Уточнить поиск
Результаты 71-80 из 6,546
Taguchi Optimization of Adsorptive Treatment of Effluent from Lead-acid Battery Recycling unit Using Pressmud-a Sugar Industry Waste Полный текст
2020
Meshram, S. | Thakur, C. | Soni, A. B.
Lead-acid battery recycling is one of the organized process which helps in overcoming the demand of lead for the production of the storage batteries. During recycling, a large amount of effluent is generated which contains lead beyond the permissible limit and harmful for the environment. This effluent was treated by adsorption as an alternative technique by using another waste (pressmud) as an adsorbent obtained from the sugar industry. Properties of the pressmud were determined through Fourier transform infrared spectroscopy, scanning electron microscope and X-ray diffraction analysis. Taguchi method L16 orthogonal array (4^3) was used for batch adsorption study for the parameters, initial pH, adsorbent dose and contact time. The optimum value for the adsorption of Pb(II) onto pressmud was found at effluent pH 4.5, adsorbent dose 1.0 g/50mL and time 240 min from the Signal-to-Noise ratio analysis. Kinetic and isotherm studies were also carried out to understand the mechanism of adsorption. Langmuir isotherm fitted best to the experimental data with R2=0.994 and kinetics of adsorption followed the pseudo-second-order model with R2=0.993.
Показать больше [+] Меньше [-]Application of Pollution Indices and Health Risk Assessment of Heavy Metals in the waters of a South-eastern Nigeria River Полный текст
2020
Anyanwu, E. D. | Adetunji, O. G. | Nwachukwu, E. D.
This study on the heavy metal content of a local drinking water source in South-east Nigeria was carried out in 3 sampling stations between May 2019 and October 2019. Pollution indices and health risk assessment for non-carcinogenic were used to check the water’s suitability for human consumption. The indices were heavy metal pollution index (HPI) and Contamination Index (Cd). Eight metals were evaluated with standard methods and compared with Nigerian and WHO drinking water standards. Some metals like iron, lead and cadmium exceeded the recommended limits. The stations Heavy Metal Pollution Index ranged between 511.4 and 512.4 while the monthly values ranged between 279.8 and 547.6; all exceeding the threshold value of 100. Contamination Index ranged between 3.12 and 3.32 (stations) and -0.80 to 4.80 (month) indicating high contamination potential and low to high contamination potentials respectively. All the hazard indices also exceeded one (1). Stations 1 and 2 were higher in all the indices. All the indices were linked the high values of iron, lead and cadmium, influenced by sand mining activities. The pollution indices and Health Risk Assessment converged to show that the waters of Iyiakwu River are not fit for human consumption. The children are more vulnerable since it the main source of drinking water in the area.
Показать больше [+] Меньше [-]Sorption of PAHs to microplastic and their bioavailability and toxicity to marine copepods under co-exposure conditions Полный текст
2020
Sørensen, Lisbet | Rogers, Emilie | Altin, Dag | Salaberria, Iurgi | Booth, Andy
Organic chemical pollutants associated with microplastic (MP) may represent an alternative exposure route for these chemicals to marine biota. However, the bioavailability of MP-sorbed organic pollutants under conditions where co-exposure occurs from the same compounds dissolved in the water phase has rarely been studied experimentally, especially where pollutant concentrations in the two phases are well characterized. Importantly, higher concentrations of organic pollutants on ingested MP may be less bioavailable to aquatic organisms than the same chemicals present in dissolved form in the surrounding water. In the current study, the sorption kinetics of two model polycyclic aromatic hydrocarbons (PAHs; fluoranthene and phenanthrene) to MP particles in natural seawater at 10 and 20 °C were studied and the bioavailability of MP-sorbed PAHs to marine copepods investigated. Polyethylene (PE) and polystyrene (PS) microbeads with mean diameters ranging from 10-200 µm were used to identify the role of MP polymer type and size on sorption mechanisms. Additionally, temperature dependence of sorption was investigated. Results indicated that adsorption dominated at lower temperatures and for smaller MP (10 µm), while absorption was the prevailing process for larger MP (100 µm). Monolayer sorption dominated at lower PAH concentrations, while multilayer sorption dominated at higher concentrations. PE