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1.
Water Sci Technol ; 80(3): 597-606, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596270

RESUMO

Despite recent developments in process-based modeling of treatment wetlands (TW), the dynamic response of horizontal flow (HF) aerated wetlands to interruptions of aeration has not yet been modeled. In this study, the dynamic response of organic carbon and nitrogen removal to interruptions of aeration in an HF aerated wetland was investigated using a recently-developed numerical process-based model. Model calibration and validation were achieved using previously obtained data from pilot-scale experiments. Setting initial concentrations for anaerobic bacteria to high values (≈ 35-70 mg L-1) and including ammonia sorption was important to simulate the treatment performance of the experimental wetland in transition phases when aeration was switched off and on again. Even though steady-state air flow rate impacted steady-state soluble chemical oxygen demand (CODs), ammonia nitrogen (NH4-N) and oxidized nitrogen (NOx-N) concentration length profiles, it did not substantially affect corresponding effluent concentrations during aeration interruption. When comparing simulated with experimental results, it is most likely that extending the model to include mass transfer through the biofilm will allow to better explain the underlying experiments and to increase simulation accuracy. This study provides insights into the dynamic behavior of HF aerated wetlands and discusses assumptions and limitations of the modeling approach.


Assuntos
Carbono/análise , Nitrogênio/análise , Eliminação de Resíduos Líquidos , Poluição da Água/estatística & dados numéricos , Áreas Alagadas , Análise da Demanda Biológica de Oxigênio , Desnitrificação
2.
Sci Total Environ ; 690: 1131-1139, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470476

RESUMO

Dissolved organic carbon (DOC) turnover in aquatic environments is modulated by the presence of other key macronutrients, including nitrogen (N) and phosphorus (P). The ratio of these nutrients directly affects the rates of microbial growth and nutrient processing in the natural environment. The aim of this study was to investigate how labile DOC metabolism responds to changes in nutrient stoichiometry using 14C tracers in conjunction with untargeted analysis of the primary metabolome in upland peat river sediments. N addition led to an increase in 14C-glucose uptake, indicating that the sediments were likely to be primarily N limited. The mineralisation of glucose to 14CO2 reduced following N addition, indicating that nutrient addition induced shifts in internal carbon (C) partitioning and microbial C use efficiency (CUE). This is directly supported by the metabolomic profile data which identified significant differences in 22 known metabolites (34% of the total) and 30 unknown metabolites (16% of the total) upon the addition of either N or P. 14C-glucose addition increased the production of organic acids known to be involved in mineral P dissolution (e.g. gluconic acid, malic acid). Conversely, when N was not added, the addition of glucose led to the production of the sugar alcohols, mannitol and sorbitol, which are well known microbial C storage compounds. P addition resulted in increased levels of several amino acids (e.g. alanine, glycine) which may reflect greater rates of microbial growth or the P requirement for coenzymes required for amino acid synthesis. We conclude that inorganic nutrient enrichment in addition to labile C inputs has the potential to substantially alter in-stream biogeochemical cycling in oligotrophic freshwaters.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Poluentes da Água/análise , Carbono/análise , Água Doce/química , Nitrogênio/análise , Fósforo/análise
3.
Sci Total Environ ; 690: 1228-1236, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470485

RESUMO

The synthesis of manufactured soils converts waste materials to value-added products, alleviating pressures on both waste disposal infrastructure and topsoils. For manufactured soils to be effective media for plant growth, they must retain and store plant-available nutrients, including nitrogen. In this study, biochar applications were tested for their ability to retain nitrogen in a soil manufactured from waste materials. A biochar, produced from horticultural green waste, was added to a manufactured soil at 2, 5 and 10 % (by weight), then maintained at 15 °C and irrigated with water (0.84 mL m-2 d-1) over 6 weeks. Total dissolved nitrogen concentrations in soil leachate decreased by 25.2, 30.6 and 44.0 % at biochar concentrations of 2, 5 and 10 %, respectively. Biochar also changed the proportions of each nitrogen-fraction in collected samples. Three mechanisms for biochar-induced nitrogen retention were possible: i) increased cation and anion exchange capacity of the substrate; ii) retention of molecules within the biochar pore spaces; iii) immobilisation of nitrogen through microbial utilisation of labile carbon further supported by increased soil moisture content, surface area, and pH. Dissolved organic carbon concentrations in leachate were reduced (-34.7 %, -28.9 %, and -16.7 %) in the substrate with 2, 5 and 10 % biochar additions, respectively. Fluorescein diacetate hydrolysis data showed increased microbial metabolic activity with biochar application (14.7 ±â€¯0.5, 25.4 ±â€¯5.3, 27.0 ±â€¯0.1, 46.1 ±â€¯6.1 µg FL g-1 h-1 for applications at 0, 2, 5, and 10 %, respectively), linking biochar addition to enhanced microbial activity. These data highlight the potential for biochar to suppress the long-term turnover of SOM and promote carbon sequestration, and a long-term sustainable growth substrate provided by the reuse of waste materials diverted from landfill.


