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1.
Chemosphere ; 262: 128102, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182125

RESUMO

Novel pectin derived from sweet potato residue was modified by high hydrostatic pressure (HHP)-assisted pectinase and then used for Pb2+ removal from aqueous solutions. The removal characteristics and mechanisms were also investigated. Results showed that modified sweet potato pectin exhibited greater adsorption performances for Pb2+ than that of natural ones, and showed excellent eco-friendly properties and good potential for adsorption of some other heavy metals (such as Cu2+). The adsorption curves were much more conformed to Langmuir model, and the highest capacity for Pb2+ adsorption was 263.15 mg/g with 1.00% pectin at pH 7. Chemical adsorption process of pectin for Pb2+ absorption involved O-containing functional groups (O-H, COO-), cation exchange, and along with electrostatic interactions. Overall, the results in this study indicated that sweet potato pectin modified with HHP-assisted pectinase had the potential to become an environmentally friendly coagulant-flocculant agent for the heavy metal adsorption, especially for Pb2+.


Assuntos
Pressão Hidrostática , Ipomoea batatas/química , Chumbo/análise , Pectinas/química , Poligalacturonase/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Pectinas/isolamento & purificação , Águas Residuárias/química
2.
Bull Environ Contam Toxicol ; 105(5): 777-783, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33044567

RESUMO

The capacity of Lemna minor to remediate toxic heavy metals from wastewater is reasonably well documented. In view of the pivotal role of this species in the environmental clean-up, here we evaluated the bioaccumulation potential of L. minor for cadmium (Cd), lead (Pb), and nickel (Ni) through a controlled experiment. L. minor tolerated the metals Cd, Ni, and Pb up to 0.5, 5, and 8 mg/L, respectively, and beyond these concentrations the toxicity symptoms appeared. Bio-concentration factor varied at different concentrations of heavy metals tested. Overall, L. minor showed good phytoremediation potential for all the three tested heavy metals (Cd, Ni, and Pb), though in relative terms it was more effective in extracting Ni and Cd, as compared to Pb, both in single and mixed concentrations. In view of the growing pollution in Kashmir Himalayan aquatic habitats the phytoremediation by invasive species such as L. minor promises to be one of the best choices than other native plants for cleaning up of polluted soils/water because of its fast growth rate, high abundance, easy handling, and wide distribution in Kashmir Himalayan aquatic ecosystems.


Assuntos
Organismos Aquáticos/metabolismo , Araceae/metabolismo , Bioacumulação , Metais Pesados/metabolismo , Águas Residuárias/química , Organismos Aquáticos/crescimento & desenvolvimento , Araceae/crescimento & desenvolvimento , Biodegradação Ambiental , Cádmio/análise , Cádmio/metabolismo , Ecossistema , Índia , Lagos , Chumbo/análise , Chumbo/metabolismo , Metais Pesados/análise , Níquel/análise , Níquel/metabolismo
3.
Bull Environ Contam Toxicol ; 105(5): 764-769, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33044568

RESUMO

The combustion of alkyl-lead gasolines was the primary anthropogenic source of Pb in the second half of the twentieth century. Previously deposited Pb-aerosols enriched the organic matter and Fe-oxi-hydroxides phases of soils, which long after continue being transported downstream to be an important source of Pb into the ocean. Geochemical partition of Pb was determined in estuarine sediments of the Jamapa River, southern Gulf of Mexico, by the Tessier's sequential extraction protocol. The residual fraction, conformed by siliciclastic particles, contain the highest proportion of Pb (8.6 µg/g = 70%), been the main source into the ocean. However, as the organic carbon and Fe,MnO(OH) fractions, together summed the 26% of total Pb in samples, so, it is assumed that previously deposited anthropogenic Pb, from alkyl-lead gasolines, still is an important source of this element, that is transported by the Jamapa River, enriching the coastal area.


