Stream Samples Research Articles

Diurnal detection of environmental DNA of the semi-aquatic water shrew Chimarrogale platycephala using 25-h water sampling in streams

Diurnal detection of environmental DNA of the semi-aquatic water shrew Chimarrogale platycephala using 25-h water sampling in streams

An Evolving Fuzzy Neural Network Based on Or-Type Logic Neurons for Identifying and Extracting Knowledge in Auction Fraud

The rise in online transactions for purchasing goods and services can benefit the parties involved. However, it also creates uncertainty and the possibility of fraud-related threats. This work aims to explore and extract knowledge of auction fraud by using an innovative evolving fuzzy neural network model based on logic neurons. This model uses a fuzzification technique based on empirical data analysis operators in an evolving way for stream samples. In order to evaluate the applied model, state-of-the-art neuro-fuzzy models were used to compare a public dataset on the topic and, simultaneously, validate the interpretability results based on a common criterion to identify the correct patterns present in the dataset. The fuzzy rules and the interpretability criteria demonstrate the model’s ability to extract knowledge. The results of the model proposed in this paper are superior to the other models evaluated (close to 98.50% accuracy) in the test.

Detection of the New Class of Hypersonic Targets under Emerging Hyperspectral Sample Streams: An Unsupervised Isolation Forest Solution

Rapid detection of the new class of hypersonic targets (HTs) presenting unknown military threats in space-based surveillance will guarantee aerospace security. This paper proposes an unsupervised subclass definition and an efficient isolation forest based on an anomalous hyperspectral feature selection (USD-EiForest) algorithm to detect the new class of never-before-seen HTs under emerging hyperspectral sample streams. First, we reveal that the hyperspectral features (HFs) of the new class of HTs have no anomaly characteristics when compared to the globally observed samples while having prominent anomaly characteristics when compared to the subclasses of observed samples. Second, an unsupervised subclass definition method adapted to HTs is utilized to classify the observed samples into several subclasses. Then, an efficient isolation forest is designed to determine whether the data stream sample in each subclass indicates anomaly features that mark the detection of the new class of hypersonic targets (DNHT). Finally, we experiment on the simulated hyperspectral HTs data sets considering the RAM-C II HT as the observed samples and the HTV-2 HT as the unknown samples. The results suggest that the performance of our proposal has competitive advantages in terms of accuracy and detection efficiency.

Study to determine efficacy of urinary HPV 16 & HPV 18 detection in predicting premalignant and malignant lesions of uterine cervix.

To evaluate clinical performance and diagnostic accuracy of urinary HPV for non-invasive screening of high-grade precancerous and cancerous cervical lesions in a visual inspection under acetic acid (VIA) -positive cohort. The study included 180 women aged 35-65 years, who were VIA positive in a colposcopy clinic. All participants had the initial stream of a random urine sample tested for the presence of high-risk HPV (hrHPV) types 16 and 18 and acetowhite lesions were biopsied per protocol. Concordance analysis was conducted to assess agreement between detection of hrHPV in urine and the presence of premalignant and malignant lesions in cervix on histopathology. Measures of diagnostic accuracy were estimated to evaluate the performance of urinary HPV against histopathology (reference standard). Substantial agreement between urinary HPV detection and histopathology was found (Cohen's κ is 0.696, P≤ 0.001), with an agreement in 88.9% of the cases and disagreement in 11.1%. The diagnostic performance of urinary HPV in predicting the presence of a high-grade precancerous or cancerous lesion was as follows: sensitivity 67%, specificity 97%, positive predictive value 89%, and negative predictive value 88.8%. HPV DNA detection from urine has good concordance with the histopathology for detection of precancerous and cancerous lesions of the cervix. Further studies on optimization of urine sampling and processing techniques are warranted.

