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Unbalanced fertilization lacking nitrogen (N), phosphorus (P), or potassium (K) is a worldwide phenomenon; however, whether they affect bacterial community composition and intraspecific interactions in a similar pattern and how they affect bacterial activity are not systematically compared. Soils under different kinds of unbalanced fertilization in a 21-year field experiment were collected to investigate the variation in dehydrogenase activity (DHA), bacterial community diversity, structure, composition, and possible interactions. Compared to the balanced fertilization of NPK, the DHA from unbalanced fertilization of NP, PK, and NK was 8.70, 11.59, and 14.17% lower, respectively, and from the unfertilized treatment (Nil) was 13.41% lower; however, the Shannon index from NP, PK, and Nil was 4.48–7.21% higher and from NK was 3.95% lower. Based on principal coordinate analyses (PCoA), bacterial community structure was separated by N application or not along PCo1 and was further separated by P application or not along PCo2, indicating a more influence by N deficiency. Moreover, the structure was mainly determined by soil pH, soil organic carbon (SOC), and total phosphorus (TP). The network complexity using co-occurrence analysis followed the order NP > NPK > PK > NK > Nil, indicating a more influence by P deficiency on intraspecific interactions. Structural equation modeling (SEM) revealed that the reduced DHA in NP was mainly regulated by the decreased SOC and increased Shannon index, in PK by the decreased SOC and increased Shannon index and pH, and in NK by the decreased SOC and TP and increased PCo2. The significantly lower abundance of Bacteroidetes and Chitinophagaceae in NK may also contribute to the reduced DHA. Our results imply that N deficiency had the greatest impact on bacterial community structure and composition, P deficiency had the greatest impact on network construction and bacterial activity, and K deficiency has minimal effect. Our results also suggest that main factors regulating the variation in soil functions may vary among different nutrient deficiencies. [ABSTRACT FROM AUTHOR]

As a step toward bioaugmentation of coking wastewater treatment 45 bacteria strains were isolated from the activated sludge of a coking wastewater treatment plant (WWTP). Three strains identified as Bacillus cereus, Pseudomonas synxantha, and Pseudomonas pseudoaligenes exhibited high dehydrogenase activity which indicates a strong ability to degrade organic matter. Subsequently all three strains showed high naphthalene degradation abilities. Naphthalene is a refractory compound often found in coking wastewater. For B. cereus and P. synxantha the maximum naphthalene removal rates were 60.4% and 79.8%, respectively, at an initial naphthalene concentration of 80 mg/L, temperature of 30 °C, pH of 7, a bacteria concentration of 15% (V/V), and shaking speed of 160 r/min. For P. pseudoaligenes, the maximum naphthalene removal rate was 77.4% under similar conditions but at 35 °C. [ABSTRACT FROM AUTHOR]

Certain agricultural practices, such as the repeated application of herbicides or organic amendments to soil, can influence herbicide dissipation. This research has studied the effects of two repeated applications of mesotrione, pethoxamid, and triasulfuron on their dissipation rates in unamended soil (S) and soil amended with green compost (S+GC) or sewage sludge (S+SS). The dissipation experiment has also included an evaluation of the adsorption of the three herbicides by soils and of changes in soil dehydrogenase activity (DHA). The adsorption of the three herbicides by amended soils (Kf range 0.83–2.98) was higher than by unamended soil (Kf range 0.20–0.64). The adsorption coefficients (Kd) of mesotrione and triasulfuron were higher for S+SS, while that of pethoxamid was higher for S+GC, but no relationship between values for the time to 50% degradation (DT 50 ) and adsorption coefficients could be determined. The repeated application of mesotrione decreased its dissipation rate in unamended soil (DT 50 increased from 4.75 to 8.15 days) and amended soils (DT 50 increased from 11.7 to 28.2 days in S+GC and from 17.7 to 37.9 in S+SS), whereas the repeated application of pethoxamid increased its dissipation rate in all the treatments, and the rate for triasulfuron increased only in amended soils. The highest DT 50 values for pethoxamid (12.3 days) and triasulfuron (57.1 days) were in S+GC, and the lowest in S+SS (8.35 and 24.7 days). Soil DHA was stimulated by the presence of GC in the soil and by the first application of mesotrione. The second application of mesotrione and pethoxamid positively affected soil DHA, but this did not occur for triasulfuron. The repeated applications of herbicides and soil organic amendments have different effects on herbicide dissipation, adsorption, and soil DHA, and they should be taken into account when assessing soil quality and other potential environmental implications of pesticide use. [ABSTRACT FROM AUTHOR]

Three different methods of bacterial viability monitoring were compared to detect chemically or thermally inactivated Escherichia coli. Direct colony enumeration, live/dead bacterial cell staining with a fluorescent dye, and the dehydrogenase activity assay were compared with respect to their ease of use and time required to perform the three different tests. The green (live cell)/red (dead cell) ratio obtained from the fluorescent bacterial cell staining approach showed a linear relationship with the colony forming units; the result obtained with dehydrogenase was similar to those. The sensitivity of the monitoring methods to detect bacterial deactivation varied with different disinfection conditions. After thermal treatment, the sensitivity of the staining approach was lower, while that of the dehydrogenase activity assay was the highest. After chemical treatment, the sensitivity of detection for both methods was similar. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to present variability of content and quality of soil organic matter on the landslide surface. Attempts were made to demonstrate the progress of the process of soil cover restoration 7 years after the landslides and biochemical activity of soil associated with the restoration of soil cover.Materials and methods: The landslide area was located in southern Poland, in the Sucha Forest District. The soil properties were studied on a regular grid of points, which covered the entire area of the landslide. In soil samples, particle size, soil aggregates content, pH, total carbon and nitrogen content, microbial biomass carbon and nitrogen and the activity of dehydrogenases were determined. Additionally, the fractions of soil organic matter were used in the study as an indicator of soil quality due to the many important interactions of these components in the soil system.Results and discussion: This study identified the landslide area as characterised by a stronger diversification of physical, chemical, and biological properties. The upper part of the landslide (in the area referred to as the landslide niche) is strongly eroded and characterised by the least advanced soil cover recovery. Additionally, low soil organic matter content was observed in the upper part of the landslide, which restricted biological activity of the studied soils. Soil microbial biomass carbon increased with restoration of landslide soils.Conclusions: The soil organic matter plays a key role for the initial stage of soil formation on a landslide. The amount of soil organic matter on the studied landslide had a positive effect on the microbial biomasses C and N, dehydrogenases activity. Estimating the soil organic matter fraction can be utilised as an indicator of changes in soil. [ABSTRACT FROM AUTHOR]

