Уточнить поиск
Результаты 3961-3970 из 4,309
Early metal pollution in southwestern Europe: the former littoral lagoon of El Almarjal (Cartagena mining district, S.E. Spain).A sedimentary archive more than 8000 years old Полный текст
2017
Manteca, José-Ignacio | Ros-Sala, Milagros | Ramallo-Asensio, Sebastián | Navarro Hervás, Francisca | Rodríguez Estrella, Tomás | Cerezo-Andreo, Felipe | Ortiz-Menéndez, José-Eugenio | de-Torres, Trinidad | Martínez Andreu, Miguel
A borehole drilling campaign has allowed the study of a former littoral lagoon located next to the harbour city of Cartagena in South-East Spain (close to the Sierra de Cartagena polymetallic ore deposits). This lagoon, which developed during the Holocene, was first a shallow sedimentary marine environment and later evolved into a swampy semi-endorheic basin named “Almarjal” (after the Arab term from the fourteenth century). The lagoon eventually dried out and at present forms part of the substratum of the modern sector of the city urban area. The basin representative sediments are sapropelic black silty facies forming a continuous sedimentary archive, accounting for more than 8000 years of depositional phenomena. The geochemical study of these sediments, together with their absolute calibrated dating by ¹⁴C, allows definition of successive stages of mining and metallurgical activities in the area. In turn, this information provides a more comprehensive perspective regarding metal pollution, particularly lead contamination during different periods of the Recent Prehistory and the Classical Age. The results indicate that the beginning of contamination by lead and other heavy metals occurred as early as 4500 years ago, when the Final Chalcolithic period was taking place in the South-East of the Iberian Peninsula. This finding provides further insights regarding the debate on the origins of lead mining and metallurgy in SE Spain.
Показать больше [+] Меньше [-]Understanding brassinosteroid-regulated mechanisms to improve stress tolerance in plants: a critical review Полный текст
2017
Nawaz, Fahim | Naeem, Muhammad | Zulfiqar, Bilal | Akram, Asim | Ashraf, Muhammad Yasin | Raheel, Muhammad | Shabbir, Rana Nauman | Hussain, Rai Altaf | Anwar, Irfan | Aurangzaib, Muhammad
Brassinosteroids (BRs) are steroidal plant hormones involved in regulation of physiological and molecular processes to ameliorate various biotic and abiotic stresses. Exogenous application of BRs to improve stress tolerance in plants has recently become a high research priority. Several studies have revealed the involvement of these steroidal hormones in upregulation of stress-related defense genes and their cross talk with other metabolic pathways. This is likely to stimulate research on many unanswered questions regarding their role in enhancing the ability of plants to tolerate adverse environmental conditions. Thus, this review appraises new insights on mechanisms mediating BR-regulated changes in plants, focused mainly on their involvement in regulation of physiological and molecular mechanisms under stress conditions. Herein, examples of BR-stimulated modulation of antioxidant defense system and upregulation of transcription factors in plants exposed to various biotic (bacterial, viral, and fungal attack) and abiotic stresses (drought, salinity, heat, low temperature, and heavy metal stress) are discussed. Based on these insights, future research in the current direction can be helpful to increase our understanding of BR-mediated complex and interrelated processes under stress conditions.