particles representing ingestible (10 µm) and non-ingestible (100 µm) MP for the marine copepod species Acartia tonsa and Calanus finmarchicus were used to investigate the availability and toxicity of MP-sorbed PAHs. Studies were conducted under co-exposure conditions where the PAHs were also present in the dissolved phase (Cfree), thereby representing more environmentally relevant exposure scenarios. Cfree reduction through MP sorption was reflected in a corresponding reduction of lethality and bioaccumulation, with no difference observed between ingestible and non-ingestible MP. This indicates that only free dissolved PAHs are significantly bioavailable to copepods under co-exposure conditions with MP-sorbed PAHs. | publishedVersion
Показать больше [+] Меньше [-]Monitoring the occurrence of microplastic ingestion in otariids along the peruvian and chilean coasts Полный текст
2020
Pérez Venegas, Diego J. | Toro Valdivieso, Constanza | Ayala, Félix | Brito, Beatriz | Iturra, Lunna | Arriagada, Maite | Seguel, Mauricio | Barrios, Carmen | Sepúlveda, Maritza | Oliva, Doris | Cárdenas Alayza, Susana | Urbina, Mauricio A. | Jorquera, Alberto | Castro Nallar, Eduardo | Galbán Malagón, Cristóbal
Repeated reports of microplastic pollution in the marine pinniped diet have emerged in the last years. However, only few studies address the drivers of microplastics presence and the potential implications for monitoring microplastic pollution in the ocean. This study monitored their in the scats (N = 205) of four pinniped species/subspecies at five different locations in the southern Pacific Ocean (Peru and Chile). Samples from all rookeries contained microplastics, and overall, 68% of the examined scats contained fragments/fibers, mostly blue colored. We confirmed that 81.5% of the fragments/fibers were anthropogenic in origin , but only 30% were polymers. Scats from Juan Fernandez Archipelago presented higher microplastic concentrations than continental rookeries. Also, the common diet in each location may influence the levels found in the samples. This study presents a useful non-invasive technique to track plastic pollution in top predator diets as bioindicators for future surveillance/management plans applied to different location. | Rufford Foundation: N 18815-1. Dirección de Investigación y Doctorados, Universidad Andres Bello. Comisión Nacional de Investigación Científica y Tecnológica (CONICYT), CONICYT FONDECYT: 11150548, 116504, 111609059. Instituto Antártico Chileno Grant: INACh RT_12_17. Conicyt PCI: REDI 170292, REDI 170403. Ministerio de Economia, Fomento y Turismo through Iniciativa Científica Milenio (Núcleo Milenio INVASAL). Direccion de Investigación Universidad de Variarais: DIUV 38/2013. Morris Animal Foundation fellowship: N D16ZO-413. Saint Louis Zoo. Chicago Zoological Society. Kansas City Zoo. Woodland Park Zoo.
Показать больше [+] Меньше [-]The effect of long-term use on the Catch efficiency of Biodegradable gillnets Полный текст
2020
Grimaldo, Eduardo | Herrmann, Bent | Jacques, Nadine | Kubowicz, Stephan | Cerbule, Kristine | Su, Biao | Larsen, Roger B. | Vollstad, Jørgen
The effect of long-term use on the catch efficiency of biodegradable gillnets was investigated during commercial fishing trials and in controlled lab aging tests. The relative catch efficiency between biodegradable and nylon gillnets was evaluated over three consecutive fishing seasons for Atlantic cod (Gadus morhua) in Norway. The biodegradable gillnets progressively lost catch efficiency over time, as they caught 18.4%, 40.2%, and 47.4% fewer fish than the nylon gillnets during the first, second, and third season, respectively. A 1000-hour aging test revealed that both materials began to degrade after just 200 h and that biodegradable gillnets degraded faster than the nylon gillnets. Infrared spectroscopy revealed that the chemical structure of the biodegradable polymer changed more than the nylon. Although less catch efficient than nylon gillnets, biodegradable gillnets have great potential for reducing both capture in lost fishing gear and plastic pollution at sea, which are major problems in fisheries worldwide. | publishedVersion
Показать больше [+] Меньше [-]Cadmium distribution in mature durum wheat grains using dissection, laser ablation-ICP-MS and synchrotron techniques * Полный текст
2020
Yan, Bofang | Isaure, Marie-Pierre | Mounicou, Sandra | Castillo-Michel, Hiram | De Nolf, Wout | Nguyen, Christophe | Cornu, Jean-Yves
Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for micro-scale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process.