The contact assay measuring the inhibition of Arthrobacter globiformis dehydrogenase activity as an endpoint to evaluate the toxicity of solid samples was tested in an international ring-test to validate its performance for ISO standardization (ISO/CD 18187). This work reports the results of the ring-test involving 9 laboratories from six countries. At least 8 valid data sets were obtained for each sample and more than three quarters of the participants attained the validity criteria defined in the standard. The coefficient of variation within (CV r ) and between (CV R ) laboratories was generally on average <15% and <30% for negative and positive controls, respectively. Regarding solid samples, the laboratories provided a similar ranking of the samples based on their toxicity, despite some variation in the LOEC values. The logarithmic within-lab standard deviation <0.50 for soils and <0.25 for wastes evidenced a good repeatability. The between-lab variability assessed by a CV R <30%, minimum-maximum factor <4 and a reproducibility standard deviation (SD R ) <0.13 for a great part of the solid samples, confirmed the test reproducibility. Overall, this assay proved to be robust, sensitive and feasible for routine use towards the quality assessment of soils and wastes. [ABSTRACT FROM AUTHOR]

In order to study the influence of different concentrations of zinc and sulfachloropyridazine sodium (SCPS) on anaerobic digestion (AD) during biogas production, we determined the levels of urease, dehydrogenase activity, and volatile fatty acids (VFAs) in batch tests. The experiments were conducted in small AD devices at a temperature of 37 °C using swine manure and wheat straw as raw materials. Four digestion trials were performed using different zinc and SCPS contents: control digestion with no additives (CK), SCPS at 630 mg kg-1 dry weight (S), SCPS at 630 mg kg-1 with zinc at 500 mg kg-1 dry weight (SL), and SCPS at 630 mg kg-1 with zinc at 5,000 mg kg-1 dry weight (SH). The biogas accumulation under S was 1.7 times that with CK, while SL and SH produced 78% and 35% of that under S, respectively. Correlation analysis showed that the accumulated biogas was significantly negatively correlated (p< 0.05) with VFAs, and the urease activity was significantly negatively correlated (p< 0.01) with zinc and significantly positively correlated with VFAs (p <0.05). The dehydrogenase activity was strongly correlated (p<0.01) with the biogas accumulated during the AD of swine manure. [ABSTRACT FROM AUTHOR]

In this study, the variation of reactor performance, biofilm property and microbial community in response to the elevated Cu (II) in Anammox system were investigated. The nitrogen removal, extracellular polymeric substance (EPS) and copper content in biofilm, soluble microbial products (SMP), dehydrogenase activity (DHA) and microbial community were evaluated. The self-recovery ability was also investigated after stopping Cu (II) supply. Results showed the long-term feeding of Cu (II) significantly suppressed the nitrogen removal in Anammox system. The nitrogen removal rate (NRR) decreased to 0.210, 0.145 and 0 kg m −3 d −1 , respectively in 1, 5 and 10 mg L −1 Cu (II), from the initial 0.50 kg m −3 d −1 , with the decreasing ratio of 57.3%, 71.0% and 100%. With the elevation of Cu (II), the SMP, EPS and copper content gradually increased while DHA sharply decreased. Cu (II) improved the microbial diversity and lowered the Candidatus Kuenenia abundance to 1.36% from the initial 6.50%. The self-recovery ability of Anammox system was unsatisfactory, the NRR only recovered to 26.7% after one month operation free from Cu (II). Finally, the mechanism of Cu (II) interacting with Anammox biofilm was analyzed. [ABSTRACT FROM AUTHOR]

For the first time, the N,N-(pyromelitoylimidyl)-bis-(4-hydroxy tyrosine dimethyl ester benzyl sulfonamide) (PHTBS) as diphenolic monomer containing tyrosine was formed in three steps. PHTBS employed as a monomer in the design of biodegradable and biological polymers. The polycondensation of the this monomer with various aromatic and aliphatic diisocyanates such as 4,4′-methylenebis-(4-phenylisocyanate) (a), hexamethylene diisocyanate (b), isophorone diisocyanate (c) and toluene-2,4-diisocyanate (d) was carried out under traditional polymerization conditions to give poly(urethane-imide-sulfonamide)s (PUIS)s as pseudo-poly(amino acid)s (PAAs). The novel PHTBS and obtained PUISs were characterized with FTIR, 13C-NMR, 1H-NMR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy and elemental analysis. Differential scanning calorimetry and thermogravimetric analysis were used to determine the thermal properties of the polymers. Morphology probes showed these PUISs were nanoshape polymers. On the basis of thermogravimetric analysis data, such PUISs are thermally stable and can be classified as self-extinguishing polymers. The obtained PUISs possessed more bioactivity, moderate thermal stability and high solubility in common organic solvents. Furthermore, soil enzymatic of the PHTBS and the obtained PUISs assay showed that the synthetic materials are biologically active and then could be classified as bioactive and biodegradable compounds. [ABSTRACT FROM AUTHOR]

In an ongoing field experiment, organic and conventional farming (control) were compared for onion bulb yield, biochemical quality, soil organic carbon (SOC), and microbial activity after the sixth cropping cycle. The treatments used for organic production were farmyard manure (FYM, 20,000 kg ha−1), poultry manure (PM, 10,000 kg ha−1), vermicompost (VC, 10,000 kg ha−1), neem cake (NC, 5000 kg ha−1), and a combination of FYM (5000 kg ha−1), PM (2500 kg ha−1), VC (2500 kg ha−1), and NC (1250 kg ha−1); all treatments were compared with the control. Organic treatments produced 24.6–43.6% lower yield consistently for 6 years than the control treatment. No significant difference was observed between PM, FYM, and VC treatments for the bulb yield. Bulb analysis during the sixth year indicated that plants that received FYM, PM, or VC had higher levels of total phenol, total flavonoid, ascorbic acid, and quercetin-3-glucoside than the control plants. All the five organically treated sets had significantly higher values of SOC, microbial population, fungal-to-bacterial ratio, and dehydrogenase activity than the control and the initial values in each treated set. The results indicate that FYM, PM, or VC application enhances biochemical quality and organic farming is more sustainable than conventional farming. [ABSTRACT FROM AUTHOR]

Purpose: A simple disposal of metal-contaminated sediment on land can inevitably lead to increased soil concentrations of the elements, which consequently jeopardizes the soil environment for living organisms. In order to make the metal-contaminated sediment recyclable and reusable, one possible option is sediment stabilization using immobilizing amendments, in which the metals can be immobilized and the bioavailable fraction accounting for metal toxicity can be reduced. Materials and methods: In the present study, three immobilizing amendments, including zeolite, calcium carbonate (CaCO), and manganese dioxide (MnO), were compared for their ability in reducing cadmium (Cd) bioavailability in the soil receiving Cd-contaminated sediment. Soil chemical analysis, calcium chloride (CaCl)-extractable Cd fraction, plant uptake, and microbial assay were employed to give a relative comprehensive comparison with regard to the amendment efficacy. Results and discussion: Results showed that although the total concentrations of Cu, Pb, and Zn were increased with the addition of sediment in soil, they were still under the guideline limit set at an elevated pH condition. Compared with zeolite and MnO, CaCO showed the best mitigating effects on Cd toxicity, evidenced by reduced CaCl-extractable Cd concentrations, increased dehydrogenase activities, and reduced Cd uptake by sorghum. Conclusions: Incorporation of CaCO with contaminated sediment was a new option of dredged sediment treatment for land application in Dongting Lake region, where the sediment was deviated from the 'waste' stream without causing much concern on soil health. [ABSTRACT FROM AUTHOR]

