خيارات البحث
النتائج 3341 - 3350 من 4,043
Heavy metal and trace elements in riparian vegetation and macrophytes associated with lacustrine systems in Northern Patagonia Andean Range النص الكامل
2016
Juárez, Andrea | Arribére, María A. | Arcagni, Marina | Williams, Natalia | Rizzo, Andrea | Ribeiro Guevara, Sergio
Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.
اظهر المزيد [+] اقل [-]Mobility and plant availability of risk elements in soil after long-term application of farmyard manure النص الكامل
2016
Tlustoš, Pavel | Hejcman, Michal | Hůlka, Martin | Patáková, Michaela | Kunzová, Eva | Száková, Jiřina
Crop rotation long-term field experiments were established in 1955 and 1956 at three locations in the Czech Republic (Čáslav, Ivanovice, and Lukavec) differing in their climatic and soil physicochemical properties. The effect of long-term application of farmyard manure and farmyard manure + NPK treatments on plant-available, easily mobilizable, potentially mobilizable, and pseudo-total contents of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) contents in soils (in 2013) as well as the uptake of these elements by winter wheat (Triticum aestivum L.) grain and straw were analyzed in the two following seasons: 2012 and 2013. The treatments resulted in increasing the soil pH level when compared to the control, but the cation exchange capacity remained unchanged. Although all fertilizers were applied for six decades, the pseudo-total concentration elements in both the soil and wheat plants stayed far below those of the Czech and European threshold limits for agricultural soils and cereals for human nutrition and feedstuff. Although the mobile pools of As, Cu, and Zn were slightly changed at the treated soils, these changes were not related to the element uptake by the wheat plants. Moreover, the effect of the location and growing season was more decisive for the differences in soil and plant element contents than for the individual treatments. Thus, the long-term application of farmyard manure did not result in any substantial change in risk element contents in both soils and winter wheat plants.
اظهر المزيد [+] اقل [-]Predicting bromide incorporation in a chlorinated indoor swimming pool النص الكامل
2016
Chowdhury, Shakhawat | Mazumder, Abu Jafar | Husain, Tahir
The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9–11.1) and 1.4 (range 0.52–2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5–7.5) and 1.2 (range 0.6–2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m³, respectively, and their ranges were 36.3–105.8 and 44.1–133.6 μg/m³, respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools.
اظهر المزيد [+] اقل [-]Physical properties of particulate matter from animal houses—empirical studies to improve emission modelling النص الكامل
2016
Mostafa, Ehab | Nannen, Christoph | Henseler, Jessica | Diekmann, Bernd | Gates, Richard | Buescher, Wolfgang
Maintaining and preserving the environment from pollutants are of utmost importance. Particulate matter (PM) is considered one of the main air pollutants. In addition to the harmful effects of PM in the environment, it has also a negative indoor impact on human and animal health. The specific forms of damage of particulate emission from livestock buildings depend on its physical properties. The physical properties of particulates from livestock facilities are largely unknown. Most studies assume the livestock particles to be spherical with a constant density which can result in biased estimations, leading to inaccurate results and errors in the calculation of particle mass concentration in livestock buildings. The physical properties of PM, including difference in density as a function of particle size and shape, can have a significant impact on the predictions of particles’ behaviour. The aim of this research was to characterize the physical properties of PM from different animal houses and consequently determine PM mass concentration. The mean densities of collected PM from laying hens, dairy cows and pig barns were 1450, 1520 and 2030 kg m⁻³, respectively, whilst the mass factors were 2.17 × 10⁻³, 2.18 × 10⁻³ and 5.36 × 10⁻³ μm, respectively. The highest mass concentration was observed in pig barns generally followed by laying hen barns, and the lowest concentration was in dairy cow buildings. Results are presented in such a way that they can be used in subsequent research for simulation purposes and to form the basis for a data set of PM physical properties.
