High rates of domestic sewage sludge on a calcareous soil and their effect on wheat growth using a pot experiment

A pot experiment was carried out to explore the use of high loading rates of domestic sewage sludge from Jeresh (Jordan) on a calcareous soil. Sludge was mixed with soil in volume ratios of 1:8, 1:6, 1:4, 1:2, 1:1, 2:1, and 4:1 with the unamended soil as a control. Wheat (Triticum durum L.) was grown in the pots for 60 days. The addition of sludge at a ratio of 1:8 increased wheat growth significantly; 1:6 ratio resulted in better growth than the control, although the increase was not significant at the 5% probability level. Other ratios suppressed wheat growth. The analysis of sludge-soil mixtures indicated that the addition of sludge increased the extractable P, K, Fe, Zn, Mn, and Cu in the mixtures. The addition of sludge to soil increased N and P in wheat tissue to optimum levels, but decreased K content. Iron and Zinc increased in wheat tissue due to the addition of sludge to soil, however Mn and Cu were not much affected.     

Congener-specific evaluation of biota-sediment accumulation factor model for HCHs and DDTs under small-scale in situ riverine condition

Purpose

The congener-specific biota-sediment accumulation factors (BSAFs) model for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) was evaluated for four different freshwater fish species (Orienus plagiostomus, Tor putitora, Glyptothorax punjabensis, and Cyprinus carpio) in in situ riverine conditions of Kabul River, Pakistan.

Materials and methods

The congeners of HCH and DDT were quantified using gas chromatograph (GC-ECD). The BSAF for each congener (HCHs and DDTs) was calculated from paired observation of congener’s measured concentrations in fish and sediment taken at the same site. Pearson’s correlation and linear regression analyses were performed to determine the influence of sediment organic carbon fraction (f _soc ) and organism lipid fraction (f _lipid ) on BSAF, and the relationship between BSAFs and logarithm of octanol-water partition coefficients (log K _ows) of HCH and DDT congeners, respectively.

Results and discussion

The BSAFs for total HCH (t-HCH) and total DDT (t-DDT) ranged from 0.6 to 1.5 and from 0.2 to 1.6, respectively. The model was significantly influenced by both fish (p = 0.004) and chemical types (p = 0.002) at 95 % confidence level. The sediment organic carbon fraction (f _soc ) and fish lipid fraction (f _lipid ) had not-too-weak effects on BSAF values for all fish species. The BSAF values were linearly fitted with logarithmic octanol-water partition coefficients (log K _ows) of HCH and DDT congeners, despite the different chemical structures, and different compound class significant negative correlations between log K _ows and BSAF values were found, indicating that hydrophobicity is one of the key factors influencing the bioaccumulation potential of the investigated compounds.

Conclusions

The present study confirmed the applicability of the BSAF model as a screening tool for predicting bioaccumulation of sediment-associated HCH and DDT congeners in investigated fish species under small-scale in situ riverine conditions of Kabul River and suite the model for benthic fish (G. punjabensis) on the basis of the 25th and 75th percentiles of congener-specific BSAF values.

     

Comparative Analysis of CD4+ and CD8+ T Cells in Tumor Tissues,Lymph Nodes and the Peripheral Blood from Patients with Breast Cancer

Background: CD4+ and CD8+ T cells are the main types of lymphocytes in cell-mediated immunity and play a central role in the induction of efficient immune responses against tumors. The frequencies of T cell subtypes in the peripheral blood and tumor tissues, and draining lymph nodes (dLN) can be considered as useful markers for evaluation of the immune system in cancers. Methods: In this study, the frequencies of CD4+ and CD8+ T cells in blood, tumor tissues, and dLN samples of breast cancer patients were compared with each other and with similar tissues from normal individuals. Immunophenotyping was carried out by flow cytometry and the expression levels of CXCL10, granzyme B, and mammaglobin were evaluated by real-time PCR. Results: In the peripheral blood, there were no differences in the T cell subsets between the patients and the normal individuals. The frequency of CD8+ T cells was significantly higher in tumor tissue than normal breast tissues while granzyme B expression was similar. Based on mammaglobin expression levels, dLN have been classified into micro- and macro-metastatic dLN. We found significantly lower frequency of CD4+ in macro-metastatic dLN than micro-metastatic dLN. CD8+ frequency was similar in both dLN; however, granzyme B expression was higher in micro-metastatic ones. There was not any significant difference in CXCL10 expression between the two types of dLN. Conclusion: Based on our results, although the tumor does not affect the systemic immunity, tumoral cells affect the local immune system in the tumoral tissues and the metastatic dLN. Key Words: Breast neoplasms, CD4+ T lymphocyte, CD8+ T lymphocytes, CXCL10, Granzymes     

High specific activity in low microbial biomass soils across a no-till evapotranspiration gradient in Colorado

