Antibacterial activity of soil-bound antibiotics

There is some concern that antibiotic residues in land-applied manure may promote the emergence of antibiotic resistant bacteria in the environment. The goal of this study was to determine whether or not soil bound antibiotics are still active against bacteria. The procedure involved sorbing various amounts of tetracycline or tylosin on two different textured soils (Webster clay loam [fine-loamy, mixed, superactive, mesic Typic Endoaquolls] and Hubbard loamy sand [sandy, mixed, frigid Entic Hapludolls]), incubating these soils with three different bacterial cultures (an antibiotic resistant strain of Salmonella sp. [Salmonella(R)], an antibiotic sensitive strain of Salmonella sp. [Salmonella(S)], and Escherichia coli ATCC 25922), and then enumerating the number of colony forming units relative to the control. Incubation was done under both static and dynamic conditions. Soil-adsorbed antibiotics were found to retain their antimicrobial properties since both antibiotics inhibited the growth of all three bacterial species. Averaged over all other factors, soil adsorbed antimicrobial activity was higher for Hubbard loamy sand than Webster clay loam, most likely due to higher affinity (higher clay content) of the Webster soil for antibiotics. Similarly, there was a greater decline in bacterial growth with tetracycline than tylsoin, likely due to greater amounts of soil-adsorbed tetracycline and also due to lower minimum inhibitory concentration of most bacteria for tetracycline than tylosin. The antimicrobial effect of tetracycline was also greater under dynamic than static growth conditions, possibly because agitation under dynamic growth conditions helped increase tetracycline desorption and/or increase contact between soil adsorbed tetracycline and bacteria. We conclude that even though antibiotics are tightly adsorbed by clay particles, they are still biologically active and may influence the selection of antibiotic resistant bacteria in the terrestrial environment.     

EPA worst case water microcosms for testing phage biocontrol of Salmonella

A microplate method was developed as a tool to test phages for their ability to control Salmonella in aqueous environments. The method used EPA (U.S. Environmental Protection Agency) worst case water (WCW) in 96-well plates. The WCW provided a consistent and relatively simple defined turbid aqueous matrix, high in total organic carbon (TOC) and total dissolved salts (TDS), to simulate swine lagoon effluent, without the inconvenience of malodor and confounding effects from other biological factors. The WCW was originally defined to simulate high turbidity and organic matter in water for testing point-of-use filtration devices. Use of WCW to simulate lagoon effluent for phage testing is a new and innovative application of this matrix. Control of physical and chemical parameters (TOC, TDS, turbidity, temperature, and pH) allowed precise evaluation of microbiological parameters (Salmonella and phages). In a typical application, wells containing WCW were loaded with Salmonella enterica susp. enterica serovar Typhimurium (ATCC14028) and treated with phages alone and in cocktail combinations. Mean Salmonella inactivation rates (k, where the lower the value, the greater the inactivation) of phage treatments ranged from -0.32 to -1.60 versus -0.004 for Salmonella controls. Mean log(10) reductions (the lower the value, the greater the reduction) of Salmonella phage treatments were -1.60 for phage PR04-1, -2.14 for phage PR37-96, and -2.14 for both phages in a sequential cocktail, versus -0.08 for Salmonella controls. The WCW microcosm system was an effective tool for evaluating the biocontrol potential of Salmonella phages.     

RESPONSES OF HETEROTHROPHIC BACTERIAL POPULATIONS TO pH CHANGES IN COAL ASH EFFLUENT1

ABSTRACT: Total culturable heterotrophic bacteria in a coal ash basin and drainage system were monitored over a period of two years. In the first year heavy (bottom) ash was sluiced to the basin resulting in a pH of 6.5. During the second year fly ash was precipitated and added to the sluice lowering the basin pH to 4.6. Sulfate concentrations during 1975 ranged from 16–73 ppm (mean 33) and in 1976 from 44–88 ppm (mean 72). Mean annual basin temperatures were 28.8 and 26.0 C, respectively. Approximately 1500 m in the receiving swamp below the basin, mean pH and temperature were 6.8 and 22.2 C for the first year, and 5.4 and 22.1 C for the second. Total culturable bacteria and diversity (colony types) were reduced at all sampling stations by 44 and 30 percent, respectively, whereas the percentage of the population comprised of chromagenic bacteria increased by 51 percent at the lower pH; Data indicated the pH had a greater effect than did water temperature when temperature was within the range of 15–25 C. The predominant genera within the system in the first year were Bacillus, Sarcina, Achromobacter, Flavobacterium, and Pseudomonas. In the second year, at the lower pH, predominant genera were Pseudomonas, Flavobacterium, Chromobacterium, Bacillus, and Brevibacterium.     

