Effect of Molasses on Regrowth of E. coli O157:H7 And Salmonella in Compost Teas

Compost water extracts (compost teas) are gaining popularity among organic growers, largely because of their disease suppressive activity when applied to foliage or soil. Production methods often include addition of supplemental constituents, particularly molasses, to stimulate plant-beneficial microbial populations. We have found that molasses amendments also favor regrowth of human pathogenic bacteria, raising public health concerns about potential contamination of treated crops, particularly produce intended for fresh consumption. Using disease outbreak strains marked with green fluorescent protein (GFP) and spontaneous antibiotic-resistance, we found that regrowth of Salmonella enterica serovar Thompson and Escherichia coli O157:H7 was positively correlated with molasses concentration. For Salmonella, regrowth was also dependent on the type of starter compost material used. Salmonella populations increased from 1 at time 0 to over 1000 CFU ml^?1 in dairy manure compost tea with 1% molasses, and from 1 at time 0 to over 350,000 CFU ml^?1 in chicken manure compost tea by 72 h. E. coli populations increased from 1 at time 0 to approximately 1000 CFU ml^?1 in both types of tea by 72 h. Pathogen regrowth did not occur when molasses was eliminated or kept to 0.2%.     

Effects of Land Use Conversion from Native Forests to Exotic Plantations on Nitrogen and Phosphorus Retention in Catchments of Southern Chile

In six small catchments located at the Cordillera de la Costa in southern Chile (40° S), concentrations and fluxes of NO₃-N, NH₄-N, organic-N, total-N and total-P in bulk precipitation and runoff water were measured. The main objective of this study was to compare nitrogen and phosphorus retention of catchments with varying land cover of native forest and exotic plantations, in order to evaluate possible effects of land use change. Nitrate-N was the dominant fraction (>50%) of nitrogen loss, especially in the catchments dominated by exotic plantations. In the catchment with native forests, NO₃ ^? only contributed with 34% of the nitrogen loss and DON was the main output with 55%. Annual NO₃ ^? export was lower in the catchment with native forest compared to the catchments with exotic plantations where the streamflow output exceed the precipitation input. Average inputs of total-N were 2.6 kg ha^?1 year^?1 (DIN?=?1.4 kg ha^?1 year^?1, DON?=?1.2 kg ha^?1 year^?1) and outputs were 1.7 kg ha^?1 year^?1 (DIN?=?1.2 kg ha^?1 year^?1, DON?=?0.5 kg ha^?1 year^?1). Annual retention of total nitrogen fluctuated between 61% in a catchment dominated by native forests to 15% in catchments dominated by exotic plantations of Eucalyptus sp. Nitrogen retention was positively related with native forest coverage. The N retention capacity of the catchments could be both attributed to consequences of clear cutting practices and differences in vegetation cover.     

Nutrient dynamics of field-weathered Delmarva poultry litter: implications for land application

To develop phosphorus-based agronomic application rates of phytase-diet, bisulfate-amended Delmarva poultry litter in conservation tillage systems, nutrient release dynamics of the organic fertilizer under local weather conditions were investigated. Delmarva poultry litter was placed in polyvinyl chloride columns to a depth of 5 cm and weathered in the field for 570 days. Leachate from the columns was collected and measured for concentrations of various nutrients. Cumulative release of the nutrients as a function of weathering time was modeled, and the nutrient supply capacity was determined. Poultry litter leachate contained high contents of dissolved organic carbon (15–31,500 mg L^?1), nitrogen (N 5–7,070 mg L^?1), phosphorus (P 5–230 mg L^?1), potassium (K⁺ 2–7,140 mg L^?1), and other nutrients. Release of most nutrients occurred principally in the first 100 days, but for P and calcium (Ca²⁺), it would last for years. The release kinetics of N followed a logarithm equation, while P and K demonstrated a sigmoidal logistic pattern. The nutrient supply capacity of surface-applied Delmarva poultry litter was predicted at 10.9 kg N Mg^?1, 6.5 kg P Mg^?1, 34.7 kg K⁺ Mg^?1, 5.4 kg Ca²⁺ Mg^?1, and 14.0 kg SO ₄ ^2? Mg^?1. The results suggest that Delmarva poultry litter should be applied to conservation tillage systems at 6.6 Mg ha^?1 that would furnish 25 kg P ha^?1 and 63 kg N ha^?1 to seasonal crops. In repeated annual applications, the rate should be reduced to 5.2 Mg ha^?1, with supplemental N fertilization to meet crop N requirements.     