To study the change of the aerobic granules' microbial community in the present of antibiotics, ampicillin (AMP) was selected as a model component. With acetate as carbon source, different concentrations of AMP (5, 10 and 15 mg L −1 ) were applied to the inflow intermittently and the results showed that the stability of the aerobic granules was maintained below 10 mg L −1 AMP. Simultaneously, under exposure to 5 and 10 mg L −1 AMP, the COD removal efficiency in the batch reactors remained at 86% and AMP was degraded almost completely with a removal efficiency of 97%. However, the EPS concentration and dehydrogenase activity decreased constantly with increasing AMP dosage. High-throughput sequencing analysis revealed that Proteobacteria was the most prominent phylum in the whole experiment and contributed to the degradation of AMP. The percentages of Azoarcus and Mycoplana increased at 10 mg L −1 AMP. In addition, Hydrogenophaga and Enterococcus played a key role in the microbial metabolism. [ABSTRACT FROM AUTHOR]

This study investigated the distribution of ion contents and microorganisms during the electro-bioremediation (EK–Bio) of petroleum-contaminated saline soil. The results showed that soil ions tend to accumulate around the electrodes, and the concentration was correlated with the distance from the electrodes. The average soil ion content was 7.92 g/kg around the electrodes (site A) and 0.55 g/kg at the furthest distance from the electrodes (site B) after 112 days of treatment, while the initial average content was 3.92 g/kg. Smooth linear (R2= 0.98) loss of soil ions was observed at site C, which was closer to the electrodes than site B, and had a final average soil ion content of 1.96 g/kg. The dehydrogenase activity was much higher in EK–Bio test soil than in the Bio test soil after 28 days of treatment, and followed the order: site C > site B > site A. However, the soil dehydrogenase activity dropped continuously when the soil ion reached very high and low concentrations at sites A and B. The soil microbial community varied in sample sites that had different ion contents, and the soil microbial diversity followed the order: site C > site B > site A. The applied electric field clearly enhanced the biodegradation efficiency for soil petroleum contaminants. However, the biodegradation promotion effects were weakening in soils where the ion contents were extremely high and low (sites A and B). These results can provide useful information for EK–Bioremediation of organic-contaminated saline soil. [ABSTRACT FROM AUTHOR]

An experiment was conducted to study the effect of tillage, wheat residues and biofertilizers on chemical and biological properties of soil in soybean-wheat cropping system at the Research Farm of Punjab Agricultural University, Ludhiana during kharif season of 2014 and 2015. It was observed that sowing with Happy Seeder and Straw Chopper + Zero Tillage recorded significantly higher dehydrogenase activity at 60 and 90 days after sowing and an increase in population of Bradyrhizobium and plant growth promoting rhizobacteria (PGPR) at harvest of soybean as compared to conventional sowing. Dual inoculation of Bradyrhizobium and PGPR significantly increased the population of Bradyrhizobium and PGPR in soil after harvest. Non-significant effects of different planting methods and biofertilizer inoculation were reported on soil properties viz. pH, EC, organic carbon, available nitrogen, available phosphorus and available potassium over a period of two years. However, a significant improvement in soil chemical properties may be expected over long-term application of crop residues with zero tillage. [ABSTRACT FROM AUTHOR]

In organic farming the use of mineral fertilizers is highly restricted; hence biofertilizers are often used. The aim of the research was to investigate the effects of different fertilizers on soil microbial communities and enzymatic activity after conventional production. A field with potato cultivation under conversion to an organic system was established. The nitrogen organic fertilizer Bioilsa and two microbial biofertilizers - UGmax and EM - were used. The highest values of dehydrogenase activity (DHA) were observed in the soil where UGmax was used alone. Application of biofertilizers also caused an increase of DHA in variants with Bioilsa fertilizer. The differences in activity of phosphatase in relation to application of different biofertilizers were observed, but it was higher than in variants with Bioilsa. Application of Bioilsa had a positive effect on activity of acid and alkaline phosphatases, but probiotic EM reduced this positive effect. The total number of bacteria and actinobacteria was the highest in EM variants, not fertilized with Bioilsa. In the case of the fungal population no correlation with fertilization was noted. We conclude that biofertilizers can activate the microbial and enzymatic activity of the soil after intensive agriculture production and can neutralize the negative impact on these parameters of nitrogen fertilizer. [ABSTRACT FROM AUTHOR]

The variation of carotenoid and bacteriochlorophyll in photosynthetic bacteria (PSB) by high salinity stress (20–100 g L −1 ) was investigated. Results showed that PSB could grow in high salinity wastewater and the productions of two pigments were affected by the salinity significantly. Suitable salinity stress could enhance their productions while excessive salinity would impede the productions. When the NaCl concentration was 50 g L −1 , the PSB were stimulated continuously during the whole culture period, and the productions of carotenoid and bacteriochlorophyll were 1.17 and 1.45-fold of the control group. The variation of dehydrogenase activity indicated that high salinity changed the metabolic activity greatly, and the highest level of dehydrogenase activity appeared at 50 g L −1 NaCl condition. Mechanisms analysis showed that the variations of pigments and dehydrogenase were related to self-protection. At the same time, pollutants in high salinity wastewater were removed by PSB. The COD and NH 3 -N removals under 20–100 g L −1 NaCl concentration were around 33.5–66.1%. The biomass yields were over 0.2 mg-biomass (mg-COD-reduction) −1 under all situations and salinity benefitted the biomass yield. [ABSTRACT FROM AUTHOR]

This study was aimed to investigate the effect of moderate pressure on organic matter removal efficiency and microbial population of activated sludge treating saline wastewater. The activated sludge was cultivated with a gradual increase of salt concentrations under gage pressure of 0.3 MPa for 71 days. Microbial diversities of activated sludge sampled in different stages of domestication were investigated by Illumina sequencing technology. Results showed that pressurized aeration could improve the treatment efficiency and the dehydrogenase activity (DHA) of activated sludge, especially at high salinity (35, 50 g NaCl L −1 ). Bacterial richness and community diversity of activated sludge in the pressurized reactor were significantly higher than those in the control reactor. Microbial population structures were quite different between the two reactors. More species originating from fresh wastewater biological treatment process would survive and remain in pressurized activated sludge. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the mutual effect of the PAHs fluorene and pyrene on their respective biodegradation and dissipation processes in an agricultural soil, and to determine the effect of hydroxypropyl-β-cyclodextrin (HPBCD), used to increase the bioavailability of PAHs, on such processes. Fluorene dissipation was primarily due to abiotic processes, although a small contribution from biodegradation was also observed. Therefore, fluorene dissipation did not increase with HPBCD and its presence did not significantly alter the dehydrogenase activity. In contrast to fluorene, pyrene dissipation depended primarily on biotic factors, with endogenous soil microorganisms capable of degrading pyrene, with large increases in dehydrogenase activity. HPBCD increased biodegradation rate of pyrene. The co-contamination of soil with both PAHs did not affect fluorene evolution, but significantly inhibited pyrene biodegradation. The different abilities of soil bacterial consortia to catabolize these PAHs are discussed. Additionally, the possibility that the abiotic loss of fluorene through volatilization had a significant effect on the microbial community biodegradation of both fluorene and pyrene is examined. [ABSTRACT FROM AUTHOR]