ENVIRONMENTAL FACTORS INFLUENCING SUSPENDED SOLIDS IN THE LOXAIIATCHEE ESTUARY,FLORIDA1

ABSTRACT: A study was initiated to examine the effects of wind speed, wind direction, freshwater inflow, and tide height on suspended solid concentration and distribution in the Loxahatchee estuary, Florida. Recent efforts to increase freshwater flows in this system raised concerns that suspended solid concentrations would increase as well, which might result in negative impacts for the estuary. The data indicated that total suspended solids (TSS) in the estuary are derived primarily from the inlet and not from freshwater tributaries. In addition, total suspended solids and volatile suspended solids were correlated strongly with salinity, suggesting that suspended sediments act conservatively throughout this system. No one environmental factor had an overwhelming influence on suspended solid concentration throughout the estuary; different regions of the estuary were influenced by different factors. Freshwater inflow was negatively related to TSS in the upper reaches of the estuary but was positively related to TSS in the central embayment region of the estuary. We attribute this latter finding to the fact that extremely high inflows both prevented the normal transport upstream of tidal borne suspended sediments and promoted mixing when the freshwater front moving downstream confronted the tidal front moving upstream. Wind speed, wind direction, and tide height had relatively small effects on TSS concentration but were most influential in reaches upstream of the central embayment, where tidal velocity begins to diminish.     

SUSPENDED SEDIMENT PRODUCTION FROM FORESTED WATERSHEDS ON OAHU,HAWAII1

Suspended sediment from forested and agricultural watersheds was sampled over a five-year period on the island of Oahu. A variety of storm conditions were sampled, giving a measure of the extreme variability in suspended sediment production. Total annual suspended sediment from all watersheds sampled ranged from 8400 kg/km² to 617,000 kg/km². Normally, about 90 percent of the total suspended sediment was produced during less than 2 percent of the time. Suspended sediment concentrations rapidly increased during rising stream flow resulting from rain storms. Time to peak of less than two hours is common, with a similarly rapid return to prestorm conditions. The data presented indicate the great variability of suspended sediment yields, making establishment of effective standards difficult.     

Evaluation of Microbial Communities Colonizing Stone Ballasts at Diesel Depots

In this study, we evaluated the heterotrophic microbial communities colonising stone ballasts at diesel depots. The number of bacteria (both total culturable heterotrophic bacteria and hydrocarbon-degrading bacteria) was proportional to the level of hydrocarbon contamination. However, there was no significant difference in the level of total culturable heterotrophs (TCHs) and the hydrocarbon degrading bacteria. Addition of nutrients to the ballast stimulated the biological activity and possibly the removal of hydrocarbons. However, this was only evident in the highly contaminated stone ballasts samples. The biological activity was evaluated using CO₂ production. The production of CO₂ was higher in nutrient amended treatments in which high numbers of TCHs were present. Characterisation of heterotrophic communities using Biolog revealed differences in the microbial metabolic profiles for the different sites. The results suggest that the heterotrophic microbial communities at different diesel depots are different.     

RESPONSE OF BACTERIA TO THE PRESENCE OF CARBARYL IN WATER. I. RESPONSE OF BACTERIAL INDICATORS VS. RESPONSE OF PATHOGENIC BACTERIAL SPECIES1

ABSTRACT: Escherichia coli, Streptococcus faecalis, Salmonella typhimurium, and Staphylococcus aureus were tested by plate counts and Warburg respirometry to determine effects of the presence of carbaryl in water. E. coli and S. typhimurium were initially stimulated in the presence of the insecticide whereas S. faecalis and S. aureus were inhibited. Over a period of days, all bacteria died off more rapidly in the presence of carbaryl. The implications of these data in regards to bacteriological testing of water quality are discussed.     