Показать больше [+] Меньше [-]First measurement of human exposure to current use pesticides (CUPs) in the atmosphere of central Chile: The case study of Mauco cohort Полный текст
2020
Cortés, Sandra | Pozo, Karla | Llanos, Yasna | Martínez, Natalia | Foerster, Claudia | Leiva, Cinthya | Ustáriz, Javier | Přibylová, Petra | Klánová, Jana | Jorquera, Héctor
Chile is a leading agricultural producer and thus consumer of insecticides, herbicides, and fungicides. In Molina, Central Chile, a prospective cohort has been established for studying the incidence and risk factors of chronic diseases in the adult population. Our goals were to measure airborne current use pesticides (CUPs), assess their spatial distribution and potential sources, and estimate health risks for the population in Molina. CUPs were measured using passive air samplers (PAS), deployed on six sites from October 2015 to August 2016. Thirty-eight pesticides were analyzed using high performance liquid chromatography (HPLC), but only nine of them were detected. Chlorpyrifos (CPF) was detected with air concentrations ranging from 444 to 14 624 (pg m(-3)). Diazinon, atrazine, dimethoate, metolachlor, simazine, terbuthylazine and tebuconazole were also detected; only pendimethalin had concentrations as high as those of CPF, with a maximum of 14 927 (pg m(-3)). Backward wind trajectories were used to estimate locations of potential sources contributing to airborne CUPs concentrations. Most of the exposure to CUPs was associated with local sources, while regional sources southern/eastern/western of Molina appear to contribute as secondary sources (soil evaporation followed by atmospheric transport) in spring and summer seasons. A health risk assessment using US-EPA's methodology was carried out for inhalation exposure of detected pesticides. None of the measured CUPs were associated with a hazard quotient (HQ) greater than 1, indicating no significant risk due to inhalation of pesticides in Molina's population with the exception of the group of children below 12 years old. However, further investigations are needed to evaluate others CUPs exposure route such as food consumption and dermal exposure to improve our health risk estimations. | Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) 15130011-15110020 180078 1161673 Vicerrectoria de Investigacion, Pontificia Universidad Catolica de Chile 9/2014 RECETOX Research Infrastructure LM2015051 CZ.02.1.01/0.0/0.0/16_013/0001761
Показать больше [+] Меньше [-]The 2016 red tide crisis in southern Chile: Possible influence of the mass oceanic dumping of dead salmons Полный текст
2020
Armijo, Julien | Oerder, Vera | Auger, Pierre-Amaël | Bravo Lizana, Angela | Molina, Ernesto
In 2016, a massive harmful algal bloom (HAB) of Alexandrium catenella around Chiloe island caused one of the major socio-ecological crisis in Chilean history. This red tide occurred in two distinct pulses, the second, most anomalous, bursting with extreme toxicity on the Pacific coast, weeks after the highly controversial dumping off Chiloe of 4,700 t of rotting salmons, killed by a previous HAB of Pseudochattonella verruculosa. We study the transport of this pollution, analyzing the physical oceanographic conditions during and after the dumping. We find that a cyclonic gyre was present between the dumping site and the coast, visible in satellite altimetry and sea surface temperature data. Using Lagrangian simulations, we confirm that near-surface currents could have brought part of the pollution to the coast, and fueled the bloom. This scenario explains also the anomalous later finding of ammonium near Chiloe. Finally we discuss the mismanagement of risk throughout the events. | Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 3150587
Показать больше [+] Меньше [-]Measurements of underwater noise radiated by commercial ships at a cabled ocean observatory Полный текст
2020
Zhang, Guosong | Forland, Tonje Nesse | Johnsen, Espen | Pedersen, Geir | Dong, Hefeng
Measurements of underwater noise radiated under ship normal operations are presented. The acoustic data, from the cabled ocean observatory, are analyzed under each identified ship passage, which was obtained by the Automatic Identification System. Under each passage, sound pressure level is calculated to observe local noise variations due to shipping noise. This paper emphasizes the study of noise variations at the observatory, presents the noise measurements under identified ship passages in the last several years, and provides references for predictive models of underwater noise pollution from commercial ship traffic. From the passages of one ship to the passages of 26 ships, the measurements reveal similar variation patterns when the ships traveled at similar courses, but different patterns when they traveled at different courses. When evaluating the noise variations due to ship traffics, it is important to consider the shipping noise propagation as well as ship movement. | publishedVersion
Показать больше [+] Меньше [-]Gaps in current Baltic Sea environmental monitoring – Science versus management perspectives Полный текст
2020
Kahlert, Maria | Eilola, Kari | Mack, Leoni | Meissner, Kristian | Sandin, Leonard | Strömberg, Helena | Uusitalo, Laura | Viktorsson, Lena | Liess, Antonia
Legislations and commitments regulate Baltic Sea status assessments and monitoring. These assessments suffer from monitoring gaps that need prioritization. We used three sources of information; scientific articles, project reports and a stakeholder survey to identify gaps in relation to requirements set by the HELCOM's Baltic Sea Action Plan, the Marine Strategy Framework Directive and the Water Framework Directive. The most frequently mentioned gap was that key requirements are not sufficiently monitored in space and time. Biodiversity monitoring was the category containing most gaps. However, whereas more than half of the gaps in reports related to biodiversity, scientific articles pointed out many gaps in the monitoring of pollution and water quality. An important finding was that the three sources differed notably with respect to which gaps were mentioned most often. Thus, conclusions about gap prioritization for management should be drawn after carefully considering the different viewpoints of scientists and stakeholders. | publishedVersion
Показать больше [+] Меньше [-]