Acid mine drainage (AMD) impairs many streams throughout the historical and current coal mining regions. Abandoned mines often have sulfur-rich coal that produces sulfuric acid after exposure to water and oxygen. These streams are characterized by lowered pH, increased metal load, and decreased biotic assemblage complexity in comparison to unimpaired streams. Remediation efforts using alkaline addition have been successful in reducing the impacts of AMD by improving the chemical environment and reestablishing biotic assemblages that more closely resemble unimpacted streams. We used phospholipid fatty acids (PLFA) to detect changes in biofilm fatty acid profiles, differences in specific fatty acid biomarkers, and nutritional quality among AMD-unimpaired, AMD-impaired, and AMD-remediated stream sites in southeastern Ohio (USA). In general, the physical, chemical, and biological measurements of the remediated sites were intermediate between the unimpaired and impaired streams. PLFA content was five times greater in AMD-unimpaired sites when compared to AMD-impaired and double that of AMD-remediated sites. PLFA profiles separated sites of the three categories into two statistically distinct groups: AMD-unimpaired/AMD-remediated and AMD-impaired. The results of this study showed that PLFA profiles have great promise as an additional metric to evaluate AMD impact for stream biomonitoring programs.

γ-Hexachlorocyclohexane (γ-HCH) persists in the environment and is recalcitrant to microbial degradation. To determine the extent of the microbial potential for the degradation of γ-HCH the diversity of bacteria from 12 soil samples collected around insecticide- and pesticide-producing factories in Egypt were assessed and compared with biofilm communities grown on γ-HCH microcrystals. From all samples, highly diverse microbes were isolated, able to grow on γ-HCH as sole source of carbon. The same soil samples were used to inoculate γ-HCH microcrystals on a substratum in microcosms to grow biofilm communities. All soil samples formed multispecies biofilms on γ-HCH. Biofilms stained with Nile Red showed distinct cell clusters of high hydrophobicity, and it is speculated that these aggregates have a substantial role in the degradation of the hydrophobic substrate. While many Bacillus species were isolated, this group was almost absent in the different biofilm communities. The finding of cells with highly hydrophobic envelopes together with the differences in species composition between isolates and interacting microbial communities points to fundamental differences in the interaction with hydrophobic substrates of single strains and microbial communities.

The overapplication of endosulfan on crops has resulted in the widespread contamination of soil. In this study, we examine the potential for bioremediation of the bacteria strain Alcaligenes faecalis JBW4 in degrading endsosulfan in soils. Bacteria were inoculated into sterilized and non-sterilized soils (Argi-Udic Ferrosols and Hapli-Udic Isohumosols) spiked with endosulfan. The results obtained from polymerase chain reaction-denaturing gradient gel electrophoresis indicate that JBW4 colonized Argi-Udic Ferrosols and Hapli-Udic Isohumosols successfully. The degradation efficiencies of α and β isomers of endosulfan by JBW4 were higher in Hapli-Udic Isohumosols than in Argi-Udic Ferrosols, and α and β isomers were degraded by 100.0 and 69.8%, respectively. In addition, detected endosulfan metabolites were either endosulfan ether and endosulfan lactone. Results of the single-cell gel electrophoresis assay showed that the toxicity of endosulfan and its metabolites in Hapli-Udic Isohumosols decreased after 77 days when compared to those in Argi-Udic Ferrosols after degradation by JBW4. Strain JBW4 is an excellent bio-remediator through its ability to degrade endosulfan in contaminated Argi-Udic Ferrosols and Hapli-Udic Isohumosols.

In Mexico, the mangrove is distributed in 764,486 ha, comprising the Atlantic coast from the Laguna Madre in Tamaulipas to Chetumal Bay in the Caribbean and in the Pacific from Ensenada, Baja California to Chiapas. On the coast of Oaxaca, coexist four species: red mangrove (Rhizophora mangle), white mangrove (Laguncularia racemosa) button mangrove (Conocarpus erectus) and black mangrove (Aviccenia germinans). In the Laguna “Salina” Tonameca, grows and develops the white, button, and black mangroves, whose spatial distribution decreases by deforestation, land use change, and increased saline substrate. Salinity of soil and waters, its concentration, and tipogenesis associated with the growth of mangrove trees were determined. Three saline gradients were identified in rainy season (gradient I: 2.18 dS m⁻¹; gradient II: 9.95 dS m⁻¹ and gradient III: 36.14 dS m⁻¹); while in drought season four gradients were detected (gradient I: 1.15 dS m⁻¹; II: 17.83 dS m⁻¹; III: 39.06 dS m⁻¹ and IV: 57.75 dS m⁻¹). The interannual saline variation is due to climatics, hydrologycal, and geomorpholigical conditions of the substrate. The lake salinity is hydrochloric, predominantly NaCl salt, of intense osmotic effect, which largely explains the mangrove halophytism. Moisture diluting brackish water, such that low salt conditions promotes growth and development of mangrove, but at concentrations > 35 g L⁻¹ limits their growth. In drought, hypersaline (>70 g L⁻¹) prevents the establishment and repopulation of this species.

