Role of streambed biofilms in the removal of biodegradable contaminants from shallow streams

Biological activity in shallow streams is dominated by biofilms which are attached to the surface of the streambed. Although biofilm kinetic models are well developed and are successfully applied to biological treatment process, they cannot be applied directly to predict water quality in shallow streams, because the area and mass-transport aspects of streambed biofilms are complicated and not defined. Therefore, the main purpose of this study was to develop area and mass-transport functions for cobble-and gravel-lined streambeds. An artificial stream was used to grow biofilms and conduct kinetic experiments on the biofilm utilization of an easily degraded sugar. Media size (i.e., cobble or gravel) and flow velocity were varied over a wide range of values typical to shallow streams. Water velocity had short-term and long-term effects on the rate of contaminant removal. The short-term effects were related to increased mass-transport kinetics for higher flow velocities, while the long-term effects also included increased surface colonization by biofilm. The cobble streambed was more sensitive to short-term changes in water velocity than was the gravel bed, and it gave faster removal kinetics. Equations to predict the mass transfer coefficients were appropriate for more than one biofilm community, as long as the same medium size was used. The simulations from the water quality models containing the biofilm reaction term were markedly different from the simulations from traditional water-quality models that use only suspended organism kinetics.U.S. Department of the InteriorU.S. Geological SurveyOpe

Using native warm-season grass, forb and legume mixtures for biomass, livestock forage and wildlife benefits : a case study (2017)

Case StudyThis guide is a companion to MU Extension publications G9422, Integrating Practices That Benefit Wildlife With Crops Grown for Biomass in Missouri, and G9423, Mixtures of Native Warm-Season Grasses, Forbs and Legumes for Biomass, Forage and Wildlife Habitat, which outlines the benefits of using these mixtures of native warm-season forages and provides information to help landowners make informed decisions on enhancing wildlife habitats while producing crops for biomass. Establishment and management practices, as well as yield results, are presented as a case study in this guide so that others can implement similar practices on their property

Perils of a Modern Collector

Provides the history of starting the Greater Boston Philatelic Society.&nbsp

Letter from George Gantzer

Letter concerning a position at Utah Agricultural College

Characterization of runoff and infiltration from no-till soybeans with selected winter cover crops

The influence of "living mulch" winter cover crops on soil loss, runoff amount and quality and soybean growth was studied at the Midwest Claypan Experimental runoff plots located on Mexico silt loam (Udollic Ochraqualf). Experimental treatments consisted of no-till soybeans with: 1) canada bluegrass (Poa compressa L.), 2) chickweed (Stellaria media h), 3) downy brome (Bromus tectorum L.), and 4) no cover crop (CK). Runoff, sediment, dissolved nutrients, soil water content, and plant growth characteristics were measured. For chickweed (CW), canada bluegrass (CB) and downy brome (DB) treatments, runoff was reduced 66, 56, and 80 percent (P [less than] 0.01), and soil loss was decreased 61, 97, and 95 percent (P [less than] 0.01), respectively, vs. the CK treatment. Concentrations of dissolved NH4+-N and P04-3-P in runoff water from cover crop plots were 2 to 2.8 times higher than the CK (P [less than] 0.05). Runoff from the CK had a higher concentration of dissolved No3--N. Total amounts of dissolved N03--N losses were significantly decreased by 71, 73, and 76 percent (P [less than] 0.01) and NH4+-N losses reduced by 40, 36, and 46 percent (P [less than] 0.10) for treatments of CW, CB, and DB vs. the CK, respectively. P04-3-P losses also were decreased by 50, 21, and 39 percent for CW, CB, and DB vs. CK, but differences were not significant (P [greater than] 0.10). Lower plant populations and delayed plant development decreased soybean yield in cover crop treatments from 18 to 62 percent (P [less than] 0.01) vs. the CK.Project # G-1235-03 Agreement # 14-08-0001-G-1235-0