Assuntos
Sequestro de Carbono , Eliminação de Resíduos , Solo/química , Resíduos/análise , Carbono/química , Carvão Vegetal , Nitrogênio/análise
4.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2883-2891, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529862

RESUMO

To provide theoretical basis for management of Pinus sylvestris var. mongolica mixed plantation, the variation of soil carbon, nitrogen and phosphorus stoichiometry in different P. sylvestris var. mongolica belt-mixed plantations were explored. Taking the monoculture plantation as control, soil samples were collected at the distance of 0, 1, 2, 3, and 4 m from the center point in P. sylvestris var. mongolica and Ulmus pumila mixed plantation and P. sylvestris var. mongolica and Maackia amurensis mixed plantation along the two directions of P. sylvestris var. mongolica and its associated species in different soil layers. Contents and stoichiometric ratios of soil organic C, total N, total P, available N, available P were analyzed. The results showed that soil organic C, total N, and available N in P. sylvestris var. mongolica mixed plantations were higher than those in pure plantation. The soil organic C, total N contents, C/N and C/P in deep soil layers were increased under P. sylvestris var. mongolica and U. pumila mixed plantation. The soil N content increased but P content decreased in P. sylvestris var. mongolica and M. amurensis mixed plantation. With the increases of distance from the center of mixed plantation, soil C/N firstly increased and then decreased, while soil total P and available P contents decreased and N/P increased in P. sylvestris var. mongolica belt. Soil C/N decreased and available P contents firstly increased and then decreased with the increases of distance from the center in U. pumila belt of P. sylvestris var. mongolica and U. pumila mixed plantation. Soil total N content firstly decreased and then increased in P. sylvestris var. mongolica belt, but it firstly increased and then decreased in M. amurensis belt of P. sylvestris var. mongolica and M. amurensis mixed plantation. P. sylvestris var. mongolica mixed plantation could improve soil C and N stocks compared with pure plantation. The best mixed mode was P. sylvestris var. mongolica and U. pumila mixed by one row, as well as P. sylvestris var. mongolica and M. amurensis mixed in two rows.


Assuntos
Florestas , Nitrogênio/análise , Fósforo/análise , Pinus sylvestris , Pinus , Carbono , China , Solo/química
5.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2915-2922, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529865

RESUMO

We analyzed the effects of slope direction on soil nutrients and ecological stoichiometry by collecting soil samples from different slope directions (shady slope and sunny slope) of the bamboo forest in Longyou County, Zhejiang Province. The results showed that soil nutrients were affected by slope direction and soil depth. The nutrients level of soils in the sampling area showed the trends of shady slope > sunny slope, and surface soil > bottom soil. Compared to sunny slope, the cation exchange capacity (CEC), the contents of total organic carbon, total nitrogen, alkaline hydrolyzed nitrogen, available phosphorus, total potassium and available potassium of shady soils significantly increased by 43.7%, 103.8%, 92.0%, 75.5%, 22.4%, 89.4% and 240.7%, respectively. There was no significant difference in total phosphorus contents between shady slope and sunny slope. At all soil layers, there was no significant difference of C/N ratio between shady and sunny slopes. The average C/P ratio of shady slope was 180.8%, 42.0% and 54.3% higher than that of sunny slope at 0-20 cm, 20-40 cm and 40-60 cm, respectively. At each soil layer, the average C/K and N/K ratios between shady and sunny slopes had no significant difference. The average C/K and N/K ratios of shady slope and sunny slope were all significantly different among the three soil layers. In the shady slope, the contents of soil organic carbon showed significantly positive correlation with total nitrogen, total phosphorus, total potassium, and soil available nutrients. Overall, soil nutrients and ecological stoichiometry characteristics of shady slope of bamboo forest were superior to those of sunny slope.