The Nature and Distribution of Metals in Soils of the Sydney Estuary Catchment, Australia

Total topsoil 50th percentile Cu, Pb and Zn concentrations (n?=?491) in the Sydney estuary catchment were 23 ??g?g^?1, 60 ??g?g^?1 and 108 ??g?g^?1, respectively. Nine percent, 6% and 25% of samples were above soil quality guidelines, respectively and mean enrichment was 14, 35 and 29 times above background, respectively. Soils in the south-eastern region of the catchment exhibited highest metal concentrations. The close relationship between soil metal and road network distributions and outcomes of vehicular emissions modelling, strongly suggested vehicular traffic was the primary source of metals to catchment soils. Catchment soil and road dust probably make an important contribution to contamination of the adjacent estuary. The concentration of soil metals followed the land use trend: industrial?>?urban?>?undeveloped areas. A high proportion (mean 45%, 62% and 42%, for Cu, Pb and Zn, respectively) of metals in the soils may be bioavailable.     

Plasma B-esterase and Glutathione S-transferase Activities in the South American Reptiles Caiman latirostris (Crocodylia, Alligatoridae) and Phrynops hilarii (Testudines, Chelidae)

We determined normal plasma butyrylcholinesterase (BChE), carboxylesterase (CbE using ??-NA substrate), and glutathione S-transferase (GST) activities in Caiman latirostris and Phrynops hilarii to obtain reference values for organophosphorus (OP) pesticide monitoring. BChE and CbE sensitivity to malaoxon was also evaluated. C. latirostris (N?=?12; six males and six females) and P. hilarii (N?=?12; seven males and five females) were obtained from the programs Yacaré (Entre Ríos Province, Argentina) and Zoo of Córdoba (Córdoba Province, Argentina). Mean total (female and male) plasma BChE activity was significantly different between reptile species, ranging between 0.337?±?0.085???mol?min^?1?ml^?1 of plasma for C. latirostris and 0.251?±?0.070???mol?min^?1?ml^?1 of plasma for P. hilarii. However, plasma CbE (??-NA) and GST activities were significantly higher in P. hilarii (4.81?±?1.00 and 0.145?±?0.045???mol?min^?1?ml^?1 of plasma, respectively) than in C. latirostris (0.57?±?0.20 and 0.059?±?0.013???mol?min^?1?ml^?1 of plasma, respectively). No significant differences in B-esterase and GST activities were detected between sexes, except CbE (??-NA) for C. latirostris. IC₅₀ values for BChE and CbE (??-NA) suggested different sensitivity levels between species and between sexes. The results demonstrate that plasma esterase activity varied between species, but not between sexes (except CbE for C. latirostris). The in vitro inhibition tests indicated that CbE (??-NA) is more sensitive to inhibition than BChE. C. latirostris may be the reptile species most vulnerable to field pesticide exposure because this reptile presents the lowest CbE activity levels and its B-esterase levels seem more sensitive to OP.     

Isolation and characterization of multi-potential Rhizobium strain ND2 and its plant growth-promoting activities under Cr(VI) stress

Soil contaminated by chromium (Cr) is a major concern for sustainable agriculture. Considering this as a basis, the present study was designed to isolate Cr(VI)-reducing and plant growth-promoting bacterial strain from contaminated sampling sources. In this study, Rhizobium strain ND2 was isolated from the root nodules of Phaseolus vulgaris grown in leather industrial effluent contaminated soil. The strain ND2 exhibited strong resistance to different heavy metals and reduced 30 and 50 µg ml^?1 concentrations of Cr(VI) completely after 80 and 120 h of incubation, respectively, as well as chromium adsorption and immobilization were confirmed by scanning electron microscopic equipped with energy X-ray spectroscopy. In addition, the strain produced 21.73 and 36.86 µg ml^?1 of indole-3-acetic acid at 50 and 100 µg ml^?1 of L-tryptophan supplimentations, respectively. Strain ND2 positively affected the exo-polysaccharide, ammonia, protease and catalase production and stimulated root length of various test crops under Cr(VI) stress. Moreover, Rhizobium strain ND2 has the potential to colonize the diverse agricultural crops. Thus, the present findings strongly suggested that the multipotential properties of ND2 could be exploited for bioremediation of contaminated sites with Cr(VI) as well as potential bio fertilizer for enhancing the agricultural productivity.     

