds of tested heavy metals are relatively low.

Occurrence of pharmaceuticals and personal care products and associated environmental risks in the central and lower Yangtze river, China

Pharmaceutical and personal care products (PPCPs) residues are being highlighted around the world as of emerging concern in surface waters. Here the occurrence of PPCPs in the central and lower Yangtze River, along with four large freshwater lakes within the river basin (Dongting, Poyang, Tai, and Chao) was reported. Fifteen out of twenty selected PPCPs were detected in the collected surface water samples. Caffeine, paraxanthine, sulfamethazine, and clindamycin were detected with 100 percent frequency in the Yangtze River. In the river, the highest average concentration was observed for erythromycin (296ngL−1), followed by caffeine (142ngL−1) and paraxanthine (41ngL−1). In the four lakes, total PPCP concentrations were much higher in the Chao (1547ngL−1) and Tai (1087ngL−1) lakes compared to the Poyang (108ngL−1) and Dongting (137ngL−1) lakes. Lincomycin and clindamycin were most abundant in the lakes, especially in the Tai Lake. Environmental risk assessment for the worst case scenario was assessed using calculated risk quotients, and indicates a high environmental risk of erythromycin and clarithromycin in the Yangtze River, clarithromycin in the Chao Lake, and clindamycin in the Tai Lake.

Physico-Chemical Assessment of Surface Water Quality With Respect to Seasonal Variation Around Amarkantak Thermal Power Plant, Chachai, Madhya Pradesh, India

The current research is an outcome of periodic physico- chemical observation and analysis of seasonal surface water samples collected from adjacent locations of ATPS, Chachai, (M.P.) India. The surface water quality typically subjects to geo-morphological and environmental conditions which are the key source to assess the alteration in physico chemical properties of water quality of the system and surroundings. In order of determine the Physico-Chemical Quality of Surface water considering the suitability for agriculture and domestic purposes. Hence 5 nos. of surface water samples from five identified locations were collected and analysed followed by summer, monsoon and winter seasons. Significant differences have been observed in the physico-chemical analysis of the collected surface water samples. The pH of the samples varied from 7.28 - 7.98 with conductivity 162-363 µs/cm. Total hardness noted from 102 -178 ppm, while Ca-hardness reported 58-110 ppm and Mg-hardness ranged from 34-72 ppm. Alkalinity of water samples were observed from 104-126 ppm. Total Dissolved Solid of collected water samples varied from 97-236 ppm while in fluctuation in chloride concentration observed in between 12-68 ppm. Adequate seasonal variations observed and reported 14 NTU (min) to 130 NTU (max). The seasonal changes also effected silica concentration of water sample with a range 5.8-76.5 ppm. After analysis of surface water sample, values of seasonal alternation compared against the prescribed limits of BIS-10500:2012.

Evaluating the exchange of DDTs between sediment and water in a major lake in North China

A large-scale sampling program was conducted to simultaneously collect surface water, overlying water, pore water, and sediment samples at monthly intervals between March and December 2010 from Baiyangdian Lake, North China to assess the distribution of DDTs and determine the net direction of sediment-water exchange. Total DDT concentrations ranged 2.36-22.4 ng/L, 0.72-21.9 ng/L, 2.25-33.7 ng/L, and 4.42-7.29 ng/g in surface water, overlying water, pore water, and sediments, respectively, which were at the intermediate levels compared to those of other area around the world. Seasonal variations of DDTs were featured by higher concentration in summer. This was likely associated with (a) the increase of land runoff in the summer and (b) application of dicofol and DDT-containing antifouling paints for ships in summer. Sediment-water fugacity ratios of the DDT isomers were used to predict the direction of the sediment-water exchange of these isomers. The sediment-surface water, sediment-overlying water, and sediment-pore water fugacity ratios of DDT isomers averaged 0.34, 0.44, and 0.1, which are significantly lower than the equilibrium status (1.0), suggesting that the net flux direction were from the water to sediment and the sediment acted as a sink for the DDTs. The difference of DDT concentrations between sediment and water samples was found to be an important factor affecting the diffusion of DDT from the water to sediment.

