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1.
Environ Monit Assess ; 192(11): 699, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33044641

RESUMO

The present study was intended to determine the potentially toxic elements (PTEs) concentration in fly ash (FA), soil, plant, and vegetable to assess the impacts of pollution on the nearby areas of coal-fired thermal power plant (TPP). The PTEs concentrations (mg/kg) in FA were Cr (48-74) > Pb (41-65) > Cd (7.4-9.7) > As (3.19-4.43) > Hg (0.518-0.598). The contamination factor (Cf) for Cd was highest in agricultural soil (Cf = 22) followed by roadside soil (Cf = 20), and forest soil (Cf = 15), which showed that the soil was strongly polluted due to the presence of Cd. The ecological risk index (ERI) in the topsoil of roadside area was also very high (1130), due to the high value of ecological risk factor of Cd (898) and Hg (213). The health risk associated with the intake of soil containing PTEs were also estimated by calculating hazard index (HI), and the values showed that the risk posed to children was minimum (HI < 1). But in case of roadside area, the HI was very close to one (0.975) indicating that the prolong exposure may pose severe health risk. The bioaccumulation coefficient of all PTEs for Albizia lebbeck and Madhuca longifolia were < 1, indicating less PTEs accumulation in the plant species. The hazard quotient of all PTEs (except of Hg) through vegetable consumption (Allium cepa and Raphanus sativus) was > 1, which signifies that the long-time consumption of contaminated vegetables may cause severe risk to the people.


Assuntos
Metais Pesados , Poluentes do Solo , Criança , Carvão Mineral , Monitoramento Ambiental , Humanos , Índia , Metais Pesados/análise , Centrais Elétricas , Medição de Risco , Solo , Poluentes do Solo/análise , Verduras
2.
Environ Monit Assess ; 192(11): 670, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33009644

RESUMO

Antarctica is considered as one of the most pristine areas on Earth. However, increasing intensity of human presence on the sixth continent (scientific operations, functioning of the numerous scientific stations, tourism activities) makes it crucial to investigate the level of environmental pollution within the vulnerable ecosystem of Antarctica. Soils play a significant role in processes of accumulation, mobilization, redistribution of chemical elements within landscapes, and ecosystems. The aim of this work was to analyze the levels of 17 polycyclic aromatic hydrocarbons and eight trace elements in soils of King George and Ardley islands, Western Antarctica. Moreover, our work was aimed to determine the trends and reasons of anthropogenic pollution of Antarctic soils and characterization of accumulation levels of trace elements and PAHs. Results showed the predominance of light PAHs in all studied sites. The content of benzo(a)pyrene does not exceed the threshold concentration (adopted by different national environmental legislation systems). At the same time, the content of benzo(a)pyrene, which is a marker of anthropogenic contamination, is relatively low or equal to 0 in soils of reference landscapes. Cu and Zn were found as most abundant elements in all studied soils. The highest lead concentration content has been described in soil from Bellingshausen station. In general term, obtained Igeo values for trace elements in all samples were under or slightly above the 0 level, indicating low to moderate pollution of the studied soils. This study also contributes new data on trace element accumulation in soils strongly influenced by ornithogenic factor. Principal component analysis allowed to estimate the probable sources of specific trace metals and their relationship with soil variables. Ornithogenic factor has been also revealed as a driver for some trace element accumulation especially in breeding penguin colonies. High contents of organic matter in ornithogenic habitats could increase trace metal mobility, environmental risks for surrounding terrestrial environments should be considered.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes do Solo/análise , Oligoelementos/análise , Regiões Antárticas , Ecossistema , Monitoramento Ambiental , Humanos , Ilhas , Solo
3.
Environ Monit Assess ; 192(11): 672, 2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33009971

