Bacteria, actinomycetes, and fungi are the dominant components of the soil microflora, and some of their species can perform denitrification. The aim of this study was to investigate the interactions of three kinds of denitrifiers in mix-culturing systems. Three denitrifying strains, i.e., one bacterial strain (strain B5), one actinomycete strain (strain A2), and one fungal strain (strain F1), were isolated from a rice paddy soil. Denitrifier interactions were examined by analyzing the population dynamics and metabolic substance in the mix-culturing systems with two and three strains and by estimating the effects of cell-free culture filtrates on the strains. Results showed that the growth of B5 was enhanced by F1 and A2, respectively, and nitrate removal proportions in the culture systems increased from 52% (B5) to 64% (B5 + F1) and 67% (B5 + A2), and the nitrate removal was further enhanced in the three strain mix-culturing system (74%, A2 + F1 + B5). Strain B5 stimulated the cell growth of A2 directly and indirectly. The existence of A2 was lethal for cell growth of F1, while A2 was also suppressed by F1. The suppressive interaction reduced nitrate removal rates from the single systems of 12.8 (F1) and 11.5 mg L−1 day−1 (A2) to 8.75 mg L−1 day−1 (A2 + F1). Likewise, F1 was inhibited by B5. The results also showed that the cell-free culture filtrates of other strains suppressed the cell growth of B5 and F1, respectively, but enhanced the cell growth of A2. In addition to the direct effect of cell-free culture filtrates, other indirect relationships could affect the denitrifier spatial distributions and balance of the suppression or promotion effects, which were beneficial to maintain the microbial structure and function stability with a low nitrous oxide emission in the soil.

Animal wastes are commonly used in a sustainable manner to fertilize crops. However, manures contain numerous pathogenic bacteria that can impact animal and human health. Treatment of animal waste by anaerobic digestion has the potential to reduce pathogen loading to land. This study was conducted to determine the fate of bacteria applied in raw and anaerobically digested dairy slurries that were broadcast and subsurface applied in a field of forage grasses. Digested slurry had significantly fewer indicator bacteria, Escherichia coli and fecal coliform at time of application. Anaerobic digestion did not increase the survivability of indicator bacteria. Waste treatment and application method did not affect the rate of bacteria die-off. There were fewer E. coli and fecal coliform at the end of each trial in the soils that received digested slurry. Anaerobic digestion of dairy waste has the potential to reduce pathogenic bacteria loading to cropland.

Since swine wastewater is used by farmers for soil fertilization, evaluation of toxic compounds or micro-contaminants of separate streams is required. This paper uses the toxicity identification evaluation (TIE) procedure for the physicochemical and ecotoxicological characterization of swine wastewater. To distinguish the most important toxic compounds, a physicochemical characterization and phase I-TIE procedure were performed. The acute toxic effect of swine wastewater and treated fractions (phase II-TIE) were evaluated using Daphnia magna determining 48-h LC50. Results show a high level of conductivity (23.5 μS cm−1), which is explained as due to the concentration of ions, such as ammonium (NH 4 + –N 1.6 g L−1), sulfate (SO 4 2− 397.3 mg L−1), and chlorine (Cl− 1,230.0 mg L−1). The acute toxicity of the swine wastewater was evaluated on D. magna (48-h LC50 = 3.4%). Results of the different water treatments indicate that anionic exchange treatments could reduce 22.5% of swine wastewater’s acute toxicity by reducing chlorine (to around 51%) and conductivity (8.5%). On the other hand, cationic exchange treatment increased acute toxicity on D. magna (% RT = −624.4%), by reducing NH 4 + –N (around 100%) and total nitrogen (95.5%). This finding suggests that part of the toxicity comes from anionic compounds, such as chlorine.

Lead (Pb) is known as an important aquatic contaminant with different toxic effects on various organisms. Until now, only few quantitative investigations have been published comparing Pb content in different organs of adult freshwater crabs. Their capacity to bioaccumulate other heavy metals is already known, and they can potentially transfer Pb to the terrestrial systems, as they are frequent trophic items of reptiles and birds, even humans. The objectives of this study were to assess Pb accumulation in the gills, carapace, digestive gland, and quela muscle of the freshwater crab Zilchiopsis oronensis, and to correlate bioaccumulation with morphometric data and sex. The crabs were manually caught in unpolluted ponds of the middle Paraná River alluvial valley (Santa Fe, Argentina). After the acclimation period, they were individually and randomly exposed per quadruplicate to three Pb experimental doses: 20, 40, and 80 mg Pb/L, in plastic cages during 15 days. After dissecting the crabs, the tissues were analyzed for lead in a Perkin Elmer Analyst 800 atomic absorption spectrometer. We found significant differences (p < 0.05) between the control and each one of the treatments but not between treatments (p > 0.05) and highly significant differences (p < 0.0001) between Pb concentration in organs. The Tukey posttest showed significant differences (p < 0.05) between gills–carapace, gills–digestive gland, and gills–quela muscle. The weight of the crabs only showed a negative correlation with Pb in the quela muscle (r = −0.53; p = 0.03). Pb in the carapace (but not in the other tissues) was positively correlated with the width (p = 0.571) and length (p = 0.616). Males accumulated more Pb than females, though not significantly. The present paper is aimed to contribute to our knowledge on Pb accumulation in freshwater crabs and select the better indicator organisms for biomonitoring.