Security Bug Report Classification using Feature Selection, Clustering, and Deep Learning

As the numbers of software vulnerabilities and cybersecurity threats increase, it is becoming more difficult and time consuming to classify bug reports manually. This thesis is focused on exploring techniques that have potential to improve the performance of automated classification of software bug reports as security or non-security related. Using supervised learning, feature selection was used to engineer new feature vectors to be used in machine learning. Feature selection changes the vocabulary used by selecting words with the greatest impact on classification. Feature selection was able to increase the F-Score across the datasets by increasing the precision. We also explored unsupervised classification based on clustering. A distribution of software issues was created using variational autoencoders, where the majority of security related issues were closely related. However, a portion of non-security issues also ended up in the distribution. Furthermore, we explored recent advances in text mining classification based on deep learning. Specifically, we used recurrent networks for supervised and semi-supervised classification. LSTM networks outperformed the Naive Bayes classifier in projects with a high ratio of security related issues. Sequence autoencoders were trained on unlabeled data and tuned with labeled data. The results showed that using unlabeled software issues different from the testing datasets degraded the results. Sequence autoencoders may be used on large datasets, where labeled data is scarce

Timing of Nordic Hamstring Exercise in Youth Soccer Players to Reduce Injury

The Nordic hamstring exercise (NHE) has been demonstrated to be an effective strength exercise to help mitigate the risk of hamstring injury in soccer players. It is a component of the FIFA 11+ grassroots injury prevention program, which is a series of warm-up exercises designed to be administered in large groups and at minimal cost. Recent evidence in adults suggests that the acute fatigue associated with the NHE may increase the risk of injury during training, causing some to suggest moving the NHE until the end of training. PURPOSE: To determine whether this same level of fatigue persists in young soccer players, where training intensities and volumes are often much lower than in adults. METHODS: We designed a field-based crossover experimental study where youth soccer players completed two experimental sessions in a randomized manner. Participants included 18 youth players (mean ± SD: males, n=18; age 15.5 ± 0.7 years, height 1.77 ± 0.13 m, weight 66.4 ± 10.8 kg) participating in the Major League Soccer (MLS) Next player development pathway in Phoenix, USA. One session included the NHE as part of a standardized warm-up prior to a 75-minute standardized training session, and the alternative session incorporated the NHE at the end of the training session. Maximal hamstring force was measured at baseline, post-warm-up, and after completion of training. RESULTS: There was no interaction, condition, or main effect of NHE timing as indicated by maximal force output in the left (p \u3e 0.69) and right leg (p \u3e 0.65). CONCLUSION: Our findings add to the growing body of literature with regard to lower-limb fatigue profiles and adolescent soccer players, as well as suggest youth soccer coaches should not be concerned with the timing of these interventions, allowing them to focus instead on adherence and player buy-in

Fractal scaling of apparent soil moisture estimated from vertical planes of Vertisol pit images

Image analysis could be a useful tool for investigating the spatial patterns of apparent soil moisture at multiple resolutions. The objectives of the present work were (i) to define apparent soil moisture patterns from vertical planes of Vertisol pit images and (ii) to describe the scaling of apparent soil moisture distribution using fractal parameters. Twelve soil pits (0.70 m long × 0.60 m width × 0.30 m depth) were excavated on a bare Mazic Pellic Vertisol. Six of them were excavated in April/2011 and six pits were established in May/2011 after 3 days of a moderate rainfall event. Digital photographs were taken from each Vertisol pit using a Kodak™ digital camera. The mean image size was 1600 × 945 pixels with one physical pixel ≈373 μm of the photographed soil pit. Each soil image was analyzed using two fractal scaling exponents, box counting (capacity) dimension (DBC) and interface fractal dimension (Di), and three prefractal scaling coefficients, the total number of boxes intercepting the foreground pattern at a unit scale (A), fractal lacunarity at the unit scale (Λ1) and Shannon entropy at the unit scale (S1). All the scaling parameters identified significant differences between both sets of spatial patterns. Fractal lacunarity was the best discriminator between apparent soil moisture patterns. Soil image interpretation with fractal exponents and prefractal coefficients can be incorporated within a site-specific agriculture toolbox. While fractal exponents convey information on space filling characteristics of the pattern, prefractal coefficients represent the investigated soil property as seen through a higher resolution microscope. In spite of some computational and practical limitations, image analysis of apparent soil moisture patterns could be used in connection with traditional soil moisture sampling, which always renders punctual estimate

