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.

This study aims to evaluate a new biosorbent derived from co-composting eggshell with other organic materials (potato peels, grass clipping, and rice husk) for uptaking Pb(II) from an aqueous medium. This biosorbent contains a high amount of eggshell (30 % w/w; CES) and its performance was compared to mature compost without eggshell (CWES) and natural eggshell (ES). Sorption kinetics and equilibrium data were fitted to pseudo-second-order and Langmuir models, respectively. From a kinetic point of view, lead sorption into CES was fast, attaining equilibrium within less than 180 min. Batch experiments indicated that maximum sorption capacity of Pb into CES is 23 mg g⁻¹. The sorption capacity of CES was not significantly dependent on pH within the range of 2–5.5. In comparison to ES, organic matter of CES provided supplementary sites for lead sorption and an increase of 43 % in the sorption capacity was observed. Nevertheless, CWES was the biosorbent with higher sorption capacity. Still, this study points out the potential of new use of CES as an effective biosorbent to lead removal from aqueous matrices.

From 2010 to 2012, the Yangtze River and Hanjiang River (Wuhan section) were monitored for estrogenic activities during various water level periods. Using a recombinant yeast estrogen screen (YES) assay, 54 water samples were evaluated over the course of nine sampling campaigns. The mean 17β-estradiol equivalent (EEQ) value of raw water from the Yangtze River was 0–5.20 ng/L; and the EEQ level from the Hanjiang River was 0–3.22 ng/L. In Wuhan, drinking water treatment plants (DWTPs) using conventional treatments reduced estrogenic activities by more than 89 %. In general, water samples collected during the level period showed weaker estrogenic activities compared to those collected during the dry period. The samples collected in 2010 showed the strongest estrogenic activities of the 3-year period. The lack of correlations between estrogenic activities and selected common water quality parameters showed that estrogenic activity cannot be tied to common water quality parameters.

Within the Global Mercury Observation System (GMOS) project, long-term continuous measurements of total gaseous mercury (TGM) were carried out by a monitoring station located at Celestun, Yucatan, Mexico, a coastal site along the Gulf of Mexico. The measurements covered the period from January 28th to October 17th, 2012. TGM data, at the Celestun site, were obtained using a high-resolution mercury vapor analyzer. TGM data show values from 0.50 to 2.82 ng/m³ with an annual average concentration of 1.047 ± 0.271 ng/m³. Multivariate analyses of TGM and meteorological variables suggest that TGM is correlated with the vertical air mass distribution in the atmosphere, which is influenced by diurnal variations in temperature and relative humidity. Diurnal variation is characterized by higher nighttime mercury concentrations, which might be influenced by convection currents between sea and land. The back trajectory analysis confirmed that local sources do not significantly influence TGM variations. This study shows that TGM monitoring at the Celestun site fulfills GMOS goals for a background site.

The cleansing efficiencies of laundry detergents depend on composition and variation of ingredients such as surfactants, phosphate, and co-builders. Among these ingredients, surfactants and phosphate are considered as hazardous materials. Knowledge on compositions and micellar behavior is very useful for understanding their cleansing efficiencies and environmental impact. With this view, composition, critical micelle concentration, and dissolved oxygen level in aqueous solution of some laundry detergents available in Bangladesh such as keya, Wheel Power White, Tibet, Surf Excel, and Chaka were determined. Surfactant and phosphate were found to be maximum in Surf Excel and Wheel Power White, respectively, while both of the ingredients were found to be minimum in Tibet. The critical micelle concentration decreased with increasing surfactant content. The amount of laundry detergents required for efficient cleansing was found to be minimum for Surf Excel and maximum for Chaka; however, cleansing cost was the highest for Surf Excel and the lowest for Tibet. The maximum amount of surfactants and phosphate was discharged by Surf Excel and Wheel Power White, respectively, while discharges of both of the ingredients were minimum for Tibet. The maximum decrease of dissolved oxygen level was caused by Surf Excel and the minimum by Tibet. Therefore, it can be concluded that Tibet is cost-effective and environment friendly, whereas Surf Excel and Wheel Power White are expensive and pose a threat to water environment.