The need to identify microbial community parameters that predict microbial activity is becoming more urgent, due to the desire to manage microbial communities for ecosystem services as well as the desire to incorporate microbial community parameters within ecosystem models. In dryland agroecosystems, microbial biomass C (MBC) can be increased by adopting alternative management strategies that increase crop residue retention, nutrient reserves, improve soil structure and result in greater water retention. Changes in MBC could subsequently affect microbial activities related to decomposition, C stabilization and sequestration. We hypothesized that MBC and potential microbial activities that broadly relate to decomposition (basal and substrate-induced respiration, N mineralization, and β-glucosidase and arylsulfatase enzyme activities) would be similarly affected by no-till, dryland winter wheat rotations distributed along a potential evapotranspiration (PET) gradient in eastern Colorado. Microbial biomass was smaller in March 2004 than in November 2003 (417 vs. 231 μg g⁻¹ soil), and consistently smaller in soils from the high PET soil (191 μg g⁻¹) than in the medium and low PET soils (379 and 398 μg g⁻¹, respectively). Among treatments, MBC was largest under perennial grass (398 μg g⁻¹). Potential microbial activities did not consistently follow the same trends as MBC, and the only activities significantly correlated with MBC were β-glucosidase (r = 0.61) and substrate-induced respiration (r = 0.27). In contrast to MBC, specific microbial activities (expressed on a per MBC basis) were greatest in the high PET soils. Specific but not total activities were correlated with microbial community structure, which was determined in a previous study. High specific activity in low biomass, high PET soils may be due to higher microbial maintenance requirements, as well as to the unique microbial community structure (lower bacterial-to-fungal fatty acid ratio and lower 17:0 cy-to-16:1ω7c stress ratio) associated with these soils. In conclusion, microbial biomass should not be utilized as the sole predictor of microbial activity when comparing soils with different community structures and levels of physiological stress, due to the influence of these factors on specific activity.     

Effect of the nitrification inhibitor nitrapyrin on the fate of nitrogen applied to a soil incubated under laboratory conditions

The aim of this study was to examine the effect of the nitrification inhibitor nitrapyrin on the fate and recovery of fertilizer nitrogen (N) and on N mineralization from soil organic sources. Intact soil cores were collected from a grassland field. Diammonium phosphate (DAP) and urea were applied as N sources. Cores were equilibrated at –5 kPa matric potential and incubated at 20 °C for 42 to 56 days. Changes in NH₄⁺‐N, accumulation of NO₃^–‐N, apparent recovery of applied N, and emission of N₂O (acetylene was used to block N₂O reductase) were examined during the study. A significant increase in NH₄⁺‐N released through mineralization was recorded when nitrapyrin was added to the control soil without N fertilizer application. In the soils to which N was added either as urea or DAP, 50–90 % of the applied N disappeared from the NH₄⁺‐N pool. Some of this N (8–16 %) accumulated as NO₃^–‐N, while a small proportion of N (1 %) escaped as N₂O. Addition of nitrapyrin resulted in a decrease and delay of NH₄⁺‐N disappearance, accumulation of much lower soil NO₃^–‐N contents, a substantial reduction in N₂O emissions, and a 30–40 % increase in the apparent recovery of added N. The study indicates that N recovery can be increased by using the nitrification inhibitor nitrapyrin in grassland soils at moisture condition close to field capacity.     

Plant density and nitrogen effects on growth dynamics,light interception and yield of maize

Maize (Zea mays L.) growth and yield are most sensitive to variations in plant density and nitrogen (N) in north-western Pakistan. This study was conducted on the Agricultural Research Farm of NWFP (North West Frontier Province) Agricultural University, Peshawar, from 2002–2004 to establish an accurate plant density and N management system aimed at high yield of maize. The 2 × 3 × 6 factorial experiment was designed having two plant densities (P1 = 60,000 and P2 = 100,000 plants ha^?1) and three nitrogen rates (N1 = 60, N2 = 120 and N3 = 180 kg N ha^?1) applied to the main plots, while six split application for N in different proportions were applied to subplots at different growth stages of maize in two equal (S1), three equal (S2), three unequal (S3), four equal (S4), five equal (S5) and five unequal splits (S6) at sowing and with 1st, 2nd, 3rd and 4th irrigation at two-week intervals. Growth rate and yield increased with elevated dose and number of N split applications. Improved endurance to high stands allowed maize to intercept and use solar radiation more efficiently, contributing to the remarkable increase in the crop growth rate and yield.     

Efficiency of Dry Matter and Nitrogen Accumulation and Redistribution in Wheat as Affected by Tillage and Nitrogen Management

Field experiments were conducted over 2 years with the hypothesis that farmyard manure (FYM), soybean residue (SR) as sole and/or in combination with urea under different tillage practices has similar effects on crop nitrogen (N) status and accumulation of dry matter (DM). Conventional ploughed plots had higher DM than other. Post anthesis accumulation of DM for minimum tillage (MT) was 4% higher than DT. Incorporation of 20 tons FYM ha^?1 combined with 30 or 60 kg ha^?1 had higher DM and N partitioned to leaves, stem, and spike than control. Leaves accumulated more DM at anthesis stage than other, whereas stem and spike at maturity than earlier stages. Fertilized plots had higher DM and N redistribution efficiency than control. However, N remobilization increased linearly with increasing DM accumulation (r² = 22%). It was concluded that FYM coupled with N under MT showed marked variations for DM partition and N status in wheat than other treatments.     

Application of redox mediator to accelerate selenate reduction to elemental selenium by Enterobacter taylorae

Acceleration of bacterial reduction of selenate [Se(VI)] to insoluble elemental Se [Se(0)] plays an important role in Se bioremediation. Anthraquinone-2,6-disulfonate (AQDS), a redox mediator, was assessed for its ability to enhance the reduction of Se(VI) (2000 microg/L) to Se(0) by Enterobacter taylorae in various media. The results showed that addition of AQDS did not increase Se(VI) reduction in the media containing 50 and 250 mg/L yeast extract, suggesting that E. taylorae cannot directly use anthrahydroquinone-2,6-disulfonate (AHQDS, a reduced form of AQDS) to respire Se(VI). An increase of yeast extract concentration from 50 to 250 mg/L in the medium dramatically enhanced the AQDS function for rapid reduction of selenite [Se(IV)] to Se(0). During an 8-day experiment, 85-91% of the added Se was reduced to Se(0) in the AQDS-amended medium in comparison to formation of 46% of Se(0) in the medium without AQDS. These results show that redox mediators have great application potential in bioremediation of Se in Se-contaminated water.