Microhabitat and Landscape Drivers of Richness and Abundance of Freshwater Mussels (Unionida: Unionidae) in a Coastal Plain River

Although rivers support significant unionid mussel (Unionida: Unionidae) diversity, Gulf of Mexico tributary rivers have been subject to changes in water quality and habitat due to altered watershed land use. We quantified mussel species richness and relative abundance and environmental factors in small tributary streams of the Pearl River, Mississippi-Louisiana. Freshwater mussel and habitat surveys were conducted at 27 stream sampling sites over two summers (9 sites revisited), and coverage of seven land use categories and seven geological categories above each reach were calculated. Mussels were patchily distributed (53% of sites sampled yielded mussels) and typically not abundant (only 26% of sites yielded >10 mussels). Surveys revealed nine species, with total abundance ranging from 0–66 mussels and richness ranging from 0–5 species per site. Assemblages were driven by an upper to lower watershed gradient of decreasing CPUE and richness, with microhabitat and water quality, land cover, and geology locally modifying this gradient. Environmental variables did not seem of sufficient magnitude to account for the patchy distributions and low abundances of mussels at most study sites, and we hypothesize that high discharge events related to tropical storm passage may have exerted an overriding influence on mussel assemblages in these streams through direct mortality and/or altered availability of suitable glochidial hosts.

Comparative Study of Indicator Organisms in Different Water Sources in North Bank Area of Makurdi

This study compared the presence of indicator organisms in different domestic water sources in the North Bank area of Makurdi. The water sources included stream waters, well waters, and borehole waters. Total bacteria count, total coliform count, microscopic examination, and biochemical tests were the parameters measured. The results obtained showed that all the different water sources had the presence of total bacteria and coliforms except the borehole water along Ter Guma Street (B1) which only showed the presence of total bacteria. The total bacteria count was found to be more (2.91 x 107 cfu/ml) in the stream water samples along University of Agriculture Road (ST2) and least in B2 water samples (6.76 x 106 cfu/ml) with no significant difference (p>0.05). Total coliform counts were found in all the water sources except in B1 water sample, while, the well water sample from Old Lafia Road (W2), had the highest total coliform count (1600 MPN/100 ml). Coliform isolates including Escherichia coli, Streptococcus faecalis, Staphylococcus aureus, Salmonella spp, Pseudomonas aeruginosa, and Klebsiella pneumoniae were found in the water samples, with well water from Old Lafia Road (W2), having more of the isolates. This study reveals that all the water sources studied were contaminated by the presence of microorganisms including indicator organisms, above the recommended by WHO, for a domestic water source. Further study to investigate the physicochemical parameters of these water sources is suggested.

Comprehensive toxicity screening of Pazarsuyu stream water containing heavy metals and protective role of lycopene

In this study, heavy metal pollution in the Pazarsuyu stream of Giresun province and the protective role of lycopene against the toxicity caused by this pollution were investigated using the Allium test. Germination percentage, root length and weight gain as physiological markers of toxicity; mitotic index (MI), micronucleus (MN) and chromosomal aberrations (CAs) as genetic markers of toxicity; malondialdehyde (MDA) level, superoxide dismutase (SOD) and catalase (CAT) activities as biochemical markers of toxicity, and meristematic cell damages were used as anatomical markers. For this aim Allium cepa L. bulbs were divided into six groups and germinated for 72 h with 215 mg/L and 430 mg/L doses of lycopene, tap water and stream water. Heavy metals pollution was analyzed with ICP-MS and Fe > Sr > Ba > Be > Mo > Li were determined according to the rate of presence in the water samples of Pazarsuyu. As a result, germination-related parameters and meristematic cell proliferation of bulbs germinated with Pazarsuyu water samples decreased significantly. Germination percentage, root length and weight gain of the group treated with Pazarsuyu water samples were decreased 50%, 73% and 68%, respectively compared to control. In addition, MN and CAs frequencies, indicating the genotoxic effects, were increased and significant abnormalities were detected in MDA, SOD and CAT levels, which indicate the deterioration of antioxidant/oxidant balance. CA observed with high frequency was also confirmed by DNA fragmentation determined by the Comet test. Stream water application promoted anatomical damages such as epidermis and cortex cell damage, accumulation of some substances in cortex cells, flattened cell nucleus and non-apparent appearance of conduction tissue in root tip meristem cells. All these abnormalities observed in A. cepa root tip cells were associated with the presence of heavy metals in the water samples. Simultaneous application of lycopene with stream water reduced the effects of heavy metals and resulted in a dose-dependent improvement in all parameters studied. Lycopene application showed a protective role by providing an increase in germination parameters and MI, decrease in MN and CAs frequencies, and improvements in MDA, SOD and CAT activities. As a result, heavy metals detected in the water samples of Pazarsuyu stream caused multiple toxicities in the bio-indicator plant, and lycopene reduced this toxicity and recorded a protective role.