Assuntos
Monitoramento Ambiental/métodos , Estuários , Sedimentos Geológicos/química , Chumbo/análise , Rios/química , Poluentes Químicos da Água/análise , Golfo do México , México
4.
Bull Environ Contam Toxicol ; 105(5): 685-691, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33067667

RESUMO

Owls are predators that perform important ecological functions. There are several threats to owl conservation such as the bioaccumulation of chemicals through environmental contamination. The high probability of bioaccumulation in these animals is related to their role as predators and high trophic positions. The objective of this study was to quantify four elements (cadmium, chromium, nickel, and lead) as the biomarkers of environmental exposure in owls. To this end, we analyzed pellets and feathers of different owl species. These matrices were contaminated with all four elements, with chromium most commonly detected. Chromium and nickel were found in the pellets in all 10 months of the study, and May was the month with the highest concentrations of all the elements. Tyto furcata appears to bioaccumulate more elements in its feathers than Megascops spp. and Athene cunicularia. Our findings showed bioaccumulation of these four elements in owls and their environment.


Assuntos
Monitoramento Biológico/métodos , Poluição Ambiental/análise , Plumas/química , Conteúdo Gastrointestinal/química , Metais Pesados/análise , Estrigiformes/crescimento & desenvolvimento , Animais , Cádmio/análise , Cromo/análise , Refluxo Laringofaríngeo , Chumbo/análise , Metais Pesados/metabolismo , Níquel/análise
5.
Wei Sheng Yan Jiu ; 49(5): 755-758, 2020 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-33070819

RESUMO

OBJECTIVE: To investigate the level of lead in cereals and related products from Zhejiang market, and to provide the preliminary assessment. METHODS: Lead was detected in 4855 samples of cereals and related products during 2014-2019, food consumption data was taken from Zhejiang residents' consumption survey in 2015-2016. RESULTS: The total detection rate of lead in cereals and related products was 59. 03%, and the acceptance rate was 99. 3% when compared to the national food safety standards(GB 2762-2017). The average lead level in cereals and related products was 0. 031 mg/kg, high mean level was found in millet with 0. 049 mg/kg, low mean level was in grain cans with 0. 020 mg/kg. The average dietary exposure to lead via cereals and related products was 0. 16 µg/(kg·d), and 0. 45 µg/(kg·d) for high consumer(P97. 5). CONCLUSION: Lead in cereals and related products are at very low contamination levels, residents' average daily intake of lead from grains and products was low in Zhejiang Province, but measures are still needed to reduce lead in cereal products considering the adverse health effects of lead.


Assuntos
Grão Comestível , Chumbo , Exposição Dietética , Grão Comestível/química , Contaminação de Alimentos/análise , Inocuidade dos Alimentos , Chumbo/análise
6.
PLoS One ; 15(9): e0239732, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986774

RESUMO

A large assemblage (n = 307) of architectural glasses (tesserae and windows) from the early 8th-century Umayyad residential site at Khirbat al-Minya was analysed by laser ablation inductively coupled plasma mass spectrometry. Trace element patterns are essential to establish the provenance of the base glass, while the comparative evaluation of the colouring and opacifying additives allow us to advance a production model for the manufacture of glass mosaic tesserae during the early Islamic period. The primary glass types are Levantine I and Egypt 1a, as well as a few older, reused tesserae, and Mesopotamian plant ash glass used for amber-coloured window fragments. Chemical data revealed fundamental differences in the colouring and opacification technologies between the Egyptian and Levantine tesserae. Co-variations of lead and bismuth, and copper, tin and zinc in the Egypt 1a tesserae provide first evidence for the production of different mosaic colours in a single workshop, specialising in the manufacture of tesserae of different colours. No such trend is apparent in the Levantine samples. Red, cobalt blue and gold leaf tesserae were found to be exclusively made from a Levantine base glass, indicating that the generation of some colours may have been a specialised process. The same may apply to the amber-coloured window glass fragments of Mesopotamian origin that exhibit very unusual characteristics, combining elevated copper (2% CuO) with an excess in iron oxide (5% Fe2O3). These findings have significant implications for the production model of strongly coloured glass and the exploitation of resources during the early Islamic period.


