خيارات البحث
النتائج 3711 - 3720 من 6,560
Environmental Implications from Long-term Citrus Cultivation and Wide Use of Cu Fungicides in Mediterranean Soils النص الكامل
2020
Triantafyllidis, Vassilios | Zotos, Anastasios | Kosma, Chariklia | Kokkotos, Efthimios
Citrus fruits are cultivated in more than 100 countries around the world. The main citrus fruit–producing counties are Brazil, China, and the USA although the whole Mediterranean region ranks first worldwide. In Greece, citrus occupy an area of about 40.000 ha, representing 43% of total fruit crops. Soil quality is affected by long-term citrus cultivation. Soil organic matter is depleted in long-term citrus cultivation, in contrast to nutrients that seemed to increase in the following descending order: POₗₛₑₙ > Naₑcₓₕ > NO₃-N > Kₑcₓₕ > Caₑcₓₕ > Mgₑcₓₕ due to usual management practices. To evaluate the environmental impact due to broad use of Cu fungicides in long-term citrus cultivation, Cu total fraction and DTPA-extractable in agricultural soil were determined. Soil contamination rate was evaluated via proper indices of different sensitivities on their calculations. In particular, 22% of samples in older orchards were highly polluted based on the single-factor pollution index (PI). The index geo-accumulation index (Igeo) presented hysteresis in comparison with PI, which was more sensitive, comprehensive, and reliable, able to describe better the pollution classification of citrus soils. The calculation of monomial potential ecological risk for Cu showed that in older citrus groves, the average value was 11.8, while the max value was 49.8 indicating moderate ecological risk suggesting the negative environmental impact of intensive citrus cultivation. These results denote the need to preserve soil fertility and prevent potential toxic element accumulation due to long-term cultivation management practices, aiming to achieve soil sustainability and food security in National or Euro-Mediterranean scale.
اظهر المزيد [+] اقل [-]Spatial Distribution and Ecological Risk Assessment of Natural Radionuclides and Trace Elements in Agricultural Soil of Northeastern Nile Valley, Egypt النص الكامل
2020
Monged, Mohamed H. E. | Hassan, Hanan B. | El-Sayed, Salah A.
Being known with its agricultural fertility, the soil of the Nile Valley of Egypt was subjected to degradation due to fast urbanization and increased industrial activities in recent years. The quality of the agricultural soil and associated radiological health hazards to farm workers in the Northeastern Nile Valley was assessed based on the trace metal analyses (Hg, Cd, Zn, Pb, Cu, Mn, and Fe) and natural radionuclide measurements (²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K, and ²¹⁰Pb) of twenty soil samples. Results indicated that the agricultural soil has concentrations of trace elements below the soil world average. However, a significant enrichment in Cd and Cu content was observed in some soil sites. The enrichment in some trace elements contents, especially the Cd metal, was attributed to the effects of the natural and human factors, including the occurrence and distribution of silt and clay deposits, the extensive use of municipal wastewater and pesticide, the incineration of agricultural wastes, and the emission from bricks factories and mazut-fired thermal power plants around the area. The estimated contamination and ecologic risk indices revealed that some soils in the area are uncontaminated with trace elements; others are “moderately contaminated” soil to “contaminated.” Results from the radiological measurements revealed that the activity concentrations of the investigated radionuclides were also below the world median activities of soil. The total annual effective dose rates from the different exposure pathways were calculated. The estimated excess lifetime cancer risk values for farm workers were greatly higher than that of the soil world average. This implies a high probability of introducing cancer over the lifetime of farmers in the study area.
اظهر المزيد [+] اقل [-]Environmental degradation, economic growth, and energy innovation: evidence from European countries النص الكامل
2020
ʻAlī, Muḥammad | Raza, Syed Ali | Khamis, Bilal
This study aims to explore the relationship of environmental degradation with economic growth and energy innovation by utilizing the panel data of 33 European countries by covering the period of 1996 to 2017. We use the cross-sections independence and control the heterogeneity between cross-sections by using the second-generation econometric of panel data. The Westerlund bootstrap co-integration, CIPS unit root test, Pedroni co-integration, panel causality techniques, and FMOLS have been used to analyze the relationship. The result of the study shows that all the variables are integrated in the long run. Energy innovation has a negative and significant impact on environmental degradation. On the other hand, gross domestic product has a U-shape and significant relationship with environmental degradation by supporting Kuznets curve. Therefore, this study helps not only the policymaker and government but also the people and businessmen on how they can increase the growth of the business and economy without effecting the environment.
