Acute toxicity of cadmium to fish Labeo rohita and copepod Diaptomus forbesi pre-exposed to CaO and KMnO4

96-h LC₅₀ values of cadmium (Cd) to fish Labeo rohita and the copepod Diaptomus forbesi, determined by static bioassays, were, respectively, 89.5 and 10.2 mg/l. LC₅₀ values increased significantly when fish pre-exposed to 100–350 mg/l CaO or 0.5–1.5 mg/l KMnO₄ for 4 d and the copepod to 20–70 mg/l CaO or 0.25–1.0 mg/l KMnO₄ for same period. The LC₅₀ values also increased when the pre-exposure period of CaO was increased to 12 d at concentration 100 mg/l for fish and 20 mg/l for copepod. All fish died when pre-exposed to 1.5 mg/l KMnO₄ for 8 d. But LC₅₀ values of Cd to copepod increased when pre-exposure period of 0.5 mg/l KMnO₄ was increased from 4 to 8 d.     

Two-dimensional modeling of torrefaction of a large biomass particle

A two-dimensional (2-D) model is developed to predict the torrefaction behavior of a large wet biomass particle. Although one-dimensional (1-D) model is found to be adequate for L/D ≥ 6, the necessity of using 2-D model at lower L/D ratios and higher torrefaction temperature is established. Errors up to 18% are observed in predicted mass fractions between 1-D and 2-D models. The center temperatures differed more, up to 96%, between z = 0 and z = L/2 in 2-D model which is not captured by the 1-D model. The model predictions agree well with the experimental results of the present authors and others. The evolution of the temperature profile is found to govern the mass fraction profile. At higher reactor temperature, three distinct zones are visible in the contour plots: peripheral fully torrefied zone, intermediate torrefying zone, and core with unreacted virgin biomass zone. Simulation studies show the formation of two symmetric annular hot spots at the ends, which move inward axially and subsequently merge at the center, the rate being faster for smaller L/D ratio. However, 1-D model does not provide such insight. The effects of reactor temperature, particle size, the residence time, and the initial moisture content on the torrefaction behavior are investigated.     

Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine,cyanuric acid and biuret in industrial wastewater

An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL^?1, 265.6 and 1805.2 µg mL^?1 and 1.85 and 16.12 µg mL^?1, respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples, however, was degraded up to T4 treatments and was persistent in the T5 treatment. Probably, accumulation of this metabolite inhibited atrazine/cyanuric acid degradation by the enrichment culture in undiluted wastewater.     

Dissolved Organic Carbon and Estrogen Transport in Surface Runoff From Agricultural Land Receiving Poultry Litter1

Dutta, Sudarshan, Shreeram Inamdar, Jerry Tso, Diana S. Aga, and J. Tom Sims, 2012. Dissolved Organic Carbon and Estrogen Transport in Surface Runoff from Agricultural Land Receiving Poultry Litter. Journal of the American Water Resources Association (JAWRA) 48(3): 558-569. DOI: 10.1111/j.1752-1688.2011.00634.x Abstract: Dissolved organic carbon (DOC) provides a reactive substrate for the transport of organic contaminants with runoff. Very few studies have investigated the export of DOC from agricultural land, especially those receiving manure applications. We investigated exports of DOC in surface runoff from agricultural fields receiving various treatments of poultry litter (raw vs. pelletized). In addition, we also investigated how estrogens in runoff were associated with DOC. Different forms of estrogens studied were: estrone, 17β-estradiol, estriol, and their conjugates. Experimental agricultural plots were 12 m × 5 m long and had reduced tillage and no-till management practices. The aromatic content of DOC was characterized using specific ultraviolet absorbance (SUVA). Flow-weighted concentrations of DOC and SUVA in surface runoff from plots with poultry litter were significantly (p ≤ 0.10) greater than the control (no litter) plots. Compared to pelletized poultry litter, reduced-tillage plots with raw litter yielded higher DOC concentrations and SUVA values. No significant differences (p ≥ 0.10) in DOC and SUVA were observed between litter treatments for plots with no-till. Total estrogen concentrations (including all forms) were positively and significantly (p ≤ 0.10) correlated with DOC. These results can help select and guide agricultural management practices that can reduce the exports of DOC and associated contaminant from agricultural land receiving manure applications.     

Effect of acute exposure of acephate on hemocyte abundance in a non-target victim Drosophila melanogaster

Organophosphate insecticide acephate was tested to investigate effects on hemocyte abundance in a non-target dipteran insect Drosophila melanogaster. For this purpose, third-instar larvae were fed on four graded concentrations (2, 4, 6, or 8 μg/ml) acephate for a period of 12 and 24 hr (acute treatment). Control groups were simultaneously maintained for comparison. Relative proportions of plasmatocytes in hemolymph smear were found to fall with increasing concentrations of the test chemical. Similar decreasing trend in population of lamellocytes was also noted after 12 and 24 hr chemical exposure. In contrast to plasmatocytes and lamellocytes, crystal cell number was found to rise with increasing pesticide concentration. Several factors like oxidative stress, apoptosis induction, and mitotic failure might be the cause of reduced plasmatocyte and lamellocyte count. The elevated number of crystal cells in hemolymph smears is directly indicative of high melanin synthesis that assists larvae to combat chemical stress, since melanin is well known for its potential to minimize physical, chemical, and pathogenic stress.     