Assuntos
Florestas , Nitrogênio/análise , Fósforo/análise , Solo , China , Ecologia , Nutrientes , Sasa
6.
Environ Monit Assess ; 191(9): 543, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31388832

RESUMO

This study evaluates the impact of leachates from a municipal dumpsite on the quality of domestic water sources in the area for potable use. Concentrations of leachate-associated organic contaminants (such as diethyl-phthalate, total organic halogen (TOH); 2,4-dichlorophenol; nonylphenol-ethoxylate; methyl-ethyl-phthalate; borneol; total organic carbon (TOC); total Kjeldahl-nitrogen (TKN); ammonium-nitrogen (NH3-N); nitrate (NO3); nitrate-nitrogen (NO3-N); and total phosphorus (TP)) in rivers and groundwater in the Enugu Metropolis in southeastern Nigeria were assessed in this study. Results of laboratory analyses indicate that the average values of diethyl-phthalate, borneol, TOH, nonylphenol-ethoxylate and TOC are 0.08 mg/l, 0.04 mg/l, 1.05 mg/l, 0.2 mg/l and 1.64 mg/l, respectively for groundwater and 0.1 mg/l, 0.03 mg/l, 0.74 mg/l, 0.19 mg/l and 1.74 mg/l, respectively, for rivers. Three (diethyl-phthalate, borneol and TOH) out of these major five contaminants, in both rivers and groundwater, exceeded the maximum permissible limits, suggesting that the domestic water sources are marginally contaminated by the leachates. ANOVA test result suggests that the data sources were significantly variable, while principal component and correlation analyses identified TOH, 2,4-dichlorophenol, TKN, NO3, NO3-N, TP and borneol, which originated most probably from degradation of plastic materials and organic wastes in the dumpsite, as the priority contaminants. Consumption of domestic water sources within the dumpsite area, in untreated state, could lead to health risks as these priority organic contaminants are mostly carcinogenic, toxic and injurious to human systems.


Assuntos
Monitoramento Ambiental/métodos , Água Subterrânea/química , Rios/química , Instalações de Eliminação de Resíduos , Poluentes Químicos da Água/análise , Compostos de Amônio/análise , Água Potável/química , Humanos , Nigéria , Nitratos/análise , Nitrogênio/análise , Ácidos Ftálicos/análise , Água/química
7.
Sci Total Environ ; 691: 1282-1296, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466208

RESUMO

Lowland coastal areas as the Po Delta (Italy) are often intensively cultivated and affected by nitrogen imbalance due to fertilizers leaching to groundwater and export via run-off. To address this issue several agricultural best practices have been proposed, like limiting the amount of fertilizers and increasing soil organic matter content. In this study, groundwater samples were analysed for major ions and stable isotopes of H2O, C, N and S using multi-level sampler (MLS) from two contrasting depositional environments, one representative of alluvial plain (AP) and the other representative of a reclaimed coastal plain (RCP). In each site, controlled plots with different agriculture practice including fertilizers and tillage and compost amendment and no tillage were considered in the study. Tracer test results highlight that recharge water infiltrated at the start of the controlled study has not yet reached the saturated zone, thus current groundwater concentrations are representative of former agricultural practices. Stable isotopes show a clear distinction between different sources of nitrogen in both sites, from synthetic fertilizers to sedimentary nitrogen pool and atmospheric input. The main source of sulphate in groundwater is pyrite and fertilizers. Denitrification, sulphate reduction and methanogenesis were involved in the C, N and S cycle in the RCP site characterized by low hydraulic conductivity sediments and high SOM. These processes were not relevant in the AP site characterized by oxic condition and low SOM, but some evidence of denitrification was found in one of the AP sites. High resolution monitoring was a key tool to identify the different redox zones responsible for N, C and S cycling in these aquifers. This study shows that a clear understanding of transit times in the vadose zone is a key prerequisite to evaluate the effect of controlled agriculture practice on the quality of shallow groundwater.