اظهر المزيد [+] اقل [-]Preliminary investigation on the effect of earthworm and vegetation for sludge treatment in sludge treatment reed beds system النص الكامل
2016
Chen, Zhongbing | Hu, Shanshan | Hu, Chengxiao | Huang, Liangliang | Liu, Hongbo | Vymazal, Jan
Sewage sludge treatment is becoming one of the most significant challenges for domestic wastewater management. Optimization of sludge management for reducing sludge handling cost in wastewater treatment plant is highly demanded. Sludge treatment reed bed system (STRB) is an eco-environmentally friendly technology which has a low investment input and reduced costs for operation and maintenance. The objective of this study is to evaluate the effect of earthworm assistant STRB in terms of sludge dewatering and stabilization of surplus sludge. The results show that draining and evapotranspiration (ET) take the main role for sludge dewatering; with maximum of 77 and 43 % water was removed through draining and ET, respectively. Plants improved ET rate up to 13.1 % in the planted STRB compare with the unplanted STRB. The combination of plants and earthworms increased ET rate of 20.9 % more than the control STRB (unplanted without earthworms). The planted STRB with earthworm reached the lowest water content in accumulated sludge of 46 %. There was a systematic increase of total solids (TS) concentration from 0.5 % in the influent to 25–54 % in the accumulated sludge. Earthworms enhanced the sludge stabilization dramatic with the ratio of volatile solids (VS)/TS decreased from 49 % in the influent to 18 % in the accumulated sludge in the earthworm assistant STRB. The results demonstrated a good efficiency for sludge dewatering and stabilization with the assistant of earthworms in STRBs, which can be an alternative technology for sludge treatment in wastewater treatment plants.
اظهر المزيد [+] اقل [-]Leaf-based physiological, metabolic, and ultrastructural changes in cultivated cotton cultivars under cadmium stress mediated by glutathione النص الكامل
2016
Daud, M. K. | Mei, Lei | Azizullah, Azizullah | Dawood, Muhammad | Ali, Imran | Mahmood, Qaisar | Ullah, Waheed | Jamīl, Muḥammad | Zhu, S. J.
Cadmium (Cd) pollution is present in the world over especially in the industrialized parts of the world. To reduce Cd accumulation in various crops especially food crops, alleviating agents such as reduced glutathione (GSH) can be applied, which are capable either to exclude or to sequester Cd contamination. This study investigated the leaf-based spatial distribution of physiological, metabolic, and microstructural changes in two cotton cultivars (Coker 312 and TM-1) under GSH-mediated Cd stress using single levels of Cd (50 μM) and GSH (50 μM) both separately and in mix along with control. Results showed that GSH revived the morphology and physiology of both cotton cultivars alone or in mix with Cd. Cd uptake was enhanced in all segments of leaf and whole leaf upon the addition of GSH. GSH alleviated Cd-induced reduction in the photosynthetic pigment compositions and chlorophyll a fluorescence parameters. Mean data of biomarkers (2,3,5-triphenyltetrazolium (TTC), total soluble protein (TSP), malondialdehyde (MDA), hydrogen peroxide (H₂O₂)) revealed the adverse effects of Cd stress on leaf segments of both cultivars, which were revived by GSH. The oxidative metabolism induced by Cd stress was profoundly influenced by exogenous GSH application. The microstructural alterations were mainly confined to chloroplastic regions of leaves under Cd-stressed conditions, which were greatly revived upon the GSH addition. As a whole, Cd stress greatly affected TM-1 as compared to Coker 312. These results suggest a positive role of GSH in alleviating Cd-mediated changes in different leaf sections of cotton cultivars.
اظهر المزيد [+] اقل [-]The use of food waste-based diets and Napier grass to culture grass carp: growth performance and contaminants contained in cultured fish النص الكامل
2016
Cheng, Zhang | Mo, Wing-Yin | Nie, Xiang-Ping | Li, Kai-Bing | Choi, Wai-Ming | Man, Yu-Bon | Wong, Ming-Hung
The present study used commercial feeds, food waste feeds, Napier grass, and mixed feeds (food waste feed to Napier grass ratio, 1:10) to feed grass carp (Ctenopharyngodon idellus). The results indicated that grass carp fed with food waste feeds and mix feeds achieved growth performance (based on specific growth rate and feed conversion ratio) that was similar to commercial feeds (p > 0.05). Concentrations of metalloid/metals in food waste feeds and polycyclic aromatic hydrocarbons (PAHs) in Napier grass were relatively higher than other types of fish feeds (p < 0.05). However, most of the metalloid/metals and PAH levels in fish fed with four types of fish feeds were not significantly different (p > 0.05). These findings show that food waste feeds are suitable for using in the production of fish feed and Napier grass can be served as supplemental feeds for grass carp, and hence reducing the production cost.