RESUMO

The effects of soil compaction on porosity (α), bulk density (ρs), and saturated hydraulic conductivity (Ksat) can create a physical barrier in the soil, reducing the vertical movement of toxic elements in the soil profile. However, the indirect effects of compaction in altering the forms and availability of heavy metals in soil have not been well-studied. This study examined the influence of compaction on forms of lead (Pb) in soils with contrasting texture. Four levels of compaction were imposed on a sandy loam and a clayey soil, which were artificially contaminated based on their maximum Pb adsorption capacity. Compaction had different effects on Pb forms depending on soil texture. In the sandy loam soil, compaction had a dual beneficial effect in mitigating the impact of Pb contamination, since it decreased Ksat, reducing metal transport to deeper soil layers, and also prevented transformation to more available Pb forms (soluble and exchangeable). Instead, there was an increase in the most environmentally stable forms of Pb (inner sphere adsorption on iron and manganese oxides). In the clayey soil, compaction caused a significant increase in soluble and exchangeable Pb, accompanied by a significant reduction in environmentally stable Pb (inner sphere adsorption on gibbsite and kaolinite). In addition, studies about Pb contents under compacted soil layers should be investigated, mainly in clayey soils with edible crops, and environmental remediation practices that involve the machines traffic (for example, phytoremediation-successive cultivation of Pb-hyperaccumulating plants) should be used with care to minimise the compaction of clayey soils.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Monitoramento Ambiental , Chumbo , Solo
4.
Environ Monit Assess ; 192(11): 673, 2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33011855

RESUMO

Plant responses to heavy metals and their storage constitute a crucial step to understand the environmental impacts of metallic trace elements (MTEs). In controlled experiments, we previously demonstrated the tolerance and resilience of Japanese knotweed to soil artificial polymetallic contamination. Using the same experimental design, we tested here the effect of three individual MTEs on Fallopia × bohemica performance traits. Rhizome fragments from three different sites (considered as distinct morphotypes) were grown in a greenhouse for 1 month on a prairial soil artificially contaminated with either Cd, Cr (VI) or Zn at concentrations corresponding to relatively highly polluted soils. Our results confirmed the high tolerance of Bohemian knotweed to metal stress, though, plant response to MTE pollution was dependant on MTE identity. Bohemian knotweed was stimulated by Cr (VI) (increased root and aerial masses), did not display any measurable change in performance traits under Cd at the high dose of 10 mg kg-1, and uptook all MTEs in its rhizome, but only Zn was transferred to its aerial parts. We also highlighted changes in root secondary metabolism that were more accentuated with Zn, including the increase of anthraquinone, stilbene and biphenyl derivatives. These results compared to multi-contamination experiments previously published suggest complex interactions between metals and plant, depending principally on metal identity and also suggest a potential role of soil microbes in the interactions.


Assuntos
Fallopia , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Cádmio , Monitoramento Ambiental , Metabolismo Secundário , Zinco
5.
J Environ Qual ; 49(1): 172-183, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016355

RESUMO

Use of recycled concrete aggregate (RCA) as highway basecourse material conserves virgin aggregate, reduces energy consumption and CO2 emissions, and may also decrease costs during construction. However, concerns remain over possible negative environmental impacts associated with high pH (>11) effluent from RCA in contact with water. This study examines the reactive transport of high-pH and high-alkalinity water, modeled on RCA leachate, through model subgrade soils. By developing an understanding of the reactions controlling effluent neutralization, this study aims to quantify the change in pH from the discharge site through surrounding subgrade soils. Four types of subgrade soils with a range of mineral composition, Atterberg limits, and cation exchange capacities (CECs) are examined. They include a clayey sand (SC10), low-plasticity clays (M14, SC25), and a high-plasticity clay (CH38). Batch reaction experiments are used to develop kinetic parameters describing the neutralization of high-pH and -alkalinity leachate by clay minerals through mineral dissolution and reprecipitation. Given this information, a reactive transport model incorporating advection, diffusion, and reaction is used to model the change in pH as a function of distance traveled through model subgrade soils and is applied to laboratory-scale column experiments. The rate at which the high pH front travels is directly related to a soil's clay mineral content. Soils with high CECs effectively delay the propagation of hydroxide front by the dissolution of clay minerals. This study demonstrates that common subgrade soils with moderate clay content will effectively neutralize high pH leachate initially produced by RCA.


