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1.
Science ; 367(6485): 1425-1426, 2020 03 27.
Artículo en Inglés | MEDLINE | ID: mdl-32217713

Asunto(s)
Clima , Agua , Ecosistema
2.
Environ Monit Assess ; 192(4): 243, 2020 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-32193684

RESUMEN

Elimination of toxic dyes from industrial effluents before discharge into the environment is very essential to reduce the impact created on the environment. The process of adsorption is widely used for the removal of toxic dyes through suitable adsorbents. In the present study, a novel adsorbent prepared from Cereus sp. for the removal of Congo red from the aqueous solution phase. Adsorption experiment was conducted in batch mode and the effect of adsorbent dose (1-12 g/l), dye concentration (100-250 mg/l), and contact time (5-120 min) was determined. Twelve isotherm models namely Langmuir, Freundlich, Jovanovic, Temkin, Elovich, Dubinin-Radushkevich, Halsey, Hill-Deboer, Flory-Huggins, Flower-Guggenheim, Kiselev, and Harkins-Jura were fitted with the experimental data. Cuticle-removed cladodes (CRC) from biomass gave maximum adsorption capacity of 27.02 mg/g, whereas cuticle (C) resulted in maximum adsorption capacity of 52.63 mg/g according to Langmuir isotherm. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetic models were examined. Pseudo-second-order kinetics better fitted for both adsorbents. This is the first exhaustive study to systematically find cuticle portion has better adsorption of Congo red than the cladodes of Cereus sp. The study also highlights that cutin polyesters present in the cuticle might be responsible for higher adsorption of dyes compared with its counterpart CRC. The present study provides the first evidence that cutin polymer can be used for adsorption of Congo red. It significantly contributes to advancement for new biobased materials for monitoring and remediation of water resources contaminated with toxic dyes.


Asunto(s)
Rojo Congo , Anémonas de Mar , Contaminantes Químicos del Agua , Agua , Adsorción , Animales , Rojo Congo/aislamiento & purificación , Concentración de Iones de Hidrógeno , Cinética , Anémonas de Mar/metabolismo , Termodinámica , Agua/química , Purificación del Agua/métodos
3.
World J Microbiol Biotechnol ; 36(3): 51, 2020 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-32157408

RESUMEN

Culture-independent molecular-based approaches can be used to identify genes of interest from environmental sources that have desirable properties such as thermo activity. For this study, a putative thermo stable endoglucanase gene was identified from a mixed culture resulting from the inoculation of Brock-CMcellulose (1%) broth with mudspring water from Mt. Makiling, Laguna, Philippines that had been incubated at 90 °C. Genomic DNA was extracted from the cellulose-enriched mixed culture and endo1949 forward and reverse primers were used to amplify the endoglucanase gene, which was cloned into pCR-script plasmid vector. Blastn alignment of the sequenced insert revealed 99.69% similarity to the glycosyl hydrolase, sso1354 (CelA1; Q97YG7) from Saccharolobus solfataricus. The endoglucanase gene (GenBank accession number MK984682) was determined to be 1,021 nucleotide bases in length, corresponding to 333 amino acids with a molecular mass of ~ 37 kDa. The endoglucanase gene was inserted into a pET21 vector and transformed in E. coli BL21 for expression. Partially purified recombinant Mt. Makiling endoglucanase (MM-Engl) showed a specific activity of 187.61 U/mg and demonstrated heat stability up to 80 °C. The thermo-acid stable endoglucanase can be used in a supplementary hydrolysis step to further hydrolyze the lignocellulosic materials that were previously treated under high temperature-dilute acid conditions, thereby enhancing the release of more glucose sugars for bioethanol production.