Nutrient delivery by groundwater discharge to headwater streams in agricultural catchments

AbstractNutrient concentrations in riparian groundwater are variable from site to site, making it challenging to use these data to quantify nutrient fluxes contributed by groundwater discharge to headwater streams. Instead, we define event‐excluded baseflow (BFEE), and use stream discharge data and stream samples collected during BFEEto estimate groundwater discharge and loading of nutrients to the streams. Based on this method, in two study catchments (Thames River basin, Ontario, Canada) groundwater discharge during BFEEcontributed about 30% of the total streamflow and 20%–30% of the total loading of soluble reactive phosphorus (SRP) and nitrate. Previous estimates of baseflow using hydrographic separation techniques indicate that groundwater discharge likely contributes even larger fractions, ~50%–60% of flow in these catchments. We infer that groundwater likely contributes ~40% of the annual SRP load and ~ 50%–60% of the nitrate‐N load. These results indicate that groundwater discharge plays an important role in the nutrient loading to headwater streams. This reinforces the findings of earlier studies that have inferred a dominant influence of legacy reservoirs of nutrients in the subsurface of similar agricultural catchments on the loads of these nutrients in headwater streams.

Impact of exposure to arsenic on the bacterial microbiota associated with river biofilms in the Pampas region

Freshwater contamination by arsenic (As) is a worldwide problem. It may be found in Pampean streams of Argentina at concentrations higher than those recommended by international organizations and stipulated by national regulations. Exposure to high As concentrations causes serious consequences to both human health and the environment. The general objective of this work was to evaluate the effect of As on the biofilm microbiota structure from Naveira stream, Luján, Province of Buenos Aires (Coordinates: 34º34′02″ S 59º03′51″ W). The biofilm collected was cultivated in glass aquaria at different As III concentrations (0, 0.2 and 20 mg / L), inside incubation chambers under controlled conditions (16 h light: 8 h dark and 24 ± 1 °C) and constant aeration for 31 d, with partial water renewal every 9 d. We amplified the hypervariable regions V3 and V4 of the bacterial 16S rRNA gene from biofilm bacterial community samples to determine the diversity and abundance of the different taxa. The taxonomic composition of each sample, the alpha diversity of each treatment and the main metabolic pathways were analyzed. Principal Component Analysis of the present phyla and a Linear Discriminant Analysis of the metabolic pathways was also performed. Significant changes were observed in relation to the taxonomic composition of the bacterial community after exposure to the metalloid. However, this effect was not observed at the low concentration used (0.2 mg / L), which is the one that corresponds to ecologically relevant levels. The significantly affected phyla were Verrucomicrobiota, Acidobacteriota, Patescibacteria, Hydrogenedentes and WPS-2. The relative abundances of the Verrucomicrobiota, WPS-2 and Patescibacteria groups were notably decreased in the treatment with high As, while the Acidobacteria group was increased in both treatments with As. The stream samples showed greater bacterial diversity than those grown in the laboratory without As. Finally, it was possible to characterize the metabolic profile of the biofilm developed under natural conditions in the leaves of the aquatic plant Elodea canadensis in the Naveira stream. In addition, results showed that biosynthesis-related pathways were more abundant at the high As concentration treatment (20 mg / L).

Duplex detection of foodborne pathogens using a SERS optofluidic sensor coupled with immunoassay