Assuntos
Agricultura , Monitoramento Ambiental , Água Subterrânea/química , Carbono , Itália , Nitrogênio/análise , Enxofre , Água , Poluentes da Água/análise
8.
Environ Monit Assess ; 191(9): 539, 2019 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-31377943

RESUMO

The externalities generated by disorderly urbanization and lack of proper planning becomes one of the main factors that must be considered in water resource management. To address the multiple uses of water and avoid conflicts among users, decision-making must integrate these factors into quality and quantity aspects. The water quality index (WQI), using the correlation matrix and the multivariate principal component analysis (PCA) and cluster analysis (CA) techniques were used to analyze the surface water quality, considering urban, rural, and industrial regions in an integrated way, even with data gaps. The results showed that the main parameters that impacted the water quality index were dissolved oxygen, elevation, and total phosphorus. The results of PCA analysis showed 86.25% of the variance in the data set, using physicochemical and topographic parameters. In the cluster analysis, the dissolved oxygen, elevation, total coliforms, E. coli, total phosphorus, total nitrogen, and temperature parameters showed a significant correlation between the data's dimensions. In the industrial region, the characteristic parameter was the organic load, in the rural region were nutrients (phosphorus and nitrogen), and in the urban region was E. coli (an indicator of the pathogenic organisms' presence). In the classification of the samples, there was a predominance of "Good" quality, however, samples classified as "Acceptable" and "Bad" occurred during the winter and spring months (dry season) in the rural and industrial regions. Water pollution is linked to inadequate land use and occupation and population density in certain regions without access to sanitation services.


Assuntos
Monitoramento Ambiental , Escherichia coli/crescimento & desenvolvimento , Poluição da Água/análise , Qualidade da Água/normas , Recursos Hídricos , Brasil , Análise por Conglomerados , Análise Multivariada , Nitrogênio/análise , Fósforo/análise , Análise de Componente Principal , Rios , Estações do Ano , Temperatura Ambiente , Urbanização
9.
Bioresour Technol ; 291: 121880, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31374415

RESUMO

This study focused on evaluate the effectiveness of biochar alone compare integrated with bacterial consortium amendment on the gaseous emissions mitigation as well as carbon and nitrogen sequestration during pig manure composting. Six additive treatments were performed based on uniform mixing pig manure with wheat straw [bacterial consortium (T2), 12%wood biochar (T3), 12%wood biochar + bacterial consortium (T4), 12%wheat straw biochar (T5), 12%wheat straw biochar + bacterial consortium (T6), while T1 without any additive]. The results obviously indicated that integrated use of biochar and bacterial consortium could remarkably relieved gaseous emissions, improved carbon and nitrogen conservation as well as accelerated maturity of composting. Notably the optimum combination was existed in T6 owing to lowest nutrient losses (nitrogen and carbon losses were 9.91 g/kg and 189.54 g/kg) and gas emissions (30.16 g/kg) as well as supreme maturity (germination index > 100%); it's an economic-practical and environmental protection novel disposal approach for solid waste.


Assuntos
Carvão Vegetal/metabolismo , Compostagem , Gases/metabolismo , Esterco , Nutrientes , Animais , Carbono/metabolismo , Nitrogênio/análise , Suínos , Triticum/química , Madeira/química
10.
Water Sci Technol ; 80(1): 144-152, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31461431

RESUMO

Nitrogen removal is an obstacle for the wide application of wastewater ecological soil infiltration (WESI) system in domestic wastewater treatment. In this study, matrix dissolved oxygen (DO), nitrogen removal and nitrous oxide (N2O) emission in aerated pilot WESI systems were investigated under different aeration times (1, 2, 3, 4 and 6 h/d) and aeration rates (1, 2, 3 and 4 L/min). The results showed that aerobic conditions in upper matrix and anoxic or anaerobic conditions in the subsequent matrix were developed in an aerated/non-aerated cycle at the optimal aeration condition of aeration time of 4 h/d and aeration rate of 3 L/min. Simultaneously, high removal efficiency of chemical oxygen demand (COD) (97.9%), NH4+-N (98.2%), total nitrogen (TN) (90.7%) and low N2O emission rate (13.2 mg/(m2 d)) were obtained. The results would provide optimal aeration parameters for application of intermittent aerated WESI systems.