Assuntos
Poluentes do Solo/análise , Solo , Argila , Concentração de Íons de Hidrogênio , Reciclagem
6.
J Environ Qual ; 49(1): 184-193, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016369

RESUMO

Phosphorus deficiency and excess are concomitant problems in agricultural soils of the mid-Atlantic region. A fundamental understanding of soil P speciation is essential to assess P fate and transport in these soils. Current methods for soil P speciation often rely on sequential chemical extractions, which can introduce artifacts during analysis. To overcome limitations of current methods, this study evaluated synchrotron-based micro-focused X-ray fluorescence (µ-XRF) and X-ray absorption near-edge spectroscopy (µ-XANES) techniques to assess soil P speciation in agricultural soils collected from the mid-Atlantic region of the United States. Three soils with varying chemical and physical properties were analyzed with µ-XRF maps collected at high (12,000 eV) and tender (2240 eV) energies to evaluate colocation of P with Fe, Al, Ca, and Si in soil samples, and µ-XANES spectra were collected at the P K-edge for P hotspots. Combined µ-XRF and µ-XANES analysis was useful for identifying Ca phosphate, Fe phosphate, Al-sorbed P, and Fe-sorbed P species in heterogeneous soil samples. X-ray fluorescence maps were valuable to distinguish Al-oxide sorbed P from Fe-oxide sorbed P species. A low signal-to-noise ratio often limited µ-XANES data collection in regions with diffuse, low concentrations of P. Therefore, some P species may not have been detected during analysis. Even with varying degrees of self-absorption and signal-to-noise ratios in µ-XANES spectra, important inferences regarding P speciation in mid-Atlantic soils were made. This study highlights the potential of µ-XANES analysis for use in environmental and agricultural sciences to provide insights into P fate and transport in soils.


Assuntos
Poluentes do Solo/análise , Solo , Fósforo , Síncrotrons , Espectroscopia por Absorção de Raios X
7.
J Environ Qual ; 49(2): 460-471, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016418

RESUMO

The agricultural reuse of urban sewage sludge (USS) modifies soil properties depending on sludge quality, management, and pedo-environmental conditions. The aim of this microcosm study was to assess C mineralization and subsequent changes in soil properties after USS addition to two typical Mediterranean soils: sandy (Soil S) and sandy loam (Soil A) at equivalent field rates of 40 t ha-1 (USS-40) and 120 t ha-1 (USS-120). Outcomes proved the biodegradability of USS through immediate CO2 release inside incubation bottles in a dose-dependent manner. Accordingly, the highest rates of daily C emission were recorded with USS-120 (3.7 and 3.9 mg kg-1 d-1 for Soils S and A, respectively) after 84 d of incubation at 25 °C. The addition of USS also improved soil fertility by enhancing soil macronutrients, microbial proliferation, and protease activity. Protease showed significant correlation with N, total organic C, and heterotrophic bacteria, reflecting the biostimulation and bioaugmentation effects of sludge. Soil indices like C/N/P stoichiometry and metabolic quotient (qCO2 ) varied mostly with mineralization rates of C and P in both soils. Despite a significant increase of soil salinity and total heavy metal content (lead, nickel, zinc, and copper) with USS dose, wheat germination was not affected by these changes. Both experimental soils showed intrinsic (Soil A) and incubation-induced (Soil S) phytotoxicities that were alleviated by USS addition. This was likely due to the enhancement of biodegradation and/or retention of phytotoxicants originating from previous land uses. Urban sewage sludge amendments could have applications in soil remediation by reducing the negative effects of allelopathic and/or anthropogenic phytoinhibitors.