About the Authors

About the authors.&nbsp

Chlordane movement during rainfall

Indoor rainfall simulation experiments were conducted to quantify the mass of technical chlordane leaving an experimental soil box in runoff, splash and leachate. The initial mass of technical chlordane was uniformly distributed throughout the soil at concentrations equal to those recommended for termite control around basement and foundation walls. Two silt loam soils and one sandy soil were studied. The mass of chlordane in runoff adsorbed to organic matter was estimated to be 16 times the mass of chlordane in runoff adsorbed to clay. For a soil with a clay-to-organic-matter ratio as high as 66, the mass of chlordane in runoff appears to be predominantly a function of clay content. For a soil with a clay-to-organic-matter ratio as low as 2 to 5, the mass of chlordane in runoff appears to be predominantly a function of organic matter content. An increase in rainfall intensity from 51 to 102 mm/hr increased chlordane mass in runoff by 300 to 500 percent. This increase in rainfall intensity increased the chlordane-to-sediment mass ratio in the runoff by 7 to 18 percent. The chlordane mass in runoff was 5 to 9 times as great as the mass of bromide in runoff. The chlordane mass in splash was 25 percent of the chlordane mass in runoff. Only the sandy soil at the higher rainfall intensity produced leachate. The chlordane mass in this leachate during the rainfall period was 37 percent of the chlordane mass in runoff and 264 percent of the chlordane mass in splash. The total chlordane mass which left the soil box by runoff, splash and leachate was equivalent to 4 to 44 mg per square foot of treated surface. This amounted to 0.03 to 0.31 percent of the original chlordane mass applied to the experimental soil box. This could potentially occur from previous legal surface applications in agriculture and turf management, from more recent illegal surface applications in agriculture and turf management, from proper use (according to label directions) as a subsurface termiticide but where depth of untreated cover soil was insufficient, from improper use as a subsurface termiticide where treated soil remained uncovered at the surface or from disturbance by new construction of large areas treated in previous years. This type of horizontal movement of chlordane and other organochlorine pesticides has been documented. Bennett et al. (1974) measured 70 ppb of gamma chlordane in the top five inches of soil located 10 feet away from a foundation wall treated 21 years earlier. Lichtenstein (1958) found higher concentrations of the organochlorine insecticides aldrin, lindane and DDT on the downslope side than on the upslope side of treated test plots. Similarly, Peach et al. (1973) found surface movement of aldrin, lindane and heptachlor toward points of lower elevation in a sloping field. Haan (1971) conducted laboratory rainfall-runoff experiments following surface treatment with aldrin, dieldrin and DDT and found that sediment carried more than twice as much pesticide mass as the water. Wauchope (1978) reviewed the literature on pesticide losses in runoff water from agricultural fields. He found that organochlorine pesticides lose about 1 percent of the total mass applied to the field through runoff. This compared to other commercial pesticides which lose 0.5 percent or less unless severe rainfall conditions occur within 2 weeks after application. Another important consideration is the mass of pesticide located within a few millimeters of the soil surface. Investigators have found that it is this zone from which pesticides are released during rainfall. Sharpley (1985) studied 5 soils and found the depth of this zone to range from 2 to 4 mm for 4 percent slopes under 50 mm/hr rainfall intensity to 13 to 37 mm for 20 percent slopes under 160 mm/hr rainfall intensity.Project # G-1432-04 Agreement # 14-08-0001-G-1423-0