CONTROL OF SUSPENDED SOLIDS AND PHYTOPLANKTON WITH FISHES AND A MUSSEL1

ABSTRACT: Filtering efficiency of the fathead minnow (Pimephales promelas), gizzard shad (Dorosoma cepedianum), carp (Cyprinus carpio), and a freshwater mussel (Elliptio coinpianata) was measured in field and laboratory trials to assess the ability of each species to control phytoplankton and suspended solid densities. All fish species tested were ineffective filterers and generally increased, rather than suppressed, algal and suspended solid concentrations. Filtering efficiencies of fish varied between -354 and 84 percent, depending on the size, shape, abundance, palatability, composition, and resistance to digestion of the particles. Because of poor filtering abilities, unpredictable feeding habits, and sensitivity to stress, the fish species examined are not effective biological controls in waste lagoons. In contrast, the freshwater mussel Elliptio was a highly effective control organism, averaging 66 percent filtering efficiency over a wide size range of algal and suspended particles. Filtration efficiency was positively correlated with mussel density. Elliptio was efficient at filtering small particles, which are particularly difficult to remove. Mean filtration rates ranged from 53 to 134 ml/mussel/h depending on the algal species consumed and algal densities (range 50–180,000 cells/ml) and 3 mg/L/mussel/h on suspended solids (range 14 to 112 mg/L). Water clarification was facilitated by both direct consumption and pseudofeces deposition. Elliptio and probably other mussel species can effectively control algae and suspended solids in wastewater lagoons and eutrophic lakes, if environmental conditions, especially dissolved oxygen levels, are suitable (>5 mg/L) for their survival.     

WATER QUALITY AND SOURCE OF FRESHWATER DISCHARGE TO THE CALOOSAHATCHEE ESTUARY,FLORIDA1

ABSTRACT: The Caloosahatchee River has two major sources of freshwater one from its watershed and the other via an artificial connection to Lake Okeechobee. The contribution of each source to the freshwater discharge reaching the downstream estuary varies and either may dominate. Routine monitoring data were analyzed to determine the effects of total river discharge and source of discharge (river basin, lake) on water quality in the downstream estuary. Parameters examined were: color, total suspended solids, light attenuation, chlorophyll a, and total and dissolved inorganic nitrogen and phosphorus. In general, the concentrations of color, and total and dissolved inorganic nitrogen increased, and total suspended solids decreased, as total discharge increased. When the river basin was the major source, the concentrations of nutrients (excepting ammonia) and color in the estuary were relatively higher than when the lake was the major source. Light attenuation was greater when the river basin dominated freshwater discharge to the estuary. The analysis indicates that water quality in the downstream estuary changes as a function of both total discharge and source of discharge. Relative to discharge from the river basin, releases from Lake Okeechobee do not detectably increase concentrations of nutrients, color, or TSS in the estuary.     

Effects of Turbidity,Sediment, and Polyacrylamide on Native Freshwater Mussels

Turbidity is a ubiquitous pollutant adversely affecting water quality and aquatic life in waterways globally. Anionic polyacrylamide (PAM) is widely used as an effective chemical flocculent to reduce suspended sediment (SS) and turbidity. However, no information exists on the toxicity of PAM‐flocculated sediments to imperiled, but ecologically important, freshwater mussels (Unionidae). Thus, we conducted acute (96 h) and chronic (24 day) laboratory tests with juvenile fatmucket (Lampsilis siliquoidea) and three exposure conditions (nonflocculated settled sediment, SS, and PAM‐flocculated settled sediment) over a range of turbidity levels (50, 250, 1,250, and 3,500 nephelometric turbidity units). Survival and sublethal endpoints of protein oxidation, adenosine triphosphate (ATP) production, and protein concentration were used as measures of toxicity. We found no effect of turbidity levels or exposure condition on mussel survival in acute or chronic tests. However, we found significant reductions in protein concentration, ATP production, and oxidized proteins in mussels acutely exposed to the SS condition, which required water movement to maintain sediment in suspension, indicating responses that are symptoms of physiological stress. Our results suggest anionic PAM applied to reduce SS may minimize adverse effects of short‐term turbidity exposure on juvenile freshwater mussels without eliciting additional lethal or sublethal toxicity.     

