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Результаты 3471-3480 из 4,937
Quantitative source apportionment of water solutes and CO2 consumption of the whole Yarlung Tsangpo River basin in Tibet, China Полный текст
2019
Liu, Jiaju | Zhao, Yunpeng | Li, Zheng | Guo, Huaicheng
The Tibetan Plateau is known as the “Asian water tower,” and the Yarlung Tsangpo (YT) River is the largest river that originates in and flows across the southern Tibetan Plateau. Although the solute source of YT River has been extensively and qualitatively analyzed, there is a lack of the quantitative analysis for the whole basin and seasonal variation of hydrochemical characteristics. Here, 212 samples obtained in the mainstream and tributary of YT River in different (wet, normal, and dry) periods were used for the solute apportionment using the mass balance model. The results showed that the solutes in YT River water were mainly derived from the carbonate and silicate rock weathering that accounts 42.2% and 26.9% in the total solute source, respectively, as the complex geological conditions in the basin. A part of the ions (7.5%) was also originated from the atmospheric precipitation as the abundant rainfall in the wet period. Meanwhile, the contribution of solute sources had no significantly seasonal variation in the upstream, whereas it had significantly seasonal variation in the downstream with the tropical climate and heavy rainfall. Importantly, the rock weathering of the basin could consume so much atmospheric CO₂ (0.54% of the consumption at global with the only 0.16% of the global surface area) that could mitigate the global warming, which followed an increasing trend from upstream to downstream. The quantitative analysis of the solute source for YT River fills in the gaps in the chemically characteristic cognition of the basin. It is beneficial for the water resource management for the Asian. The proportion of solute sources in the YT River and its tributaries for wet (W), normal (N), and dry (D) periods
Показать больше [+] Меньше [-]Combined effect of polystyrene plastics and triphenyltin chloride on the green algae Chlorella pyrenoidosa Полный текст
2019
Yi, Xianliang | Chi, Tongtong | Li, Zhaochuan | Wang, Jianfeng | Yu, Mingyue | Wu, Minghuo | Zhou, Hao
The combined effect of polystyrene (PS) particles and triphenyltin chloride (TPTCl) to the green algae Chlorella pyrenoidosa was studied. The 96 h IC₅₀ of TPTCl to the green algae C. pyrenoidosa was 30.64 μg/L. The toxicity of PS particles to C. pyrenoidosa was size-dependent, with the 96 h IC₅₀ at 9.10 mg/L for 0.55 μm PS but no toxicity observed for 5.0 μm PS. The exposure to 0.55 μm PS led to damage on structure of algal cells, which could in turn cause inhibition on photosynthesis and population growth of the green algae. TPTCl concentrations in test medium were lowered by 15–19% at presence of 0.55 μm PS particles, indicating a reduced bioavailability of TPTCl. In spite of this reduced bioavailability, the presence of PS increased the toxicity of TPTCl, which might be attributed to facilitated uptake of TPTCl by the green algae after the damage of cell structure. The overall results of the present study provided important information on the effect of PS on the bioavailability and toxicity of TPTCl to phytoplankton species.
Показать больше [+] Меньше [-]The effects of urbanization and globalization on CO2 emissions: evidence from the Sub-Saharan Africa (SSA) countries Полный текст
2019
Ṣalāḥuddīn, Muḥammadu | Ali, Md Idris | Vink, N. | Gow, Jeff
Ecological modernization theories suggest that it is hard to determine a priori the environmental effects of urbanization, while neoliberal doctrine advocates a positive role of globalization in developing economies especially in terms of reducing poverty and inequality. Yet, the environmental effect of globalization is not unanimous. This study employs second-generation panel regression techniques that account for heterogeneous slope coefficients and cross-sectional dependence to estimate the impacts that urbanization and globalization have on CO₂ emissions for a panel of 44 Sub-Saharan Africa (SSA) countries for the period 1984–2016. Also, a causality test that considers both these issues is performed. The estimated coefficient of urbanization is positive, statistically significant, and highly consistent across different estimation techniques. The magnitude of the coefficient and level of significance are different in different econometric estimations. In most specifications, the estimated coefficient on the globalization variable is statistically insignificant. Urbanization is found to cause emissions. The environmental implications of these results are discussed with a set of policy recommendations for an environmentally better SSA region.
Показать больше [+] Меньше [-]Tibial growth plate vascularization is inhibited by the dithiocarbamate pesticide thiram in chickens: potential relationship to peripheral platelet counts alteration Полный текст
2019
Huang, Shuzheng | Li, Lei | Rehman, Mujeeb Ur | Gao, Jin-dong | Zhang, Li-hong | Tong, Xiao-le | Waqas, Muhammad | Li, Jia-kui
The widespread use of thiram has raised concerns for health and its toxic effects, but the underlying toxicity mechanism on platelets and bones is poorly defined. Here, we found a significant increase in the number of platelets in chickens with the thiram intake, due to the increased expression of thrombopoietin mRNA in the dysfunction liver. Furthermore, the decreased vascular distribution and cell death of chondrocytes in the tibial growth plates (TGPs) were observed, resulting in bone growth inhibition, which is associated with the abnormal activation of platelets leading to the extraordinary decrease of vascular endothelial growth factor A (VEGFA) and angiopoietin-1 protein were released and their corresponding receptors VEGFR2 and Tie-2 expressions were also reduced in the TGPs. Taken together, these findings revealed that thiram has an adverse effect on bones and platelets, which may have a high risk of thrombosis and osteoarthritis.