Assuntos
Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Solo , Carbono/análise , Biomarcadores Ambientais , Esgotos
8.
J Environ Qual ; 49(2): 378-391, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016419

RESUMO

The persistent environmental relevance of phosphorus (P) and P sorption capacity (PSC) on P loss to surface waters has led to proposals for its inclusion in soil fertility and environmental management programs. As fertility and environmental management decisions are made on a routine basis, the use of laborious P sorption isotherms to quantify PSC is not feasible. Alternatively, pedotransfer functions (pedoTFs) estimate PSC from routinely assessed soil chemical properties. Our objective was to examine the possibility of developing a suitable pedoTF for estimating PSC and to evaluate subsequent PSC-based indices (P saturation ratio [PSR] and soil P storage capacity [SPSC]) using data from an in-field laboratory where tile drain effluent is monitored daily. Phosphorus sorption capacity was well predicted by a pedoTF derived from soil aluminum and organic matter (R² = .60). Segmented-line relationships between PSR and soluble P were observed in both desorption assays (R² = .69) and drainflows (R² = .66) with apparent PSR thresholds in close agreement at 0.21 and 0.24, respectively. Negative SPSC values exhibited linear relationships with increasing soluble P concentrations in both desorption assays and drainflows (R² = .52 and R2  = .53 respectively), whereas positive SPSC values were associated with low SP concentrations. Therefore, PSC-based indices determined using pedoTFs could estimate the potential for subsurface soluble P losses. Also, we determined that both index thresholds coincided with the critical soil-test P level for agronomic P sufficiency (22 mg kg-1 Mehlich-3 P) suggesting that the agronomic threshold could serve as an environmental P threshold.


Assuntos
Fósforo , Poluentes do Solo/análise , Alumínio , Solo
9.
J Environ Qual ; 49(2): 417-427, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016420

RESUMO

Isotopically exchangeable metals in soil, also termed labile metals, are reversibly bound to soil surface and are a better index of the environmental risk of the metals than are their total concentrations. In this study, labile fractions of potentially toxic elements were surveyed in metal mining-impacted soils of Mexico to test the relative importance of soil properties (pH, effective cation exchange capacity, organic matter, etc.) or attributes of the mines (ore type and lithology, metal mineralogy, etc.) on the fractions of labile elements. Mining waste-impacted soils, corresponding uncontaminated soils and mining waste were collected around 11 metal mines in Mexico presenting contrasting ore types. Pseudo-total concentrations and labile fractions of Cd, Ni, Zn, Pb, Cu, and As were determined by aqua regia digestion and isotope dilution, respectively. Pseudo-total concentrations of these elements ranked: waste > contaminated soil > uncontaminated soils, and Zn and As dominated the concentrations of toxic elements. The labile fractions (% of total) in the soils ranked, with median values in brackets, Pb (22) > Cd (18) > Cu(15) > Ni∼Zn(13) > As(9). The labile fractions of waste samples were slightly higher than those of soil samples suggesting either a high weathering of mining wastes or the stabilization of heavy metals by soil. Stepwise multiple regression showed that soil properties rather than source attributes primarily explained the %E of most elements, except for Zn and As for which the ore lithology was the dominant factor. This study showed that earlier generic models explain metal lability adequately in mining waste-impacted soils.


Assuntos
Arsênico , Poluentes do Solo/análise , Monitoramento Ambiental , México , Solo
10.
J Environ Qual ; 49(2): 346-357, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016421

RESUMO

Nonylphenol (NP) is considered a major contaminant that must be removed to enable safe and environmentally friendly land application of sewage sludge. Phytoremediation is a technology in which plants are used to remove and/or stabilize organic and inorganic contaminants present in the soil, municipal wastewater, and sewage sludge. In this study, a 391-d large pot experiment was conducted to remove NP from sewage sludge by phytoremediation using Zea mays L. 'Yunshi-5', Lolium perenne L., and co-cropping of the two plants. The fate of NP in the soil under the sewage sludge was assessed at the same time. At the end of the experiment, the NP levels in sludge from the various treatments were as follows: control (38.60%) > L. perenne (31.27%) > Z. mays (16.25%) > co-cropping (15.28%). Degradation followed an availability-adjusted first-order kinetics with a decreasing order of half-lives as follows: control (88.2 d) > L. perenne (87.3 d) > co-cropping (66.2 d) > Z. mays (59.1 d). The results indicated that Z. mays and co-cropping could both degrade NP. The concentrations of NP in tissues of different plants differed significantly. The mean bioconcentration factors for Z. mays and L. perenne were 0.16 and 3.69, respectively. Direct removal of NP from sewage sludge by plant uptake was negligible, as was downward movement of NP in the system. Moreover, NP was not detected in soils in any treatments at harvest.