Factors controlling sediment and phosphorus export from two Belgian agricultural catchments

Sediment and total phosphorus (TP) export vary through space and time. This study was conducted to determine the factors controlling sediment and TP export in two agricultural catchments situated in the Belgian Loess Belt. At the outlet of these catchments runoff discharge was continuously measured and suspended sediment samples were taken during rainfall events. Within the catchments vegetation type and cover, soil surface parameters, erosion features, sediment pathways, and rainfall characteristics were monitored. Total P content and sediment characteristics such as clay, organic carbon, and suspended sediment concentration were correlated. Total sediment and TP export differ significantly between the monitored catchments. Much of the difference is due to the occurrence of an extreme event in one catchment and the morphology and spatial organization of land use in the catchments. In one catchment, the direct connection between erosive areas and the catchment outlet by means of a road system contributed to a high sediment delivery ratio (SDR) at the outlet. In the other catchment, the presence of a wide valley in the center of the catchment caused sediment deposition. Vegetation also had an effect on sediment production and deposition. Thus, many factors control sediment and TP export from small agricultural catchments; some of these factors are related to the physical catchment characteristics such as morphology and landscape structure and are (semi)permanent, while others, such as vegetation cover and land use, are time dependent.     

ESTIMATING THE SUSPENDED SEDIMENT LOAD IN RESERVOIRS1

ABSTRACT: The total suspended sediment loads of four north Mississippi reservoirs were determined from measurements of concentrations of suspended sediment in a vertical profile at several locations on each reservoir made during the year. These data were combined with the stage-height and known stage-volume relationships for each reservoir in a numerical integration to determine the total suspended sediment in the water body. Total suspended sediments were estimated using the product of the suspended sediment concentration in the surface water by the appropriate reservoir volume. The averaged ratios of the estimated to measured suspended sediment loads for each reservoir exceeded 0.90. Since the concentration of suspended sediments in surface waters of north Mississippi reservoirs has been shown as highly correlated with spectral reflectance, estimating the total suspended sediment of these reservoirs using remotely sensed spectral reflectance data is possible.     

FRESH GROUND WATER STORED IN AQUIFERS UNDER THE CONTINENTAL SHELF: IMPLICATIONS FROM A DEEP TEST,NANTUCKET ISLAND,MASSACHUSETTS1

ABSTRACT: A deep water-resource and stratigraphic test well near the center of Nantucket Island, about 40 miles (64 km) off the New England Coast, has encountered freshwater at greater depth than predicted by the Ghyben-Herzberg principle. An uppermost lens of fresh-water, which occupies relatively permeable glacial-outwash sand and gravel to a depth of 520 ft. (158 m), is probably in hydrodynamic equilibrium with the present level of the sea and the height of the water table. However, two zones of freshwater between 730-820 ft. (222-250 m) and 900-930 ft. (274-283 m) are anomalously deep. A third zone extending from 1150-1500 ft. (350-457 m) contains slightly salty ground water (2 to 3 parts per thousand dissolved solids). Several explanations are possible, but the most likely is that large areas of the Continental Shelf were exposed to recharge by precipitation during long periods of low sea level in Pleistocene time. After the last retreat of glacial ice, seawater rapidly drowned the shelf around Nantucket Island. Since then, about 8000 years ago, the deep freshwater zones which underlie dense clay layers have not had time to adjust to a new equilibrium. Under similar circumstances freshwater may remain trapped under extensive areas of the Continental Shelf wherever clay confining beds have not permitted saltwater to intrude rapidly to new positions of hydrodynamic equilibrium. The implications are far reaching because all continental shelfs were exposed to similar hydrologic influences during Pleistocene time.     