Dissolved Organic Carbon in Association with Water Soluble Nutrients and Metals in Soils from Lake Okeechobee Watershed, South Florida

Water quality of Lake Okeechobee has been a major environmental concern for many years. Transport of dissolved organic matter (DOM) in runoff water from watershed is critical to the increased inputs of nutrients (N and P) and metals (Cu and Zn). In this study, 124 soil samples were collected with varying soil types, land uses, and soil depths in Lake Okeechobee watershed and analyzed for water-extractable C, N, P, and metals to examine the relationship between dissolved organic carbon (DOC) and water soluble nutrients (N and P) and metals in the soils. DOC in the soils was in 27.64?C400 mg kg^?1 (69.30 mg kg^?1 in average) and varied with soil types, land uses, and soil depth. The highest water-extractable DOC was found in soils collected in sugar cane and field crops (277 and 244 mg kg^?1 in average, respectively). Water soluble concentrations of N and P were in the range of 6.46?C129 and 0.02?C60.79 mg kg^?1, respectively. The ratios of water-extractable C/N and C/P in soils were in 0.68?C12.52 (3.23 in average) and 3.19?C2,329 (216 in average), and varied with land uses. The lowest water-extractable C/N was observed in the soils from dairy (1.66), resident (1.79), and coniferous forest (4.49), whereas the lowest water-extractable C/P was with the land uses of dairy (13.1) and citrus (33.7). Therefore, N and P in the soils under these land uses may have high availability and leaching potential. The concentrations of water soluble Co, Cr, Cu, Ni, and Zn were in the ranges of?<?method detection limit (MDL)?C0.33, <MDL?C0.53, 0.04?C2.42, <MDL?C0.71, and 0.09?C1.13 mg kg^?1, with corresponding mean values of 0.02, 0.01, 0.50, 0.07, and 0.37 mg kg^?1, respectively. The highest water soluble Co (0.10 mg kg^?1), Cr (0.26 mg kg^?1), Ni (0.31 mg kg^?1), and Zn (0.80 mg kg^?1) were observed in soils under the land use of sugar cane, whereas the highest Cu (1.50 mg kg^?1) was with field crop. The concentration of DOC was positively correlated with total organic carbon (TOC) (P <0.01), water soluble N (P <0.01), electrical conductivity (EC, P <0.01), and water soluble Co, Cr, Ni, and Zn (P <0.01), and Cu (P <0.05), whereas water soluble N was positively correlated with water soluble P, Cu, and Zn (P <0.01) in soils. These results indicate that the transport of DOC from land to water bodies may correlate with the loss of macro-nutrients (N, P), micro-nutrients (Cu, Zn, and Ni), and contaminants (Cr and Co) as well.     

Cadmium adsorption as influenced by poultry manure addition in soils of South-Western Nigeria

Soil contamination with heavy metals is of great concern worldwide because of its negative effects on human health and environment. The objective of this study was to evaluate the influence of poultry manure on cadmium (Cd) adsorption characteristics in soils from ten different land uses and to determine the effects of Cd adsorption on soil properties. Laboratory experiments were carried out using Cd concentrations ranging from 0 to 160 mg Cd L^?1 and poultry manure rates ranging from 0 to 8% w/w basis. Results showed that all the soils exhibited varying capacity to adsorb Cd with values ranging from 28.78 to 130.2 mgkg^?1; 126.2 to 153.5 mgkg^?1 and 126.2 to 156.1 mgkg^?1 for 0%, 4% and 8% poultry manure at 160 mgkg^?1 initial Cd concentrations, respectively. Lowest Cd adsorbed (28.78 mgkg^?1) was recorded in samples from 6 months fallow and highest (156.1 mgkg^?1) from vegetable field. On the average, capacity to adsorb Cd was 72.1%, 99.7% and 95.3% with 0%, 4% and 8% applied poultry manure, respectively. Organic carbon, CEC, pH were significantly correlated with Cd adsorption. Poultry manure use will increase Cd adsorption and decrease Cd in the environment.     