Assuntos
Arquitetura/história , Vidro/química , Vidro/história , Cor , Corantes/análise , Cobre/análise , Egito , Compostos Férricos/análise , História do Século XVIII , Chumbo/análise , Espectrometria de Massas/métodos , Oriente Médio , Minerais/análise , Estanho/análise , Oligoelementos/análise
7.
Ecotoxicol Environ Saf ; 205: 111333, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979802

RESUMO

Plant growth-promoting rhizobacteria (PGPR) are a specific category of microbes that improve plant growth and promote greater tolerance to metal stress through their interactions with plant roots. We evaluated the effects of phytoremediation combining the cadmium accumulator Solanum nigrum L. and two Cd- and Pb-resistant bacteria isolates. To understand the interaction between PGPR and their host plant, we conducted greenhouse experiments with inoculation treatments at Nanjing Agricultural University (Jiangsu Province, China), in June 2018. Two Cd- and Pb-resistant PGPR with various growth-promoting properties were isolated from heavy metal-contaminated soil. 16S rRNA analyses indicated that the two isolates were Bacillus genus, and they were named QX8 and QX13. Pot experiments demonstrated that inoculation may improve the rhizosphere soil environment and promote absorption of Fe and P by plants. Inoculation with QX8 and QX13 also enhanced the dry weight of shoots (1.36- and 1.7-fold, respectively) and roots (1.42- and 1.96-fold) of plants growing in Cd- and Pb-contaminated soil, and significantly increased total Cd (1.28-1.81 fold) and Pb (1.08-1.55 fold) content in aerial organs, compared to non-inoculated controls. We also detected increases of 23% and 22% in the acid phosphatase activity of rhizosphere soils inoculated with QX8 and QX13, respectively. However, we did not detect significant differences between inoculated and non-inoculated treatments in Cd and Pb concentrations in plants and available Cd and Pb content in rhizosphere soils. We demonstrated that PGPR-assisted phytoremediation is a promising technique for remediating heavy metal-contaminated soils, with the potential to enhance phytoremediation efficiency and improve soil quality.


Assuntos
Cádmio/análise , Chumbo/análise , Rhizobiaceae/metabolismo , Microbiologia do Solo , Poluentes do Solo/análise , Solanum nigrum/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , China , Chumbo/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , RNA Ribossômico 16S , Rizosfera , Solo/química , Poluentes do Solo/metabolismo , Solanum nigrum/crescimento & desenvolvimento , Solanum nigrum/metabolismo
8.
Sci Total Environ ; 740: 139992, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32927536

RESUMO

Mining activities at Duparquet in Western Quebec (Canada) have significantly affected the local environment and left behind significant amounts of metals. Monitoring this contamination is essential to infer its past and present impacts on environmental quality and to evaluate the resulting human exposure. In that context, we measured long time series of Pb concentrations and their corresponding stable isotope ratios in long-lived white cedars (Thuja occidentalis L.) growing at Duparquet Lake in order to evaluate potential time variations of the Pb environmental contamination as well as to identify the responsible source(s). Results show that before 1950, Pb at Duparquet is mostly terrigenous. Lead concentrations rapidly increase afterwards. A simultaneous shift to lower 206Pb/207Pb ratios identifies the smelting of Abitibi ores as the source of contamination. An isotope mass balance model evaluates at roughly 7.5-20%, 5-40%, 5-9% and <3% the Pb contributions from local smelters at distances of 3.6, 3.9, 7 and 9 km, respectively. The dispersion of the Pb contamination plume is possibly driven by the distance from the Beattie smelter. We finally estimated a delay of at least 13 years between atmospheric emissions from the Beattie smelting activities and the time they are recorded by tree rings. Ultimately, this study demonstrates that white cedar tree rings series provide reliable archives of past and present Pb atmospheric contamination.


Assuntos
Chumbo/análise , Thuja , Canadá , Monitoramento Ambiental , Isótopos/análise , Quebeque
9.
Chemosphere ; 258: 127405, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947677