Показать больше [+] Меньше [-]Self-templated microwave-assisted hydrothermal synthesis of two-dimensional holey hydroxyapatite nanosheets for efficient heavy metal removal Полный текст
2019
Su, Yiping | Wang, Jing | Li, Shun | Zhu, Jianhua | Liu, Weishu | Zhang, Zuotai
Heavy metals have caused serious environmental problems and threat to human health. Ultrathin and holey two-dimensional (2D) nanosheets have recently drawn significant attention as superb adsorbent material to remove heavy metal ions due to their unique physicochemical properties. Herein, we report a self-template-directed ultrafast reaction route to synthesis porous hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) nanosheets via a microwave-assisted hydrothermal method using poly(allylamine hydrochloride) as an additive. The resulting hydroxyapatite nanosheets showed a high specific surface area (92.9 m² g⁻¹) and excellent adsorption performance for various heavy metal ions including Pb(II), Cu(II), and Cd(II), with maximum adsorption capacities of 210.5, 31.6, and 24.9 mg g⁻¹, respectively. The adsorption kinetics fitted well with the pseudo-second-order equation and the equilibrium data showed a high correlation coefficient with the Langmuir model. Based on the experimental results and analysis, we can conclude that the sorption of heavy metal ions with the hydroxyapatite nanosheets mainly attributes to surface complexation and cation exchange. The present synthetic strategy allows the fast and massive production of porous hydroxyapatite ultrathin nanosheets and may also potentially be applicable to the fabrication of other metal phosphates with assembled or hierarchical porous structures towards various applications such as water purification.
Показать больше [+] Меньше [-]Economics of death and dying: a critical evaluation of environmental damages and healthcare reforms across the globe Полный текст
2019
Batool, Rubeena | Zaman, Khalid | Khurshid, Muhammad Adnan | Sheikh, Salman Masood | Aamir, Alamzeb | Shoukry, Alaa Mohamd | Sharkawy, Mohamed A. | Aldeek, Fares | Khader, Jameel | Gani, Showkat
The economics of death and dying highlighted that environmental factors negatively influence healthcare sustainability. Therefore, this study conducted a system-based literature review to identify the negative externality of environmental damages on global healthcare reforms. Based on 42 peer-reviewed papers in the field of healthcare reforms and 12 papers in the field of environmental hazards, we identified 25 factors associated with death and dying and 15 factors associated with health-related damages across the world respectively. We noted that environmental factors are largely responsible to affect healthcare sustainability reforms by associating with the number of healthcare diseases pertaining to air pollutants. The study suggests healthcare practitioners and environmentalists to devise long-term sustainable healthcare policies by limiting highly toxic air pollutants through technology-embodied green healthcare infrastructure to attained efficient global healthcare recovery.
Показать больше [+] Меньше [-]Effect of installed capacity size on environmental efficiency across 528 thermal power stations in North China Полный текст
2019
Wu, Chao | Oh, Keunyeob | Long, Xingle | Zhang, Jing
Thermal power plants are the main source of carbon dioxide emissions in China. Beijing-Tianjin-Hebei and their neighborhood provinces are the most polluted regions in China. Environmental efficiencies of 528 thermal power plants were evaluated through metafrontier epsilon-based measure, which aimed to overcome the invalid inferences of radial or non-radial model. We also analyzed the heterogeneity of environmental efficiency across different regions by considering environmental technology differences. Bootstrap regression was used in order to testify three different hypotheses to address the disadvantages of conventional regression. We found that environmental efficiency in Beijing and Tianjin is higher than the other regions and is becoming divergent. In addition, coal consumption intensity negatively affects environmental efficiency. Large-scale power stations are more environmental efficient than smaller ones. Longer equipment utilization hour can enhance energy performance of power stations, which can decrease carbon emissions and increase environmental efficiency. It is better to promote technology transfer from regions with higher environmental efficiency to regions with lower environmental efficiency. Low-carbon technologies should be promoted to decrease carbon emissions.