Relationship Between Fecal Indicators in Sediment and Recreational Waters in a Danish Estuary

The European Union has introduced a new bathing water directive where future classification of recreational waters will be based on the microbial parameters Escherichia coli, and intestinal enterococci. Introduction of enterococci as a new quality parameter may pose a challenge in some areas because relatively less is known about these organisms compared to E. coli. In the present study, the relative abundance of intestinal enterococci, E. coli, and ten fecal sterol and stanol biomarkers were investigated in water and sediment at two estuarine beach sites affected by fecal pollution. In the bathing water, enterococci were relatively more abundant at low E. coli concentrations. In the sediment, enterococci were generally more abundant than E. coli with surface concentrations between 1.0?×?10² and 4.5?×?10³ CFU cm^?3. Enterococci populations were relatively similar in water and sediment, and were phenotypically different from that of nearby pollution sources. The putative human specific genetic marker esp in Enterococcus faecium was not detected in water or sediment samples despite occasional inputs of human waste from storm water overflows. Sterol and stanol profiles suggested a direct link between water and sediment pollution profiles on days with wind conditions that facilitated resuspension. Sediment resuspension may occur at wind speeds exceeding 6–8 m s^?1, and could contribute significantly to enterococci concentrations in the overlying water. The study emphasized that recontamination of the water column due to wind induced resuspension should be considered when evaluating indicator levels and microbial hazards in estuarine recreational waters.     

Use of nitrogen process inhibitors for reducing gaseous nitrogen losses from land-applied farm effluents

Applications of dairy farm effluents to land may lead to ammonia (NH₃) volatilization and nitrous oxide (N₂O) emissions. Nitrogen (N) transformation process inhibitors, such as urease inhibitors (UIs) and nitrification inhibitors (NIs), have been used to reduce NH₃ and N₂O losses derived from agricultural N sources. The objective of this study was to examine the effects of amending dairy effluents with UI (N-(n-butyl) thiophosphoric triamide (NBTPT)) and NI (dicyandiamide (DCD)) on NH₃ and N₂O emissions. Treatments included either fresh or stored manure and either fresh or stored farm dairy effluent (FDE), with and without NBTPT (0.25 g kg^?1 N) or DCD (10 kg ha^?1), applied to a pasture on a free-draining volcanic parent material soil. The nutrient loading rate of FDE and manure, which had different dry matter contents (about 2 and 11 %, respectively) was 100 kg N ha^?1. Application of manure and FDE led to NH₃ volatilization (15, 1, 17 and 0.4 % of applied N in fresh manure, fresh FDE, stored manure and stored FDE, respectively). With UI (NBTPT), NH₃ volatilization from fresh manure was significantly (P?<?0.05) decreased to 8 % from 15 % of applied N, but the UI did not significantly reduce NH₃ volatilization from fresh FDE. The N₂O emission factors (amount of N₂O–N emitted as a percentage of applied N) for fresh manure, fresh FDE and stored FDE were 0.13?±?0.02, 0.14?±?0.03 and 0.03?±?0.01 %, respectively. The NI (DCD) was effective in decreasing N₂O emissions from stored FDE, fresh FDE and fresh manure by 90, 51 and 46 % (P?<?0.05), respectively. All types of effluent increased pasture production over the first 21 days after application (P?<?0.05). The addition of DCD resulted in an increase in pasture production at first harvest on day 21 (P?<?0.05). This study illustrates that UIs and NIs can be effective in mitigating NH₃ and N₂O emissions from land-applied dairy effluents.     

Lantana camara——an Ecological Bioindicator Plant for Decontamination of Pb-Impaired Soil Under Organic Waste-Supplemented Scenarios