RESUMO

Chelation of lead (Pb) is an important factor in enhancing the Pb mobility thereby improving availability to promote phytoremediation of Pb from contaminated soil. The study was conducted to evaluate the effect of amendments in enhancing the phytoremediation of Pb in soil. For this purpose, soil was spiked to obtain desired Pb concentrations (0-1500 mg kg-1) and pots were filled. One month old and uniform seedlings of Pelargonium hortoum were transplanted into each pot. Five different amendments i.e. compost (0-10%), ammonium nitrate (0-10 mmol kg-1), TiO2NPs (0-100 mg kg-1), citric acid (0-10 mmol kg-1) and EDTA (0-5 mmol kg-1), were applied. Overall, ammonium nitrate, EDTA and citric acid application increased the Pb concentration, however, compost and TiO2NPs decreased the concentration in roots and shoots. At 1500 mg Pb kg-1, Pb concentration in shoots was increased by 0.9-, 0.6- & 0.8-folds and in roots by 1.8-, 1.3- & 1.7-folds upon EDTA, ammonium nitrate and citric acid application, respectively. TiO2NPs and compost application decreased Pb concentration by 29% & 35% in shoots and 25% & 51% in roots, respectively. At the highest level of Pb (1500 mg kg-1), plant biomass was increased by 26.6%, 19.5%, 17.9% and 18.4% upon application of compost, TiO2 NPs, ammonium nitrate and citric acid, respectively. However, EDTA reduced the plant dry biomass by 28.4%. The accumulated Pb content was recovered as Pb-nanoparticles, which were in anatase phase, size ranged between 98 and 276 nm. Among all the studied amendments, citric acid efficiently increased Pb phytoaccumulation without any toxicity.


Assuntos
Biodegradação Ambiental , Chumbo/análise , Poluentes do Solo/análise , Biomassa , Quelantes , Ácido Cítrico , Compostagem , Ácido Edético , Chumbo/metabolismo , Pelargonium , Raízes de Plantas , Solo , Poluentes do Solo/metabolismo
10.
Ecotoxicol Environ Saf ; 205: 111132, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32836155

RESUMO

Due to high sorption capacity for heavy metals, magnetic biochar (MBC) has the potential to adsorb heavy metals in soils, which are then removed together with MBC from soils by a magnetic field. In this study, two magnetic biochars (MBC300 and MBC700) were derived from the magnetization of wheat straw biochars pyrolyzed at 300 and 700 °C. Strong binding of Pb with iron oxide particles deposited on biochar was observed. After the MBCs (7.5%, w/w) were applied to two naturally Pb-polluted soils (named as He-soil and Hu-soil) for 720 h, the removal efficiency of Pb from the soil by MBC300 (26.8-40.1%) was similar (p > 0.05) to that by MBC700 (25.1-42.1%). This is because MBC300 has lower sorption capacity for Pb but higher recovery percentage from soils as a result of lower saturation magnetization. The removal efficiencies of Pb by the two MBCs were 13-17% higher for He-soil than for Hu-soil, which was due to higher proportion of mobile forms of Pb in He-soil (82.3%) than in Hu-soil (51.5%). Spectroscopic analysis indicated that Pb in soils tended to bind onto the surface of MBC in more stable forms. Moreover, removing Pb from soils by MBC could decrease Pb concentration in ryegrass by about 30%. Therefore, it might be a potential method to remedy Pb-polluted soils.


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Adsorção , Carvão Vegetal , Poluição Ambiental/análise , Chumbo/análise , Lolium , Fenômenos Magnéticos , Metais Pesados/análise , Pirólise , Solo/química , Poluentes do Solo/análise , Triticum
11.
J Environ Radioact ; 222: 106367, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32795842

RESUMO

210Po and 210Pb are well-known tracer pairs for some biomass and chemical processes in the marine system. In this study, 210Po and 210Pb were analyzed in surface seawater collected from the East China Sea (ECS), in atmospheric deposition, and in riverine input water collected along the ECS coast. The atmospheric fallouts of 210Po and 210Pb were higher in the dry season, due to the arrival of storm dust from the northwestern region of China. In the riverine input water, the particulate 210Po and 210Pb dominated (corresponding to 33-94% and 50-92% of the total, respectively), especially during the flood season. In the surface seawaters, the percentage of particulate 210Po (17-85%) was generally greater than that of 210Pb (10-76%). Additionally, in the Changjiang Estuary, log Kd(Po) and log Kd(Pb) were negatively correlated with log suspended particulate matter (SPM) (R = 0.71, P = 0.013 for Po, R = 0.67, P = 0.019 for Pb). 210Pb showed a stronger "particle effect" than 210Po when SPM <1.00 mg L-1, and vice versa when SPM >1.00 mg L-1. The deficit of 210Po relative to 210Pb gradually decreased from the Changjiang Diluted Water, to the Shelf Merged Water and the Taiwan Warm Current Water. The mass balance of 210Po and 210Pb in the water column of the estuary indicated that the Changjiang River was the dominating input source (providing 91% and 88% of the 210Po and 210Pb, respectively); meanwhile, the shelf export was the dominating output source (accounting for 68% and 78% of the 210Po and 210Pb, respectively).