Показать больше [+] Меньше [-]Chlorpyrifos pollution: its effect on brain acetylcholinesterase activity in rat and treatment of polluted soil by indigenous Pseudomonas sp Полный текст
2017
Sharma, Shelly | Singh, Partap Bir | Chadha, Pooja | Saini, Harvinder Singh
The study was aimed to evaluate the levels of chlorpyrifos (CPF) pollution in agricultural soil of Punjab, India, its detrimental effects on acetylcholinesterase (AChE) activity in rat brain and bioremediation of soils polluted with CPF using indigenous and adapted bacterial lab isolate. The analysis revealed that soil samples of Bathinda and Amritsar regions are highly contaminated with chlorpyrifos showing 19 to 175 mg/kg concentrations of CPF. The non-targeted animals may get poisoned with CPF by its indirect dermal absorption, inhalation of toxic fumes and regular consumption of soiled food grains. The study indicated that even the lowermost concentrations of CPF, 19 and 76 mg/kg of soil found in the Amritsar and Bathinda regions respectively can significantly inhibit the AChE activity in rat brain within 24 h of its treatment. This represents the antagonistic effect of CPF on AChE which is a prime neurotransmitter present in all living beings including humans. In light of this, an attempt was made to remediate the polluted soil, a major reservoir of CPF, using Pseudomonas sp. (ChlD), an indigenous bacterial isolate. The culture efficiently degraded 10 to 100 mg/kg chlorpyrifos supplemented in the soil and utilized it as sole source of carbon and energy for its growth. Thus, this study provides a detailed insight regarding the level of CPF pollution in Punjab, its detrimental effects on mammals and bio-based solution to remediate the sites polluted with CPF.
Показать больше [+] Меньше [-]Optimizing the phosphorus use in cotton by using CSM-CROPGRO-cotton model for semi-arid climate of Vehari-Punjab, Pakistan Полный текст
2017
Amin, Asad | Nasim, Wajid | Mubeen, Muhammad | Nadeem, Muhammad | Ali, Liaqat | Hammad, Hafiz Mohkum | Sultana, Syeda Refat | Jabran, Khawar | Rehman, M Habib ur | Ahmad, Shakeel | Awais, Muhammad | Rasool, Atta | Shah, Fahad | Saud, Shah | Shah, Adnan Noor | Ihsan, Zahid | Shahzād, ʻAlī | Bajwa, Ali Ahsan | Hakeem, Khalid Rehman | Ameen, Asif | Amānullāh, | Hafeez-ur-Rahman, | Alghabar, Fahad | Jatoi, Ghulam Hussain | Akram, Muhammad | Khan, Aziz | Islam, Faisal | Ata-Ul-Karim, Syed Tahir | Rehmani, Muhammad Ishaq Asif | Hosena, Sājida | Razaq, Muhammad | Fathi, Amin
Crop nutrient management is an essential component of any cropping system. With increasing concerns over environmental protection, improvement in fertilizer use efficiencies has become a prime goal in global agriculture system. Phosphorus (P) is one of the most important nutrients, and strategies are required to optimize its use in important arable crops like cotton (Gossypium hirsutum L.) that has great significance. Sustainable P use in crop production could significantly avoid environmental hazards resulting from over-P fertilization. Crop growth modeling has emerged as an effective tool to assess and predict the optimal nutrient requirements for different crops. In present study, Decision Support System for Agro-technology Transfer (DSSAT) sub-model CSM-CROPGRO-Cotton-P was evaluated to estimate the observed and simulated P use in two cotton cultivars grown at three P application rates under the semi-arid climate of southern Punjab, Pakistan. The results revealed that both the cultivars performed best at medium rate of P application (57 kg ha⁻¹) in terms of days to anthesis, days to maturity, seed cotton yield, total dry matter production, and harvest index during 2013 and 2014. Cultivar FH-142 performed better than MNH-886 in terms of different yield components. There was a good agreement between observed and simulated days to anthesis (0 to 1 day), days to maturity (0 to 2 days), seed cotton yield, total dry matter, and harvest index with an error of −4.4 to 15%, 12–7.5%, and 13–9.5% in MNH-886 and for FH-142, 4–16%, 19–11%, and 16–8.3% for growing years 2013 and 2014, respectively. CROPGRO-Cotton-P would be a useful tool to forecast cotton yield under different levels of P in cotton production system of the semi-arid climate of Southern Punjab.