Spatial distribution of perfluoroalkyl acids in the Pearl River of Southern China

An intensive campaign was conducted in September 2012 to collect surface water samples along the tributaries of the Pearl River in southern China. Thirteen perfluoroalkyl acids (PFAAs), including perfluorocarboxylates (PFCAs, C4–C11) and perfluorosulfonates (PFSAs, C4, C6–C8, and C10), were determined using high-performance liquid chromatography/negative electrospray ionization–tandem mass spectrometry (HPLC/(-)ESI–MS/MS). The concentrations of total PFAAs (ΣPFAAs) ranged from 3.0 to 52ngL−1, with an average of 19±12ngL−1. The highest concentrations of ΣPFAAs were detected in the surface water of the Dong Jiang tributary (17–52ngL−1), followed by the main stream (13–26ngL−1) and the Sha Wan stream (3.0–4.5ngL−1). Perfluorooctanoate (PFOA), perfluorobutane sulfonate (PFBS), and perfluorooctane sulfonate (PFOS) were the three most abundant PFAAs and on average accounted for 20%, 24%, and 19% of ΣPFAAs, respectively. PFBS was the most abundant PFAA in the Dong Jiang tributary, and PFOA was the highest PFAA in the samples from the main stream of the Pearl River. A correlation was found between PFBS and PFOA, which suggests that both of these PFAAs originate from common source(s) in the region. Nevertheless, the slope of PFBS/PFOA was different in the different tributaries sampled, which indicates a spatial difference in the source profiles of the PFAAs.

LANDSLIDE ON LOCATION OF WATER SOURCE STUDENAC NEAR BIJELJINA, REPUBLIKA SRPSKA

<p>The landslide is located in the hinterland of water source "Studenac" in the local community Gornja Cadjavica near Bijeljina. The field where the triggered landslide occurred is conditionally stable slope. It is overgrown with forest trees and therefore it was not a subject of interest in terms of its stability until the water source and accompanying local road have been constructed in the lower part of the slope. Additionally the slope was undercut resulting in jeopardizing its conditional natural stability. At first, it was about some slight ground movements requiring no significant interventions. As the time was passing by site conditions have been changing. During winter and spring time movement of rock blocks is more intense due to large amount of surface and underground water whereby such a process was significantly slower and almost calm in the summer time. Such a cycle was repeated for several years until late 2010 when massive collapse of the unstable zone, which might be called ‘landslide’, endangered not only the local road but also the water source. For the purposes of overviewing the site and landslide characteristics as a whole, exhaustive researches were carried out within the part of the site affected by sliding at the surface of about 0,4 ha. A field surveying of wider area was also conducted. The landslide is located at relatively steep slope where the height distance between the crown and the toe of the landslide is 14,0 m. General slope angle is up to 100 and in those parts where landslides occur they are up to 250 . Sliding plane has been formed at depth of 2,5 to 4 m depending on terrain morphology, in clay of high plasticity (CH groups). The main cause of landslides is surface and underground water. Within the scope of remediation project two restorative measures were applied. The main recovery measure was placement of AB retaining concrete wall which was intended to accept the pressures of soil mass and to prevent it from slipping, namely to maintain the slope in stable condition. The other remedial measure was construction of an open perimeter canal at the slope above the retaining wall for the purposes of collecting surface water flowing towards the main body of the landslide and its diversion outside the sliding area.</p>

Sensitivity Analysis of Annual Nitrate Loads and the Corresponding Trends in the Lower Illinois River

Riverine nutrient concentrations and loads in the Midwestern United States have been identified as a major source of nutrients for the Mississippi River, causing hypoxia in the Gulf of Mexico. The Illinois River is one of the major contributors of nutrients to the Mississippi River, draining more than 40% of Illinois and parts of Indiana and Wisconsin. The main goals of this study were to calculate annual average nitrate concentration and annual total loads in the Lower Illinois River and its tributaries for 1975–2010, and to determine how the selection of different approaches affects the calculated trends. The Illinois Environmental Protection Agency (IEPA) has been collecting surface water quality data in Illinois since the early 1970s. This study used nitrite-N+nitrate-N (NO2+NO3) samples provided by IEPA and collected from the Illinois River at Havana and Valley City, Sangamon River at Oakford, and La Moine River at Ripley for the period 1975 to 2010. Discharge data concurrent with routine water quality samples were applied to a suite of approaches to estimate daily concentration and load for the period of analysis, including the seven-parameter regression equation along with several modeling residual adjustment techniques and the weighted regression on time, discharge, and season (WRTDS) method. The calculated annual mean concentration and annual total loads for NO2+NO3 for the period of record were discussed in relation to different approaches.

Evaluating the sediment-water exchange of hexachlorocyclohexanes (HCHs) in a major lake in North China.