Assuntos
Esgotos , Poluentes do Solo/análise , Biodegradação Ambiental , Fenóis/análise
11.
J Environ Qual ; 49(2): 450-459, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016422

RESUMO

The management of root and crown diseases of turfgrasses is challenging. To manage these diseases, golf course superintendents and other turfgrass managers often spray fungicides at a high carrier volume and irrigate after application to move fungicides into the root zone. Furthermore, previous research has demonstrated that soil surfactants can increase fungicide movement and distribution in soil. Two laboratory experiments were conducted using lysimeters, which were coated with sand on their inner walls to prevent preferential flow and contained 90/10% sand/peat moss (v/v), to determine the effects of soil surfactants on movement of selected fungicides in soil. The soil surface in the first experiment was treated three times at 2-wk intervals with one of three soil surfactants: Aquifer (propoxylated polyethylene glycols), Fleet (polyoxyalkylene polymers), and Revolution (modified alkylated polyol). The soil in the second experiment was treated with only Revolution four times at 2- to 3-wk intervals. Immediately after the final surfactant application, soil columns were treated with 14 C-labeled fungicide. 14 C-Myclobutanil was applied in the first experiment, and 14 C-azoxystrobin and 14 C-propiconazole were applied in the second experiment. In the first experiment, 14 percent units more of the recovered 14 C-myclobutanil was detected in the 5- to 7.6-cm sampling depth, and >4 percent units more was detected in the 7.6- to 10.2-cm depth after soil surfactant application compared with the fungicide-alone treatment. Each soil surfactant also yielded >28% more leachate than the nontreated control. In the second experiment, the total recovered 14 C-azoxystrobin and 14 C-propiconazole in the 7.6- to 10.2-cm depth increased by 2.8 and 1.9 percent units, respectively, compared with soil treated with fungicide alone. These data indicate that soil surfactant inclusion may increase fungicide distribution in soil, which may enhance the efficacy of fungicides in suppressing root and crown diseases.


Assuntos
Fungicidas Industriais , Golfe , Poluentes do Solo/análise , Solo , Tensoativos , Estados Unidos
12.
J Environ Qual ; 49(2): 428-439, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016425

RESUMO

Biochar (charcoal made from biomass in the pyrolysis process) has found broad application in agriculture. It helps to improve both the physical and chemical properties of soil through decontamination of heavy metals and pesticides. This work examines the potential for biochar application to improve the radiological condition of soil. We investigated the activity concentration of natural and anthropogenic radionuclides in soil samples collected from fields treated with various doses of biochar (in 1-100 Mg ha-1 ). In addition, we directly measured radon emission rate at the experimental fields. The analyses were performed using gamma spectrometry and an active method for radon emission using an AlphaGUARD instrument equipped with an accumulation box. The results of activity concentration assessments for six radionuclides, five natural and one anthropogenic, show that the only effect of biochar application into the soil is associated with the reduction of soil bulk density by this material. The radon emission rate increased by 6 mBq m-1 s-1 , on average, depending on the biochar dose (from 1 to 100 Mg ha-1 ). Our results demonstrate that application of biochar into soil kept without vegetation had a limited influence on the radioactivity in the environment.