Assuntos
Chumbo , Polônio , Monitoramento de Radiação , Poluentes Radioativos da Água , China , Monitoramento Ambiental , Chumbo/análise , Material Particulado , Polônio/análise , Rios , Taiwan , Poluentes Radioativos da Água/análise
13.
Bull Environ Contam Toxicol ; 105(2): 283-290, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32734360

RESUMO

The current study investigated the efficiency of sepiolite (SE), sodium humate (HS), microbial fertilizer (JF) and SE combined with JF/HS in a ratio of 2:1 (w/w) (JF-2SE and HS-2SE) on Cd, Pb and As bioavailability in field trials with rice (Oryza sativa L.). The results showed that all the amendments remarkably decreased (p < 0.05) the contents of available Cd and available Pb in soil. Only JF-2SE treatment reduced available As concentration in soil. All the amendments were found to effectively reduce (p < 0.05) the contents of As in brown rice. Both JF-2SE and HS-2SE co-applications reduced the concentrations of Cd in brown rice to 0.108 and 0.135 mg kg-1, and that of Pb reduced to 0.2 and 0.175 mg kg-1, which met the national standard limit of China. Thus, the co-application of JF/HS-2SE can be a promising remediation strategy in Cd, Pb and As co-contaminated paddy soil.


Assuntos
Cádmio/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Disponibilidade Biológica , Cádmio/análise , China , Poluição Ambiental , Fertilizantes , Chumbo/análise , Silicatos de Magnésio , Oryza , Solo/química , Poluentes do Solo/análise
14.
Chemosphere ; 261: 127721, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32745740

RESUMO

The uptake and distribution of Pb and the mechanisms involved in the metal tolerance have been investigated in a mine population of Biscutella auriculata. Seedlings were exposed to 125 µM Pb(NO3)2 for 15 days under semihydroponic conditions. The results showed an increase in the size of Pb-treated seedlings and symptoms of toxicity were not observed. ICP-OES analyses showed that Pb accumulation was restricted to root tissue. Imaging of Pb accumulation by dithizone histochemistry revealed the presence of the metal in vacuoles and cell wall in root cells. The accumulation of Pb in vacuoles could be stimulated by an increase in phytochelatin PC2 content. Pb did not promote oxidative damage and this is probably due the increase of antioxidative defenses. In the leaves, Pb produced a significant increase in superoxide dismutase activity, while in roots an increase in catalase and components of the Foyer- Halliwell-Asada cycle were observed. The results indicated that Biscutella auriculata has a high capacity to tolerate Pb and this is mainly due to a very efficient mechanism to sequester the metal in roots and a capacity to avoid oxidative stress. This species could therefore be very useful for phytostabilization and repopulation of areas contaminated with Pb.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Antioxidantes/metabolismo , Bioacumulação/efeitos dos fármacos , Brassicaceae/metabolismo , Chumbo/metabolismo , Mineração , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Brassicaceae/efeitos dos fármacos , Brassicaceae/crescimento & desenvolvimento , Catalase/metabolismo , Chumbo/análise , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Fitoquelatinas/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Poluentes do Solo/análise
15.
Bull Environ Contam Toxicol ; 105(3): 428-432, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32740744

RESUMO

The accumulation of Cd and Pb in rice grains poses a potential threat to human health, which is a subject of increasing concern across the globe. We examined the effect that foliar spraying of Zn-ethylenediaminetetraacetate (Zn-EDTA) (0.3% and 0.5% w/v) during the early-grain filling stage has on rice grain yield and Cd, Pb, Zn and Fe contents in rice tissues via a field experiment. The grain yield significantly decreased with the foliar application of 0.5% Zn-EDTA. In rice grain, foliar spraying of 0.5% Zn-EDTA significantly decreased the Cd and Pb contents, but increased the Zn and Fe contents. The main reasons for the decrease in the Cd and Pb content in grain were the inhibition of Cd and Pb by roots and the increased Fe content in grain via Zn-EDTA application. The foliar spraying of Zn-EDTA decreased the grain yield and Cd and Pb contents, while increased the Zn and Fe contents in grains.