A large-scale sampling program was conducted to simultaneously collect surface water, overlying water, pore water and sediment samples at monthly intervals from March to December 2010 from the Baiyangdian Lake, North China to assess the distribution of hexachlorocyclohexanes (HCHs) and determine the net direction of sediment-water exchange. Total HCHs concentrations ranged from 6.30-53.90 ng L (-1), 16.59-148.48 ng L(-1), 247.93-459.07 ng L (-1) and 3.60-12.50 ng g(-1) in surface water, overlying water, pore water and sediments, respectively, which was at the intermediate level compared to those of other areas in China. Seasonal variations of HCHs were featured by lower concentrations in April, July and November due to the dilution of HCHs caused by a great deal of fresh water being allocated to the Baiyangdian Lake in these months. Sediment-water fugacity ratios of the HCH isomers were used to predict the direction of the sediment-water exchange of these isomers. The sediment-surface water and sediment-overlying water fugacity ratios of HCH isomers averaged 11.4 and 3.0, which is significantly greater than the equilibrium status (1.0), suggesting that the net flux directions were from the sediment to water and the sediment acted as a secondary source to the water. Sediment-pore water fugacity ratios indicated near equilibrium or escape from pore water to sediment, depending on the isomer and sampling time. The difference of HCH concentrations between sediment and water samples were found to be an important factor affecting the diffusion of HCH from the sediment to water.

Relationships of surface water, pore water, and sediment chemistry in wetlands adjacent to Great Salt Lake, Utah, and potential impacts on plant community health

We collected surface water, pore water, and sediment samples at five impounded wetlands adjacent to Great Salt Lake, Utah, during 2010 and 2011 in order to characterize pond chemistry and to compare chemistry with plant community health metrics. We also collected pore water and sediment samples along multiple transects at two sheet flow wetlands during 2011 to investigate a potential link between wetland chemistry and encroachment of invasive emergent plant species. Samples were analyzed for a suite of trace and major elements, nutrients, and relevant field parameters. The extensive sampling campaign provides a broad assessment of Great Salt Lake wetlands, including a range of conditions from reference to highly degraded. We used nonmetric multidimensional scaling (NMS) to characterize the wetland sites based on the multiple parameters measured in surface water, pore water, and sediment. NMS results showed that the impounded wetlands fall along a gradient of high salinity/low trace element concentrations to low salinity/high trace element concentrations, whereas the sheet flow wetlands have both elevated salinity and high trace element concentrations, reflecting either different sources of element loading or different biogeochemical/hydrological processes operating within the wetlands. Other geochemical distinctions were found among the wetlands, including Fe-reducing conditions at two sites and sulfate-reducing conditions at the remaining sites. Plant community health metrics in the impounded wetlands showed negative correlations with specific metal concentrations in sediment (THg, Cu, Zn, Cd, Sb, Pb, Ag, Tl), and negative correlations with nutrient concentrations in surface water (nitrite, phosphate, nitrate). In the sheet flow wetlands, invasive plant species were inversely correlated with pore water salinity. These results indicate that sediment and pore water chemistry play an important role in wetland plant community health, and that monitoring and remediation efforts should consider pore water and sediment chemistry in addition to surface water chemistry.

High Seroprevalence of Rift Valley Fever and Evidence for Endemic Circulation in Mbeya Region, Tanzania, in a Cross-Sectional Study

BackgroundThe Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus. RVFV mostly causes outbreaks among domestic ruminants with a major economic impact. Human infections are associated with these events, with a fatality rate of 0.5–2%. Since the virus is able to use many mosquito species of temperate climates as vectors, it has a high potential to spread to outside Africa.Methodology/Principal FindingsWe conducted a stratified, cross-sectional sero-prevalence survey in 1228 participants from Mbeya region, southwestern Tanzania. Samples were selected from 17,872 persons who took part in a cohort study in 2007 and 2008. RVFV IgG status was determined by indirect immunofluorescence. Possible risk factors were analyzed using uni- and multi-variable Poisson regression models. We found a unique local maximum of RVFV IgG prevalence of 29.3% in a study site close to Lake Malawi (N = 150). The overall seroprevalence was 5.2%. Seropositivity was significantly associated with higher age, lower socio-economic status, ownership of cattle and decreased with distance to Lake Malawi. A high vegetation density, higher minimum and lower maximum temperatures were found to be associated with RVFV IgG positivity. Altitude of residence, especially on a small scale in the high-prevalence area was strongly correlated (PR 0.87 per meter, 95% CI = 0.80–0.94). Abundant surface water collections are present in the lower areas of the high-prevalence site. RVF has not been diagnosed clinically, nor an outbreak detected in the high-prevalence area.ConclusionsRVFV is probably circulating endemically in the region. The presence of cattle, dense vegetation and temperate conditions favour mosquito propagation and virus replication in the vector and seem to play major roles in virus transmission and circulation. The environmental risk-factors that we identified could serve to more exactly determine areas at risk for RVFV endemicity.

