Fumigation is an important crop protection practice employed to control soil pathogens and diseases. Metham sodium and cadusafos are two commonly used soil fumigants for this purpose. However, little information is available on their effects on non-target soil organisms. The aim of the study was to determine the ecotoxicity of these chemical fumigants on earthworms (organismal responses and DNA damage) and soil microbial communities. Changes in soil microbial community function and structure were evaluated by means of Biolog™ Ecoplates and phospholipid fatty acid (PLFA) analyses, respectively. Both fumigants had a significant (p < 0.05) negative impact on all earthworm endpoints. Earthworms did not reproduce; biomass was affected negatively and manifested significant DNA damage with metham sodium causing more pronounced effects in comparison to cadusafos. The fumigants had an inhibitory effect on microbial growth. No lasting effects were observed in the community structure but cadusafos had a pronounced effect on the microbial community functional diversity. Metham sodium and cadusafos had varying effects on earthworm and microbial endpoints. This illustrates the importance of using different bioindicators to get a better understanding of the overall effects on the soil ecosystem.

Balancing the nitrogen derived from sewage effluent and fertilizers is essential for efficiently utilizing the nitrogen and minimizing the environmental degradations when applying sewage effluent. Pot experiments of maize (Zea mays L.) under drip irrigation were performed using ¹⁵N labeled urea to quantify the nitrogen balances of sewage effluent and fertilizers. Field experiments were conducted to confirm the findings of pot experiments. Four nitrogen rates ranging from 0 to 2.64 g/pot (0–210 kg/ha equivalently) for pot experiments and from 0 to 180 kg/ha for field experiments were established applying either secondary sewage effluent (SW) or groundwater (GW). Both pot and field experiments revealed that SW irrigation boosted nitrogen uptake and yield of maize compared to GW irrigation. However, the sewage-derived effects decreased with increasing nitrogen rates. SW irrigation could facilitate the uptake of ¹⁵N labeled urea relative to GW irrigation. Nonetheless, the nitrogen containing in effluent possibly had lower uptake effectiveness than the fertilizer urea for maize, suggesting greater potential for nitrogen losses resulting from effluent nitrogen compared to urea nitrogen. The percentage utilization of effluent nitrogen declined from 43 to 34% in 2014 and 48 to 32% in 2015 as nitrogen rates increased from 0 to 2.64 g/pot. Besides, the percentages utilization of total nitrogen (including effluent and fertilizers) under SW irrigation increased from 43 to 55% in 2014 and from 48 to 55% in 2015 when the rates increased from 0 to 1.76 g/pot, and subsequently decreased to 48% in 2014 and 44% in 2015 at the rate of 2.64 g/pot. This result was strengthened by the pattern of nitrogen recovery efficiency observed in the field experiments. Overall results of pot and field experiments recommended an optimal rate of 120 kg/ha for maize under drip irrigation applying SW to maximize nitrogen use efficiency and achieve an acceptably high yield.

The current study investigates the impact of recharging of partially treated wastewater through an infiltration basin on the groundwater aquifer quality parameters. A monitoring program supported by a geographic information analysis (GIS) tool was used to conduct this study. Groundwater samples from the entire surrounding boreholes located downstream the infiltration basin, in addition to samples from the recharged wastewater coming from the Beit Lahia wastewater treatment (BLWWTP), were monitored and analysed between 2011 and 2014. The analysis was then compared with the available historical data since 2008. Results revealed a groundwater replenishment with the groundwater level increased by 1.0–2.0 m during the study period. It also showed a slight improvement in the groundwater quality parameters, mainly a decrease in TDS, Cl⁻ and NO₃ ⁻ levels by 5.5, 17.1 and 20%, respectively, resulting from the relatively better quality of the recharged wastewater. Nevertheless, the level of boron and ammonium in the groundwater wells showed a significant increase over time by 96 and 100%, respectively. Moreover, the infiltration rate was slowed down in time due to the relatively high level of total suspended solid (TSS) in the infiltrated wastewater.