Asunto(s)
Celulasa/genética , Celulasa/metabolismo , Celulosa/metabolismo , ADN , Genómica , Agua/metabolismo , Secuencia de Aminoácidos , Archaea/enzimología , Archaea/genética , Bacterias/enzimología , Bacterias/genética , Secuencia de Bases , Clonación Molecular , Estabilidad de Enzimas , Escherichia coli/genética , Concentración de Iones de Hidrógeno , Peso Molecular , Filipinas , Proteínas Recombinantes , Alineación de Secuencia , Sulfolobales/enzimología , Sulfolobales/genética , Temperatura Ambiental , Microbiología del Agua
4.
Water Res ; 174: 115625, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32114016

RESUMEN

Water distribution system contamination events caused by intentional, negligent, or accidental intrusion of biological, chemical, or radioactive contaminants have significant impacts on the health of the populations that it services. Therefore, it is important to have an effective plan that can be readily implemented to minimize the impact of these contamination events. However, limited research has been focused on strategic planning of the decontamination process of the contaminated infrastructure. This paper proposed a framework for assembling a disinfection plan in real-time by (1) partitioning a WDS into a number of district metered areas (DMAs), (2) generating a solution region for each of the DMAs, and (3) assemble an effective decontamination plan using solution region generated. This framework has been applied to three contamination events. The results show that, when planning for the decontamination stage of a contamination event, the use of the proposed framework can (1) significantly reduce the response time, (2) improve the quality of the decontamination plan, and (3) provide a model for optimizing the resource allocation.


Asunto(s)
Desinfección , Agua , Descontaminación
5.
Science ; 367(6484): 1377-1379, 2020 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-32193328

RESUMEN

Hybridization-interbreeding between species-is generally thought to occur randomly between members of two species. Contrary to expectation, female plains spadefoot toads (Spea bombifrons) can increase their evolutionary fitness by preferentially mating with high-quality males of another species, the Mexican spadefoot toad (Spea multiplicata). Aspects of Mexican spadefoot males' mating calls predict their hybrid offspring's fitness, and plains spadefoot females prefer Mexican spadefoot males on the basis of these attributes, but only in populations and ecological conditions where hybridization is adaptive. By selecting fitness-enhancing mates of another species, females increase hybridization's benefits and exert sexual selection across species. Nonrandom mating between species can thereby increase the potential for adaptive gene flow between species so that adaptive introgression is not simply happenstance.


Asunto(s)
Anuros/fisiología , Hibridación Genética , Preferencia en el Apareamiento Animal , Reproducción , Selección Genética , Animales , Anuros/genética , Ecosistema , Femenino , Aptitud Genética , Masculino , Vocalización Animal , Agua
6.
J Environ Manage ; 261: 109921, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148251

RESUMEN

Most estimations of residential water demand are based on single-equation models that rely on assumptions that are most often not compatible with the fundamental principles of consumer theory. In this paper, we relax these assumptions by using a more flexible system of demand estimation, the Quadratic Almost Ideal Demand System (QUAIDS) (Banks et al., 1997) and reveal the existence in our sample of substitution and complementary patterns as well as non-linearities in Engel curves for water consumption. Water demand would not be, therefore, linear in income and separable from other goods consumed within the household. In this context the QUAIDS functional specification is expected to be more consistent with observed consumer behavior. Our results seem to confirm this expectation; when compared to the linear, log-linear and double-log models commonly used in water demand estimation, QUAIDS seems to produce a better overall fit and a better fit to the asymmetric shape of the real distribution of water consumption. This has important implications in terms of public policy, as it allows to explore how water policies interact with other goods consumed within the household (e.g. water-energy nexus or efficient household appliances). Furthermore, differential responses to pricing policies and taxes across the income distribution can be considered, thus contributing to avoid undesired redistributive effects and water poverty.