Tertiary-Treated Municipal Wastewater is a Significant Point Source of Antibiotic Resistance Genes into Duluth-Superior Harbor

In this study, the impact of tertiary-treated municipal wastewater on the quantity of several antibiotic resistance determinants in Duluth-Superior Harbor was investigated by collecting surface water and sediment samples from 13 locations in Duluth-Superior Harbor, the St. Louis River, and Lake Superior. Quantitative PCR (qPCR) was used to target three different genes encoding resistance to tetracycline (tet(A), tet(X), and tet(W)), the gene encoding the integrase of class 1 integrons (intI1), and total bacterial abundance (16S rRNA genes) as well as total and human fecal contamination levels (16S rRNA genes specific to the genus Bacteroides ). The quantities of tet(A), tet(X), tet(W), intI1, total Bacteroides , and human-specific Bacteroides were typically 20-fold higher in the tertiary-treated wastewater than in nearby surface water samples. In contrast, the quantities of these genes in the St. Louis River and Lake Superior were typically below detection. Analysis of sequences of tet(W) gene fragments from four different samples collected throughout the study site supported the conclusion that tertiary-treated municipal wastewater is a point source of resistance genes into Duluth-Superior Harbor. This study demonstrates that the discharge of exceptionally treated municipal wastewater can have a statistically significant effect on the quantities of antibiotic resistance genes in otherwise pristine surface waters.

Coupling Numerical and Physical Modeling for Analysis of Flow in a Diversion Structure with Coanda-effect Screens

There is an increasing need to screen water in surface water collection systems to remove floating debris and small aquatic organisms to protect receiving water bodies. Recently, the Albuquerque Metropolitan Arroyo Flood Control Authority (AMAFCA, New Mexico, USA) has actively introduced structural debris removal from storm-water facilities as a best management practice. In the South Diversion Channel Project, AMAFCA’s objective is to divert the flow at the upstream end of the existing concrete structure and remove debris from this flow using Coanda-effect screens before allowing it to re-enter the channel. Design limitations, such as access to the debris removal site, existing components of the concrete structure, topography of the site, and need for flow-regulating structures complicate the design. This paper shows how numerical modeling tools (Delft3D-FLOW model) and physical modeling can be used in conjunction to observe flow patterns in a diversion structure and around Coanda-effect screens, estimate design parameters and thereby provide design recommendations.

Geology and geophysics of the West Nubian Paleolake and the Northern Darfur Megalake (WNPL–NDML): Implication for groundwater resources in Darfur, northwestern Sudan

The recent delineation of a vastly expanded Holocene paleo-lake (the Northern Darfur Megalake which was originally mapped as the West Nubian Paleolake and here will be referred to as WNPL–NDML) in Darfur in northwestern Sudan has renewed hopes for the presence of an appreciable groundwater resource in this hyper-arid region of Eastern Sahara. This paleolake which existed within a closed basin paleo-drainage system might have allowed for the collection of surface water which was subsequently infiltrated to recharge the Paleozoic–Mesozoic Nubian Aquifer. However, the presence of surface exposures of Precambrian crystalline rocks in the vicinity of the paleolake has been taken as indicating the absence of a thick Paleozoic–Mesozoic sedimentary section capable of holding any meaningful quantity of groundwater. This work integrates surface geology and gravity data to show that WNPL–NDML is underlain by NE-trending grabens forming potential local Paleozoic–Mesozoic aquifers that can hold as much as 1120 km 3 of groundwater if the sedimentary rocks are completely saturated. Nevertheless, it is advised here that recharge of the Nubian aquifer under WNPL–NDML is insignificant and that much of the groundwater is fossil water which was accumulated during different geological times much wetter than today’s hyper-arid climate in Eastern Sahara. Excessive extraction will lead to quick depletion of this groundwater resource. This will result in lowering of the water table which in turn might lead to the drying out of the oases in the region which provide important habitats for humans, animals and plants in northern Darfur.

