Accurately measuring air concentrations of agricultural fumigants is important for the regulation of air quality. Understanding the conditions under which sorbent tubes can effectively retain such fumigants during sampling is critical in mitigating chemical breakthrough from the tubes and facilitating accurate concentration measurements. Using laboratory experiments, we studied the effects of air flow rate (100–1000 mL min⁻¹) and sampling time (2–16 h) on the breakthrough of co-applied chloropicrin (CP) and 1,3-dichloropropene (1,3-D) from 600-mg XAD-4 sorbent tubes. Due to the reversible adsorption of the chemicals, it was not possible to determine a tube adsorption capacity that was true across all flow and sample time conditions. Flow rate exerted the stronger influence on breakthrough, particularly for CP, with flow rates in excess of 200 mL min⁻¹ resulting in significant system losses even at the shortest sampling time (2 h). A flow rate of 200 mL min⁻¹ should therefore not be exceeded, irrespective of flow rate. With the use of a single tube (no backup), sampling times up to 4 h showed no system losses (100 % retention). Using a primary and backup tube, sampling periods up to 16 h also resulted in retention of all the added chemical masses. The information will be useful in establishing effective air quality monitoring programs following fumigation events.

Global warming and pollution are the twin crises experienced globally. Biological offset of these crises are gaining importance because of its zero waste production and the ability of the organisms to thrive under extreme or polluted condition. In this context, this review highlights the recent developments in carbon dioxide (CO₂) capture from flue gas using microalgae and finding the best microalgal remediation strategy through contrast and comparison of different strategies. Different flue gas microalgal remediation strategies discussed are as follows: (i) Flue gas to CO₂ gas segregation using adsorbents for microalgal mitigation, (ii) CO₂ separation from flue gas using absorbents and later regeneration for microalgal mitigation, (iii) Flue gas to liquid conversion for direct microalgal mitigation, and (iv) direct flue gas mitigation using microalgae. This work also studies the economic feasibility of microalgal production. The study discloses that the direct convening of flue gas with high carbon dioxide content, into microalgal system is cost-effective.

Because of its persistent usage and broad-spread applicability, chlorpyrifos with high potential damage to non-target organism can be found widely in the environment. However, the relevant researches about the effects of chlorpyrifos on soil fungi, an important part of microorganisms in the planting soil, are very limited, especially when chlorpyrifos is applied in actual agricultural practices. In this study, the soils, planted with Brassica juncea (L.) Czerniak (big mustard), treated with chlorpyrifos were analyzed during vegetable growth to be harvested. The effects of chlorpyrifos on fungal abundance and community structure were determined by quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE). The results revealed that chlorpyrifos was removed only 15.20 % on the 15th day after being sprayed. Chlorpyrifos caused inhibition on soil fungi diversity and fungal abundance significantly decreased from the early days after application. Furthermore, an obvious change in fungal community structure was found in the treatments compared with the controls, especially a significant change of Fusarium sp., which maintained stable abundance in the controls but fell sharply when chlorpyrifos started to be used and then significantly increased in the treatments, even over the controls finally. In contrast to the controls, the effects from chlorpyrifos could change soil fungal structure by affecting soil pH, while the other soil physicochemical properties without significant influence from chlorpyrifos.

Olive-oil production has a vital impact on the socioeconomic development in most Mediterranean countries, where 97.5 % of the world oil is produced. However, the olive-oil extraction process generates considerable quantities of an agro-industrial effluent, olive mill wastewater (OMW), which has negative impact on the environment and biological life. The objective of this study was to evaluate the potential use of OMW treated by different technologies in irrigation and determine its effect on the plant growth and soil quality parameters. Different technologies were used to treat the OMW, the resultant treated OMW was used to irrigate the maize planted in the pot experiment. The results indicated that UOMW increased soil salinity and reduced plant growth, while the treated OMW by different technologies improved plant growth and resulted in lower soil pH. The impact on other soil properties varied depending on the techniques used for treatments. Although treated OMW enhanced plant growth compared with the untreated, the plant growth remained lower than that obtained using the potable water with fertilizers, indicating lack of some essential plant nutrients.