Assuntos
Cádmio/análise , Ácido Edético/química , Chumbo/análise , Oryza/fisiologia , Poluentes do Solo/análise , Grão Comestível/química , Humanos , Oryza/efeitos dos fármacos , Folhas de Planta/química , Raízes de Plantas/química , Solo , Zinco/análise
16.
Bull Environ Contam Toxicol ; 105(3): 366-371, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32840648

RESUMO

Ground venison packets from shotgun- and archery-harvested White-tailed Deer in Illinois in 2013 and 2014 were analyzed for metal contamination. Radiographs indicated that 48% of 27 ground venison packets from 10 shotgun-harvested deer contained metal fragments, while none of the 15 packets from three archery-harvested deer contained fragments. ICP-MS analysis verified that all metal fragments from seven of the venison samples from shotgun-harvested deer were composed of lead, with average concentrations from 1.04 to 8.42 µg g-1, dry weight. A single serving of ground venison containing one of these metal fragments embedded in it would be predicted to have a lead concentration ranging from 6.4 to 51.8 µg g-1. Sixty percent of 20 commercial meat processing plants surveyed by phone in 2018 and 2019 indicated that they mixed venison from multiple deer when preparing ground venison products. However, our results do not show any cross-contamination in archery-harvested ground venison processed prior to the firearm hunting seasons.


Assuntos
Cervos/metabolismo , Poluentes Ambientais/metabolismo , Chumbo/metabolismo , Carne/análise , Animais , Illinois , Chumbo/análise
17.
Environ Sci Technol ; 54(15): 9474-9482, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32638591

RESUMO

In recent years, environmental lead (Pb) exposure through drinking water has resulted in community public health concerns. To understand potential impacts on blood Pb levels (BLLs) from drinking water Pb reduction actions (i.e., combinations of lead service lines [LSL] and corrosion control treatment [CCT] scenarios), EPA's Stochastic Human Exposure and Dose Simulation (SHEDS)-Multimedia/Integrated Exposure Uptake and Biokinetic (IEUBK) model was applied for U.S. children aged 0 to <6 years. The results utilizing a large drinking water sequential sampling data set from 15 cities to estimate model input concentration distributions demonstrated lowest predicted BLLs for the "no LSLs" with "combined CCT" scenario and highest predicted BLLs for the "yes LSLs" and "no CCT" scenario. Modeled contribution to BLLs from ingestion of residential drinking water ranged from ∼10 to 80%, with the highest estimated for formula-fed infants (age 0 to <1 year). Further analysis using a "bounding" data set spanning a range of realistic water Pb concentrations and variabilities showed BLL predictions consistent with the sequential sampling-derived inputs. Our study illustrates (1) effectiveness of LSL replacement coupled with CCT for reducing Pb in drinking water and children's BLLs, and (2) in some age groups, under realistic local and residential water use conditions, drinking water can be the dominant exposure pathway.


Assuntos
Água Potável , Poluentes Químicos da Água , Criança , Corrosão , Exposição Ambiental/análise , Humanos , Lactente , Chumbo/análise , Poluentes Químicos da Água/análise , Abastecimento de Água
18.
Chemosphere ; 260: 127574, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32688316