Asunto(s)
Comercio , Agua , Composición Familiar , Renta , Impuestos
7.
J Environ Manage ; 261: 110198, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148271

RESUMEN

Globally, buildings are recognized as one of the highest users of freshwater resources. Consuming enormous amounts of constructional and operational water deplete water resources and ultimately generates a high environmental impact. This is mainly due to the energy required for the water cycle of built environments, which involves raw water treatment and distribution, use within buildings, and wastewater treatment. Moreover, the impact of water use varies significantly among countries/regions, due to different water use cycles. For example, many countries use conventional water treatments, while others rely on advanced desalination. Unlike building energy use, the impact of water use in buildings has not been captured fully in research. Given the significant impact of water use in buildings and global environmental degradation, we aimed to review studies concentrating on constructional and operational water use and associated environmental impacts, as well as studies that employed life cycle assessment (LCA) on this topic. The review indicated that a limited number of studies have focused on this serious issue in recent years, and their aims differed greatly. Therefore, there is a notable research gap in comprehensive environmental impact assessment including the total human water use cycle. Complete environmental assessment through LCA enables building professionals to understand the wide-ranging impact of water use in a building's life cycle from the environmental perspective in a given region. Additionally, this approach can benefit policymakers setting guidelines for new sustainable water strategies aimed at reducing environmental impacts.


Asunto(s)
Purificación del Agua , Agua , Ambiente , Agua Dulce , Humanos , Aguas Residuales
8.
J Environ Manage ; 261: 110214, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148284

RESUMEN

The increased frequency of drought events in recent years is known to be responsible for significantly altering plant biodiversity in many of Earth's ecosystems, though the specifics of vegetation-drought interactions, especially the cumulative and time-lag responses, remains unclear. This study aimed to quantitatively investigate how grassland vegetation over the Chinese Loess Plateau (CLP) reacts to drought, specifically the observed cumulative and time-lag effects which are caused, using a combination of the Normalized Difference Vegetation Index (NDVI) and a multiple time-scale drought index (Standardized Precipitation and Evapotranspiration Index, SPEI). Our results revealed that while drought conditions have widespread cumulative impacts on grass growth in the CLP, the time lag effect of drought covered about half of the total area of the CLP. The cumulative effect of drought on grass was found to take place over various time scales, ranging from 5 to 10 months, while the time lag effect occurred within 2-3 months. The different response time of vegetation growth to the cumulative effect of drought in the CLP was found to be highly related to different water conditions. The accumulated months and mean rmax-cum both had a significant negative correlation with the mean annual SPEI (R2 = 0.90, P < 0.001; R2 = 0.70, P < 0.001, respectively). The lagged months and mean rmax-lag were also found to be negatively correlated with the mean annual SPEI (R2 = 0.547, P < 0.05; R2 = 0.785, P < 0.01, respectively).


Asunto(s)
Sequías , Ecosistema , Pradera , Plantas , Agua
9.
J Environ Manage ; 261: 110223, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148293

RESUMEN

Activated persulfate, as a member of the broad group of Advanced Oxidation Processes (AOPs), has emerged as a promising method for the elimination of microorganisms in aqueous matrices. This study evaluates the disinfection efficiency of this technique with respect to the inactivation of Escherichia coli and Enterococcus faecalis in water samples, as representative Gram negative and Gram positive bacterial indicators, respectively. In this perspective, various activators were employed, namely, ferric ion, heating, ultrasound application and UVA irradiation, which exhibited different bactericidal effect, depending on the operating conditions and the structural properties of each species. The highest disinfection rates were achieved with 200 mg/L of persulfate and ferric ion or heating as activators. For instance, 6 Log reductions were recorded within only 10-15 min when 30 mg/L of iron were applied, whereas the same bacterial removal was noted upon heat-activation at 50 °C, but in longer periods (i.e. 45-60 min). Nevertheless, in all cases E. faecalis was more resistant than E. coli, which was readily inactivated in shorter treatment periods. The overall process activity was deteriorated above the limit of 200 mg/L of persulfate. Ultrasound application exhibited lower performance, as even more prolonged treatment was required (120-150 min) for the same bacterial decay with the persulfate concentration not affecting substantially the process. In an attempt to improve the ultrasound activity, it was combined together with iron but with no synergistic results, as no actual enhancement of the method was observed. Finally, UVA did not seem to serve as an activator under the applied conditions, taking into account that it resulted in negligible loss of bacterial viability. Based on the current results, activated persulfate may be used successfully for disinfection purposes; however, the appropriate establishment of process variables is mostly required, considering the various resistance levels of aquatic microorganisms under stressed conditions.