Assuntos
Nitrogênio/análise , Óxido Nitroso , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Desnitrificação , Solo
11.
Environ Monit Assess ; 191(9): 559, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31402394

RESUMO

Various daily human activities can result in the release of pollutants of different chemical constituents and specific gravities into natural soils. Pollution of natural soils is a recurring occurrence in the environment and it contributes greatly to the alteration of soils properties. The results of an assessment of the effects of selected petroleum-derived and vegetable oils on soil physicochemical and hydraulic properties are presented in this work. Topsoil samples at a depth of 0-20 cm of the same textural class were collected from the order Lixisols and Nitisol within Ogun State, southwest Nigeria. Surface soil samples were collected and treated with petrol, diesel and palm oil at two different volumes (50 and 100 ml). Investigated soil properties include particle size distribution, soil pH, bulk density (BD), total porosity (TP), saturated hydraulic conductivity (Ksat), available water capacity (AWC), total carbon (TC), total nitrogen (TN), organic matter (OM) content, cation exchange capacity (CEC), potassium, sodium, and soil resistivity. Analysis of variance and Pearson's correlation were used to study the variations of the relationship of analyzed soil properties under different soil types and treatments. The regression analysis shows that all the generated models for predicting Ksat values under different soil treatments had R2 values ranging from 0.999 to 1.000. Results showed that treatment with either petroleum-derived or lipids has no effects on soil pH and textural class. Results further revealed that palm oil contamination at 50 ml recorded least values of Ksat in the two soil types. In all cases, BD and Ksat of the contaminated soils of the two sampling locations were reduced compared with their control values. Correlation coefficient showed expected strong negative correlation between TP and BD as well as between any two of organic parameters (TC, TN, and OM) and soil resistivity, TC, and TN at 1% level in both soil types. Two-way ANOVA showed that there were significant differences at 5% level between the two locations with respects to BD, TP, and CEC while significant differences in Ksat, pH, TC, TN, and OM occur between soils from the two locations under various treatments at 5% level.


Assuntos
Monitoramento Ambiental , Petróleo/análise , Poluentes do Solo/análise , Carbono/análise , Humanos , Nigéria , Nitrogênio/análise , Óleos Vegetais/análise , Solo/química , Água/análise
12.
Sci Total Environ ; 689: 1348-1357, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31466171

RESUMO

It is generally accepted that urban vegetation absorbs air pollutants resulting in improved air quality. However, limited work has provided experimental data that can be used to quantify this. In this study, Sophora japonica in the near-road environment was studied, and stable isotopes were used to estimate the proportional contributions of different nitrogen sources to the trees. δ15N and δ18O values were quantified for plant (n = 254) and soil samples (n = 86) collected from 12 sampling sites in Beijing. The elemental composition (total nitrogen (TN) and total carbon (TC)) of both samples types, and the ionic concentration (NO3- and NH4+) of soil samples were also measured. δ15N in S. japonica sampled near the road was significantly lower than in samples collected far from the road. Variation of δ18O, TN, and TC in plant samples could not be explained by the road distance. Using the SIAR Bayesian isotope mixing model and the mixing polygon method, the average proportional contributions of three nitrogen sources for the tree samples among all experiment sites were estimated, with the proportion for each nitrogen source following the order: soil (69.2%) > traffic-related NOx (19.3%) > dry deposition (11.5%). In addition, the results of the Bayesian model revealed that the nitrogen contribution of traffic-related NOx at road-adjacent sites (23.0%) was higher than the contribution of traffic-related NOx at sites far from the road (16.4%). These results indicated that the S. japonica in near-road green spaces was significantly influenced by traffic-related NOx emissions that were characterized by lower δ15N values. We found that using the SIAR Bayesian isotope mixing model and mixing polygon method, the potential nitrogen sources of plants could be estimated and the proportional contributions estimated by the model can reflect the plant's ability to absorb air-borne NOx.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Nitrogênio/análise , Sophora/fisiologia , Poluição do Ar/estatística & dados numéricos , Teorema de Bayes , Biodegradação Ambiental
13.
Science ; 365(6455)2019 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-31439763

RESUMO

Ballard et al argue that our prediction of a 30-year or longer recovery time for Gulf of Mexico water quality is highly uncertain, and that much shorter time lags are equally likely. We demonstrate that their argument, based on the use of a two-component regression model, does not sufficiently consider fundamental watershed processes or multiple lines of evidence suggesting the existence of decadal-scale lags.