Показать больше [+] Меньше [-]Electrochemical disinfection and removal of ammonia nitrogen for the reclamation of wastewater treatment plant effluent Полный текст
2017
Ding, Jing | Zhao, Qing-Liang | Jiang, Jun-Qiu | Wei, Liang-Liang | Wang, Kun | Zhang, Yun-Shu | Hou, Wei-Zhu | Yu, Hang
Residual ammonia and pathogenic microorganisms restrict the reclamation and reuse of wastewater treatment plant (WWTP) effluent. An electrochemical system was developed for the simultaneous removal of ammonia and disinfection of actual WWTP effluent. The performance of the electrochemical process on synthetic wastewater at different chloride ion concentrations was also investigated. Results demonstrated that the optimal chloride concentration for ammonia and Escherichia coli (E. coli) removal was 250 mg/L. Successful disinfection of E. coli in actual effluent was achieved at 0.072 Ah/L, but the inverse S-type inactivation curve indicated that there was a competitive consumption of strong oxidants and chloramines working as another disinfectant. A higher electric charge (0.58 Ah/L) was required to simultaneously reduce E. coli and ammonia to levels that meet the reclamation requirements for WWTP effluent. At this electric charge, no trihalomethane, chlorate, or perchlorate in the system was observed, indicating the biological safety of this process. These results demonstrate the potential of this electrochemical process as a tertiary wastewater treatment process for WWTP effluent reclamation purposes.
Показать больше [+] Меньше [-]High levels of mercury in wetland resources from three river basins in Ghana: a concern for public health Полный текст
2017
Gbogbo, Francis | Otoo, Samuel D. | Huago, Robert Quaye | Asomaning, Obed
Crustaceans, mollusks, and fish are wetland resources that constitute an important source of protein and foreign exchange for the Ghanaian population, and many species of these are sold in the open market and restaurants, yet studies on their heavy metal contents are generally scarce. This paper evaluates the levels of mercury in five species of crustaceans, two species of mollusks, and ten species of fish inhabiting three river basins with different catchment activities in Ghana. These include the Ankobra Basin, characterized with mining and agriculture, Densu Basin, associated with urban waste discharges and agriculture, and Lower Volta River Basin, associated with agricultural activities. Mercury concentration was highest in Ankobra (2.5 ± 2.59 μg g⁻¹) followed by Densu (1.75 ± 1.35 μg g⁻¹) and Volta (0.74 ± 1.46 μg g⁻¹). The mercury load of the organisms range from <0.1 to 4 μg g⁻¹ with the highest load in Cynoglossus senegalensis at Ankobra. Except for Panaeus notialis from Densu and Ankobra, and three other species from Ankobra (Tympanotonus fuscatus, Cardisoma armatum, Callinectes amnicola) in which mercury was not detected, mercury loads of all the organisms were above the permissible limit of 0.5 mg kg⁻¹ established by Commission Regulation-EC (2006) for fishery products and muscle meat of fish. Weekly quantities of crustaceans and mollusks considered safe for consumption by adults ranged from 88 and 1000 g while that of the fishes were between 70 and 700 g (on a dry weight basis) depending on the species. It was clear that some caution needs to be exercised in the consumption of Ghana’s fresh and brackish water fisheries.
Показать больше [+] Меньше [-]The influence of maternal exposure history to virus and medicine during pregnancy on congenital heart defects of fetus Полный текст
2017
Liang, Qianhong | Gong, Wei | Zheng, Dongming | Zhong, Risheng | Wen, Yunjie | Wang, Xiaodan
Congenital heart disease (CHD) is the most common birth defect. It is due to dysfunction of the heart and great vessels during embryo development stage, or the channel was not closed after birth. This study focuses on investigating the influence of virus infection and medicine history during pregnancy on the incidence rate of CHD of fetus. We conducted a retrospective birth cohort study of infant born in the maternal and child health hospital of Fanyu district in Guangzhou. Five thousand three hundred eighty one cases with complete medical records, including mothers, fathers, and infants, were enrolled. The exposure history of mothers to virus and medicine from 6 months before pregnancy to prenatal examination was investigated, including mflu, mumps, measles, rubella, chickenpox, and hepatitis and antibiotics, tocolytic agent, anticonvulsants, antipyretic and analgesic, antitumor drug, folic acid supplement, and contraceptive. The relationship between virus infection and medicine history during pregnancy and CHD was analyzed. There was statistical difference between a normal group and a defected group in influenza infection and tocolytic agent and contraceptive pill. The exposure history to influenza and medicines, such as tocolytic agent and contraceptive pill, during pregnancy influenced the incidence rate of CHD of fetus.