Asunto(s)
Purificación del Agua , Agua , Desinfección , Escherichia coli , Oxidación-Reducción , Rayos Ultravioleta
10.
J Environ Manage ; 261: 110231, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148301

RESUMEN

Owing to uneven development and unbalanced resource endowments within China, ensuring reliable energy, water and food supply is a core challenge to regional socio-economic development. This study makes a first attempt to examine and compare demand-driven energy, water and arable land (E-W-L) resource outsourcings within China based on the latest multi-regional input-output model. Results show that interprovincial trade reallocated 73.4%, 33.9% and 38.1% of the national total E-W-L resource inputs in 2012, respectively. Investment was the dominant final demand category for driving energy requirements, while consumption was the leading final demand category for water and arable land requirements. Important provincial regions and critical transmission sectors for the trade of embodied E-W-L resources are identified. Substantial E-W-L resources were transferred from the central and western regions to the eastern regions. Especially, Inner Mongolia was the top interregional net exporter of embodied energy, while Jiangsu topped the net importer list. Regarding virtual water transfer, Xinjiang and Shandong were the biggest interregional net exporters and net importers, respectively, while Heilongjiang and Guangdong stood out in the net trade of embodied arable land. Owing to the impact of interprovincial trade, the resource occupancy levels of the eastern developed area were much higher than those of the northeastern, central and western areas. The imbalances in the levels of socio-economic development amongst provincial regions are mirrored by their patterns of E-W-L uses and related trade transfer. Understanding the synchronal outsourcings of E-W-L resource requirements provides important implications for targeted resource management in Chinese interprovincial supply chains.


Asunto(s)
Abastecimiento de Agua , Agua , China , Desarrollo Económico , Abastecimiento de Alimentos
11.
J Environ Manage ; 261: 110232, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148302

RESUMEN

To protect fragile groundwater-dependent environments of arid zones, it is important to monitor soil moisture and groundwater evaporation. Hence, it is important to assess new methods to quantify these environmental variables. In this work, we propose a new method to determine groundwater evaporation rates by combining the actively heated fiber-optic (AHFO) method with vadose zone modeling, assuming that the evaporation front remains at the soil surface. In our study, the AHFO method yielded estimates of the soil moisture (θ) profile with a spatial resolution of ~6.5 mm and with an error of 0.026 m3 m-3. The numerical model resulted in a slightly different θ profile than that measured, where the largest differences occurred at the soil surface. Sensitivity and uncertainty analyses highlighted that a better precision is required when determining the soil hydraulic parameters. To improve the proposed method, the soil heat-vapor-water dynamics should be included and the assumption that the evaporation front remains at the soil surface must be relaxed. Additionally, if the AHFO calibration curve is enhanced, the errors of the estimated θ profile can be reduced and thus, successful estimation of the evaporation rates for a wider range of soil textures can be achieved. The spatial scales measured are an important advantage of the proposed method that should be further explored to improve the analysis presented here.