Assuntos
Radioatividade , Poluentes do Solo/análise , Carvão Vegetal , Solo
13.
J Environ Qual ; 49(2): 472-482, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016429

RESUMO

Manure elemental composition determination is essential to develop farm nutrient budgets and assess environmental risk. Portable X-ray fluorescence (PXRF) spectrometers could facilitate hazardous waste-free, rapid, and cost-effective elemental concentration determinations. However, sample moisture is a problem for elemental concentration determination by X-ray methods. The objective of this study was to quantify the effect of sample moisture content, predict moisture content, and correct for moisture effect on elemental concentration determinations in livestock manure. Oven-dried manure samples (n = 40) were ground and adjusted to five moisture ranges of (w/w moisture) <10%, 10-20%, 20-30%, 40-50%, and 60-70%. Samples were scanned by PXRF for 180 s using a vacuum (<1,333 Pa) and without a filter. The presence of moisture negatively affected elemental determination in manure samples. Calibrations (n = 200) were prepared using random forest regression with detector channel counts as independent variables. A three-step validation was performed using all the data, random cross-validation and external validation. The back end of the spectrum (14-15 keV) had strong predictive power (r2  = .98) for moisture content. The random forest approach increased r2 between PXRF and wet chemical methods from <.66 to >.90 for P, K, and Mg and from .78 to .98 for Fe, compared with linear, nonlinear, and Lucas-Tooth and Price equations. These results indicated that elemental concentration can accurately be measured in dried and moist manure samples using PXRF and expands the potential applications of PXRF to in situ elemental determinations for agricultural and environmental samples.


Assuntos
Esterco , Poluentes do Solo/análise , Agricultura , Animais , Monitoramento Ambiental , Espectrometria por Raios X
14.
J Environ Qual ; 49(2): 358-367, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016432

RESUMO

In this work, the use of a coupled process, alkyl glycoside (APG) enhanced soil desorption followed by the zero-valent iron-ethylenediaminetetraacetic acid (EDTA)-air (ZEA) Fenton-like system, was investigated for the remediation of a simulated hexachlorobenzene (HCB)-contaminated diatomite soil and a real HCB-contaminated soil. Three surfactants with different concentrations were studied to obtain the suitable soil desorption agent. Compared with APG0810 and Triton x-100, APG0814 showed a better solubilization effect due to its lower critical micelle concentration. With addition of 3000 mg L-1 APG0814, 35% of HCB was removed from contaminated diatomite soil, and a small amount of residual APG in diatomite soil was found to be beneficial for the soil dispersion. After treatment with the ZEA system, the removal efficiency of HCB in the diatomite soil desorption solution reached 76% in 2 h; we observed that a small amount of APG retained in the desorption solution accelerated the HCB removal. A real HCB-contaminated soil was used to verify the remediation effects. This study demonstrates that our approach is a feasible alternative for remediating soil contaminated with hydrophobic organic compounds.


Assuntos
Recuperação e Remediação Ambiental , Poluentes do Solo/análise , Ácido Edético , Glicosídeos , Hexaclorobenzeno , Ferro , Solo
15.
J Environ Qual ; 49(5): 1359-1369, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016446

RESUMO

Cadmium concentrations in cacao (Theobroma cacao L.) beans from South America often exceed trade limits. Liming soil is advocated as a remediation option, but amendments cannot be incorporated into the entire root zone without harming the trees. An experiment was set up to identify how Cd uptake varies within the root zone when surface and subsurface soil layers are either limed or not. The experiment used 22-cm-height pots with top and bottom layers using surface and subsurface soil samples from a cacao field. The potted soils were either surface limed or not or fully limed and layers spiked with stable 108 Cd isotope in various combinations to trace the plant Cd provenance. The root distribution was neither affected by liming nor by soil source; 70% of the root biomass was present in the top layer. Plants grown on the fully limed surface soil had 1.7 times lower Cd concentrations in leaves than the unlimed treatments, whereas this concentration was 1.2 times lower when only the top layer was limed (surface soil used in both layers). The isotope dilution data showed that surface soil liming enhanced Cd uptake from the unlimed bottom layer compared with the unlimed soil, suggesting compensating mechanisms. The pots containing surface soil over subsurface soil also showed that compensating effect but, due to lower phytoavailable Cd in the subsurface soil, surface liming still effectively reduced foliar Cd. We conclude that liming might be a feasible mitigation strategy, but its effectiveness is limited when Cd phytoavailability remains untreated in the subsurface layer.