Assessing effects of aerobic and anaerobic conditions on phosphorus sorption and retention capacity of water treatment residuals

Water treatment residuals (WTRs) are the by-products of drinking water clarification processes, whereby chemical flocculants such as alum or ferric chloride are added to raw water to remove suspended clay particles, organic matter and other materials and impurities. Previous studies have identified a strong phosphorus (P) fixing capacity of WTRs which has led to experimentation with their use as P-sorbing materials for controlling P discharges from agricultural and forestry land. However, the P-fixing capacity of WTRs and its capacity to retain sorbed P under anaerobic conditions have yet to be fully demonstrated, which is an issue that must be addressed for WTR field applications. This study therefore examined the capacity of WTRs to retain sorbed P and sorb further additional P from aqueous solution under both aerobic and anaerobic conditions. An innovative, low cost apparatus was constructed and successfully used to rapidly establish anoxic conditions in anaerobic treatments. The results showed that even in treatments with initial solution P concentrations set at 100 mg l(-1), soluble reactive P concentrations rapidly fell to negligible levels (due to sorption by WTRs), while total P (i.e. dissolved + particulate and colloidal P) was less than 3 mg l(-1). This equated to an added P retention rate of >98% regardless of anaerobic or aerobic status, indicating that WTRs are able to sorb and retain P in both aerobic and anaerobic conditions.     

THE EFFECTS OF SELECTED HERBICIDES ON BACTERIAL POPULATIONS IN AN AQUATIC ENVIRONMENT1

ABSTRACT: Heterotrophic, mesophilic bacteria derived from, and maintained in, a freshwater environment were subjected to three classes of herbicides. Diuron, 2,4,5-Trichlorophenoxyacetic acid, and paraquat, used as water soluble solutions, were added (0.7 and 1.4 mgA) to a laboratory culture of bacteria. Total numbers of the bacteria, representing several genera, were monitored for alteration of numbers and types. Temperature, pH, and dissolved oxygen were monitored and the culture medium was tested for residual herbicide. Alterations observed in populations were considered to result from herbicide additions. Each herbicide tested was found to affect bacterial populations differently. Reasons for observed differences are discussed. In this aquatic environment the herbicides remained qualitatively measurable for periods up to three weeks.     

TEMPORAL VARIABILITY OF WATER QUALITY IN THE ST. LUCIE ESTUARY,SOUTH FLORIDA1

ABSTRACT: Four years of monthly freshwater discharge and constituent concentration data from three tributaries were related to a concurrent series of data for three segments of the St. Lucie Estuary in South Florida using multiple regression and time-series analysis techniques. Water quality parameters examined were dissolved inorganic and total nitrogen and phosphorus, chlorophyll a, total suspended solids, turbidity, and color. On monthly time scales, a multiple regression, which included freshwater discharge, freshwater constituent concentration, and dilution with ocean water (salinity) as independent variables, explained 50 percent or less of the variability in estuarine constituents. No single independent variable explained more variation than another. By contrast, on seasonal (wet, dry) time scales, freshwater discharge explained the bulk of variation in estuarine water quality (up to 93 percent). On monthly time scales, variability in concentrations of nutrients and other constituents may be largely controlled by processes internal to the system. At seasonal time scales, freshwater discharge appears to drive variability in most estuarine water quality parameters examined. Results indicate that management of tributary input on a seasonal basis, with the expectation of achieving seasonal concentration goals in the estuary, would have a higher probability of success than managing on a monthly basis.     

含硫低浊度采油污水絮凝处理技术的研究

中原油田明二污属含硫低浊度污水,处理后水主要用于回注。文章通过pH调节剂的优选、除硫剂优选并与絮凝药剂联合,对明二污含硫低浊度污水进行了絮凝处理。结果表明:当pH值为7.5、2#絮凝剂加量为50mg/L、有机絮凝剂加量为0.5mg/L、除硫剂加量为20mg/L时,处理后水中的悬浮物、总铁和含油量分别达到1.9mg/L、0.43mg/L和0mg/L;SRB、TGB均为102个/mL;腐蚀速率及结垢量分别降到0.062mm/a和1.9mg/L;污泥产生量降低到0.23～0.26mg/L;在90℃时的结垢量由地层水的23.3mg/L降低到1.9mg/L,处理后的水达到中原油田回注水的水质标准,并且水质稳定。     