Wide use of dyes in production of fabric becomes the most problematic and generates high amount of liquid effluent pollutants to the surface water. The potential of waste materials, pineapple (Ananas comosus) leaf powder and lime (Citrus aurantifolia) peel powder, to remove Remazol Brilliant Blue R (RBBR) from aqueous solution through adsorption process was investigated. Batch experiments were conducted at initial dye concentration of 500 mg/L. Data analysis showed a removal percentage more than 90 %. The Langmuir, Freundlich, and Temkin isotherm models were also investigated to study the mechanism of dye molecules onto adsorption process. The optimum equilibrium was obtained by the Langmuir isotherm (R ² = 0.9945) for pineapple leaves and (R ² = 0.9994) for lime peel. The maximum monolayer adsorption capacity adsorbents onto RBBR (9.58 mg/g) were achieved. The pseudo-second-order kinetic indicates that the rate constant was 1.00. The specific area of both adsorbents was identified as homogenous structure and was characterized by field emission scanning electron microscopy (FESEM) analysis. The surface functional groups responsible for dye uptake by adsorbents indicate that both adsorbents were defined as carboxyl group which consists of carbonyl and hydroxyl groups and were analyzed by Fourier transform infrared spectrometry (FTIR) analysis. The overall study indicates that adsorbents prepared from pineapple leaves and lime peels are alternative low-cost product in dye removal from aqueous solution.

The major obstacle to biological denitrification is the cost of the carbon source used as electron donor. Therefore, it is desirable to identify inexpensive alternatives to enable efficient denitrification. Corn husk, a type of agroforestrial waste, has the potential to release organic materials. This study investigated the possibility of enhancing aerobic denitrification by thermophilic Chelatococcus daeguensis TAD1 when corn husk that had been pretreated with hydrolysate was employed as the carbon source. The results showed that the particle size of 10–40 mesh, the NaOH dose of 0.01 mol L⁻¹, the loading dose of 60 g L⁻¹, the temperature of 40 °C, and pretreatment time of 24 h were appropriate to release available carbon source for denitrification by TAD1. Additionally, an initial pH of 8.5 was optimal for denitrification with maximum N₂O production as low as 0.053 % of denitrified NO₃ ⁻-N, which was the least at pH 6.0–9.0, taking advantage of corn husk hydrolysate (CHH). At an initial NO₃ ⁻-N of 253.36 mg L⁻¹, the denitrification rate and removal efficiency reached 24.55 mg L⁻¹ h⁻¹ and 96.91 %, respectively, without accumulation of nitrite and N₂O utilizing CHH as a sole carbon source. To sum up, CHH was an economical and efficient carbon source for aerobic denitrification by TAD1 with low levels of N₂O, capable of tolerating the fluctuation of pH and the high nitrate load.

This study aims at investigating heavy metal mobility and bioavailability in sediments from the Mexicana and Jaralito streams, Northern Mexico. A chemical partition analysis (sequential extraction) was performed to determine geochemical phases in which metals are found. Geoaccumulation index (Igeo) and enrichment factor values were obtained from analytical results and geochemical baseline data. Sediments showed high concentrations (mg/kg) of Cd (below detection limit, BDL-3.50), Cr (3–41), Cu (238–1090), Fe (41267–61033), Mn (678–1143), Ni (18–35), Pb (51–124), and Zn (116–356). Metal concentrations in geochemical phases exhibited the following order: residual > interchangeable > Fe/Mn oxide > carbonate >organic matter/sulfide. Both streams presented high degree of enrichment for Cu, Fe, Mn, Ni, Pb, and Zn, indicating anthropic origin of these metals. Metal mobilities in Jaralito and the Mexicana were Fe > Cu > Mn > Pb > Zn > Ni > Cr and Fe > Cu > Mn > Zn > Ni > Pb > Cr > Cd, respectively. Jaralito and the Mexicana sediments exhibit a mostly gravel-sandy texture with higher metal contents than in fine fractions. Sediment Geoaccumulation index values suggest that Jaralito features moderate to strong contamination by Ni, Pb, and Cu, whereas the Mexicana features strong contamination by Cd, Cu, Pb, and moderate contamination by Ni, Pb, and Zn. The quality criteria comparisons (LEL and SEL) indicate these areas are contaminated by metals and represent a substantial environmental risk because of high metal mobility and availability. Future studies on water chemistry and biota are needed to fully assess pollution impact in the Jaralito and Mexicana streams. The probability of adverse biological effects from high metal levels in those streams confirms the urgency of implementing effective environmental management practices.