An incubation experiment was conducted to evaluate the effects that three types of biomass ash, each applied at two doses, exert on the nutrient availability in a calcareous soil. The application of the ash from dry olive cake or greenhouse vegetable wastes significantly increased soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable phosphorus (P), potassium (K), sodium (Na), copper (Cu) and zinc (Zn) as well as exchangeable and non-exchangeable K and Na. Wood ash was effective only for increasing soil ABDTPA-extractable Zn and Cu. By contrast, the three types of biomass ash hardly increased soil ABDTPA-extractable Fe or Mn. The high content in carbonate of the soil appears to minimize the potential of the ash to increase the micronutrients availability, which shortened with longer incubation time. Soil ABDTPA-extractable heavy metals were not detected in the different treatments tested. Other parameters of the soil, as pH and organic carbon, were scarcely affected by the ash, while conductivity and dehydrogenase activity increased. [ABSTRACT FROM AUTHOR]

The experimental plots used in the study were located in the middle forest zone (elevation: 900-950 m a.s.l.) on two nappes of the flysch Carpathians in southern Poland. The aim of this study was to assess the effects of serpentinite in combination with nitrogen, phosphorus, and potassium fertilizers on selected chemical properties of the soil and activity of dehydrogenase and urease in the studied soils. All fertilizer treatments significantly enriched the tested soils in magnesium. The use of serpentinite as a fertilizer reduced the molar ratio of exchangeable calcium to magnesium, which facilitated the uptake of magnesium by tree roots due to competition between calcium and magnesium. After one year of fertilization on the Wisła experimental plot, the pH of the Ofh horizon increased, while the pH of the mineral horizons significantly decreased. Enrichment of serpentinite with nitrogen, phosphorus, and potassium fertilizers stimulated the dehydrogenase activity in the studied organic horizon. The lack of a negative effect of the serpentinite fertilizer on enzyme activity in the spruce stand soil showed that the concentrations of the heavy metals added to the soil were not high enough to be toxic and indicated the feasibility of using this fertilizer in forestry. [ABSTRACT FROM AUTHOR]

We investigated the effects of several tree species on dehydrogenase and urease activities in soils derived from two different parent materials (glaciofluvial sand and loess) in forested areas in southern Poland. We hypothesized that coniferous forests (pine, spruce) alter the soil cation exchange capacity (CEC) and decrease soil pH and, therefore, might decrease soil enzyme activities compared with broadleaf species growing on similar soils. Eight paired plots (12 × 12 m) were established on glaciofluvial sand in pine ( Pinus sylvestris) + oak ( Quercus robur) and spruce ( Picea abies) + pine stands, as well as on loess-derived soils: beech ( Fagus sylvatica) + pine and hornbeam ( Carpinus betulus) + pine stands. Each plot was a 4 × 4 m grid with 16 sampling points. In soil samples pH, soil texture, and organic carbon, nitrogen, base cation contents, dehydrogenase and urease activities were determined. On both parent materials, the soil pH was lower under coniferous species than under broadleaf species. The acidifying effect of tree species on sandy soil was in the order of spruce = pine > oak, while that on loess was pine > beech > hornbeam. Hornbeam and oak increased the soil pH and stimulated enzyme activity in the soil. The content of fine fraction enhanced potential enzyme activities in soils, thus the loess soils had greater dehydrogenase and urease activity. The results suggest that pine stores more soil organic C in association with silt increasing the pool of stabilized soil organic C. [ABSTRACT FROM AUTHOR]

The toxicity of water-receiving bodies, the effluent and other treatment stages in wastewater treatment plants has recently been of interest to the public due to the lack of a regulated toxicity-based index for wastewater discharge in China. This study aimed to evaluate the conventional pollution parameters and toxicities of wastewaters collected at different treatment stages from a pharmaceutical industrial park wastewater treatment plant through dehydrogenase activity (DHA) and bioluminescent bacteria ( Vibrio qinghaiensis ) tests. The results of an analysis of conventional parameters indicated that the total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH 3 N), and total phosphorus (TP) were largely removed after various treatments. However, the TN, NH 3 N and COD still exceeded the regulated standards. The tested pharmaceutical park effluents were mainly polluted with organic pollutants and nitrogenous. The toxicity test results indicated that the toxicities could be markedly reduced after treatment, with the toxicities of two out of the six effluent samples at different treatment stages being greater than the influent toxicity. Spearman’s rank correlation coefficients indicated a significantly positive correlation between the toxicity values obtained using the DHA and Vibrio qinghaiensis tests. Compared with the DHA measurement, the Vibrio qinghaiensis test was faster and more sensitive. Meanwhile, the toxicity indicators were significantly and positively correlated with the TSS, TN, TP and COD concentrations. These results may aid the understanding of the toxicity of pharmaceutical industrial park wastewaters and toxicity removal using the treatment techniques that are currently utilized in China. [ABSTRACT FROM AUTHOR]

Evaluating the impact of cultivation systems for improving the management of agricultural soil is difficult. Traditional ploughing cultivation can contribute to soil erosion. An alternative to conventional tillage is conservation tillage. The aim of our study was to determine the influence of different cultivation systems on the biochemical and biological activity of soil under sugar beets. The conventional tillage treatment with soil ploughing to a depth of 35 cm was the control treatment (CT). For comparison, we analysed the following conservation tillage systems consisting of shallow or deep-soil ripping: 1. Tillage to a depth of 35 cm and sowing into stubble mulch (MS35). 2. Tillage to a depth of 15 cm and sowing into stubble mulch (MS15). 3. Tillage to a depth of 15 cm and sowing into white mustard mulch (MG). 4. Strip-till on stubble mulch to a depth of 25 cm and instantaneous beet seed sowing (STS). 5. Strip-till to a depth of 25 cm on white mustard mulch and instantaneous beet seed sowing (STG). The soil samples that were used for biochemical and microbiological analyses were collected during four terms in each year, which coincided with the four consecutive stages of the development of sugar beets. During both years of research we obtained results concerning the influence of different soil cultivation methods on the number of selected groups of soil microorganisms and the enzymatic activity under sugar beets. In 2012-13 the highest bioactivity was noted in the period of the greatest demand of sugar beets for nutrients, at the phase when the rows of plants were closing in. At that time the content of actinobacteria in the soil collected from the sites where STS had been applied was 42% greater than in the soil from the ploughing cultivation system. Apart from that, in this same term, whenever conservation tillage was applied the activity of dehydrogenases and phosphatases always increased. [ABSTRACT FROM AUTHOR]