Controlling Runoff from Subtropical Pastures Has Differential Effects on Nitrogen and Phosphorus Loads

A 4-yr (2005-2008) study was conducted to evaluate the potential of pasture water management for controlling nutrient losses in surface runoff in the Northern Everglades. Two pasture water management treatments were investigated on Bahia grass ( Flüggé) pastures: reduced flow and unobstructed flow. The reduced flow treatment was applied to four of eight 20.23-ha pastures by installing water control structures in pasture drainage ditches with flashboards set at a predetermined height. Four other pastures received the unobstructed-flow treatment, in which surface runoff exited pastures unimpeded. Automated instruments measured runoff volume and collected surface water samples for nutrient analysis. In analyzing data for before-after treatment analysis, the 2005 results were removed because of structural failure in water control structures and the 2007 results were removed because of drought conditions. Pasture water retention significantly reduced annual total nitrogen (TN) loads, which were 11.28 kg ha and 6.28 kg ha, respectively, in pastures with unobstructed and reduced flow. Total phosphorus (TP) loads were 27% lower in pastures with reduced flow than in pastures with unobstructed flow, but this difference was not statistically significant. Concentrations of available soil P were significantly greater in pastures with reduced flow. Pasture water retention appears to be an effective approach for reducing runoff volume and TN loads from cattle pastures in the Northern Everglades, but the potential to reduce TP loads may be diminished if higher water table conditions cause increased P release from soils, which could result in higher P concentration in surface runoff.

South Florida Water Management District ambient pesticide monitoring network: 1992 to 2007

The South Florida Water Management District has collected surface water and sediment samples for analysis of over 80 pesticides since 1992. Residues of atrazine and DDE-p,p(') are nearly ubiquitous throughout the sampling area. Surface water concentrations of atrazine at nine of 14 selected monitoring locations exhibited a downward trend and none of the detected concentrations exceeded established levels of concern. Seventy-five percent of the sampled locations had average sediment residues of DDE-p,p(') at levels that may impact sediment-dwelling organisms. Monitoring locations with the highest average DDE-p,p(') concentrations (based on detected values) and the highest percentage of pesticide detections did not exhibit consistent trends. Some locations exhibited increasing trends while trends at other locations showed a decrease in concentrations. Additionally, specific location concentrations for ethion, diazinon, and endosulfan documented periods of surface water quality exceedances. However, product label changes and grower education have substantially contributed to the reduced number of exceedances over time.

Fecal indicator organism density in beach sands: Impact of sediment grain size, uniformity, and hydrologic factors on surface water loading

Fecal loading to beach sands and subsequent transport to surface water may result in the degradation of surface water quality. To better understand the relationship between Escherichia coli in sands, beach hydrology, and recreational water quality, we collected surface water, groundwater, and sand samples from three Lake Michigan beaches with varying substrates (fine sand to pebbles, July 2005–June 2006). Sediment cores collected within transects perpendicular to and at fixed distances from the shoreline (0m, 10m, 20m) and surface water samples collected at a depth of 1m were analyzed for E. coli. Grain size analysis was performed on duplicate core samples to assess the relationship between E. coli density and mean grain size and uniformity. Groundwater samples, collected from shallow drive-point piezometers within the test area, were also analyzed for E. coli. E. coli density in beach sands differed significantly with distance from shore with the highest density occurring at the berm crest (0m). Mean grain size and uniformity accounted for variation in E. coli density with fine sand of uniform distribution having the highest content. E. coli density in surface water was correlated to E. coli density in beach sand samples at the berm crest. E. coli in groundwater was <10 to 579MPN/100ml (2005); none was detected in 2006. Management interventions, including altered beach grooming practices and slope assessments, may be effective in reducing E. coli content at beaches comprised of fine sands of uniform grain size, hence reducing water quality advisories.

Molecular Detection of Persistent Francisella tularensis Subspecies holarctica in Natural Waters.

Tularemia, caused by the bacterium Francisella tularensis, where F. tularensis subspecies holarctica has long been the cause of endemic disease in parts of northern Sweden. Despite this, our understanding of the natural life-cycle of the organism is still limited. During three years, we collected surface water samples (n = 341) and sediment samples (n = 245) in two areas in Sweden with endemic tularemia. Real-time PCR screening demonstrated the presence of F. tularenis lpnA sequences in 108 (32%) and 48 (20%) of the samples, respectively. The 16S rRNA sequences from those samples all grouped to the species F. tularensis. Analysis of the FtM19InDel region of lpnA-positive samples from selected sampling points confirmed the presence of F. tularensis subspecies holarctica-specific sequences. These sequences were detected in water sampled during both outbreak and nonoutbreak years. Our results indicate that diverse F. tularensis-like organisms, including F. tularensis subsp. holarctica, persist in natural waters and sediments in the investigated areas with endemic tularemia.