Показать больше [+] Меньше [-]A comparative study of cambium histology of Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) under urban pollution Полный текст
2017
de Vasconcellos, Thaís Jorge | Da Cunha, Maura | Callado, Cátia Henriques
Air pollution is considered to be one of the main causes of forest decline. The cambium is responsible for increase in tree girth, and its functioning is determined by environmental pressures. This study compared cambium histology of Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) in polluted and preserved sites in the Atlantic Rainforest domain. Samples were obtained during periods of cambial activity and dormancy and were processed and examined according to standard light microscopy techniques. In addition to differences typically observed in cambium during periods of activity and dormancy, the fusiform initials were shorter in trees of the polluted site. Furthermore, cambial rays were shorter, but larger, in the polluted site. It should be noted that all parameters related to cambial rays showed significant differences between the study sites. This is the first report of the effects of pollution on cambial activity in a South American species. The results suggest a tolerance of C. speciosa to pollution and reveal this species to be an important biomarker for environmental monitoring studies.
Показать больше [+] Меньше [-]Real-time detection of organic contamination events in water distribution systems by principal components analysis of ultraviolet spectral data Полный текст
2017
Zhang, Jian | Hou, Dibo | Wang, Ke | Huang, Pingjie | Zhang, Guangxin | Loáiciga, Hugo
The detection of organic contaminants in water distribution systems is essential to protect public health from potential harmful compounds resulting from accidental spills or intentional releases. Existing methods for detecting organic contaminants are based on quantitative analyses such as chemical testing and gas/liquid chromatography, which are time- and reagent-consuming and involve costly maintenance. This study proposes a novel procedure based on discrete wavelet transform and principal component analysis for detecting organic contamination events from ultraviolet spectral data. Firstly, the spectrum of each observation is transformed using discrete wavelet with a coiflet mother wavelet to capture the abrupt change along the wavelength. Principal component analysis is then employed to approximate the spectra based on capture and fusion features. The significant value of Hotelling’s T² statistics is calculated and used to detect outliers. An alarm of contamination event is triggered by sequential Bayesian analysis when the outliers appear continuously in several observations. The effectiveness of the proposed procedure is tested on-line using a pilot-scale setup and experimental data.
Показать больше [+] Меньше [-]Presence and distribution of current-use pesticides in surface marine sediments from a Mediterranean coastal lagoon (SE Spain) Полный текст
2017
Moreno-González, R. | León, V. M.
The spatial and seasonal distributions of current-use pesticides (CUPs), including triazines, organophosphorus pesticides, and tributylphosphate, were characterized in surface sediments from the Mar Menor lagoon during 2009 and 2010. The impact of two flash flood events on the input of CUPs and their distribution in the lagoon were also assessed. The total (dissolved + sorbed phase) input of CUPs in the two flash floods through the El Albujón watercourse into the lagoon was estimated at 38.9 kg, of which 9.9 kg corresponded to organophosphorus pesticides and 5.5 kg to triazines. CUP distribution onto sediments was not homogeneous in the lagoon due to the different contaminant sources, sediment types, and the physicochemical and hydrodynamic conditions of the Mar Menor lagoon. Thirteen CUPs were detected in 2009 and 19 in 2010, including mainly herbicides, insecticides, and the additive tributylphosphate. Mean CUP concentrations in the lagoon were generally below 20 ng g⁻¹, except for chlorpyrifos and tributylphosphate in 2010. The highest concentrations were detected in depositional areas of the lagoon, in the area of influence of the El Albujón watercourse and other wadis with groundwater contributions such as El Mirador (north) and Los Alcázares (east) and that of marine water from El Estacio channel. In fact, the maximum concentration was detected close to El Albujón watercourse (chlorpyrifos, 102.8 ng g⁻¹ dry weight). Four herbicides, two insecticides, two fungicides, and tributylphosphate showed a risk quotient higher than 1, with that for chlorpyrifos ranging from 96 to 35,200 after flash flood events.
Показать больше [+] Меньше [-]