Heavy metal extraction and processing from ores releases elements into the environment. Soil, being an "unfortunate" sink, has its bionomics impaired and affected by metal pollution. Metals sneak into the food chain and pose risk to humans and other edaphicdependent organisms. For decontamination, the use of an ecosystem-friendly approach involving plants is known as phytoremediation.In this study, different lead(Pb) concentrations(80, 40, 20, and 10 mg kg~(-1)) were used to contaminate a well-characterized soil,(un)supplemented with organic waste empty fruit bunch(EFB) or spent mushroom compost(SMC), with non-edible plant—Lantana camara. Lead removal by L. camara ranged from 45.51% to 88.03% for supplemented soil, and from 23.7% to 57.8% for unsupplemented soil(P 0.05). The EFB-supplemented and L. camara-remediated soil showed the highest counts of heavy metal-resistant bacteria(HMRB)(79.67 × 10~6–56.0 × 10~6 colony forming units(CFU) g~(-1) soil), followed by SMC-supplemented and L. camara-remediated soil(63.33 × 10~6–39.0 × 10~6 CFU g~(-1) soil). Aerial metal uptake ranged from 32.08 ± 0.8 to 5.03 ± 0.08 mg kg~(-1) dry weight, and the bioaccumulation factor ranged from 0.401 to 0.643(P 0.05). Half-lives(t_(1/2)) of Pb were 7.24–2.26 d in supplemented soil,18.39–11.83 d in unsupplemented soil, and 123.75–38.72 d in the soil without plants and organic waste. Freundlich isotherms showed that the intensity of metal absorption(n) ranged from 2.44 to 2.51 for supplemented soil, with regression coefficients of determination(R~2) between 0.901 2 and 0.984 0. The computed free-energy change(?G) for Pb absorption ranged from -5.01 to 0.49 kJ mol~(-1) K~(-1) for EFB-supplemented soil and -3.93 to 0.49 k J mol~(-1) K~(-1) for SMC-supplemented soil.     

Phosphorus Entrainment Due to Resuspension in a Lowland River, Spree, NE Germany – A Laboratory Microcosm Study

Resuspension of benthic phosphorus (P) often constitutes a high percentage of the annual P flux in lowland rivers. To study P entrainment at controlled shear velocity (u*) sediment from lowland River Spree of slower flowing (0.1–0.3 m s^?1) stretch Kossenblatt (KOB) and of faster flowing (0.5–0.7 m s^?1) stretch Freienbrink (FRB) was incubated in a microcosm at incrementally enhanced u* (0.34–1.9 cm s^?1). Particle and P entrainment rates as well as the number of particle-associated bacteria of fine-grained mud-like KOB sediment were much higher (16.7 g m^?2 h^?1, 104.9 mg P m^?2 h^?1, 15.47 10⁶ cells ml^?1) than those (4.3 g m^?2 h^?1, 2.1 mg P m^?2 h^?1, 3.06 10⁶ cells ml^?1) of coarser sandy FRB sediment. The microcosm used so far in marine research is suited to compare riverine resuspension suggesting the lower u* the more particles are deposited and the more P can be retained (KOB ? FRB). Conversely, correspondingly more and easier particulate P and bacteria can again be remobilised (KOB ? FRB) if u* increases. The general relationship found for u* and the entrainment of particulate P and bacteria as well as their decelerated and selective deposition where bacteria may stay longer in the water implies a temporarily enhanced P bioavailability, turnover and subsequent P transformations.     

The practice of leaching boron and soluble salts from fly ash-amended soils

The leachability of B and salts from two fly ash-amended soils was conducted in a column leaching experiment. Fly ash was applied to the surface 3 cm of a Baywood (acid) sand and an Arizo (calcareous) sandy, loam at 5% by weight; the columns were continously leached with Colorado River water at two different pH's. Boron from fly ash was solubilized more readily in the Baywood than in the Arizo soil. Addition of fly ash increased B levels in the leachates from 0.25 to 2.35 μg ml^?1 (Baywood) and 0.93 μg ml^?1 (Arizo). Acidified leaching water had no significant effect on B leaching patterns but resulted in leaching higher soluble salts. Approximately 348 and 161 cm of water for the Arizo and the Baywood soils respectively, would be required to reduce the B concentration below a critical limit for B sensitive crops. It is suggested that crops planted when fly ash is applied for disposal/recycling on land should be both salt and B tolerant.     

Effective Nutrient Sources for Plant Growth on Bauxite Residue: II. Evaluating the Response to Inorganic Fertilizers

An integral part of managing dust emissions from bauxite residue storage areas in Western Australia is the establishment of native vegetation and dust control crops. Recent changes to local health department regulations preclude the routine use of poultry manure, the previous standard fertilizer for growing dust control crops on bauxite residue sand. This paper reports on a field evaluation of different forms of inorganic fertilizer, to assess their effectiveness as alternatives to poultry manure for supplying nutrients to dust control crops. We compared plant growth and nutrient uptake under different forms of nitrogen (N) and phosphorus (P) fertilizers with additional potassium (K) and trace elements. A diammonium phosphate (DAP) based fertilizer blend which supplied 270 kg N ha^?1 of N and 307.5 kg P ha^?1 was found to be more effective than a superphosphate based blend containing the same amounts of these nutrients. The DAP treatment did not respond to topdressing with different N fertilizers, but plant growth in the superphosphate treatment was responsive to topdressing with N. Of the three different nitrogenous fertilizers evaluated for topdressing the superphosphate treatment (ammonium sulphate, diammonium phosphate, and urea), the ammonium based fertilizers were most effective. The DAP blend was the most cost effective of all the fertilizers studied, costing only A$1070 ha^?1 compared with A$2473 ha^?1 for the superphosphate blend and A$1600 ha^?1 for poultry manure. We concluded that the DAP fertilizer blend could be used as an effective replacement for poultry manure for growing dust control crops on bauxite residue sand.     