اظهر المزيد [+] اقل [-]Performance of Streptomyces pactum–assisted phytoextraction of Cd and Pb: in view of soil properties, element bioavailability, and phytoextraction indices النص الكامل
2020
Liu, Xiangyu | Guo, Di | Ren, Chunyan | Li, Ronghua | Du, Juan | Guan, Weidou | Li, Yiman | Zhang, Zengqiang
Microbe-assisted phytoremediation provides an eco-friendly and cost-effective approach to reclaim Cd- and Pb-contaminated soils. In this work, incubation and pot experiments were established to investigate the effect of Streptomyces pactum (Act12) combined with compost on soil physicochemical properties, enzymatic activities, and thereby acted on phytoextraction of Cd and Pb by using potherb mustard (Brassica juncea Coss.). The addition of Act12 and compost increased EC (7.2%), available phosphorus (P) (14.9%), available potassium (K) (17.0 folds), DOC (37.7%), OM (2.8 folds), urease (49.8%), dehydrogenase (2.2 folds), and alkaline phosphatase (23.0 folds) of soil, while reduced pH (7.7%) compared with control. Significant decrease of available Cd and Pb uptake was observed after adding compost and Act12 by 29.1% and 32.2%. Presence of compost and Act12 enhanced the biomass by 3.98 folds and 1.83 folds in shoots and roots of plant. Results showed the assimilation of Cd and Pb in shoots was increased by 103.8% and 48.7% due to the increased of biomass. Meanwhile, the rhizosphere effect of soil microorganisms increased the uptake of Cd (60.4%) and Pb (19.2%) in roots. These findings suggested that Act12 joined with compost-strengthened potherb mustard phytoremediation of Cd- and Pb-polluted soils, which may provide new insights into the clean-up of mining-contaminated soils in field practice.
اظهر المزيد [+] اقل [-]Detailed studies on microbial adhesion and degradation of polystyrene foam wastes (PSFW) for clean environment النص الكامل
2020
Ebciba, Chandrasekaran | Gnanamani, Arumugam
The present study explores the efficient management of non-degradable polystyrene foam wastes (PSFW) by transforming into a microbial responsive material for an effective biodegradation process. In brief, the study involves three steps, viz., (i) preparation of citrus fruit peel extract from peel wastes; (ii) dissolution of PSFW using the extract and transform to polystyrene sheet (PSS) and characterization of the sheet formed and (iii) finally the microbial adhesion and biofilm formation on PSS. Results revealed that the maximum yield of the peel extract identified as D-limonene was obtained from Citrus sinensis (8.2 ± 0.06 ml/100 g fresh waste). Characterization studies on PSS suggested that there are appreciable changes in the infrared spectrum, thermo gravimetric analysis, gel permeation chromatography analyses, and contact angle measurements in comparison with PSFW. Observations on significant variations in the glass transition temperature of PSFW (100 °C) and PSS (60 °C); decomposition temperature of PSFW (310.93 °C) and PSS (78.18 °C), and molecular weight distribution changes in PSFW (2.00 Mw/Mn) and PSS (1.03 Mw/Mn) suggested the occurrence of structural and molecular changes in PSS. Studies on microbial adhesion and biofilm formation on PSS suggested that amongst six microbial species isolated from the waste dump yard, WD03 strain identified as Lysinibacillus sp., displayed a maximum adhesion and biofilm formation on the surface of the PSS as evidenced through biofilm characterizations, SEM, and fluorescence microscopic analyses respectively. In conclusion, the transformation of PSFW to PSS and the appreciable microbial adhesion and biofilm formation suggested the possibility of the effective management of white nuisance (PSFW) wastes in the environment.
اظهر المزيد [+] اقل [-]Organophosphate toxicity: updates of malathion potential toxic effects in mammals and potential treatments النص الكامل
2020
Badr, Amira M.
Organophosphorus insecticides toxicity is still considered a major global health problem. Malathion is one of the most commonly used organophosphates nowadays, as being considered to possess relatively low toxicity compared with other organophosphates. However, widespread use may lead to excessive exposure from multiple sources. Mechanisms of MAL toxicity include inhibition of acetylcholinesterase enzyme, change of oxidants/antioxidants balance, DNA damage, and facilitation of apoptotic cell damage. Exposure to malathion has been associated with different toxicities that nearly affect every single organ in our bodies, with CNS toxicity being the most well documented. Malathion toxic effects on liver, kidney, testis, ovaries, lung, pancreas, and blood were also reported. Moreover, malathion was considered as a genotoxic and carcinogenic chemical compound. Evidence exists for adverse effects associated with prenatal and postnatal exposure in both animals and humans. This review summarizes the toxic data available about malathion in mammals and discusses new potential therapeutic modalities, with the aim to highlight the importance of increasing awareness about its potential risk and reevaluation of the allowed daily exposure level.