Herein, we developed a surface-enhanced Raman spectroscopy (SERS) optofluidic sensor coupled with immunoprobes to simultaneously separate and detect the foodborne pathogens, Escherichia coli O157:H7, and Salmonella in lettuce and packed salad. The method consists of three steps of (i) enrichment to enhance detection sensitivity, (ii) selective separation and labelling of target bacteria by their specific antibody-bearing SERS-nanotags and (iii) detection of tagged bacterial cells using SERS within a hydrodynamic flow-focusing SERS optofluidic device, where even low counts of bacterial cells were detectable in the very thin-film-like sample stream. SERS-nanotags consisted of different Raman reporter molecules, representing each species, i.e., the detection of Raman reporter confirms the presence of the target pathogen. The anti-E. coli antibody used in this study functions against all strains of E. coli O157:H7 and the anti-Salmonella antibody used in this work acts on a wide range of Salmonella enterica strains. Bacterial counts of 1000, 100, and 10 CFU/ 200 g sample were successfully detected after only 15 min enrichment. Our method showed a very low detection limit value of 10 CFU/ 200 g sample for the bacterial mixture in both lettuce and packed salad, proving the efficiency and high sensitivity of our method to detect multiple pathogens in the food samples. The total analysis time, including sample preparation for simultaneous detection of multiple bacteria, was estimated to be 2 h, which is much less than the time required in conventional methods. Hence, our proposed protocol is considered a promising rapid and efficient approach for pathogen screening of food samples.

Multimodel evaluation of longitudinal stream temperature gradient and dominant influencing factors in Michigan streams

AbstractStream temperature is an important determinant of fish growth, migration, and survival and can thus impact the structure and function of stream ecosystems. Many streams in Michigan and elsewhere in North America receive groundwater inputs that help regulate instream conditions by stabilizing discharge as well as stream temperature. However, groundwater withdrawal can cause reductions in streamflow which typically results in increased summer stream temperatures. Other atmospheric and hydrologic variables (i.e., overland discharge) also impact the rate at which stream temperature changes as it flows downstream. We deployed paired up‐ and downstream water pressure and temperature loggers within 21 stream reaches throughout the state of Michigan to quantify and model relationships between stream discharge, air temperature, and longitudinal change in stream temperature (i.e., temperature gradient). Using multimodel selection criteria, we evaluated the performance of a hierarchical suite of models that predict temperature gradient as a function of potential driving variables. The multimodel selection criteria identified a best‐fitting model that was able to model the diurnal, seasonal, and annual variations in rates of longitudinal temperature fluctuations across most sample streams. Partial regression analysis indicated that proxy variables representing solar radiation at the stream surface were generally the most influential predictors of longitudinal changes in stream temperature, but air temperature and components of streamflow including groundwater input were significant predictors and important in many streams.

Molecular Composition of Dissolved Organic Matter in the Changjiang (Yangtze River) – Imprints of Anthropogenic Impact

Understanding the biogeochemical transformation of dissolved organic matter (DOM) across fluvial networks will ultimately help to predict anthropogenic influences. To date, few studies have evaluated the anthropogenic impact on the spatial and temporal changes of DOM composition in large river systems. Here, FT-ICR-MS combined with excitation-emission matrix spectroscopy (EEMs) and biomarkers were applied to resolve chemical differences of DOM collected from the Changjiang basin at different hydrological and environmental conditions. PCA and cluster analysis illustrated that samples collected from lake systems and northern and southern tributaries differed from the two batches of main stream samples, particularly due to higher contribution of nitrogen and sulfur containing compounds. Correlation of land-use information along the tributaries with different PCA loadings indicated that agricultural, forest and wetland areas and wastewater discharge control the composition of DOM within these subregions. Higher heteroatom content (especially CHONx) in the low discharge period (2009) may be contributed by paddy soil leaching into groundwater. The relative peak magnitude of sulfur containing formulas was elevated during flood season (2010), which may be related to pollutions in areas of high population density. In addition, lignin phenol concentrations were higher in the flood season because of elevated soil erosion. Consequently, land use and human activities can strongly alter the quality and composition of DOM in watersheds flowing through densely populated regions, which may also impact or influence the riverine carbon flux in anthropogenically disturbed river systems.