Effects of three different nutrient loadings (low nutrient loading, medium nutrient loading and high nutrient loading, denoted as LNS, MNS and HNS, respectively) on the structure and functions of algal biofilm using Anabaena flos-aquae were investigated using synthetic wastewater. Nutrients removal efficiencies, biofilm thickness, microalgae dehydrogenase activity (DHA) and exopolysaccharide (EPS) productions were examined. Results showed that the changes of nutrient concentration were insignificant after 4 days of experiment for the case of HNS condition; 9 days for the case of MNS condition, and 6 days for the case of LNS condition, respectively. The biofilm thickness, nutrient removal efficiencies, algae DHA and EPS productions increased with the increase of nutrient loadings in synthetic wastewater. For the case of HNS condition, the microalgal biofilm exhibited the best performance in terms of C, N and P removal efficiencies, reaching the removal rates of 68.45, 3.56 and 1.61 mg∙L-1∙d-1 for C, N, P, respectively. This was likely because, fact with the high nutrient loading, the high biological activity could be achieved, thus resulting in high nutrient removals. The thickness of the biofilm in HNS condition was 75 µm, which was closely related to EPS production. DHA and EPS concentrations were 7.24 and 1.8 × 10-2 mg∙mm-2, respectively. It was also shown that apart from the nutrient loading, the structure and functions of microalgal biofilm were also influenced by other factors, such as illumination and temperature. [ABSTRACT FROM AUTHOR]

Intensive crop over-fertilization is causing the diffuse contamination of superficial and ground-waters by nitrates in many Mediterranean areas. At the same time this practice is also damaging the soil in the long-term. In this work the feasibility of using composts as total or partial substitutes for conventional inorganic fertilization (CIF) was evaluated in two successive crops of lettuce ( Lactuca sativa L.), one of the most consumed vegetables in Europe. The aim was to offer alternative agricultural practices that are more environmentally friendly. Treatments consisting of various rates of inorganic and organic fertilizers (composts) were assayed in quadruplicate on a sandy loam soil classified as Haplic Calcisol in Southern Spain. Macro- and micronutrients and heavy metal concentrations were analysed in soil and plant leaves. Parameters such as soil basal respiration (BR), microbial biomass C (C mic ) and dehydrogenase (DHA) and hydrolase activities, indicators of soil microbial abundance and activity, were also determined after each crop. After the second lettuce crop, certain physical soil properties such as aggregate stability and soil water holding capacity were also determined. In the first crop lettuce yields in the compost-treated soils did not significantly (p≤ 0.05) differ from the yields of CIF-treated soils. In the second crop, however, lettuce yields were higher in organically treated soils than in soils receiving only inorganic fertilization. Organic fertilizers were able to supply sufficient nutrients to achieve similar yields as those obtained with additional inorganic fertilizer. After the second crop, organically treated soils also showed higher C, N, P concentrations and higher C mic , BR and DHA than soils receiving conventional inorganic fertilization as well as improved physical conditions (a higher percentage of stable soil aggregates and a greater water holding capacity). Also after the second lettuce crop, compost-treated soils showed significantly higher β-glucosidase and phosphatase activity than CIF-treated soils. Furthermore, lettuces grown in compost-treated soils showed significantly lower leaf nitrate concentration than lettuces grown in soil receiving CIF, thus reducing the potential toxicological risks associated with consuming nitrate-rich foods. Moreover, compost fertilization did not increase the concentration of heavy metals in lettuce leaves. Results confirm that manure and sewage sludge composts can be used as an alternative to inorganic fertilization in lettuce crop cultivation, leading to similar or even higher yields and reducing nutrient-leaching risks, while improving soil chemical, physical and microbiological properties. [ABSTRACT FROM AUTHOR]

Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (T). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and T are more appropriate than EC and IC for toxicity assessments, except for long exposure times. [ABSTRACT FROM AUTHOR]

Membrane fouling alleviation by addition of poly dimethyl diallyl ammonium chloride (PDMDAAC) and magnetic powder (Fe 3 O 4 ) was investigated. It was found that magnetic powder associated with PDMDAAC had a good performance on mitigation of membrane fouling, improvement in dehydrogenase activity and enhancement of biomass growth. The optimal dose of PDMDAAC was determined by using constant pressure dead-end filtration unit. Maximum permeate flux was attained at 400 mg/L of PDMDAAC addition. Continuous experiment was conducted in a submerged membrane bioreactor (MBR) system and biomass parameters such as soluble microbial products (SMP), extracellular polymeric substances (EPS), dehydrogenase activity, zeta potential, and capillary suction time (CST) were analyzed. Best results were obtained with a combination of 120 mg/L of magnetic powder and 400 mg/L of PDMDAAC. This study results demonstrated that PDMDAAC played a major role in SMPc and EPSc reduction, whereas magnetic powder had better performance in decreasing SMPc and EPSp. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effects of conventional and organic production system on microbial activity in the soil cultivated with bean and maize crops. The trial in Đurđevo was set up according to the conventional farming system, while organic farming system was used in Futog. Two maize hybrids and two bean cultivars were used in the trial. Soil samples were collected in two periods during 2014 (before sowing, at flowering stage of bean crops, and at 9-11 leaf stage of maize) at two depths, at both locations. The following microbiological parameters were tested: the total number of microorganisms, number of ammonifiers, Azotobacter sp., free nitrogen fixing bacteria, fungi, actinomycetes, and activity of dehydrogenase enzyme. The results showed that the total number of microorganisms, number of free N-fixers and dehydrogenase activity were higher within organic production, while Azotobacter sp. was more abundant in conventional production. Variations in the number of ammonifiers, fungi and actinomycetes in relation to the type of production were not obtained. Significant differences in microbial activity were also obtained between period and depths of sampling. [ABSTRACT FROM AUTHOR]

This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound. [ABSTRACT FROM AUTHOR]

The aim of our study was to analyze the impact of soil agriculture management on bacterial abundance (expressed as total microorganism count plus copiotrophic and oligotrophic bacteria numbers) and soil dehydrogenase activity. Four different soil units agriculturally exploited (under oat-type crops) and the same number of control soils not agriculturally used were taken for study in April 2014 from the surface layer (0-20 cm). Under laboratory conditions the soils were subjected to analysis of: pH, total carbon, total microbial counts, copiotrophic and oligotrophic bacteria numbers, and dehydrogenase activity. The first consequences of agricultural practices were a decrease of pH toward acidic conditions and impoverishment of total carbon. Secondly, it was demonstrated that agricultural soil usage in relation to control sites affected biological properties by decreasing total microbial counts (by 20-75%), copio- and oligotrophic bacteria abundance (by 15-33%), and dehydrogenase activity (by 25-71). The ratio of oligotrophic to copiotrophic bacteria (O:C), being an indicator of soil biological balance, ranged 0.81-1.53 and 1.02-2.40 for arable and control soils, respectively. Lower values of biological factors observed in agricultural soils clearly indicated a progressive reduction of bacterial abundances and metabolic activities. [ABSTRACT FROM AUTHOR]