Asunto(s)
Agua Subterránea , Suelo , Calibración , Temperatura Ambiental , Agua
12.
J Environ Manage ; 261: 110247, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148313

RESUMEN

Terracing and vegetation restoration are the basic measures to protect soil from water erosion and to combat land degradation. However, long-term quantitative evaluation on the erosion control benefits of different terracing techniques and vegetation types are still insufficient, particularly under variable rainfall. The aim of this article, therefore, is to evaluate the coupling effects of different terracing-vegetation combinations and rainfall types (RTs) on runoff retention and erosion reduction in a loess hilly catchment of China. Six types of terracing-vegetation combinations, including leveled benches-C. microphylla (LM), fish-scale pits-P. orientalis (FO), leveled ditches-P. armeniaca (LA), zig terraces-P. orientalis (ZO), fish-scale pits-P. tabulaeformis (FT), zig terraces-P. tabulaeformis (ZT) and the corresponding plots with same vegetation cover and non-terracing measures were designed and monitored. Based on five consecutive years of monitoring data, 69 rainfall events causing runoff and erosion were observed. Rainfall eigenvalues, including rainfall amount (RA), maximum 10-min intensity (I10), maximum 30-min intensity (I30) and rainfall duration (RD) dominated water erosion processes. Surface runoff and sediment reduction benefits differed with different terracing techniques. Mean runoff coefficients (Rc) among all kinds of terracing-vegetation combinations were FT > LM > FO > LA > ZO > ZT, while mean soil loss rates (Em) among all kinds of combinations were FT > FO > LM > LA > ZT > ZO. ZT showed the highest mean runoff reduction (44.03%), while ZO generated the highest sediment reduction (39.08%). The worst performance was observed in FT. With regards to the results, it is necessary to select the optimal terracing-vegetation measures for erosion control based on the dominant rainfall eigenvalues in different areas. Overall, ZT, ZO and LA combinations are recommended, while uncertainty was detected in combinations with fish-scale pits. Suitable terracing-vegetation measures should be selected after considering the micro-relief construction, the optimization of plant disposition and the efficiency of water erosion reduction. Management should focus on the construction standards, the threshold of resisting erosion for each terracing measure, and timely maintenance of the terraces.


Asunto(s)
Lluvia , Agua , China , Conservación de los Recursos Naturales , Monitoreo del Ambiente , Sedimentos Geológicos , Suelo , Movimientos del Agua
13.
J Environ Manage ; 261: 110259, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148319

RESUMEN

Dredging is a globally important aquatic system management activity, used for navigation improvement, contamination removal, aggregate production and/or flood risk mitigation. Despite widespread application, understanding of the environmental effects of some dredging types remains limited. Field campaigns in 2016 and 2017 in the River Parrett estuary, UK, therefore investigated the geomorphic and physicochemical effects of Water Injection Dredging (WID), a poorly studied hydrodynamic dredging technology. WID, applied to restore channel capacity for the maintenance of flood water conveyance in the tidal River Parrett, influenced surface elevations but not grain-size characteristics of dredged bed sediments. Topographic alterations due to the 2016 WID operation were short-lived, lasting less than 10 months, although benefits of the 2017 WID operation, in terms of volumetric change, outlasted the ≈12-month study period. Dredging had a significant impact on water physicochemistry (pH, dissolved oxygen, total suspended solids and turbidity) when comparing pre- and during-dredging conditions within the dredge reach, although time-series analysis found dredging effects were comparable in magnitude to tidal effects for some parameters. WID is typically targeted at the thalweg and not the banks, rendering the geomorphic signature of the method different to those of other, often more invasive dredging technologies (e.g. mechanical dredging methods). Further, thalweg not bankside dredging may have potential positive ecological implications, particularly where the majority of biomass is located within the channel margins, as in the tidal River Parrett. Collectively, data suggest WID can be an effective method for sediment dispersal within tidal systems although regular application may be required to maintain cross sectional areas, particularly where management precedes periods of low flows and/or high rates of sediment accumulation. In future, more work is required to better understand both the physical and ecological implications of WID as a flood risk management tool in estuaries and rivers.