Development of a ddPCR assay for the detection of the Smoky Madtom (Noturus baileyi) from eDNA in stream water samples

The Smoky Madtom Noturus baileyi is a federally endangered species, whose native distribution includes lower Abrams Creek in Great Smoky Mountains National Park (GRSM) and Citico Creek in nearby Cherokee National Forest. Due to challenges for bio-monitoring posed by its nocturnality and cryptic life history, an environmental DNA (eDNA)-based approach for detection would be useful to complement existing electrofishing and seining efforts to better understand the distribution of this species. We developed a probe-based droplet digital PCR (ddPCR) assay to detect Smoky Madtoms from non-invasively collected water samples. The assay was specific to N. baileyi and did not amplify concentrated genomic DNA of 16 co-occurring or regional fish species, including the yellowfin madtom N. flavipinnis and stonecat N. flavus. The assay limit of detection (LOD) was determined to be 4.18 copies (95% CI: 3.95, 4.41). Several 2 L water samples collected from throughout various streams in GRSM in 2016 and 2017 were tested for the presence of N. baileyi using the ddPCR assay. N. baileyi was detected at two different sites in 2016 and 2017 within Abrams Creek previously known to contain N. baileyi, but no novel detections in other sampled streams were observed. This assay should prove useful for continued surveys of N. baileyi in GRSM.

Effects of human disturbance on habitat and fish diversity in Neotropical streams.

Human pressures have been intensely modifying freshwater ecosystems worldwide. We assessed the effects of human pressure on habitat diversity and primary productivity to understand the consequences on fish fauna in 25 tropical and subtropical streams of two globally important ecoregions: Iguassu and Upper Paraná. We hypothesized that the increased human pressure (urbanization and agriculture) on stream environments, both at the local and catchment scales, directly decreases habitat diversity. We also hypothesized that increased human pressure triggers changes in primary productivity and fish fauna composition and structure. We evaluated the human pressure intensity using the Integrated Disturbance Index and the Rapid Habitat Diversity Assessment protocol, which combines information about land use, land cover and environmental characteristics of the stream catchment and sampling sites. Streams with increased human disturbance had lower habitat diversity, higher primary productivity, and high non-native species abundance. Fish compositional turnover was associated with increased human disturbance. Native and degradation-sensitive fish species, especially endemic ones, were associated with streams with higher habitat diversity and forested cover. Degradation-resistant fishes, mostly non-native species, were associated with streams with higher human disturbance and urban land use. Although human pressure did not affect species richness, Shannon diversity, and Simpson dominance, there were significant effects on numerical abundance and fish species equitability. In this study, human pressure directly affected habitat structure, with indirect consequences for fish fauna, increasing the potential for local extirpation of rare species.

Sources and Drivers of ARGs in Urban Streams in Atlanta, Georgia, USA.

The spread of antibiotic resistance genes (ARGs) in the aquatic environment is an emerging concern in the interest of protecting public health. Stemming the environmental dissemination of ARGs will require a better understanding of the sources and drivers of ARGs in the water environment. In this study, we used direct measurement of sewage-associated molecular markers, the class 1 integron gene, standard water quality parameters, and watershed characteristics to evaluate the sources and drivers of ARGs in an urban watershed impacted by a gradient of human activities. Quantitative polymerase chain reaction (qPCR) was used to quantify the abundance of the sewage-associated HF183, the E. coli fecal indicator, class 1 integron gene (int1), and the ARGs sulI, sulII, tetW, tetM, ampC, and blaSHV in stream water samples collected from the Proctor Creek watershed in Atlanta, Georgia. Our findings show that ARGs were widely distributed, with detection frequencies of 96% (sulI and sulII), 82% (tetW and tetM), and 49% (ampC and blaSHV). All the ARGs were positively and significantly correlated (r > 0.5) with the HF183 and E. coli markers. Non-linear machine learning models developed using generalized boosting show that more than 70% of the variation in ARG loads in the watershed could be explained by fecal source loading, with other factors such as class 1 integron, which is associated with acquired antibiotic resistance, and environmental factors contributing < 30% to ARG variation. These results suggest that input from fecal sources is a more critical driver of ARG dissemination than environmental stressors or horizontal gene transfer in aquatic environments highly impacted by anthropogenic pollution. Finally, our results provide local watershed managers and stakeholders with information to mitigate the burden of ARGs and fecal bacteria in urban streams.