A Gram-negative bacterium strain LWD09, capable of growing aerobically on 3,4-dichloroaniline (DCA) as the sole carbon and energy source, was isolated from the farm field. This bacterium was identified as Myroides odoratimimus strain by morphological, physiological, and biochemical characteristics as well as 16S rDNA sequence. Analysis of culture pH, temperature, cells growth, and DCA concentration demonstrated that strain LWD09 could effectively degrade DCA without a lag phase. The kinetics of DCA degradation was well described using the Andrews equation, and the kinetic parameters were as follows: q max = 1.74 h−1, K s = 43.5 mg L−1, and K i = 230.3 mg L−1. In addition, strain LWD09 was found to be moderately halophilic and showed the highest power of DCA degradation in 5% NaCl (w/w, %). With initial concentrations of 30, 100, and 200 mg L−1, 100%, 80.4%, and 33.2% of DCA were transformed after 96 h in 5% NaCl, respectively. These results suggest that strain LWD09 has the potential to degrade DCA in saline wastewater. To date, this is the first report on the degradation of DCA by a M. odoratimimus strain with moderate salinity tolerance.

The main objective of this study was to examine the effect of an electro-Fenton pretreatment on the biodegradability of sulfamethazine-polluted solutions. The aim of the pretreatment was only to degrade this molecule in order to increase the biodegradability of the effluent and therefore allow a subsequent biological treatment. Preliminary tests showed the absence of biodegradability of the target compound. The degradation of sulfamethazine by electro-Fenton process was then examined using a carbon felt cathode and a platinum anode in an electrochemical reactor containing 1 L of solution. The influence of some experimental parameters such as initial concentration, temperature and current intensity on the degradation by electro-Fenton step has been investigated. In addition, the biodegradability of the solution after electrochemical pretreatment was examined and showed a Biological Oxygen Demand (BOD5) on Chemical Oxygen Demand (COD) ratio above the limit of biodegradability, namely 0.4, for several experimental conditions. The feasibility of coupling an electro-Fenton pretreatment with a biological degradation of by-products in order to mineralize polluted solutions of sulfamethazine was confirmed.

The biomass characteristics, the process performance, and the microbial community for a sequencing batch reactor (SBR) and a submerged membrane SBR (MSBR) were evaluated. A synthetic wastewater containing only 4-chlorophenol (4CP) was used as the sole source of carbon and energy. Degradation efficiencies of 4CP were higher than 99% for both reactors, and no significant differences on the 4CP degradation rates were observed for the SBR (116.9 ± 0.9 mg 4CP g VSS−1 h−1) as well as for the MSBR (117.3 ± 0.5 mg 4CP g VSS−1 h−1). Despite the similar results obtained for the physicochemical parameters, it was found that the biomass characteristics were different considering the sludge volumetric index, settling velocity, protein content in the mixer liquor, and total suspended solids in the effluent. The settling velocity was three times higher in the SBR than in the MSBR; however, a better quality, considering suspended solids, was observed for the MSBR. The protein concentration in the mixed liquor was higher in the MSBR than in the SBR, generating foaming problems in the MSBR. A similarity analysis was made with the Ochiai–Barkman index. Even though the reactors were inoculated with the same biomass, significant differences in the composition and populations dynamics were observed.

Conifer forests in the Jizerské Mountains, Czech Republic have experienced widespread and long-lasting effects related to industrial SO₂ pollution. To explore the spatial and temporal impact of this phenomenon on Norway spruce stands, a transect of sites was sampled to the southeast of the Polish coal-fired power station Turów. Tree growth at all sites displayed a significant reduction around 1980, which could not be explained by climate alone. However, by incorporating both climate and SO₂ variables in multiple regression models, the chronology trends could be explained well. The lowest growth rates were found to coincide with the period of greatest atmospheric SO₂ concentrations and the degree of suppression decreased with increasing distance from the power station. The period of growth suppression in a Silver fir site appeared to be more severe and longer in duration than for the spruce, although differing site conditions prevented a direct comparison. Fir trees also appeared to be affected by SO₂ pollution earlier in the twentieth century compared to spruce. Growth of both species, however, did not return to predicted levels following the reduction of pollution levels in the 1990s. A comparison with spruce and fir data from the Bavarian Forest, a region also affected by pollution in the past, revealed a temporal difference in growth suppression, likely related to different timings and loadings of SO₂ emissions between both regions. This study highlights pollution as another potential causal factor for the ‘divergence problem’ and dendroclimatic reconstructions in polluted regions should be developed with caution.