Olive oil agrifood industry generates large amounts of waste whose recycling as organic amendment represents an alternative to their disposal. The impact of de-oiled two-phase olive mill waste (DW) on the fate of 4-chloro-2-methylphenoxyacetic acid (MCPA) in Mediterranean agricultural soils was evaluated. Furthermore, the effect of the transformation of organic matter from this waste under field conditions was assessed. Four Mediterranean agricultural soils were selected and amended in laboratory with fresh DW and field-aged DW (DW and ADW treatments, respectively). Adsorption capacity increased by factors between 1.18 and 3.59, for the DW-amended soils, and by factor of 4.93, for ADW-amended soil, with respect to unamended soils, when 5 % amendment was applied. The DW amendment had inhibitory effect on dehydrogenase activity and slowed herbicide dissipation, whereas the opposite effect was observed in ADW treatments. In the field-amended soil, the amount of MCPA leached was significantly reduced from 56.9 % for unamended soil to 15.9 % at the 5 % rate. However, leaching losses of MCPA increased in the laboratory-amended soils, because of their high water-soluble organic carbon values which could enhance MCPA mobility, especially in the acidic soils. Therefore, the application of DW as organic amendment in Mediterranean agricultural soils could be an important management strategy to reduce MCPA leaching, especially if the organic matter had been previously transformed by ageing processes. [ABSTRACT FROM AUTHOR]

Coagulants addition to a bioreactor is a widely used technology for improving phosphorus removal. As a common and low-cost coagulant, poly-aluminum chloride (PAC) may be widely used for wastewater treatment. In this article, the impacts of PAC on activated sludge and the treatment efficiency of sequencing batch reactor were investigated over 100 d for domestic wastewater treatment. Parameters of chemical oxygen demand (COD), nitrogen, phosphorus, MLSS, oxygen uptake rate (OUR), and dehydrogenase activity (DHA) were used to assess the activated sludge performance. The addition of 40 mg PAC/L (R2) enhanced phosphorus removal from 73.3% in control with zero PAC (R1) to 92.4% due to simultaneous chemical precipitation. PAC addition improved COD removal slightly and did not affect the removal efficiency of nitrogen. The average removal efficiency of COD of the reactor increased slightly from 86.2 to 89.6% by PAC addition. In R1, TN removal was in the range from 86.3 to 90.8%. Nitrogen removal efficiency remained unaffected (slightly dropped) during simultaneous precipitation in R2 and was in the range from 84.5 to 86.8%. The average inhibition rate of DHA and OUR was 32.1 and 55.3%, respectively. PAC addition gave proof to the increase of MLSS by some 40%. Results obtained from the present work confirmed that PAC addition, despite the toxicity and inhibition on micro-organisms, favored phosphorus removal in wastewater treatment. [ABSTRACT FROM AUTHOR]

The effectiveness of ferrihydrite as amendment to restore the soil habitat functioning of a soil polluted with As by mining activities was evaluated. Its influence on As mobility and phytoavailability was also assessed. Soil treated with increasing amendment doses (0, 1, 2, and 5 %) were analyzed for soil microbiological parameters such as basal soil respiration and dehydrogenase, β-glucosidase, urease, acid and alkaline phosphatase, and arylsulfatase activities. Batch leaching tests and plant growth experiments using ryegrass and alfalfa plants were performed. The treatment with ferrihydrite was effective to reduce As mobility and plant As uptake, translocation, and accumulation. Likewise, the soil microbiological status was generally improved as derived from basal soil respiration and dehydrogenase and acid and alkaline phosphatase activities, which showed increases up to 85, 45, 11, and 47 %, respectively, at a ferrihydrite addition rate of 5 %. [ABSTRACT FROM AUTHOR]

Labile fractions of soil organic matter (SOM) have been used as indicators for land use induced changes in soil quality. Differences in soil C pools under row crop production and uncultivated soils may provide information about soil C sequestration. The impact of agroforestry consisting of poplar with wheat, rice–wheat, maize–wheat and sugarcane agro-ecosystems on total organic carbon (TOC) and labile pools, viz. water-extractable (WEOC), hot water-soluble (HWC), KMnO 4 -oxidizable, microbial biomass and mineralizable C; and organic C fractions of different oxidizability was studied at 22-sites for each land use. Cultivation resulted in decrease in TOC (21–36%) and dehydrogenase activity (by 2.8–3.4 mg kg − 1 soil h − 1 ) compared to uncultivated soils. Labile C pools, except WEOC, were correlated ( P < 0.05 ), though the amount extracted by different methods varied considerably suggesting that each method enumerated different fractions of TOC. Agroforestry and sugarcane systems were characterized by very labile C compared with uncultivated soils and the soils under rice–wheat and maize–wheat systems. Conversely, uncultivated soils and the soils under maize–wheat and rice–wheat held greater proportion of organic C in recalcitrant fractions. Results suggest that soil organic C (SOC) pools in agroforestry and sugarcane systems could be decomposed under land use alterations. However, no single soil C pool alone was suitable as a sensitive indicator for land use induced changes in SOM. A composite of soil indicators encompassing labile C, KMnO 4 -oxidizable C, non-labile and recalcitrant C, mineralizable C, basal soil respiration, and dehydrogenase activity could distinguish different land use systems. [ABSTRACT FROM AUTHOR]

Dehydrogenases are exclusively intracellular enzymes, which play an important role in the initial stages of oxidation of soil organic matter. One of the most frequently used methods to estimate dehydrogenase activity in soil is based on the use of triphenyltetrazolium chloride as an artificial electron acceptor. The purpose of this study was to compare the activity of dehydrogenases of forest soils with varied physicochemical properties using different triphenyltetrazolium chloride assays. The determination was carried out using the original procedure by Casida et al., a modification of the procedure which involves the use of Ca(OH)2 instead of CaCO3, the Thalmann method, and the assay by Casida et al. without addition of buffer or any salt. Soil dehydrogenase activity depended on the assay used. Dehydrogenase determined by the Casida et al. method without addition of buffer or any salt correlated with the pH values of soils. The autoclaved strongly acidic samples of control soils showed high concentrations of triphenylformazan, probably due to chemical reduction of triphenyltetrazolium chloride. There is, therefore, a need for a sterilization method other than autoclaving, ie a process that results in significant changes in soil properties, thus helping to increase the chemical reduction of triphenyltetrazolium chloride. [ABSTRACT FROM AUTHOR]