In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collapsing air microbubbles (MBs) with diameter less than 50 μm was developed without the use of chemicals, such as surfactants and alkalis. Diesel and rotary-vane pump oil-contaminated fine and medium sands were treated with MBs to study the effect of oil viscosity and sand grain size on oil removal with MBs. About 95 % of diesel removal was achieved for 24 h old 10 % (w/w) diesel-contaminated medium sand in contrast to only 70 % removal from fine sand after 40-min treatment with MBs. While rotary-vane pump oil removal exceeds that of diesel after 40-min treatment with MBs, combination of mechanical stirring with MBs significantly enhanced the oil removal rate, whereby 95 % diesel removal was achieved from fine sand in 30 min in contrast to only 52 % diesel removal with MBs alone. A possible MBs cleaning mechanism for oil-contaminated sand was also proposed. This study provides experimental evidence for the applicability of self-collapsing MBs as a novel chemical-free approach for cleaning oil-contaminated sand.

Volatile organic sulfur compounds (VOSCs) are frequently reported in eutrophic lakes during the process of algal blooms’ degradation. The algal-induced so-called black water blooms have been purported to be a big contributor to the production of VOSCs. However, the production mechanism of VOSCs in black water blooms and its influencing factors still remain unclear. In this study, a laboratory sediment/algal slurry experiment was carried out to investigate the formation process of black water blooms and factors such as temperature, microorganisms, and sulfate concentrations on the production of VOSCs in eutrophic lake sediments during the decomposition of algal blooms. The simulation study indicated that black water blooms can only be produced with the participation of sediment and algal together, which could be the result of low redox potential and the continuous release of ferrion irons (Fe²⁺) and hydrogen sulfide (H₂S) into the lake’s ecosystem; however, neither of algal nor sediment can induce the formation of black water blooms. In addition, the sediment + algal treatment can produce more VOSCs than a single sediment or algal treatment. Higher temperature incubation and a higher concentration of sulfate additions can enhance the concentration of H₂S and VOSCs in black water blooms. However, the addition of microbial inhibitors in the algal/sediment slurry indicated that sulfate reducing bacteria (SRB) can stimulate the production of VOSCs, whereas methanogen might consume some concentration of VOSCs and thus lower their concentration in black water blooms.

Triclosan is an antimicrobial agent which is frequently found in the aquatic environment. Photolysis is an important transformation pathway for triclosan in surface water. Though a lot of studies have been conducted on the toxicity of triclosan, few of them focused on the ecological risk of the mixture after sunlight irradiation. The aim of the present study was to investigate the potential toxicity of triclosan under light irradiation and the influence of the coexisting humic acid by bioassay. Photo-induced acute toxicity and genetic toxicity were observed in the triclosan solutions after 24 h of light irradiation. The addition of humic acid at the concentration of 1 and 5 mg/L both resulted in a significant decrease (p < 0.05) in the photo-induced toxicity of triclosan. It is suggested that the photo-transformation process and the influence of humic acid should be considered for the ecological risk assessment of triclosan in surface water since humic acid is ubiquitous in natural water.

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.

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.

Tropical forests play an important role in carbon cycle. However, the temporal and spatial variation in soil carbon dioxide (CO₂) emission of tropical forest remains uncertain, especially near the Tropic of Cancer. In this research, we studied the annual soil CO₂ fluxes from three tropical montane rainforests on the Hainan Island of China (pristine montane rainforest, PF; secondary montane rainforest, SF; and Podocarpus imbricatus plantation, PP). The results showed a lower annual average soil CO₂ flux as 6.85 ± 0.52 Mg C-CO₂ ha⁻¹ (9.17 Mg C-CO₂ ha⁻¹ in the wet season and 4.50 Mg C-CO₂ ha⁻¹ in the dry season). The CO₂ fluxes exhibited obviously seasonal variation during the study period. Among the three forest types, PF had the highest average CO₂ flux rate of 317.77 ± 147.71 mg CO₂ m⁻² h⁻¹ (433.08 mg CO₂ m⁻² h⁻¹ in the wet season and 202.47 mg CO₂ m⁻² h⁻¹ in the dry season), followed by PP of 286.84 ± 137.48 mg CO₂ m⁻² h⁻¹ (367.12 mg CO₂ m⁻² h⁻¹ in the wet season and 206.56 mg CO₂ m⁻² h⁻¹ in the dry season) and SF of 255.09 ± 155.26 mg CO₂ m⁻² h⁻¹ (351.48 mg CO₂ m⁻² h⁻¹ in the wet season and 155.71 mg CO₂ m⁻² h⁻¹ in the dry season). We found between CO₂ fluxes and soil temperature a highly significant linear relation (P < 0.01) at 5 cm depth and a highly significant exponential correlation (P < 0.01) at 10 cm depth for all three forest types; a significant linear relation (P < 0.05) between CO₂ fluxes and soil moisture content was found for SF and PF, but not for PP (P > 0.05). The CO₂ flux was significantly correlated (P < 0.05) with water-filled pore space only for PF. In conclusion, our results suggested soil CO₂ fluxes in the three forest types that exhibit obviously spatial and temporal variation, and the temperature is the major factor affecting soil CO₂ fluxes from this region.