اظهر المزيد [+] اقل [-]Ecotoxicity screening evaluation of selected pharmaceuticals and their transformation products towards various organisms [Erratum: August 2021, v.28(32), p.44582] النص الكامل
2020
Grabarczyk, Łukasz | Mulkiewicz, Ewa | Stolte, Stefan | Puckowski, Alan | Pazda, Magdalena | Stepnowski, Piotr | Białk-Bielińska, Anna
The intensive development of medical science has led to an increase in the availability and use of pharmaceutical products. However, nowadays, most of scientific attention has been paid to the native forms of pharmaceuticals, while the transformation products (TPs) of these substances, understood herein as metabolites, degradation products, and selected enantiomers, remain largely unexplored in terms of their characterization, presence, fate and effects within the natural environment. Therefore, the main aim of this study was to evaluate the toxicity of seven native compounds belonging to different therapeutic groups (non-steroidal anti-inflammatory drugs, opioid analgesics, beta-blockers, antibacterial and anti-epileptic drugs), along with the toxicity of their 13 most important TPs. For this purpose, an ecotoxicological test battery, consisting of five organisms of different biological organization was used. The obtained data shows that, in general, the toxicity of TPs to the tested organisms was similar or lower compared to their parent compounds. However, for example, significantly higher toxicity of the R form of ibuprofen to algae and duckweed, as well as a higher toxicity of the R form of naproxen to luminescent bacteria, was observed, proving that the risk associated with the presence of drug TPs in the environment should not be neglected.
اظهر المزيد [+] اقل [-]Removal of emerging pollutants in aqueous phase by heterogeneous Fenton and photo-Fenton with Fe2O3-TiO2-clay heterostructures النص الكامل
2020
Molina, Carmen B. | Sanz-Santos, Eva | Boukhemkhem, Ali | Bedia, Jorge | Belver, Carolina | Rodriguez, Juan J.
Fe₂O₃-TiO₂-clay heterostructures have been prepared using an organo-bentonite as support, which organophilic character favored the fixation of TiO₂. Furthermore, Fe₂O₃ was successfully anchored by wet impregnation. The resulting materials are characterized by a disordered layered structure and a mesoporous texture. The heterostructures were employed as catalysts for the removal of two pharmaceuticals, acetaminophen (ACE) and antipyrine (ANT), by heterogeneous Fenton and photo-Fenton processes. ACE removal under different operation conditions was studied in detail to establish structure-performance relationships, being the TiO₂ formation and the developed texture the main factors controlling the activity. ANT showed a higher refractory behavior in oxidation by Fenton. Among the technologies studied, heterogeneous photo-Fenton achieved the best catalytic performance and higher kinetic rate and mineralization degree. Iron leaching was very low, lower than 5% of the initial iron load in all cases. This work demonstrates the potential application of these heterostructures for the removal of emerging pollutants of different nature.
اظهر المزيد [+] اقل [-]Evaluation of the Swat River, Northern Pakistan, water quality using multivariate statistical techniques and water quality index (WQI) model النص الكامل
2020
Jehan, Shah | Ullah, Ihsan | K̲h̲ān, Sardār | Muhammad, Said | Khattak, Seema Anjum | Khan, Tariq
This study evaluates the characteristics of water along the Swat River, Northern Pakistan. For this purpose, water samples (n = 30) were collected and analyzed for physicochemical parameters including heavy metals (HM). The mean concentrations of physicochemical parameters and HM were within the drinking water guideline values set by the World Health Organization (WHO 2011) except 34%, 60%, and 56% of copper (Cu), nickel (Ni), and lead (Pb), respectively. Pollution sources were identified by various multivariate statistical techniques including correlation analysis (CA) and principal component analysis (PCA) indicating different origins both naturally and anthropogenically. Results of the water quality index (WQI) ranged from 13.58 to 209 with an average value of 77 suggesting poor water quality for drinking and domestic purposes. The poor water quality was mainly related to high sodium (alkalinity) and salinity hazards showing > 27% and 20% water samples have poor alkalinity and salinity hazards, respectively. Hazard quotient (HQ) and hazard index (HI) were used to determine the health risk of HM in the study area. For water-related health risk, HQᵢₙgₑₛₜᵢₒₙ, HQdₑᵣₘₐₗ, and HI values were > 1, indicating noncarcinogenic health risk (NCR) posed by these HM to the exposed population.
اظهر المزيد [+] اقل [-]Effect of water pollution control on provincial boundaries of River-Director System: based on the study of the Yangtze River valley in China النص الكامل
2020
Wang, Juan | Song, Yifei
We analyze the driving mechanism of the River-Director System reform in the article. Using the ordered probit model, the effect of the River-Director System policy was evaluated by observing the monthly water quality data of 170 water areas along the boundary of the Yangtze River system. It determines that the driving force of the local government’s basin governance under the river system is mainly the top-down policy directives and that the driving path is effective synergy, rights, and diffusion in the article. We find that the upstream provinces and municipalities that implemented reforms have significantly improved the water quality of the waters in the border basin, compared with the provinces and cities that have not implemented the reform of the river system and the river basins that have implemented policy reforms but are located in the lower reaches of the rivers. At the same time, the city’s reforms have significantly improved the quality of the junction basin water body. The implementation of the River-Director System has reduced the occurrences of local pollution emission and improved the water quality of the provincial boundaries through sewage treatment. We further validate the robustness of the basic conclusions by deleting special samples and changing the window type and other robust tests. Finally, through monthly examinations on the implementation of the policy, it finds that the effectiveness of the policy reform became more apparent in the eleventh month.
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