Effective Nutrient Sources for Plant Growth on Bauxite Residue

We conducted a field experiment to evaluate alternatives to poultry manure, the normal fertilizer used for growing dust control crops and native vegetation on bauxite residue sand. We compared plant growth, nutrient uptake and residue properties after applications of poultry manure, compost, composted poultry manure and inorganic fertilizer. The compost used was prepared from green waste treated with piggery waste. Plant growth was poor under the compost and composted poultry manure treatments, which produced 0.69 and 1.11 t ha^{? 1} of above ground biomass, respectively. This compared with 2.43 t ha^{? 1} from the inorganic fertilizer treatment which had a similar biomass to the poultry manure treatment (3.00 t ha^{? 1}). All treatments, including poultry manure, had low foliar concentrations of some nutrients, with low levels of N, P, K, Mg, Cu and Zn found in most treatments. Of the two treatments which gave effective dust control (inorganic fertilizer and poultry manure) the most economical was inorganic fertilizer which cost A$1227 ha^{? 1}. The high application rate of the poultry manure made it the most expensive fertilizer treatment at a cost of A$1650 ha^{? 1}. There appeared to be no long-term benefit of using organic amendments, as organic fertilizers did not improve residue conditions (organic matter content, pH, electrical conductivity, activity of Na⁺ ions) compared with the inorganic fertilizer. It was concluded that inorganic fertilizer could provide a suitable, cost-effective alternative to poultry manure for growth of dust control crops, with further research required to address low levels of some nutrients.     

Co-inoculation of soybeans and common beans with rhizobia and azospirilla: strategies to improve sustainability

Plant–microorganism associations have long been studied, but their exploitation in agriculture partially or fully replacing chemical fertilizers is still modest. In this study, we evaluated the combined action of rhizobial and plant growth-promoting rhizobacteria inoculants on the yields of soybean and common bean. Seed inoculation with rhizobia (1.2?×?10⁶ cells seed^?1) was compared to co-inoculation with Azospirillum brasilense in-furrow (different doses) or on seeds (1.2?×?10⁵ cells seed^?1) in nine field experiments. The best in-furrow inoculant dose was 2.5?×?10⁵ cells of A. brasilense seed^?1 for both crops. Inoculation with Bradyrhizobium japonicum increased soybean yield by an average 222 kg?ha^?1 (8.4 %), and co-inoculation with A. brasilense in-furrow by an average 427 kg?ha^?1 (16.1 %); inoculation always improved nodulation. Seed co-inoculation with both microorganisms resulted in a mean yield increase of 420 kg?ha^?1 (14.1 %) in soybean relative to the non-inoculated control. For common bean, seed inoculation with Rhizobium tropici increased yield by 98 kg?ha^?1 (8.3 %), while co-inoculation with A. brasilense in-furrow resulted in the impressive increase of 285 kg?ha^?1 (19.6 %). The cheaper, more sustainable inoculated treatment produced yields equivalent to the more expensive non-inoculated + N-fertilizer treatment. The results confirm the feasibility of using rhizobia and azospirilla as inoculants in a broad range of agricultural systems, replacing expensive and environmentally unfriendly N-fertilizers.     