Assuntos
Cacau , Poluentes do Solo/análise , Cádmio/análise , Plântula/química , Solo
16.
J Environ Qual ; 49(5): 1286-1297, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016460

RESUMO

The subsurface transport of dissolved reactive phosphorus (DRP) from artificially drained agricultural fields can impair water quality, especially in no-till fields. The distribution of soil P in the wheat (Triticum aestivum L.)-dominated Palouse region in the inland U.S. Pacific Northwest varies greatly due to its steep and complex topography, and a legacy (∼130 yr) of excessive soil erosion and deposition processes. The primary goal of this research was to better understand the magnitude and temporal dynamics of DRP export from an artificial drain line and the variability of subsurface DRP leaching within a long-term, no-till field. Dissolved reactive P in drain line effluent was monitored across three water years. Large intact soil cores were extracted at contrasting field locations (toe and top slope positions) to measure DRP leachate concentration and relative P sorption. Drain line DRP concentration was predominantly >0.05 mg L-1 and often exceeded 0.1 mg L-1 during winter and early spring. Mean leachate DRP levels were significantly higher in toe slope cores than in top slope cores (0.11 and 0.02 mg L-1 , respectively). Saturated hydraulic conductivity varied widely across cores and was not correlated with leachate DRP concentration. All soil cores exhibited high P sorption potential, even under conditions of preferential flow. These findings suggest that much of the DRP transport in these landscapes is derived from P hotspots located in toe slope positions. Application of soil P fertilizer amounts in variable rates that account for spatial variability in P transport may minimize P enrichment and subsequent leaching in these locations.


Assuntos
Fósforo/análise , Poluentes do Solo/análise , Agricultura , Monitoramento Ambiental , Noroeste dos Estados Unidos
17.
J Environ Qual ; 49(4): 973-986, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016480

RESUMO

Urban sewage sludge (USS) is increasingly applied to agricultural soils, but mixed results have been reported because of variations in reuse conditions. Most field trials have been conducted in cropping systems, which conceal intrinsic soil responses to sludge amendments due to the rhizosphere effect and farming practices. Therefore, the current field study highlights long-term changes in bare soil properties in strict relationship with soil texture and USS dose. Two agricultural soils (loamy sand [LS] and sandy [S]) were amended annually with increasing sludge rates up to 120 t ha-1 yr-1 for 5 yr under unvegetated conditions. Outcomes showed a USS dose-dependent variation of all studied parameters in topsoil samples. Soil salinization was the most significant risk related to excessive USS doses. Total dissolved salts (TDS) in saturated paste extracts reached the highest concentrations of 37.2 and 43.1 g L-1 in S soil and LS soil, respectively, treated with 120 t USS ha-1 yr-1 . This was also reflected by electrical conductivity of the saturated paste extract (ECe ) exceeding 4,000 µS cm-1 in both treatments. As observed for TDS, fertility indicators and bioavailable metals varied with soil texture due to the greater retention capacity of LS soil owing to higher fine fraction content. Soil phytotoxicity was estimated by the seed germination index (GI) calculated for lettuce, alfalfa, oat, and durum wheat. The GI was species dependent, indicating different degrees of sensitivity or tolerance to increasing USS rates. Lettuce germination was significantly affected by changes in soil conditions showing negative correlations with ECe and soluble metals. In contrast, treatment with USS enhanced the GI of wheat, reflecting higher salinity tolerance and a positive effect of sludge on abiotic conditions that control germination in soil. Therefore, the choice of adapted plant species is the key factor for successful cropping trials in sludge-amended soils.