RESUMO

Artisanal and small-scale gold mining (ASGM) operations are major contributors to the Philippines' annual gold (Au) output (at least 60%). Unfortunately, these ASGM activities lacked adequate tailings management strategies, so contamination of the environment is prevalent. In this study, soil contamination with copper (Cu), lead (Pb), zinc (Zn) and arsenic (As) due to ASGM activities in Nabunturan, Davao de Oro, Philippines was investigated. The results showed that ASGM-impacted soils had Cu, Pb, Zn and As up to 3.6, 83, 73 and 68 times higher than background levels, respectively and were classified as 'extremely' polluted (CD = 30-228; PLI = 5.5-34.8). Minerals typically found in porphyry copper-gold ores like pyrite, chalcopyrite, malachite, galena, sphalerite and goethite were identified by XRD and SEM-EDS analyses. Furthermore, sequential extraction results indicate substantial Cu (up to 90%), Pb (up to 50%), Zn (up to 65%) and As (up to 48%) partitioned with strongly adsorbed, weak acid soluble, reducible and oxidisable fractions, which are considered as 'geochemically mobile' phases in the environment. Although very high Pb and Zn were found in ASGM-impacted soils, they were relatively immobile under oxidising conditions around pH 8.5 because of their retention via adsorption to hydrous ferric oxides (HFOs), montmorillonite and kaolinite. In contrast, Cu and As release from the historic ASGM site samples exceeded the environmental limits for Class A and Class C effluents, which could be attributed to the removal of calcite and dolomite by weathering. The enhanced desorption of As at around pH 8.5 also likely contributed to its release from these soils.


Assuntos
Mineração , Poluentes do Solo/análise , Poluentes do Solo/química , Solo/química , Arsênico/análise , Arsênico/química , Cobre/análise , Cobre/química , Ouro/análise , Ferro/química , Compostos de Ferro/química , Chumbo/análise , Chumbo/química , Minerais/química , Filipinas , Sulfetos/química , Difração de Raios X , Zinco/análise , Zinco/química
19.
Chemosphere ; 260: 127646, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32683012

RESUMO

Stabilization/solidification (S/S) has been studied since 1950s and widely used for the treatment of potentially toxic elements (PTEs). The coexistence of organic matter (OM) and PTEs can cause a very complicated mechanism for cement-based S/S applications and bring challenges from both scientific and engineering perspectives. To fill in the knowledge gap, this paper investigates for the first time the effects on S/S characteristics of OM components and incubation, which are the two main factors that result in the inconsistency in the leaching characteristics from the available studies. OM samples with different components (humic acid (HA) and fulvic acid (FA)) and contents were mixed into lead-contaminated soil and incubated for different durations of up to 90 days. The experimental results show that the strength of stabilized soils increases with increasing incubation duration and the lead leaching concentration of stabilized soils is decreased by 60.7%-83.6% from zero to 90 days. The lead leaching concentration of the HA group, which is 144.0% higher with no incubation than the non-OM group, becomes 58.3% lower with 90 days of incubation. The leaching concentration of the FA group remains much higher than those of the other groups. Finally, a competing mechanism of HA-weakening cement hydration reactions and stabilizing lead with a critical incubation duration of 14 days-is proposed, together with a cooperating mechanism of FA-weakening cement hydration reactions and releasing lead.


Assuntos
Recuperação e Remediação Ambiental , Chumbo/análise , Poluentes do Solo/análise , Benzopiranos , Materiais de Construção , Poluição Ambiental , Substâncias Húmicas/análise , Solo
20.
Bull Environ Contam Toxicol ; 105(2): 325-331, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32647963

RESUMO

The objectives of this study was to diagnose Cd and Pb contamination in soil and to identify the main factors that contribute to the transfer of these elements to tomato plants and fruits and contamination levels of the fruits in tropical mountain conditions. Contamination of the study area soils by Cd and Pb was verified. This contamination stemmed from the intensive use of agricultural inputs, mainly organic fertilizers and soluble mineral fertilizers. The relief of the terrain and inadequate soil management influenced the spatial distribution of these two metals. The Cd concentration in tomato fruits was very low, but the Pb contamination detected in approximately 80% of the fruit samples was considerably higher than the limits that pose a danger to human health. The translocation of Pb to the tomato fruits was associated with the use of organic fertilizer, mainly poultry litter.


Assuntos
Cádmio/análise , Chumbo/análise , Lycopersicon esculentum/química , Poluentes do Solo/análise , Agricultura , Fertilizantes/análise , Frutas/química , Humanos , Metais Pesados/análise , Minerais , Solo , Fator de Transferência
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