Assuntos
Nitrogênio/análise , Qualidade da Água , Metas , Golfo do México
14.
Sci Total Environ ; 691: 178-186, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31319254

RESUMO

The leaves and seeds of plants frequently function as the source and sink organs for distinct metabolites, which can interactively vary in response to adverse site conditions. Subtropical soils are typically characterized as having deficient phosphorus (P), calcium (Ca), and magnesium (Mg), with enriched aluminum (Al) and iron (Fe), while Al and manganese (Mn) are toxic at low pH. It remains largely unknown how leaf- and seed-sourced metabolites are synergistically linked to adapt to P-variable soils for trees in subtropical areas. Here we quantified the metabolic and elemental profiling in the mature leaves and immature seeds of Quercus variabilis at contrasting geologically-derived phosphorus sites in subtropical China. The results revealed that carbon (C) and nitrogen (N) based metabolites (primarily sugars and organic acids), as well as enzyme- and protein/nucleic acid-related elements (N, P, Mg, and Mn) played important roles toward characterizing the profiling of metabolites and ionomes in leaves and seeds at two site types, respectively. These metabolites (sugars, amino acids, and fatty acids) and elements (N, P, Mg, and Mn) of seeds were closely related to the sugars, organic acids, and elements (N, P, Mg, and Mn) of leaves at the two site types. For the most part, the content of N and P in the soil affected the accumulation of materials (such as, starchs and proteins) in seeds, as well as N and P assimilation in leaves, by influencing C- and N-containing metabolites in leaves. These results suggested that correlated disparities of C- and N-containing metabolites, along with enzyme- and protein/nucleic acid-related elements in both leaves and seeds played important roles in plants to facilitate their adaptation to nutrient-variable sites in subtropical zones.


Assuntos
Monitoramento Ambiental , Fósforo/análise , Folhas de Planta/metabolismo , Quercus/fisiologia , Sementes/metabolismo , Oligoelementos/análise , Alumínio/análise , Cálcio/análise , Carbono/análise , China , Magnésio/análise , Manganês/análise , Minerais/análise , Nitrogênio/análise , Folhas de Planta/química , Potássio/análise , Quercus/química , Sementes/química , Solo/química
15.
Environ Pollut ; 252(Pt B): 1500-1508, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31272009

RESUMO

The application of low ozone dosage to minimize the problems caused by filamentous foaming was evaluated in two bioreactors of an urban wastewater treatment plant. Filamentous and nitrifying bacteria, as well as protist and metazoa, were monitored throughout a one-year period by FISH and conventional microscopy to examine the effects of ozone application on these specific groups of microorganisms. Multivariate data analysis was used to determine if the ozone dosage was a key factor determining the low carbon and nitrogen removal efficiencies observed throughout the study period, as well as to evaluate its impact on the biological communities monitored. The results of this study suggested that ozonation did not significantly affect the COD removal efficiency, although it had a moderate effect on ammonia removal efficiency. Filamentous bacteria were the community most influenced by ozone (24.9% of the variance explained by ozone loading rate), whilst protist and metazoa were less affected (11.9% of the variance explained). Conversely, ozone loading rate was not a factor in determining the nitrifying bacterial community abundance and composition, although this environmental variable was correlated with ammonia removal efficiency. The results of this study suggest that different filamentous morphotypes were selectively affected by ozone.


Assuntos
Microbiota/efeitos dos fármacos , Nitrogênio/análise , Ozônio/química , Esgotos/microbiologia , Águas Residuárias/microbiologia , Purificação da Água/métodos , Amônia/análise , Desnitrificação , Nitrificação , Esgotos/química , Águas Residuárias/química
16.
Sci Total Environ ; 691: 562-571, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31325856