Copyright of Minufiya Journal of Agricultural Research is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To evaluate the relationship between the potassium (K) status in the microbial community and the exchangeable K concentration in soils, the effects of K addition on microbial activity were assessed in cultivated Andisols not having received K fertilizer. Potassium limitation was not observed in the microbial community, even in a soil amended with only nitrogen (N) and phosphorus (P) but not K since 1938, though crop plants in this soil showed severe K deficiency symptoms. Furthermore, in a soil amended with NP + compost, microbial activity was limited by K only after limitation of carbon (C) and N. These results suggest that soil microorganisms demand more C and N than K, even in soils with low K availability, and also that the soil microbial community is less susceptible to K deficiency than are crop plants. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of using nanoscale zero-valent iron (nZVI) to immobilise Pb/Zn in two different soils (acidic and calcareous) and the effects of nZVI treatment on soil physico-chemical and biological properties. Soil samples spiked with Pb(II) or Zn(II) were treated with commercial nZVI suspension at a dose of 20% (28-36 mg Fe(0)/g soil) for 72 h and one month. Sequential extraction procedures showed a significant decrease of Pb/Zn bound to exchangeable and carbonate fractions and an increase of residual fraction after the treatment with nZVI. There were no significant differences in the distribution of Pb/Zn in the soil fractions between the contact times studied; the immobilisation of Pb/Zn with nZVI in the described conditions was stable at least for a month. Better immobilisation results were found for Pb than for Zn. No negative effects on soil physico-chemical and biological properties were observed. In fact, the application of nZVI stimulated the soil respiration and the dehydrogenase activity in both soils, especially in the case of Pb, probably due to the higher immobilisation percentages. These results suggest that the use of nZVI to remediate polluted soils with Pb or Zn is a promising in situ strategy, and more research is required both in the laboratory and field to investigate the effects of such a treatment to the soil ecosystem. [ABSTRACT FROM AUTHOR]

Greenhouse experiments were conducted with amendment ratios of fresh sludge compost to soil of 0, 10, 25 and 50% (w/w) to investigate the dissipation of polycyclic aromatic hydrocarbons (PAHs) in soils planted with tall fescue ( Festuca arundinacea ). The initial PAH concentrations in four amended soils increased with the more addition of compost. During the experiment, PAH concentrations decreased in all treatments, and the PAH dissipation followed the first-order kinetics. The residual concentrations in planted soils were lower than those in non-planted soils at every sampling time. After 126 days, the lowest PAH concentration was observed in the soil amended with compost at 10%. These results suggest that appropriate compost addition and planting vegetation could improve the dissipation of PAHs in soil, and the increase of soil dehydrogenase activities due to the increased density and activity of microorganism was an important indicator to obtain the high PAH removal efficiencies in soil. Moreover, some PAHs in soil were absorbed by the roots of tall fescue, then transferred to the shoots and accumulated. During this process, 2–3-ring PAHs were more likely to be absorbed, transferred, and removed in plant, but 4–6-ring PAHs were prone to be accumulated in plant tissues. [ABSTRACT FROM AUTHOR]

Present work describes microbial degradation of selected polychlorinated biphenyls (PCBs) congeners in Clophen oil which is used as transformer oil and contains high concentration of PCBs. Indigenous PCBs degrading bacteria were isolated from Clophen oil contaminated soil using enrichment culture technique. A 15 days study was carried out to assess the biodegradation potential of two bacterial cultures and their consortium for Clophen oil with a final PCBs concentration of 100 mg kg. The degradation capability of the individual bacterium and the consortium towards the varying range of PCBs congeners (di- through hepta-chlorobiphenyls) was determined using GCMS. Also, dehydrogenase enzyme was estimated to assess the microbial activity. Maximum degradation was observed in treatment containing consortium that resulted in up to 97 % degradation of PCB-44 which is a tetra chlorinated biphenyl whereas, hexa chlorinated biphenyl congener (PCB-153) was degraded up to 90 % by the consortium. This indicates that the degradation capability of microbial consortium was significantly higher than that of individual cultures. Furthermore, the results suggest that for degradation of lower as well as higher chlorinated PCB congeners; a microbial consortium is required rather than individual cultures. [ABSTRACT FROM AUTHOR]

The organic carbon content in the soils of mango orchards in subtropical region of Uttar Pradesh, is very low affecting the soil quality and nutrient release pattern. The microbial and enzyme activities of the soil are closely related to the organic matter content and influenced by hydrothermal regimes of the soil. Keeping this in view, effect of different organic and inorganic substrates was studied on dehydrogenase activity, soil organic carbon and moisture content in mango orchard soil. The soil samples across three different depths with respect to their dehydrogenase activity indicated spatial variation across soil depths and treatments. The univariate analysis showed higher variability of dehydrogenase activity in the soil surface layer as compared to the deeper depths. The highest dehydrogenase activity was observed as 2.09, 1.58 and 1.30 µg TPF g[sup -1] hr[sup -1] and the lowest as 0.92, 0.50 and 0.21 µg TPF g[sup -1] hr[sup -1] in 0-10, 10-20 and 20-30 cm depth, respectively. The results recognized that NPK application had a major role in dehydrogenase activity. Frequency distribution reveled that even after a short-term use of organic and inorganic amendments, improvement of SOC content was not above 0.50%. Higher moisture content was observed from the treatments where organic mulching and biofertilizers were added when compared with control. The results thus indicated that mango orchard soils of low fertility regions of semi-arid areas should be amended with organic substrates to enhance moisture retention, organic carbon build up and microbial activity. [ABSTRACT FROM AUTHOR]

The effect of fertilization on resistance and resilience of soil microbial activity against heat stress in the tropical soils is largely unknown. We investigated the impact of long-term (36 years) application of chemical fertilizers and farmyard manure ( FYM) on substrate-induced respiration ( SIR) and dehydrogenase activity ( DHA) and their resistance and resilience against heat stress in a sandy clay loam soil (Typic Haplustept). Surface soils from five selected treatments (Control, N, NP, NPK, NPK + FYM) under maize ( Zea mays) crop were assessed immediately after sampling (0 Day) and at 1, 14, 28 and 56 day(s) after heat stress (48 °C for 24 h). The heat stress significantly decreased soil respiration and dehydrogenase activity by 20-80 %. Recovery after stress was up to 100 % within 56 days. The combined application of NPK (balanced) and FYM was most effective in enhancing resistance and resilience (stability) of soil microbial activity against heat stress. Correlation between resistance of dehydrogenase activity and substrate-induced respiration revealed a significant relationship (R2 = 0.85). However, after stress, this correlation was initially weak but subsequently improved with time (R2 = 0.38-57), indicating different time lags to restore the normalcy of these parameters. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of this study were to assess chemical and microbial properties of different post-mining barrens afforested with Scots pine (Pinus sylvestris) and to evaluate the potential of near infrared spectroscopy (NIRS) to predict these properties in the reclaimed soils. The samples were collected from four sites at different substrates and measured for the contents of organic C (Corg), total N (Nt), Corg-to-Nt ratio, dehydrogenase activity, contents of humified C, humic acid C and fulvic acid C, cation exchange capacity, exchangeable acidity, total exchangeable bases (TEB) and base saturation. The spectra of samples were recorded between 400 and 2500nm. A modified partial least squares method with cross-validation was used to develop calibration models for prediction of chemical and microbial properties of the samples from their spectra. There were significant differences in the contents of Corg, Nt, dehydrogenase activity, pH and sorption properties between the mine soils. The samples from the studied sites had different spectral characteristics suggesting differences in chemical composition of their organic matter. “Excellent” predictive models (coefficient of correlation between the predicted and reference values ≥0.90) based on NIR spectra were developed for Nt, Corg-to-Nt ratio, humified C, humic acid C and exchangeable acidity. For other soil properties (except the TEB), “satisfactory” (r =0.80–0.90) models useful for fast screening were developed. The results indicate the potential of NIRS to predict several properties of the reclaimed mine soils. [Copyright &y& Elsevier]