Assuntos
Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Solo , Agricultura , Alface , Esgotos
18.
J Environ Qual ; 49(4): 1054-1061, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016482

RESUMO

Cadmium (Cd) can accumulate in soil from the application of phosphorus fertilizer. However, there is little information on what happens to soil Cd concentrations when Cd inputs stop. This study used soil and pasture samples collected from a long-term field trial to measure changes in Cd concentrations in soil for 22 yr after Cd inputs from fertilizer had stopped and assessed whether the application of nitrogen (N) (50 kg ha-1  yr-1 ) could increase plant uptake of Cd and reduce soil Cd concentrations. It was found that there was no significant change in total or labile soil Cd (1 M CaCl2 extractable) concentrations after Cd inputs stopped. The application of N did not significantly (P < .05) increase dry matter yield or increase Cd solubility. As a result, N did not enhance plant uptake of Cd. A mass balance that included Cd loss via plant uptake and Cd leaching confirmed they were insufficient to result in a detectable decrease in soil Cd concentration over the 22-yr interval of the trial. It appears that even an acid soil with low amounts of carbon (2.67%), iron/aluminum oxides, and clay can still strongly retain Cd, preventing Cd depletion from the soil, despite stopping Cd inputs and trying to enhance plant uptake of Cd from the application of N fertilizer.


Assuntos
Fertilizantes/análise , Poluentes do Solo/análise , Cádmio/análise , Fósforo , Solo
19.
J Environ Qual ; 49(4): 1011-1019, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016487

RESUMO

The pharmaceutical compound carbamazepine (CBZ) is a contaminant of emerging concern. Wastewater irrigation can be a long-term, frequent source of CBZ; therefore, understanding the fate and transport of CBZ as a result of wastewater reuse practices has important environmental implications. The objective of this study was to estimate long-term soil transport of CBZ originating from treated wastewater irrigation on plots under different land uses. Field data from a previous study comparing CBZ concentrations in soil under different land uses were used in numerical modeling with HYDRUS-2D for the estimation of CBZ soil transport during 20 yr of irrigation with treated wastewater. This study showed high CBZ retention in soil under all investigated land uses. Adequate modeling results were obtained by using soil organic carbon-water partitioning coefficient (Koc ) for the CBZ linear sorption coefficient (Kd ) estimation, yet an underestimation of CBZ concentration in soil was still noted. Thus, results suggest that, although highly important, organic carbon content is probably not the only soil property governing CBZ sorption at this site, indicating the potential research perspective. Modeling results showed wastewater irrigation containing CBZ for 20 yr increased the CBZ concentration in the soil profile and its vertical movement, with the slowest vertical transport rate occurring on the forested plots. Overall results suggest that a beneficial management practice could be to increase soil organic carbon (e.g., compost addition) when using treated wastewater for irrigation in order to retain CBZ in the surface soil and thus limit its leaching through the soil profile.


Assuntos
Poluentes do Solo/análise , Águas Residuárias , Carbamazepina/análise , Carbono , Solo , Eliminação de Resíduos Líquidos
20.
J Environ Qual ; 49(4): 1020-1031, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016488

RESUMO

A study was conducted to test the suitability of a range of organic and inorganic residuals mixed with municipal biosolids to create a soil amendment effective for a broad range of end uses. Biosolids suitable for unrestricted use were sourced from San Francisco, CA. Residuals including urban wood and yard waste, nut shells, biochar, and sawdust were sourced from nearby producers. Existing biosolids based soil products, peat, and a yard-food compost were used as controls. Experimental mixtures were tested for a range of soil properties, appearance, odor, germination, and growth response. Several mixtures performed as well as or better than the yard-food compost, and several performed comparably to the biosolids soil controls. Yard waste fines blended with biosolids in a 50:50 ratio by volume or yard waste fines blended with biosolids and 20% sand at 40:40:20 were highly effective across all measured indices. Mixed yard and recycled lumber fines blended with biosolids at these same ratios performed similarly well. Blends with a high percentage of char performed poorly in germination and growth response, likely as a result of elevated electrical conductivity. Certain blends such as gypsum and redwood shavings failed to mix well with biosolids to create a uniform looking material and were less visually appealing. In general, blends that met established quality control parameters for compost performed well on the measured indices. These results suggest that blending Class A biosolids with organic and inorganic feedstocks to meet quality criteria developed for compost will create marketable soil products.


Assuntos
Compostagem , Poluentes do Solo/análise , Biossólidos , Sulfato de Cálcio , Solo
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