Degradation of atrazine in mineral salts medium and soil using enrichment culture

Atrazine degrading enrichment culture was prepared by its repeated addition to an alluvial soil and its ability to degrade atrazine in mineral salts medium and soil was studied. Enrichment culture utilized atrazine as a sole source of carbon and nitrogen in mineral salts medium and degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as additional source of carbon and nitrogen, respectively. Biuret was detected as the only metabolite of atrazine while deethylatrazine, deisopropyatrazine, hydroxyatrazine and cyanuric acid were never detected at any stage of degradation. Enrichment culture degraded atrazine in an alkaline alluvial soil while no degradation was observed in the acidic laterite soil. Enrichment culture was able to withstand high concentrations of atrazine (110 μg/g) in the alluvial soil as atrazine was completely degraded. Developed mixed culture has the ability to degrade atrazine and has potential application in decontamination of contaminated water and soil.     

Phenol transformation induced by UVA photolysis of the complex FeCl<Superscript>2+</Superscript>

Here we show that the photolysis of FeCl²⁺ upon UV irradiation of Fe(III) at pH 0.5, yielding Cl^• and then Cl₂^−•, upon further reaction with Cl⁻, induces phenol degradation. The photolysis of FeCl²⁺ can be highlighted and studied as the huge interference by FeOH²⁺ can be avoided under such conditions. Our data allowed the assessment of a photolysis quantum yield for FeCl²⁺ of 5.8 × 10⁻⁴ under UVA irradiation, much lower compared to the literature value of 0.5. The discrepancy can be explained if the photolysis process is efficient but photoformed Fe²⁺ and Cl^• undergo recombination inside the solvent cage.     

Synthesizing habitat connectivity analyses of a globally important human-dominated tiger-conservation landscape

As ecological data and associated analyses become more widely available, synthesizing results for effective communication with stakeholders is essential. In the case of wildlife corridors, managers in human-dominated landscapes need to identify both the locations of corridors and multiple stakeholders for effective oversight. We synthesized five independent studies of tiger (Panthera tigris) connectivity in central India, a global priority landscape for tiger conservation, to quantify agreement on landscape permeability for tiger movement and potential movement pathways. We used the latter analysis to identify connectivity areas on which studies agreed and stakeholders associated with these areas to determine relevant participants in corridor management. Three or more of the five studies’ resistance layers agreed in 63% of the study area. Areas in which all studies agree on resistance were of primarily low (66%, e.g., forest) and high (24%, e.g., urban) resistance. Agreement was lower in intermediate resistance areas (e.g., agriculture). Despite these differences, the studies largely agreed on areas with high levels of potential movement: >40% of high average (top 20%) current-flow pixels were also in the top 20% of current-flow agreement pixels (measured by low variation), indicating consensus connectivity areas (CCAs) as conservation priorities. Roughly 70% of the CCAs fell within village administrative boundaries, and 100% overlapped forest department management boundaries, suggesting that people live and use forests within these priority areas. Over 16% of total CCAs’ area was within 1 km of linear infrastructure (437 road, 170 railway, 179 transmission line, and 339 canal crossings; 105 mines within 1 km of CCAs). In 2019, 78% of forest land diversions for infrastructure and mining in Madhya Pradesh (which comprises most of the study region) took place in districts with CCAs. Acute competition for land in this landscape with globally important wildlife corridors calls for an effective comanagement strategy involving local communities, forest departments, and infrastructure planners.     

In situ biofilm barriers: Case study of a nitrate groundwater plume,Albuquerque, New Mexico

A new use for biofilm barriers was developed and successfully applied to treat nitrate‐contaminated groundwater down to drinking water standards. The barrier was created by stimulating indigenous bacteria with injections of molasses as the carbon donor and a combination of yeast extract and trimetaphosphate as nutrients. This injection of amendments results in bacterial growth in the aquifer, which attaches to the sand grains to create a reactive semipermeable biofilm. The biofilm barrier presented in this article reduced the migration of contaminants and provided an active zone for remediation. The cylindrical biobarrier was constructed using eight wells on the perimeter forming a 60‐foot‐diameter reactive biodenitrification region. Another well at the center was installed to continuously extract the treated water. The intent was to produce a continuous source of nitrate‐free water. The system operated for over one year, and during this period, the biobarrier was revived multiple times by reinjecting molasses in the perimeter wells. Nitrate concentrations of treated water decreased from 275 mg/L (as nitrogen) to < 1 mg/L. © 2005 Wiley Periodicals, Inc.