Pesticides to control ostracods grazing on blue-green algae

Means to control ostracods grazing on blue-green algae (cyanobacteria) important in fixing nitrogen in flooded rice soils were studied. The relative acute lethal toxicity (LC₅₀⁴⁸) to the ostracods Cyprinotus carolinensis and Heterocypris luzonensis grazing on Tolypothrix tenuis was 0.4 and 2.4 μg ml^?1 for carbofuran and 4.5 and more than 56.0 μ g ml^?1 for lindane. Complete inhibition of grazing was achieved with 1.0 and 25 μ g carbofuran ml^?1 and 0.1 and 5.6μ g lindane ml^?1 for C. carolinensis and H. luzonensis, respectively. Lindane at concentrations below 0.02 μ g ml^?1 stimulated feeding by C. carolinensis on the alga. Breakdown of carbofuran markedly reduced its effectiveness as a measure to control grazing, but lindane did not rapidly lose its effectiveness. The toxicity of carbofuran to C. carolinensis feeding on T. tenuis was not affected by pH. The difference in ostracod responses to the pesticides, which may be associated with resistance acquired through previous exposure, is an important consideration in designing practical means to reduce grazing in paddy fields.     

Microbial Population Dynamics and Enzyme Activities During Composting

The changes in population size of different microbial groups (total aerobic heterotrophs, actinomycetes, fungi, fecal coliforms, ammonium- and nitrite-oxidizing bacteria, and denitrifying bacteria) and the activities of 19 different enzymes (three phosphatases, three esterases, two proteases, three amino-peptidases, and eight glycosyl-hydrolases) were examined during cocomposting of poultry litter (a mixture of poultry manure, waste feed, feathers, and wood shavings) and yard trimmings (a mixture of grass clippings, leaves, and wood barks). Three piles with forced aeration were established by mixing 2:1 (v/v) ratio of poultry litter and yard trimmings. During composting, samples were taken at three different locations (top, middle, and bottom) of the forced aeration piles for microbial and enzyme analyses. Results demonstrated that population size of different microbial groups was not a limiting factor in this composting process as the microorganisms in the poultry litter + yard trimmings compost are in great abundance. Although the numbers of these microbial groups were reduced by high temperature, their populations multiplied rapidly as composting progressed. Fecal coliforms were eliminated by day 49, suggesting that the poultry litter + yard trimmings compost showed an overall increase in diversity and relative abundance of extracellular enzymes present as composting progressed. The population of fungi and actinomycetes (microorganisms active in degradation of cellulose, hemicellulose, and lignin) were positively correlated with esterase, valine amino-peptidase, α-galactosidase, β-glucosidase, and lipase. Of all 19 enzymes examined, ß-galactosidase (enzyme involved in the hydrolysis of lactose) had the most significant positive correlation with microbial populations, such as total aerobic heterotrophs, ammonium- and nitrite-oxidizing bacteria, denitrifying bacteria, and fecal coliforms. Cystine amino peptidase, chymotrypsin, and trypsin showed no evidence of activity during the entire period of composting. This composting process represented a combined activity of a wide succession of environments in the compost pile as one microbial group/enzyme overlapped the other and each emerged gradually as a result of the continual change in temperature as well as moisture content, O₂ and CO₂ level, and progressive breakdown of complex compounds to simpler ones.     

Use of Sterol and Bile Acid Biomarkers to Identify Domesticated Animal Sources of Fecal Pollution

The objective of this study was to demonstrate the use of chemical biomarkers (fecal sterols and bile acids) to identify selected sources of fecal pollution in the environment. Fecal sterols and bile acids were determined for pig, horse, cow, and chicken feces. Ten to twenty-six fresh fecal samples were collected for each animal, and the concentrations of fecal sterols (coprostanol, epicoprostanol, cholesterol, cholestanol, stigmastanol, and stigmasterol) and bile acids (lithocholic acid, deoxycholic acid, cholic acid, chenodeoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid) were determined using a gas chromatography and mass spectrometer (GC-MS) technique. Correlation study was performed among sterol and bile acid variables for selected animals, and a ratio (cholesterol + epicoprostanol)/(deoxycholic acid + chenodeoxycholic acid + hyodeoxycholic acid) has been proposed as an indicator for assessing fecal input. The levels of (cholesterol + epicoprostanol)/(deoxycholic acid + chenodeoxycholic acid + hyodeoxycholic acid) in horse, cow, chicken and pig were observed 3.258?±?1.191, 1.921?±?1.006, 1.013?±?0.726, and 0.205?±?0.119 respectively and the ratio of horse: cow: chicken: pig was 16: 9: 5: 1. This ratio suggests the potential of sterol and bile acid biomarkers in identifying sources and occurrence of fecal matter. While additional work using polluted water (as opposed to fresh fecal samples) as well as multiple pollution sources are needed to investigate the transport of these biomarkers into water bodies.