اظهر المزيد [+] اقل [-]Characteristic variation and original analysis of emergent water source pollution accidents in China between 1985 and 2013 النص الكامل
2016
Qu, Jianhua | Meng, Xianlin | Ye, Xiuqing | You, Hong
China has suffered various water source pollution incidents in the past decades, which have resulted in severe threats to the safety of the water supply for millions of residents. From the aspects of quantity fluctuation, temporal volatility, regional inequality, pollutant category variation, and accident type differences, this study first characterizes the current status of water source contaminations in China by analyzing 340 pollution events for the period spanning from 1985 to 2013. The results show a general increase in the number of accidents during the period 1985–2006 and then a rapid decline starting in 2007. Spring and summer are high-incidence seasons for pollution, and the accident rate in developed southeastern coastal areas is far higher than that in the northwestern regions. Hazardous chemicals and petroleum are the most frequently occurring pollutants, whereas heavy metals and tailings are becoming emerging contaminants during occasional pollutions. Most of the accidents that occurred before 2005 were blamed on illegal emissions or traffic accidents; however, leakage in production has gradually become a major accident type in the past decade. Then, in combination with government actions and policy constraints, this paper explores the deep inducements and offers valuable insight into measures that should be taken to ensure future prevention and mitigation of emergent source water pollution.
اظهر المزيد [+] اقل [-]Biochar enhances the cadmium tolerance in spinach (Spinacia oleracea) through modification of Cd uptake and physiological and biochemical attributes النص الكامل
2016
Younis, Uzma | Malik, Saeed Ahmad | Rizwan, Muhammad | Qayyum, Muhammad Farooq | Ok, Yong Sik | Shah, Muhammad Hasnain Raza | Rehman, Rabia Abdur | Ahmad, Niaz
Cadmium (Cd) has no known role in plant biology and is toxic to plants and animals. The Cd mainly accumulated in agricultural soils through anthropogenic activities, such as sewage water irrigation and phosphorus fertilization. Biochar (BC) has been proposed as an amendment to reduce metal toxicity in plants. The objective of this study was to evaluate the role of BC (cotton stick at a rate of 0, 3, and 5 %) on Cd uptake and the photosynthetic, physiological, and biochemical responses of spinach (Spinacia oleracea) grown in Cd-spiked soil (0, 25, 50, 75, and 100 mg Cd kg⁻¹ soil). The results showed that Cd toxicity decreased growth, photosynthetic pigments, gas exchange characteristics, and amino acid and protein contents in 52-day-old spinach seedlings. The Cd treatments increased the concentrations of Cd, sugar, ascorbic acid, and malondialdehyde (MDA) in plants. The application of BC ameliorated the harmful effects of Cd in spinach plants. Under Cd stress, BC application increased the growth, photosynthesis, and protein contents and decreased Cd concentrations and MDA contents in plants. The maximum BC-mediated increase in dry biomass was about 25 % with 5 % BC application in control plants. It is concluded that BC could ameliorate Cd toxic effects in spinach through changing the physiological and biochemical attributes under Cd stress.
اظهر المزيد [+] اقل [-]Estimation of long-term Ca2+ loss through outlet flow from an agricultural watershed and the influencing factors النص الكامل
2016
Zhang, Wenzhao | Yin, Chunmei | Chen, Chunlan | Chen, Anlei | Xie, Xiaoli | Fu, Xingan | Hou, Haijun | Wei, Wenxue
Soil Ca²⁺ loss from agricultural lands through surface runoff can accelerate soil acidification and render soil degradation, but the characteristics of Ca²⁺ loss and influencing factors in watershed scale are unclear. This study was carried out in a watershed with various land uses in a subtropical region of China. The outlet flow was automatically monitored every 5 min all year round, and the water samples were collected twice a year from 2001 to 2011. The concentrations of Ca²⁺, Mg²⁺, K⁺, total nitrogen (TN), and total phosphorus (TP) of water samples were measured. The dynamic losses of the nutrients through the outlet flow were estimated, and the relationships between the nutrient losses and rainfall intensity as well as antecedent soil moisture were investigated. The results showed that great variations of nutrient concentrations and losses appeared during the investigation period. The average concentrations of Ca²⁺, Mg²⁺, K⁺, TN, and TP were 0.43, 0.08, 0.10, 0.19, and 0.003 mmol L⁻¹, respectively. The average Ca²⁺ loss reached 1493.79 mol ha⁻¹ year⁻¹ and was several times higher than for Mg²⁺, K⁺, and TN, about 140 times higher than for TP. Rainfall intensity had remarkable effects on Ca²⁺ concentration (P < 0.01) and loss (P < 0.05) when it reached rainstorm level (50 mm day⁻¹), while a quadratic relationship was observed between antecedent soil moisture and Ca²⁺ concentration only when rainfall intensity was less than 50 mm day⁻¹. In a word, much greater amounts of Ca²⁺ were lost from the watershed, and this may be one important contributor to the increasing acidification of acidic soils in subtropical regions.
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