ELECTROPHORETIC WATER CLARIFICATION TECHNIQUES1

Only very recently has a limited amount of attention been focused directly on electrophoresis as a method for improving water quality. This approach has been proposed primarily as a method for removal of suspended colloidal material, although solutes can also be removed by this method. Very simply electrophoresis is defined as the movement of charged suspended particles in a dc electric field. Several electrophoretic clarification systems and techniques have been developed and evaluated primarily for removing colloidal clay from suspension. The methods should apply equally well to any negatively charged particulate matter. Design for optimal clay removal efficiency and operating cost efficiency has been based upon previous theoretical results and upon modification of the combination filter-el ectrophores is model of Bier. These systems and techniques along with the theoretical developments leading to their design are discussed. Results and conclusions are given for tests that have been concluded concerning the feasibility or practicality of these electrophoretic clarification systems for commercial use. These are viewed in light of various limiting factors such as electrical conductivity of the medium, quality of water desired, colloid concentrations and electrophoretic mobility of the suspended materials.     

QUALITY STUDY OF GRAYWATER TREATMENT SYSTEMS1

ABSTRACT: A residential single family dwelling was retrofitted to recycle graywater for landscape irrigation and toilet flushing. The objective of this study was to determine improvements in graywater quality by evaluating five simple graywater treatment systems that were easily adapted to the household plumbing. The treatment systems consisted of (1) water hyacinths and sand filtration, (2) water hyacinths, copper ion disinfection, and sand filtration, (3) copper ion disinfection and sand filtration, (4) copper/silver ion disinfection and sand filtration, and (5) 20–μm cartridge filtration. Water quality parameters measured were fecal and total coliform indicator bacteria, nitrates, suspended solids, and turbidity. Reductions in bacterial concentration, suspended solids and turbidity were achieved by all systems tested. Treatment reduced nitrate concentrations to an average of 2.6 mg/liter. Reductions in suspended solids, and turbidity were influenced more by the quality of the graywater entering the treatment system than the efficiency of the systems themselves. The water hyacinths and sand filtration system provided the best graywater quality in terms of the concentrations of fecal indicator bacteria. The system providing the best water quality in regard to average suspended solids after treatment was the water hyacinths, copper ion, and sand filtration system, and the best average turbidity was achieved by the copper/silver ion generating unit with sand filtration. All systems were capable of significant reductions in fecal indicator bacteria, suspended solids, and turbidity; however, additional treatment or disinfection would be necessary to further reduce the level of coliform and fecal coliform bacteria to achieve regulatory standards in the State of Arizona.     

Potential Methods for Managing Prymnesium parvum Blooms and Toxicity,With Emphasis on Clay and Barley Straw: A Review1

Hagström, Johannes A., Mario R. Sengco, and Tracy A. Villareal, 2010. Potential Methods for Managing Prymnesium parvum Blooms and Toxicity, With Emphasis on Clay and Barley Straw: A Review. Journal of the American Water Resources Association (JAWRA) 46(1):187-198. DOI: 10.1111/j.1752-1688.2009.00402.x Abstract: Harmful algal bloom (HAB) control and mitigation is a complex problem in ecosystem management. Phytoplankton play an important role in aquatic ecosystems as primary producers and food sources for many commercially important shellfish and there are limited options for targeting just a single species within the community. Chemical treatments (e.g., algaecides), rotting barley straw, nitrogen and phosphorus manipulation, and clay and/or flocculants are but a few techniques tested or used to reduce fish kills or shellfish contamination during a HAB event. Prymnesium parvum control has focused on the use of chemicals, nutrient manipulation, and clay flocculation. However, many HAB control methods have been rejected due to their effects on ecosystems, high costs, or limited effects on target organisms. For example, rotting barley straw (Hordeum vulgare) is considered to be an environmentally friendly alternative, but has been found to have very different results on the phytoplankton community depending on the dominating taxa and is ineffective against P. parvum and dinoflagellate blooms. Clay flocculation is a useful control/mitigation technique during fish kills in marine aquaculture sites in South Korea and can be effective in freshwater if the correct combination of clay and flocculent is used. Toxins produced by P. parvum and Karenia brevis also bind to phosphatic clay, thereby removing and/or neutralizing the toxins, but there is concern that the clay will have a negative effect on sessile organisms. Some shellfish suffer high mortalities and significant impacts on somatic and reproductive tissue growth at high clay loads; however, benthic communities appear to be unchanged after five years of clay treatment in South Korea. There are likely site-specific and ecosystem-specific characteristics that make generalizations about control options difficult and require careful assessment of options at each location.