RESUMO

Nitrogen (N) fertilization in agricultural soils has been receiving worldwide attention due to its detrimental effects on ecosystem services, particularly on microbial N transformation. However, few studies provide a complete picture of N-fertilization effects on the N transformation cycle within a single agricultural ecosystem. Here, we explored the main steps of the microbial N cycle, using targeted gene abundances as proxies, in relation to soil properties, following 35 years of N-fertilization at increasing rates (0, 202 and 269 kg N/ha) in continuous corn (Zea mays L.) and corn-soybean [Glycine max (L.) Merr.] rotations. We used real-time quantitative polymerase chain reaction (qPCR) for the quantification of phylogenetic groups and functional gene screening of the soil microbial communities, including genes encoding critical enzymes of the microbial N cycle: nifH (N2 fixation), amoA (first step of nitrification), nirK and nirS (first step of denitrification), and nosZ (last step of denitrification). Our results showed that long term N-fertilization increased the abundance of fungal communities likely related to decreases in pH, and an enrichment of Al3+ and Fe3+ in exchange sites at the expense of critical macro and micronutrients. At the same time, long term N-fertilization damaged potential biological N2 fixation by significantly reducing the abundance of nifH genes in both continuous and rotated corn systems, while accelerating potential nitrification activities under continuous corn by increasing the abundance of bacterial amoA. Fertilization did not affect the abundance of denitrifying groups. Altogether, these results suggest that N fertilization in corn crops potentially decreases N2 acquisition by free-living soil microbes and stimulates nitrification activities, thus creating a vicious loop that makes the overall agricultural system even more dependent on external N inputs.


Assuntos
Agricultura/métodos , Fertilizantes , Nitrificação , Nitrogênio/metabolismo , Microbiologia do Solo , Microbiota , Nitrogênio/análise
17.
Sci Total Environ ; 690: 290-299, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31291607

RESUMO

The Hokuriku district of central Japan receives high levels of precipitation during winter, largely in the form of snow. This study aimed to elucidate the internal nitrogen dynamics in this temperate forested region with heavy snowfall using the triple oxygen and nitrogen isotopic compositions of NO3-. The isotopic compositions of NO3- in atmospheric depositions (P and Tf), with terrestrial components of the soil layer (A0, S25, S55, and S90), ground water (G), and output (St) were measured from 2015 to 2016 in a forested catchment located in the southern area of the Ishikawa Prefecture, Japan. Seasonal distributions of Δ17O(NO3-) showed a decreasing trend from the inputs to outputs of the ecosystem. We found relatively constant Δ17O(NO3-) values in the output components (G and St), but found highly fluctuating Δ17O(NO3-) values resulting from the seasonal variations in the nitrification activity within soil waters. Specifically, we observed a lower nitrifying activity in the top soil layer throughout cold periods, presumably due to the input of cold melted snow water. The general trend of increasing δ15N(NO3-) value from the input to output components, with the changes in denitrification hotspots from shallow to deeper soil layer, can be observed between warm and cold periods. Thus, the seasonal changes of hotspots related to microbial nitrification and denitrification could be noted due to the seasonal changes in the isotopic compositions of nitrate. The estimated ecosystem-scale gross nitrification and denitrification rates are low; however, the output components are relatively stable with low concentrations of nitrate, indicating that the plant uptake of nitrogen most probably occurs at greater rates and scales in this forested ecosystem. Future nitrogen deposition and the vulnerable dynamics of snow melting are likely to have impactful consequences on such localities.


Assuntos
Monitoramento Ambiental , Florestas , Ciclo do Nitrogênio , Nitrogênio/análise , Neve/química , Japão , Estações do Ano
18.
Ecotoxicol Environ Saf ; 182: 109360, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31265970

RESUMO

Interest in the application of sewage sludge as amendments to grow trees has continued to increase, especially for fast-growing trees such as poplars. In this study, two-year field trial was conducted to determine the effects of compost sewage sludge (CSS) soil application on the distributions of metal and nutrient elements in poplars (Populus × euramericana 'Guariento') and poplar growth. Soil was amended with one of four CSS treatments in both study years: control (2012, 2013: 0 t/ha), SS1 (2012: 7.5 t/ha, 2013: 15 t/ha), SS2 (2012: 15 t/ha, 2013: 30 t/ha), and SS3 (2012: 30 t/ha, 2013: 45 t/ha). During the two-year field trial period, CSS treatments significantly affected leaf K, Mg, Ni, Cr, and Pb contents and root P contents. The element contents in different plant parts responded differently to the different CSS application rates; microelement contents in roots and trace element contents in leaves were significantly affected by the high sludge treatment. The CSS application significantly influenced Ca, Na, Cu, Ni, and Pb accumulation in aerial parts of poplar and the distributions of N, S, Ni, Mg, and P between roots and leaves or stems, and significantly increased the diameter at breast height (DBH) of poplars by 2.4-18.6%. The CSS application of 15 t/ha per year resulted in the largest average increase in DBH of 11.1%; therefore, it could be considered as the most suitable application rate. In summary, CSS application can improve nutrition uptake in various parts of poplars and promote the growth of poplar. Poplar forest amendment is a good CSS disposal strategy.