Achieving sustainable water and land use systems in highly developed tropical landscapes

Water quality degradation from human related activities has become a pressing global issue, putting water security at risk around the world. Land use decisions can severely degrade stream water quality, compromising water supply and increasing water treatment costs. Here we examine changes in water quality over 20 years and their association with land use, urbanization, and sewage treatment in the state of São Paulo, Brazil. We also consider how a severe drought in 2014–2015 affected water quality, uncovering the potential impacts of a changing climate on water treatment costs. We analyzed water quality data between 2000 and 2019 from 230 monitoring stations focusing on seven metrics: dissolved oxygen, biological oxygen demand, total nitrogen, total phosphorus, turbidity, total dissolved solids, and fecal coliforms. We first calculated the number of times that metrics exceeded the legal thresholds and then assessed if metrics were improving or deteriorating over time. Across all stations, a large proportion of stream water samples failed to comply to the legal standards for human consumption for at least one water quality metric. This proportion was highest for total dissolved solids (30.7%) and total phosphorus (42.8%), with fewer samples exceeding the threshold for turbidity and dissolved oxygen. Deteriorating water quality trends over time were prevalent for dissolved solids (33.33%) and total nitrogen (52.45%), while dissolved oxygen exhibited the highest percentage of improving trends across watersheds (43.63%). Moreover, we observed that four of the seven metrics analyzed deteriorated during the 2014–2015 drought. Urbanization and agricultural activity led to deterioration of water quality, while improvement in sewage treatment infrastructure improved water quality across watersheds. The decline in water quality observed in the region, especially during the recent drought, highlights the need to develop land use management strategies to protect water quality and reduce growing costs of water treatment in the state.

Assessing the influence of water sampling strategy on the performance of tracer-aided hydrological modeling in a mountainous basin on the Tibetan Plateau

Abstract. Tracer-aided hydrological models integrating water isotope modules into the simulation of runoff generation are useful tools to reduce uncertainty of hydrological modeling in cold basins that are featured by complex runoff processes and multiple runoff components. However, there is little guidance on the strategy of field water sampling for isotope analysis to run tracer-aided hydrological models, which is especially important for large mountainous basins on the Tibetan Plateau (TP) where field water sampling work is highly costly. This study conducted a set of numerical experiments based on the THREW-T (Tsinghua Representative Elementary Watershed - Tracer-aided version) model to evaluate the reliance of the tracer-aided modeling performance on the availability of site measurements of water isotope in the Yarlung Tsangpo river (YTR) basin on the TP. Data conditions considered in the numerical experiments included the availability of glacier meltwater isotope measurement, quantity of site measurements of precipitation isotope, and the variable collecting strategies for stream water samples. Our results suggested that (1) in high-mountain basins where glacier meltwater samples for isotope analysis are not available, estimating glacier meltwater isotope by an offset parameter from the precipitation isotope is a feasible way to force the tracer-aided hydrological model. Using a set of glacier meltwater δ18O that were 2 ‰–9 ‰ lower than the mean precipitation δ18O resulted in only small changes in the model performance and the quantifications of contributions of runoff components (CRCs, smaller than 5 %) to streamflow in the YTR basin. (2) The strategy of field sampling for site precipitation to correct the global gridded isotope product of isoGSM (isotope-incorporated global spectral model) for model forcing should be carefully designed. Collecting precipitation samples at sites falling in the same altitude tends to be worse at representing the ground pattern of precipitation δ18O over the basin than collecting precipitation samples from sites in a range of altitudes. (3) Collecting weekly stream water samples at multiple sites in the wet and warm seasons is the optimal strategy for calibrating and evaluating a tracer-aided hydrological model in the YTR basin. It is highly recommended to increase the number of stream water sampling sites rather than spending resources on extensive sampling of stream water at a sole site for multiple years. These results provide important implications for collecting site measurements of water isotopes for running tracer-aided hydrological models to improve quantifications of CRCs in high-mountain basins.