Sediment losses as concentrations and yields were measured for a year from 12 segments of a newly constructed (buried) natural gas pipeline on the US Forest Service’s Fernow Experimental Forest in West Virginia. Pipeline segments were separated by waterbars which served as drainage features. Six segments were northwest-facing, and six were southeast-facing. Three segments on each aspect were seeded with warm season native herbaceous species at rates used by the Forest Service (1×). All remaining segments received seeding at three times that rate (3×). Forest Service-established rates of fertilizer, lime, and straw mulch were applied to all segments. Sediment concentrations and yields generally were highest at the start of the study, respectively, averaging approximately 1660 mg L⁻¹ and 340 kg ha⁻¹ during the first 3 months following completion of corridor reclamation, but they were less than from nearby less-steep forest road corridors. Concentrations and yields fell significantly after the first 3 months; declines were attributed to revegetation on the ROW. At the end of the first growing season, vegetative cover on all segments ranged from 55 to 79%, with no differences between seeding rates. Mean runoff was significantly higher on the northwest-facing segments than on the southeast-facing segments, but runoff volumes did not decrease on either aspect in concert with loadings or concentrations. Higher runoff on the northwest-facing segments may have been due to clay-skinned peds in subsurface soil that limited vertical drainage. Even with a heavy straw mulch cover on the right-of-way, the timing of the highest sediment losses immediately following pipeline construction suggests that implementation of additional surface-protection best management practices could be beneficial until vegetation is reestablished.

Pipe section reactor (PSR) is a well-controlled laboratory reactor, which is used to simulate the water quality variations in drinking water distribution systems. However, the hydraulics condition within PSR, which is an essential prerequisite of the water quality studies, still remains unclear. Consequently, the objective of this study is to analyze the hydraulic conditions within PSR by means of a computational fluid dynamics (CFD) approach. The influences of configuration parameters on the hydraulic conditions were tested including propeller diameter, inclined angle of the propeller, distance between the top and inner cylinder, distance between the bottom and inner cylinder, outer cylinder length, baffle length, number of the baffles, rotational speed of the propeller, and inner and outer cylinder diameters. According to the CFD analysis, an optimal structure of PSR was suggested. The data presented here could facilitate the PSR application and improve the simulation of water quality in distribution systems.

Batch adsorption studies for cadmium (Cd), copper (Cu) and chromium (Cr) onto an agricultural soil impacted by mining activities were conducted in single- and multi-component systems. The effect of initial concentration, pH and competing ions (Fe³⁺, Ca²⁺, Co²⁺, Mg²⁺, K⁺, Ni²⁺ and Zn²⁺) on adsorption was studied. The soil exhibited high adsorption capacities for the elements at all initial concentrations with the adsorption process better described by the Freundlich isotherm. Adsorption was found to proceed via an ion exchange mechanism. The pseudo second-order kinetic model described the adsorption of the elements (R ² > 0.999), indicating a chemisorption process. The adsorption of Cd increased with pH in both systems while that for Cu decreased. The adsorption of Cr decreased with pH in the single-component system, but increased in the multi-component system. The adsorption of Cd was affected more by competing ions while Cu and Cr were not significantly affected (p > 0.05). Elemental speciation under varying conditions was studied using the PHREEQC geochemical modelling code. The observed high capacity of the soil for the elements pointed to the soil’s potential as a repository, a feature that would change depending on the speciation of the elements and soil conditions.

A critical appraisal of single-step extraction procedures of chromium species from soil was done in terms of their selectivity towards Cr(III) and Cr(VI) species. Samples of natural mineral and organic soil and samples of soil enriched with different chromium compounds of various solubility (in liquid or solid form) were used to simulate contamination of soil by liquid and solid wastes. The efficiency of extraction of Cr(III) and Cr(VI) species with various reagents, e.g. acetic acid, chelating agents (EDTA, DTPA) or inorganic salts (phosphates and carbonates), was evaluated on the basis of recovery results obtained for enriched samples. None of used reagents allow for quantitative extraction of added Cr(III) form. Procedures based on extraction of soil with Na₂CO₃ at room and elevated temperature (90–95 °C) were suitable for extraction of Cr(VI) species from mineral soil, whereas for organic soil, the procedure based on extraction with Na₂CO₃ at room temperature was recommended. The developed extraction procedures were validated using certified reference material (CRM 041 soil) and applied for analysis of contaminated soil samples. The studies showed that the physical state of waste, initial form and oxidation state of chromium and soil properties influenced the final chromium species and their mobility in soil, which have an impact on contamination of environment. The analysis of contaminated soil samples from a tannery area showed that the share of Cr(VI) was very low (only 0.8–4.5%) despite the high total content of chromium, which confirmed that chromium was present in immobile forms.