Urea is considered as the most widely used nitrogen (N) fertilizer. Unfortunately, its application is associated with losses such as emissions of ammonia (NH₃) and nitrous oxide (N₂O) in a gas form. In addition to the economic loss, such N losses may threaten atmospheric quality. Application of both urease and nitrification inhibitors is advocated as an approach to mitigate these gaseous losses. Thus, laboratory studies were carried out to evaluate the effects of urease inhibitor-coated urea, nitrification inhibitor-coated urea, and other modified urea fertilizers on NH₃ volatilization and N₂O gas emissions in selected anaerobic rice soils. Copper (Cu) and Zinc (Zn) were selected as urease inhibitors and DMPP (3,4-dimethylpyrazole phosphate) as nitrification inhibitor. Nitrogen fertilizer treatments used were urea, Cu-coated urea (CuU), Zn-coated urea (ZnU), Cu + Zn-coated urea (CuZn), DMPP-coated urea (DMPPU), DMPP + Cu + Zn-coated urea (DMPPCuZn), OneBaja, sulfur-coated urea (SU), and dolomite-coated urea (DU). Results demonstrated that CuU, ZnU, DMPPCuZn, SU, and OneBaja were effective in reducing NH₃ volatilization by 12.12–37.48 % compared to urea, while DMPPU had no effect on NH₃ volatilization. Meanwhile, sulfur-coated urea (SU), CuU, ZnU, CuZn, OneBaja, DMPPU, and DMPPCuZn reduced N₂O emission over urea by 14.86, 17.57, 21.62, 29.73, 29.73, 33.78, and 48.64 %, respectively. These results suggest that using Cu, Zn, or combinations of DMPP, Cu, and Zn is recommended as an alternative to mitigate both NH₃ volatilization and N₂O emission, in addition to providing positive impact to environment.

Metal cations could enhance the sorption of tetracyclines but sometimes the effects are negligible. It is still not clear how these metals produce different effects. In this study, the sorption of chlortetracycline (CTC), tetracycline (TC), and oxytetracycline (OTC) was performed in the presence of Cd (II) to reveal the unknown mechanisms with two river sediments. It is found that Cd (II) could enhance the sorption of TCs on sediment SS, while it is negligible on sediment SY. For different tetracyclines, the enhancement effect by Cd (II) was more significant for CTC, while it is inferior for OTC and TC. Sorption isotherms of Cd (II) under strong and weak background electrolyte and pH decrease of sorption solutions indicate specific sorption is major on SY and cation exchange is significant on SS. Consequently, specific sorption is unfavorable for the enhanced sorption of TCs in the presence of Cd (II) because it is not favorable for the sorption of Cd-TCs by complexation and cation exchange. By the theoretical calculations, it is found that the significant enhancement of CTC is due to the higher electron affinity of Cd-CTC complex than the others to the surface groups. In conclusion, TCs sorption will not be affected by Cd (II) on sediments or soils with strong specific sorption characters of Cd (II).

One potential way for organic matter recovering contained in paper mill effluents can be obtaining polyhydroxyalkanoate (PHA). The aim of this work was to evaluate PHA biosynthesis from paper mill effluents by moving bed biofilm reactor (MBBR) under different operational strategies of the BOD₅/nitrogen (N)/phosphorus (P) ratio. The operational strategies were evaluated in two phases. During phase I, organic loading rates (OLRs) were increased from 0.13 to 2.99 biological oxygen demand kg BOD₅ m⁻³ day⁻¹, and in phase II, kg BOD₅ m⁻³ day⁻¹ was increased from 0.81 to 2.83. In both phases, the BOD₅/N/P ratios were 100:5:1 and 100:1:0.3. The maximum percentages of PHA-accumulating cells and organic matter removal were 85.10 and 95.60 % for phase I, both with a BOD₅/N/P ratio of 100:5:1, while in phase II, PHA biosynthesis and organic removal were 89.41 and 97.10 % with 100:1:0.3 and 100:5:1, respectively.

Tunis Gulf (northern Tunisia, Mediterranean Sea) is of great economic importance due to its abundant fish resources. Rising urbanization and industrial development in the surrounding area have resulted in an increase in untreated effluents and domestic waste discharged into the gulf via its tributary streams. Metal (Cd, Pb, Hg, Cu, Zn, Fe, and Mn) and major element (Mg, Ca, Na, and K) concentrations were measured in the grain fine fraction <63 μm by atomic absorption spectrophotometry. Results showed varying spatial distribution patterns for metals, indicating complex origins and controlling factors such as anthropogenic activities. Sediment metal concentrations are ranked as follows: Fe > Mg > Zn > Mn > Pb > Cu > Cd > Hg. Metals tend to be concentrated in proximity to source points, suggesting that the mineral enrichment elements come from sewage of coastal towns and pollution from industrial dumps and located along local rivers, lagoons, and on the gulf shore itself. This study showed that trace metal and major element concentrations in surface sediments along the Tunis Gulf shores were lower than those found in other coastal areas of the Mediterranean Sea.

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.