This outdoor research investigated the variations in soil ammonium (NH₃-N), nitrite (NO₂-N), nitrate (NO₃-N), total organic nitrogen (TON), and microbial biomass carbon (MBC) in bioretention tanks. Two biretention tanks (tank 1#: The depth of 0–20 cm was vacant aquifer layer; 20–90 cm, filled with the planting soil; 90–105 cm, filled with gravel. tank 3#: 0–20 cm was aquifer layer, 20–50 cm, filled with the planting soil; 50–90 cm, filled with blast furnace slag and sand; 90–105 cm, filled with gravel) were used with simulated rainwater discharge experiments to obtain soil samples at intervals of 1 h before the inflow and 24 h after the end of inflow. Results indicate that soil nitrogen (N) and MBC in two bioretention tanks were mainly captured at 10∼30 cm depth in soil; the content of soil NH₃-N exhibited a trend of initial decline but increase with time; the content of NO₂-N varied from 0.011 to 0.024 g/kg, and the change regularity was similar with the NH₃-N; different from the NH₃-N and NO₂-N, soil NO₃-N exhibited a trend of declining; while TON exhibited a trend of declining after slightly increase. Meanwhile, the content of NH₃-N and NO₃-N at 50 cm depth in tank 1# was slight lower than those at 10 and 30 cm; conversely, the discrepancy at the different depths in tank 3# was small. The contents of soil NH₃-N and NO₂-N before inflow were less than those after inflow, but it was adverse for NO₃-N. The NO₃-N leaching in bioretention system is a main reason for poor N removal in runoff. The content of MBC ranged from 1.055 to 1.847 g/kg and exhibited a trend of decline after increase. Furthermore, the content of MBC and TN has good linear correlation in bioretention tanks (R ² > 0.8), but it has general performance with TP (R ² > 0.5). The immobilization of NH₃-N, NO₂-N, and NO₃-N at the planting soil layer in tank 1# was greater than that in tank 3#. The N interception differences in the two tanks resulted from different infiltration rates of their underlying fillers.

Biosurfactants have been considered as promising candidates for oil spill cleanup as they are generally more biodegradable, less toxic, and better in enhancing biodegradation than chemical surfactants. This study targeted the marine microbial biosurfactants to examine their enhanced production methods and application for the removal of crude oil from soil. The biosurfactants generated by Bacillus subtilis, which was isolated from the Atlantic Ocean, were investigated in this study. The economic production medium using different carbon (n-hexadecane, diesel oil, glycerol, glucose, starch, and sucrose) and nitrogen sources (NaNO₃, (NH₄)₂SO₄, and yeast extract) was studied. The best performance of biosurfactant production was achieved when using glycerol as carbon source and sodium nitrate and yeast extract as nitrogen sources in the substrate. The production rate was enhanced five times compared with that of the original screening recipe. The fermentative production of the generated biosurfactants could reduce the surface tension of water to 27 mN/m and with strong surface activity (∼36.4 mN/m) even after dilution for 10 times. The critical micellar concentration (CMC) of the product was 507 mg/L. A thin layer chromatography (TLC) analysis indicated that the purified product was a mixture of lipopeptide and glycolipid. The microbially produced biosurfactants were further examined as a soil-washing agent to enhance crude oil removal in a soil column system. The removal rates of 58 and 65 % were achieved using the biosurfactant solution with concentrations of 4 and 8 g/L, respectively. The results demonstrated the potential of marine microbial biosurfactants in cleaning crude oil-contaminated soil.

In this study, the potential association of (citrate-stabilized) Ag (14.1 ± 1.0 nm) and CeO₂ (6.7 ± 1.2 nm) engineered nanoparticles (ENPs), or their ionic counterparts, with the submerged aquatic plant Elodea canadensis, was examined and, in particular, parameters affecting the distribution of the nanoparticles (or metal ions) between plant biomass and the water phase were assessed using five distinct aqueous matrices (i.e. tap water, 10 % Hoagland’s solution and three natural surface water samples). Individual plants were exposed to varying concentrations of Ag and CeO₂ ENPs or Ag⁺ and Ce³⁺ ions during 72-h-lasting batch experiments. A dose-dependent increase of silver or cerium in plant biomass was observed for both the nanoparticles and the ions, whereby exposure to the latter systematically resulted in significantly higher biomass concentrations. Furthermore, the apparent plant uptake of CeO₂ ENPs appeared to be higher than that for Ag ENPs when comparing similar exposure concentrations. These findings suggest that association with E. canadensis might be affected by particle characteristics such as size, composition, surface charge or surface coating. Moreover, the stability of the ENPs or ions in suspension/solution may be another important aspect affecting plant exposure and uptake. The association of the nanoparticles or ions with E. canadensis was affected by the physicochemical characteristics of the water sample. The silver biomass concentration was found to correlate significantly with the electrical conductivity (EC), dry residue (DR) and Cl⁻, K, Na and Mg content in the case of Ag ENPs or with the EC, inorganic carbon (IC) and Cl⁻, NO₃⁻, Na and Mg content in the case of Ag⁺ ions, whereas significant relationships between the cerium biomass concentration and the EC, DR, IC and Ca content or the pH, EC, DR, IC and Cl⁻, Ca and Mg content were obtained for CeO₂ ENPs or Ce³⁺ ions, respectively. Results also indicated that the Ag ENPs and Ag⁺ ions might potentially be toxic towards E. canadensis whereas no evidence of phytotoxicity was noted in the case of CeO₂ ENPs or Ce³⁺ ions.