Показать больше [+] Меньше [-]Ecological risk assessment of agricultural pesticides in the highly productive Ndop flood plain in Cameroon using the PRIMET model Полный текст
2019
Fai, Patricia Bi Asanga | Ncheuveu, Nkwatoh Therese | Tchamba, Martin Ngankam | Ngealekeloeh, Francis
Flood plains can make a significant contribution to food security due to their rich agricultural and aquaculture potentials but the misuse of pesticides in these ecosystems may seriously threaten their sustainability. We have assessed the risk of commonly used pesticides by rice and vegetable farmers on two major streams in the Ndop flood plain in Cameroon using the PRIMET model. Thirty pesticide formulations were identified containing 17 active ingredients belonging to fungicides (7), herbicides (3), and insecticides (7). Out of these, five posed acute and/or chronic risks to the streams. Chlorpyriphos-ethyl (ETR = 655), chlorothalonil (ETR = 250), and cypermethrin (ETR = 190) posed a definite acute risk to both streams. These pesticides also posed possible chronic risks with cypermethrin also posing a definite chronic risk (ETR = 1658) to fish in one of the streams. Mancozeb (ETR = 2.2) and λ-cyhalothrin (ETR = 2.8) posed a possible acute risk to both streams. It was interesting to note that most pesticides, including some of those that posed a risk, were applied at lower doses than their respective recommended doses. Differences in ETRs were also observed in the two streams with higher values occurring in the stream having a lower concentration of suspended solids. The higher velocity of the Ngwala-Mesaw stream did not affect the acute risk posed by pesticides. Pesticide toxicity was an important determinant in the risk posed and we recommend that appropriate mitigation measures be put in place to reduce the risk of these pesticides such as the implementation of an appropriate buffer zone between the edge of field and water body.
Показать больше [+] Меньше [-]Arsenic detoxification in Eucalyptus: subcellular distribution, chemical forms, and sulfhydryl substances Полный текст
2019
Wang, Weisheng | Meng, Min | Li, Lei
The Eucalyptus cultivation acreage was large in Guangxi provinces. Guanglin 9 (Eucalyptus grandis × Eucalyptus urophylla) is a widely cultivated Eucalyptus species and has been found to grow normally in soils contaminated by heavy metals such as arsenic (As), but the detoxification mechanisms are not clear yet. Through hydroponic experiment, the adsorption and detoxification of As in Eucalyptus were studied from three aspects, namely subcellular distribution of As, chemical forms of As, and the response of sulfhydryl substances. The subcellular distribution data showed that in the Eucalyptus roots, As was mainly present in the soluble fraction (66.3–79.9%), in leaves in the soluble fraction (50.6–53.8%), and the cell wall fraction (35.6–40.0%) under As stress. The chemical form data showed that in roots, As was mainly present in ethanol extraction state (29.5–40.0%), deionized water extraction state (28.3–31.7%), and sodium chloride extraction state (24.1–33.8%). As stress can induce the formation of non-protein thiols (NPT), glutathione (GSH), and phytochelatins (PCs). With the increasing As concentration, the NPT (maximum increase 55.9%) and GSH (maximum increase 79.9%) contents in roots significantly increased, while the PC content significantly increased and then significantly decreased. It is concluded that the As detoxification mechanisms of Eucalyptus are mainly vacuolar compartmentalization and the chelation of sulfhydryl substances, while cell wall adsorption and As chemical forms have limited effects on As detoxification.
Показать больше [+] Меньше [-]The total content of toxic elements in horsehair given the level of essential elements Полный текст
2019
Kalashnikov, Valeriy | Zaĭt︠s︡ev, Aleksandr | Atroschenko, Mihail | Miroshnikov, Sergey | Frolov, Alexey | Zavyalov, Oleg
Elemental status of 214 mares aged 3–7 years from 11 breeds was studied: Arabian purebred (n = 20), Bashkir (n = 20), Kabarda (n = 20), Vyatka (n = 20), Tuva (n = 19), Yakutsk (n = 30), Mezenskaya (n = 20), Thoroughbred (n = 20), Akhal-Teke (n = 20), Russian trotter (n = 15), Soviet Heavy Draft (n = 10) bred in 13 regions of Russia. The research objective is to study the content of chemical elements in hair from the horse’s mane, depending on the sum of toxic elements in animal hair expressed in moles. The elemental composition of the hair was defined by atomic emission and mass spectrometry (AES and MS). Elemental composition of biosubstrates was studied by 25 indicators (Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, I, K, Li, Mg, Mn, Na, Ni, P, Pb, Se, Si, Sn, Hg, Sr, V, Zn). In the studies, an estimate of the total toxic load of the horse’s body (∑tox) was given as the sum of mmoles of Al, Cd, Pb, Sn, Hg, and Sr in horsehair. Based on ∑tox percentile calculations, animals were divided into three groups up to 25 percentile (n = 54) with concentrations up to 1.09 mmol/kg, within the 25 and 75 percentile limits (n = 105) and over 75 percentile (n = 55) with a concentration above 6.08 mmol/kg. As follows from the obtained results, the ∑tox indicator in the mane’s hair is closely connected with the total hair mineralization. For the studied range of ∑tox values, the relationship of this indicator with 13 essential and conditionally essential chemical elements is described. Moreover, as ∑tox increases, it indicates an increase in the concentration of eleven (Ca, P, Co, Cr, Fe, I, Mn, Li, Ni, V, As) and a decrease of two elements in hair (B, Si); for six elements (K, Mg, Na, Cu, Zn, Sn), such a connection was not revealed. At ∑tox values higher than 75 percentile, a critical increase in the exchange pools of two or more toxic elements in the body was observed in 85% of cases. Intensive exchange of selenium and iodine is observed; it is expressed by an increase in the number of animals with the content of these elements in hair beyond the “physiological standard,” estimated as the range of 25–75 percentile.
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