Assuntos
Metais Pesados/análise , Populus/química , Poluentes do Solo/análise , Eliminação de Resíduos Líquidos , Agricultura , Compostagem , Nitrogênio/análise , Fósforo/análise , Folhas de Planta/química , Esgotos , Solo
19.
Sci Total Environ ; 688: 718-723, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31255809

RESUMO

Cynodon dactylon (L.) Pers (C. dactylon) is one of the dominant plants in the water level fluctuation (WLF) zone of the Three Gorges Reservoir (TGR) tributaries. However, the leaves of C. dactylon can decay to increase the inputs of nutrients under flood inundation, increasing the risk of eutrophication in the TGR tributaries. Nutrient inputs from the leaf decay of C. dactylon in three interfaces, namely, water-sediment (WS), water-C. dactylon (WC) and water-sediment-C. dactylon (W-S-C), were estimated in a 180 d inundation experiment. The results showed that the kinetic processes of total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) input accorded with the power function equation: y = axb for the WS, WC and W-S-C interfaces (R2s > 0.72, p < 0.001). The cumulative TDN input from leaf decay of C. dactylon in the WC interface was 506.44 mg N kg-1 of biomass, which was significantly higher than that in the W-S-C interface with 422.24 mg N kg-1 of biomass (p < 0.05). However, no significant differences in TDP input were found between the WC and W-S-C interfaces (p > 0.05). The total amounts of TDN and TDP inputs at the 165-175 m altitude were 21,688.81 and 13,121.68 kg year-1, respectively, which were approximately 3.17 times those from the 145-155 m altitude of the WLF zone. The amounts of TDN and TDP inputs from the leaves of C. dactylon for the whole WLF zone were 49,261.65 and 29,803.17 kg year-1, respectively, which were 0.1 and 2.7 times the annual permissible discharge amount of pollutants calculated from a municipal wastewater treatment plant with the peak flow of 60,000 m3/d according to Class I (A) of the Wastewater Discharge Standard (GB18918-2002) in China. Thus, the aboveground part of this perennial herb should be harvested in a timely manner before reflooding, especially at the higher altitudes of the WLF zone to decrease eutrophication risk.


Assuntos
Cynodon , Nitrogênio/análise , Fósforo/análise , Folhas de Planta , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Rios
20.
Environ Pollut ; 252(Pt B): 1448-1454, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31265955

RESUMO

The Keban Reservoir, which is the second man-made waterbody in Turkey, has the biggest rainbow trout production in the country. In this study, the impacts of rainbow trout farms on water and sediment chemistry were investigated. Water and sediment samples were taken at distances of 0, 10, 25, 50 and 100 m from the edge of the cages at the three fish farms, and at the respective reference stations. Samples were also taken at 0 m stations and reference stations in the late August when there were no fish in the cages. Physico-chemical variables and trace metals were analysed in all samples. Due to likely high dilution rates and recycling processes in the water column of the reservoir, little changes in the water quality parameters associated with wastes of the fish farms were noticed. When compared with those in the sediment samples at the stations near the edge of cages, the lower concentrations of total phosphorus (TP), total nitrogen (TN), organic matter (OM), total carbon (TC), sulfide (S2-), arsenic (As), cobalt (Co), copper (Cu), manganese (Mn) and zinc (Zn), and higher values of redox potential (Eh) were found at the reference stations. According to organic enrichment classification based on S2- and Eh values, sediments of the three fish farms in the period when there were fish in the cages fell into the oxic category, whereas sediments in the August (no fish farming activity) fell into the normal category. Also, it was found in the August that most of sediment quality parameters at the 0 m stations had close values to those at the reference stations. These results revealed that a three-month period when there were no fish in the cages allows for sediments to return to reference station conditions.


Assuntos
Monitoramento Ambiental/métodos , Pesqueiros , Sedimentos Geológicos/química , Poluentes Químicos da Água/análise , Água/química , Animais , Arsênico/análise , Carbono/análise , Cobre/análise , Fazendas , Peixes , Nitrogênio/análise , Oncorhynchus mykiss , Fósforo/análise , Alimentos Marinhos/análise , Oligoelementos/análise , Turquia , Qualidade da Água , Zinco/análise
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