Asunto(s)
Sedimentos Geológicos , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Estuarios , Ríos , Agua
14.
J Environ Manage ; 261: 110144, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148255

RESUMEN

Successful water recycling initiatives depend on public acceptance. In this study, we compared risk percpetions of water labeled as recycled or reclaimed.We recruited 1264 subjects in an online panel (Qualtrics) and randomly assigned them either treatment (recycled or reclaimed) water and asked about the contents and perceived risk. Participants in the reclaimed condition were more likely to perceive the water to have harmful ingredients compared to the recycled condition. The odds of direct use acceptance for those in the recycled condition are 1.41 times (or 41%) more likely than those in the reclaimed condition. Similar results were found for indirect uses. A major finding of this study is that terminology influences the perceived contaminants and risk of reused water. Prior studies have found strong evidence that the way reused water is communicated can influence public perception. Policy impilcations favor the use of recycled water, likely due to the positive connotation recycling has in the U.S. today..


Asunto(s)
Opinión Pública , Riesgo , Purificación del Agua , Agua , Humanos , Reciclaje , Aguas Residuales , Abastecimiento de Agua
15.
Waste Manag ; 105: 540-549, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-32146415

RESUMEN

The objective of this study was to investigate how addition of high-moisture waste (HMW) affects the hydraulic and mechanical behavior of municipal solid waste (MSW). Direct shear and hydraulic conductivity tests were conducted on MSW, HMW, and MSW-HMW mixtures prepared with HMW contents ranging from 20% to 80% (by total mass). Direct shear tests were conducted at normal stress between 22 and 168 kPa and hydraulic conductivity tests were conducted at vertical effective stresses of approximately 50, 100, and 200 kPa. A threshold HMW content of 40% was identified corresponding to substantial change in friction angle and hydraulic conductivity of the mixtures. Municipal solid waste and MSW-HMW mixtures with less than 40% HMW had friction angles between 29° and 32° and hydraulic conductivities greater than or equal to 1.3 × 10-6 m/s. At HMW contents above 40%, the friction angle and hydraulic conductivity decreased with increasing HMW content. At 80% HMW, the hydraulic and mechanical behavior of the MSW-HMW mixture was comparable to HMW. The HMW had a friction angle of approximately 2° and hydraulic conductivity of 1.1 × 10-11 m/s at a vertical effective stress of 50 kPa. Additional direct shear tests conducted on MSW and MSW-HMW mixtures soaked in water to simulate subsequent wetting post disposal revealed a decrease in friction angle from approximately 29° to 24° for MSW mixed with 40% HMW.


Asunto(s)
Eliminación de Residuos , Residuos Sólidos , Conductividad Eléctrica , Resistencia al Corte , Instalaciones de Eliminación de Residuos , Agua
16.
Environ Monit Assess ; 192(4): 237, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-32172384

RESUMEN

A set of indicators that focus only on numerical values is constructed based on remotely sensed images to assess soil moisture conditions. The quantitative evaluation of soil moisture variation in two periods is rarely referred to in the current literature. In this study, a scaled soil moisture monitoring index (SSMMI) was established to monitor the soil moisture status during 2010-2018 in the Daliuta Coal Mining Area (DCMA), China, based on SPOT-5, SPOT-6, and Sentinel-2 images. We also employed a gradient-based structural similarity (GSSIM) algorithm to quantitatively analyze the characteristics of the spatial distribution of the soil moisture in the DCMA. The optimal scale for exploring the spatial heterogeneity of the soil moisture was determined by local variance and semivariance methods. The results showed that the soil moisture decreased at a rate of 0.0213/a from 2010 to 2018. The areas with the extremely dry and dry levels, which were mainly located in the northwest, some regions of the central area, and the southeast of the DCMA, decreased from 14.48% in 2010 to 13.66% in 2018. The proportion of the no dry level was improved by 14.62%, while the area of the extremely wet and wet levels decreased by 13.79%. The mean value of the soil moisture in the unmined area was greater than that in the DCMA, which was larger than that in the mined area. The result of the GSSIM analysis indicated that the area of dramatic change, where the soil moisture changed substantially, was chiefly distributed in the north, west, some central regions, and some parts of the south and east of the DCMA. The region where the substantial change occurred was surrounded by a moderate-change area, which was encompassed by a low-change area. The area with dramatic and moderate decreases in the soil moisture accounted for 64.52% of the region, which was greater than that with incremental soil moisture changes, which accounted for 5.85% of the region. The area also showed decreased soil moisture from 2010 to 2018. Soil moisture changes are closely related to variations in land cover. For instance, vegetative cover over an open-pit mining area can cause a dramatic reduction in soil moisture. Ninety-three meters was the optimal scale used for monitoring the soil moisture in the DCMA, which indicates that we can adopt the SPOT-5, SPOT-6, and Sentinel-2 images to evaluate the soil moisture conditions in the DCMA.