Predicting impacts of oil spills on the environment requires a better understanding of the effects on aquatic organisms, both for single hydrocarbons and for their interactions. In this study, the individual and combined effects of the petroleum hydrocarbons phenanthrene and dibenzothiophene (DBT) were assessed on the reproductive behavior of the freshwater amphipod Hyalella azteca. Following a 24-h exposure to single polycyclic aromatic hydrocarbons (PAHs), or an equimolar mixture of phenanthrene–dibenzothiophene (Phen–DBT), mate-guarding behavior was assessed. This consisted of an assessment of the incidence of mate guarding right at the end of the exposure period and quantification of the “time taken to initiate mate guarding” (TIMG) and “proportion of time spent mate guarding” (PTMG) during a subsequent 10-min observation period in clean water. Both Phen and DBT reduced the incidence of mate guarding at the end of the exposure. TIMG and PTMG during the observation period were not affected by the PAHs other than indirectly by their effect on mate guarding status at the end of the exposure. The interaction between Phen and DBT varied among the mate guarding measures. For mate guarding status at the end of the exposure period and for TIMG, the interaction did not deviate statistically from an additive effect. For PTMG, the overall interaction was a synergistic one. This study’s findings point out that assessments of hydrocarbon toxicity need to take into account that subtle reproductive behaviors (that may be important for population persistence) may be negatively affected. The results also show that the general assumption of additive effects among PAHs may be an oversimplification.

Combustion of fossil fuels has contributed to many environmental problems including acid deposition. The Clean Air Act (CAA) was created to reduce ecological problems by cutting emissions of sulfur and nitrogen. Reduced emissions and rainfall concentrations of acidic ions have been observed since the enactment of the CAA, but soils continue to receive some acid inputs. Many soils sensitive to acid deposition are found to have low pH, a loss of base cations, and a shift in the mineral phase controlling the activity of Al³⁺ and/or SO₄²⁻. If inputs continue, soil may be depleted of base cations and saturated with Al and could cause low forest productivity. Soil samples and soil solutions from pan lysimeters were taken on ridge-tops in the Daniel Boone National Forest to evaluate potential impacts of acid deposition recently and in the future. Sample results were compared to historical data from identical locations. Physicochemical characteristics of the soils revealed that sites were very low in base saturation and pH and high in exchangeable acidity, illustrating change since previously sampled. Soil solution data indicated that sites periodically received high acid inputs leading to saturation of Al in soils and the formation of Al-hydroxy-sulfate minerals. Given these conditions, long-term changes in soil chemistry from acid deposition are acknowledged.

Nitrogen recovery and valorization is gaining interest due to the current need for nitrogen removal, so it is of great interest that ammonium-selective sorbents be evaluated. In this study, a zeolitic material synthesized from coal fly ash (Ze–Na) in sodium form as well as its modification to potassium form (Ze–K) were evaluated as sorbent materials for the recovery of ammonium from wastewater effluents. The sorption performance was assessed through three consecutive sorption-desorption cycles reporting opposite behavior in terms of ammonium sorption capacity. Decreasing in the case of Ze–Na and to slightly increase for Ze–K due to alkaline activation of zeolite surface. The maximum sorption capacities obtained were 109 ± 4 mg NH₄/g and 33 ± 1 mg NH₄/g for Ze–Na and Ze–K, respectively. It is important to point out that in the case of Ze–Na, the maximum sorbent capacity was obtained during the first sorption cycle whereas in the case of Ze–K, it was obtained during the last working cycle due to the alkaline regeneration. Kinetic studies showed that after every regeneration step, the sorption kinetics turn faster as alkaline desorption increased the zeolite-specific surface, thus increasing the size of porous and enhancing the diffusion through the particle. Results obtained indicate that sorption capacity decreased significantly after every working cycle using Ze–Na whereas Ze–K followed the opposite behavior despite its initial lower sorption capacity.