Geochemical and Petrological Survey in Northern Ethiopia Basement Rocks for Investigation of Gold and Base Metal Mineralization in Finarwa Area and Its Surrounding Southeast Zone of Tigray, Ethiopia

The study is accompanied in northern Ethiopian basement rocks, Finarwa area and its surrounding areas, south eastern Tigray. The objective of the study is to amendment field geology, mineralogy, and geochemical characteristics to deliberate about the gold and base metal mineral potential investigations. From the field observations the geology of the area haven been described and mapped based on mineral composition, texture, structure and colour of both fresh and weather rocks.The ore mineral under microscope are commonly base metal sulphides pyrrhotite, Chalcopyrite, pentilandite occurring in variable proportions. Galena, chalcopyrite, pyrite and gold mineral are hosted in quartz vein. The base metal sulfides occur as disseminated, vein filling and replacement. Geochemical analyses result from inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) indicates the threshold of geochemical anomalies is directly related to the identification of mineralization information. From samples stream sediment samples and the soil samples indicated that the most promising mineralization occur in the prospect area are gold(Au), copper (Cu) and zinc (Zn). This is also supported by the abundance of chalcopyrite and sphalerite in some highly altered samples. The stream sediment geochemical survey data shows relatively higher values for zinc compared to Pb and Cu. The moderate concentration of the base metals in some of the samples indicates availability base metal mineralization in the study area requiring further investigation. In addition the sulphide concentrations in the research area are related to different stages of mineralization and are controlled both by structures and lithology. They are well established in the slate-phyllite and metavolcanics along the shear zones and faults as disseminated and vein filling. The rock and soil geochemistry shows significant concentration of gold with maximum value of 0.33ppm and 0.97 ppm in the south western part of the study area.

Escherichia cryptic clade II through clade VIII: Rapid detection and prevalence in feces and surface water

Bacteria of the cryptic lineage of genus Escherichia, or Escherichia cryptic clades (cryptic clades), are phenotypically indistinguishable from Escherichia coli (E. coli) using standard biochemical tests. Except for clade I (C-I), cryptic clades were hypothetically believed to be environmental but not enteric. If so, they would hinder the interpretation of current E. coli-based water quality (fecal pollution) monitoring in the United States because environmental bacteria do not indicate the presence of harmful fecal material. This study was performed to develop a rapid method for the detection of cryptic clades and to investigate their potential impact on water quality monitoring. By whole-genome comparison, one gene, named ecc (Escherichiacryptic clades), was identified to be unique to C-II through C-VIII. An end-point polymerase chain reaction (PCR) method, eccPCR, was developed by targeting the ecc. The results of in-silico and wet tests demonstrated 100 % sensitivity and specificity of the eccPCR to detect C-II through C-VIII. Based on the EPA Method 1603, 519 presumptive E. coli isolates were obtained from the fecal samples of 13 different host species and 192 isolates from surface water samples taken at four locations in a watershed of mid-Missouri. As indicated by the eccPCR amplification, the overall prevalence of C-II through C-VIII in the presumptive E. coli isolates was estimated to be about 0.6 % in the fecal samples and about 1.6 % in the water samples. Therefore, the potential impact of cryptic clades on water quality monitoring may be limited if EPA Method 1603 is used. Furthermore, clades C-II through C-VIII in stream water samples were found repeatedly only at a single sampling site, but neither at the upstream sites nor five kilometers downstream of the site. The data do not support nor reject the environmental hypothesis about cryptic clades. Further study is needed to determine the implication of the observation.

Effect of process parameters on separation efficiency in a deterministic lateral displacement device

Deterministic lateral displacement (DLD) is a hydrodynamic method known for its high-resolution sorting of particles. It achieves this through a periodic array of obstacles and laminar flow that passively directs particles along in two different directions depending on the particles’ diameter. Many prior publications have been dedicated to the structural and geometrical development of DLD arrays to improve separation performance; however, a successful separation requires much more than a well-designed array. This paper shows how separation performance is affected by process parameters. For this purpose, the design and fabrication of a DLD device are described. Then three experiments show how process parameters affect the performance of the device. The first experiment uses dye solutions to visualize the formation of a hydrodynamically focused sample stream. The second experiment shows that the particle separation performance (of 7- & 15-µm particles) is affected by the way output fluids are collected. Finally, the third experiment looks at the particle separation efficiency as the input flow rates and the ratio of buffer to sample are changed. The results show that the proper range for buffer and sample flow rate in this device is 1–10 and 0.1–1 (µl/min), respectively. The buffer to sample flow rate ratio of 10 gives the highest separation efficiency, but at a lower sample throughput. The optimized values are specific for our device but demonstrate processes that we believe are universal for DLD separations.