Asunto(s)
Minas de Carbón , Monitoreo del Ambiente , Suelo , Agua/análisis , Algoritmos , China
17.
Environ Pollut ; 259: 113874, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32032982

RESUMEN

Pieces of glass as solid wastes were recycled in the synthesis of highly order MCM-41 that decorated by green fabricated Co3O4 nanoparticles using the green extract of green tea leaves forming novel green nano-composite. The synthetic Co3O4/MCM-41 exhibit high surface area, low bandgap energy (1.63 eV), and typical spherical morphology decorated by Co3O4 nanoparticles. The composite was evaluated as green photocatalyst in effective oxidation of methyl parathion pesticide in the presence of a visible light source. The degradation results revealed complete removal of 50 mg/L and 100 mg/L after 60 min and 90 min, respectively using 0.25 of the catalyst at pH 8. The detection of the TOC in the treated methyl parathion solution gives strong indications about the formation of organic intermediate compounds during the oxidation steps. The main detected intermediate compound are C6H5OH(NO2), C6H5OH, (CH3O)3P(S), C6H4(OH)2, C6H3(OH)3, C6H4(NH2)OP(O)(OCH3)2, (CH3O)2P(O)OH, (CH2)2C(OH)OH(CHO)OC(O), and HO2C(CH2)2C(O)CHO. The detected intermediate compounds converted into SO42-, PO43-, NO3-, and CO2 under the extensive photocatalytic of them over Co3O4/MCM-41. The oxidizing species trapping test verified the controlling of the methyl parathion degradation pathway by the hydroxyl radicals. Finally, the composite showed significant reusability properties and applied five times in the oxidation of methyl parathion with considerable degradation percentages.


Asunto(s)
Cobalto , Metil Paratión , Nanopartículas , Óxidos , Plaguicidas , Dióxido de Silicio , Purificación del Agua , Agua , Cobalto/química , Vidrio/química , Metil Paratión/química , Nanopartículas/química , Oxidación-Reducción , Óxidos/química , Plaguicidas/química , Dióxido de Silicio/química , Agua/química , Purificación del Agua/métodos
18.
Sci Total Environ ; 715: 136975, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32018106

RESUMEN

Dissemination of antibiotic resistance genes (ARGs) in the water environment has become an increasing concern. There have been many reports on ARGs in surface water, but little is known about ARGs in groundwater. In this study, we investigated the profiles and abundance of ARGs in groundwater in comparison with those in surface water of Maozhou River using high-throughput quantitative PCR (HT-qPCR). Totally 127 ARGs and 10 MGEs were detected by HT-qPCR, and among them the sulfonamides, multidrug and aminoglycosides resistance genes were the dominant ARG types. According to the results of HT-qPCR, 18 frequently detected ARGs conferring resistance to 6 classes of antibiotics and 3 MGEs were further quantified by qPCR in the wet season and dry season. The absolute abundance ranged from 1.23 × 105 to 8.89 × 106 copies/mL in wet season and from 8.50 × 102 to 2.65 × 106 copies/mL in the dry season, with sul1 and sul2 being the most abundant ARGs. The absolute abundance of ARGs and MGEs has no significant difference between the wet season and dry season while the diversity of ARGs in the dry season was higher than that in the wet season (p < 0.05). Totally 141 and 150 ARGs were detected in the water and sediments of Maozhou River, respectively. A total of 116 ARGs were shared among the groundwater, river water, and sediment, which accounted for 67.1% of all detected genes. Redundancy analysis further demonstrated that the environmental factors contributed 70.7% of the total ARG variations. The findings of large shared ARGs, abundant Total Coliforms and large wastewater burden in the groundwater provide a clear evidence that anthropogenic activities had a significant impact on groundwater.