Water quantity and quality were monitored for 3 years in a 360-m-long wetland with riparian fences and plants in a pastoral dairy farming catchment. Concentrations of total nitrogen (TN), total phosphorus (TP) and Escherichia coli were 210–75,200 g N m−3, 12–58,200 g P m−3 and 2–20,000 most probable number (MPN)/100 ml, respectively. Average retentions (±standard error) for the wetland over 3 years were 5 ± 1%, 93 ± 13% and 65 ± 9% for TN, TP and E. coli, respectively. Retentions for nitrate–N, ammonium–N, filterable reactive P and particulate C were respectively −29 ± 5%, 32 ± 10%, −53 ± 24% and 96 ± 19%. Aerobic conditions within the wetland supported nitrification but not denitrification and it is likely that there was a high conversion rate from dissolved inputs of N and P in groundwater, to particulate N and P and refractory dissolved forms in the wetland. The wetland was notable for its capacity to promote the formation of particulate forms and retain them or to provide conditions suitable for retention (e.g. binding of phosphate to cations). Nitrogen retention was generally low because about 60% was in dissolved forms (DON and NOX–N) that were not readily trapped or removed. Specific yields for N, P and E. coli were c. 10–11 kg N ha−1 year−1, 0.2 kg P ha−1 year−1 and ≤109 MPN ha−1 year−1, respectively, and generally much less than ranges for typical dairy pasture catchments in New Zealand. Further mitigation of catchment runoff losses might be achieved if the upland wetland was coupled with a downslope wetland in which anoxic conditions would promote denitrification.

Current non-invasive biomonitoring techniques to measure heavy metal exposure in free ranging birds using eggs, feathers and guano are problematic because essential metals copper (Cu) and zinc (Zn) deposited in eggs and feathers are under physiological control, feathers accumulate metals from surface contamination and guano may contain faecal metals of mixed bioavailability. This paper reports a new technique of measuring lead (Pb), Cu and Zn in avian urate spheres (AUS), the solid component of avian urine. These metal levels in AUS (theoretically representing the level of metal taken into the bloodstream, i.e. bioavailable to birds) were compared with levels in eggs (yolk and shell), feathers and whole guano from chickens (Gallus gallus domesticus) exposed to a heavy metal-contaminated soil (an allotment soil containing Pb 555 mg kg⁻¹ dry mass (dm), Cu 273 mg kg⁻¹ dm and Zn 827 mg kg⁻¹ dm). The median metal levels (n = 2) in AUS from chickens exposed to this contaminated soil were Pb 208 μg g⁻¹ uric acid, Cu 66 μg g⁻¹ uric acid and Zn: 526 μg g⁻¹ uric acid. Lead concentrations in egg yolk and shell samples (n = 3) were below the limit of detection (<2 mg kg⁻¹), while Cu and Zn were only consistently detected in the yolk, with median values of 3 and 70 mg kg⁻¹ (dm), respectively, restricting the usefulness of eggs as a biomonitor. Feathers (n = 4) had median Pb, Cu and Zn levels respectively of 15, 10 and 140 mg kg⁻¹ (dm), while whole guano samples (n = 6) were 140, 70 and 230 mg kg⁻¹ (dm). Control samples were collected from another chicken flock; however, because they had no access to soil and their diet was significantly higher in Cu and Zn, no meaningful comparison was possible. Six months after site remediation, by top soil replacement, the exposed chickens had median Pb, Cu and Zn levels respectively in whole guano (n = 6) of 30, 20 and 103 mg kg⁻¹ (dm) and in AUS (n = 4) of 147, 16 and 85 μg g⁻¹ uric acid. We suggest the persistent high Pb level in AUS was a consequence of bone mobilised for egg production, releasing chronically sequestered Pb deposits into the bloodstream. In contrast, AUS levels of Cu and Zn (metals under homeostatic control and sparingly stored) had declined, reflecting the lower current exposure. However because pre- and post-remediation samples were measured using different methods carried out at different laboratories, such comparisons should be guarded. The present study showed that metals can be measured in AUS, but no assessment could be made of availability or uptake to the birds because tissue and blood samples were not concomitantly analysed. A major short coming of the study was the inappropriate control group, having no access to uncontaminated soil and being fed a different diet to the exposed birds. Furthermore guano and urine analysis should have been carried out on samples from individual birds, so biological (rather than just technical) variation of metal levels could have been determined. Future studies into using AUS for biomonitoring environmental heavy metals must resolve such experimental design issues.