The objective of this article was to determine the structure of microbial communities and the activity of dehydrogenases in soil samples contaminated with four polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, anthracene, and pyrene, in the amount of 0, 1000, 2000, and 4000 mg kg−1soil DM. Organic substances—cellulose, sucrose, and compost—were added to the samples in the amount of 0 and 9 g kg−1soil DM. The experiment was performed in a laboratory on samples of loamy sand. Indices of colony development (CD) and eco-physiological diversity (EP) of organotrophic bacteria, soil resistance (RS), and soil resilience (RL) were calculated. Soil contamination with PAHs differentiated the structure of organotrophic bacteria, and the lowest CD and EP values were noted in soil samples containing pyrene. PAHs inhibited the activity of dehydrogenases, and pyrene exerted the most inhibitory effect on enzyme activity. Dehydrogenase activity was determined mainly by the applied PAH dose, the date of analysis and the type of organic substance added to soil. Low RL values indicate that exposure to PAHs induces long-term changes in dehydrogenase activity. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Switching between aerobic and anaerobic condition facilitated good dye degradation. [•] Bio-electro kinetics supported the shifts in biocatalyst metabolic activities. [•] Facultative bacteria under limited oxygen availability function in enhanced dye removal. [•] Dehydrogenase and azo reductase correlated well with the metabolic function. [Copyright &y& Elsevier]

Abstract: A survey was undertaken in the established benchmark (BM) soil series in different agro-ecological sub regions (AESR) of Black Soil Regions (BSR) in India with an objective to study the impacts of bio-climates, cropping systems and land use systems on the distribution of dehydrogenase activity (DHA) in different soil profiles. The DHA was found to decline with depth and the maximum activity was recorded within 0–30cm soil depth. Cropping systems and bio-climates significantly (p<0.01) influence the DHA in soil. Significantly (p<0.01) higher DHA was recorded in Sub-humid moist (SHm) bio-climate (2.45μg TPFg−1) followed by Semi-arid dry (SAd) (2.00μg TPFg−1) and the least in arid bio-climate (1.62μg TPFg−1). The average DHA in different bio-climates were in decreasing order of Sub-humid moist>Semi-arid dry>Sub-humid dry>arid. Legume-based cropping system recorded higher DHA (2.32–2.88μg TPFg−1) followed by cereal-based cropping system (1.29–2.82μg TPFg−1). The average DHA in different cropping systems were in decreasing order of legume>cereals>cotton>sugarcane. The comparisons of DHA in different soils indicated significant differences (p<0.01) between the soil sub groups. High management practices found to significantly increase DHA (2.15μg TPFg−1) compared to low management (1.78μg TPFg−1), whilst no significant differences were found in DHA between irrigated and rainfed system. [Copyright &y& Elsevier]

Abstract: In order to quantify the activity of heterotrophic microorganism in membrane bioreactor (MBR) for drinking water treatment, biomass respiration potential (BRP) test and 2,3,5-triphenyl tetrazolium chloride–dehydrogenase activity (TTC–DHA) test were introduced and modified. A sludge concentration ratio of 5:1, incubation time of 2h, an incubation temperature that was close to the real operational temperature, and using a mixture of main AOC components as the substrate were adopted as the optimum parameters for determination of DHA in drinking water MBR. A remarkable consistency among BDOC removal, BRP and DHA for assessing biological performance in different MBRs was achieved. Moreover, a significant correlation between the BRP and DHA results of different MBRs was obtained. However, the TTC–DHA test was expected to be inaccurate for quantifying the biomass activity in membrane adsorption bioreactor (MABR), while the BRP test turned out to be still feasible in that case. [Copyright &y& Elsevier]

The effects of mine tailings and three organic amendments (compost, bokashi and vermicompost) on the mobility factor for Pb and Zn and on the potential C and N mineralization in semi-arid agricultural and rangeland soils were examined. During the experiment, soil samples were analyzed periodically for CO2-C evolution, inorganic N, dehydrogenase activity and percent Pb and Zn mobility during 169 d of incubation. The dehydrogenase activity and CO2-C evolved were strongly inhibited by mine tailings mixed with organic compost in both agricultural and rangeland soils (37 to 43 %), followed by N mineralization in treatments with mine tailings plus bokashi or compost (13 to 26.5 %) at 169 d incubation. The highest % mobility of Pb and Zn were observed in soils amended with mine tailings alone, while the lowest was observed in agricultural soils treated with vermicompost plus mine tailings. The CO2-C evolved was fitted to first order E, while the cumulative N mineralization was fitted to the linearized power function. Mine tailings were found to influence the potential C and N mineralization rate constants in both soils. The models for C and N mineralization could be used to evaluate the effects of mine tailings, which include intrinsic parameters in the soil. [ABSTRACT FROM PUBLISHER]

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Abstract: The ecology and functional role of biological soil crusts (BSCs) in arid and semi-arid zones have been extremely well studied. However, little is known about the biochemical properties related to the number and activity of the microbiota that form the crusts, even though information about these properties is very important for understanding many of the processes that affect the formations. In this study, several properties related to the activity and number of microorganisms (biomass-C, basal respiration, dehydrogenase activity and nitrogen mineralization potential) were determined at different depths (crusts, 0–0.5 cm; middle, 0.5–3 cm and deep, 3–5 cm layers) in two types of crusts (predominated by cyanobacteria and by lichens) in the Tabernas desert (Almeria, SE Spain). The absolute values of the above-mentioned properties and the values expressed relative to the total organic carbon (TOC) content were both much higher in the crust layers than in the surface horizons of soils under Mediterranean or Atlantic climates. A large part of the TOC in the BSCs was contained in the microbiota and another large part was readily metabolized during incubation of the crusts for 10 days at 25 °C. The net nitrogen mineralization rate was also high, and ammonification predominated in the crust layers, whereas nitrification predominated in the middle and deep layers. In all types of BSCs, the microbiota colonized the deep layers, although with greater intensity in the lichen-dominated BSCs than in the cyanobacterial BSCs. The results also indicate that hydrolytic enzymes are not stabilized on soil colloids and their activity depends only on the active microbiota. [Copyright &y& Elsevier]