Asunto(s)
Agua Subterránea , Antibacterianos , Farmacorresistencia Microbiana , Genes Bacterianos , Agua
19.
Sci Total Environ ; 715: 137043, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32041059

RESUMEN

The abundance and nitrification activity of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) in bulk water and biofilm in chloraminated and chlorinated water supply systems were investigated. The abundance of AOB varied between cold and warm periods while that was the case for AOA only in biofilm. Lower ammonia concentrations favored the abundance of AOA over AOB. AOA and AOB were found more in distal zones of the distribution system (DS). Higher numbers of AOA and AOB were observed in DS associated with chloramination compared to those associated with chlorination. Significant positive correlations between ammonia-N in bulk water and AOA indicate a possibility of involvement of AOA in nitrification in DS. A separate laboratory-based experiment simulating DS condition was conducted to understand the effects of chlorine and chloramine dosages and temperature on AOA and AOB. AOA were inhibited less than AOB in the presence of lower concentrations of chlorine and chloramine (1.5 and 2.0 mg/L chlorine; 0.05-0.1 and 0.3-0.4 mg/L chloramine) while both of them were not detected at higher dosages (2.5 mg/L chlorine and 1.5-1.6 mg/L chloramine). At a low temperature (10-12 °C), chloramine and chlorine provided similar inhibition trends in which AOB were inhibited more than AOA. At a high temperature (25 °C), chloramine was less inhibitory to AOA and AOB than chlorine.


Asunto(s)
Archaea , Biopelículas , Amoníaco , Bacterias , Halogenación , Nitrificación , Oxidación-Reducción , Filogenia , Microbiología del Suelo , Agua , Abastecimiento de Agua
20.
Environ Sci Technol ; 54(6): 3510-3519, 2020 03 17.
Artículo en Inglés | MEDLINE | ID: mdl-32062972

RESUMEN

The rapid growth in U.S. unconventional oil and gas has made energy more available and affordable globally but brought environmental concerns, especially related to water. We analyzed the water-related sustainability of energy extraction, focusing on: (a) meeting the rapidly rising water demand for hydraulic fracturing (HF) and (b) managing rapidly growing volumes of water co-produced with oil and gas (produced water, PW). We analyzed historical (2009-2017) HF water and PW volumes in ∼73 000 wells and projected future water volumes in major U.S. unconventional oil (semiarid regions) and gas (humid regions) plays. Results show a marked increase in HF water use, and depleting groundwater in some semiarid regions (e.g., by ≤58 ft [18 m]/year in Eagle Ford). PW from oil reservoirs (e.g., Permian) is ∼15× higher than that from gas reservoirs (Marcellus). Water issues related to both HF water demand and PW supplies may be partially mitigated by closing the loop through reuse of PW for HF of new wells. However, projected PW volumes exceed HF water demand in semiarid Bakken (2.1×), Permian Midland (1.3×), and Delaware (3.7×) oil plays, with the Delaware oil play accounting for ∼50% of the projected U.S. oil production. Therefore, water issues could constrain future energy production, particularly in semiarid oil plays.


Asunto(s)
Agua Subterránea , Fracking Hidráulico , Contaminantes Químicos del Agua , Delaware , Gas Natural , Yacimiento de Petróleo y Gas , Estados Unidos , Agua , Pozos de Agua
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