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701.
Empirical gas emission and oxidation measurement at cover soil of dumping site: example from Malaysia 总被引:1,自引:0,他引:1
Mohammed F. M. Abushammala Noor Ezlin Ahmad Basri Hassan Basri Abdul Amir H. Kadhum Ahmed Hussein El-Shafie 《Environmental monitoring and assessment》2013,185(6):4919-4932
Methane (CH4) is one of the most relevant greenhouse gases and it has a global warming potential 25 times greater than that of carbon dioxide (CO2), risking human health and the environment. Microbial CH4 oxidation in landfill cover soils may constitute a means of controlling CH4 emissions. The study was intended to quantify CH4 and CO2 emissions rates at the Sungai Sedu open dumping landfill during the dry season, characterize their spatial and temporal variations, and measure the CH4 oxidation associated with the landfill cover soil using a homemade static flux chamber. Concentrations of the gases were analyzed by a Micro-GC CP-4900. Two methods, kriging values and inverse distance weighting (IDW), were found almost identical. The findings of the proposed method show that the ratio of CH4 to CO2 emissions was 25.4 %, indicating higher CO2 emissions than CH4 emissions. Also, the average CH4 oxidation in the landfill cover soil was 52.5 %. The CH4 and CO2 emissions did not show fixed-pattern temporal variation based on daytime measurements. Statistically, a negative relationship was found between CH4 emissions and oxidation (R 2?=?0.46). It can be concluded that the variation in the CH4 oxidation was mainly attributed to the properties of the landfill cover soil. 相似文献
702.
Alam Md. Asraful Wan Chun Tran Dang Thuan Mofijur M. Ahmed Shams Forruque Mehmood Muhammad Aamer Shaik Feroz Vo Dai-Viet N. Xu Jingliang 《Environmental Chemistry Letters》2022,20(2):1153-1168
Environmental Chemistry Letters - Microalgae are photosynthetic cell factories of global interest for fuels, food, feed, bioproducts, carbon sequestration, waste mitigation, and environmental... 相似文献
703.
Ahmed A. Al-Taani 《Environmental monitoring and assessment》2014,186(10):6223-6239
Temporal status and trends in water quality of Al-Wehda Dam, Jordan, from 2006 to 2012 indicate that the dam is subject to a combination of impacts from rainstorm and agricultural runoffs. It also revealed that mineral dissolution, sediment load, rainfall events, evaporation, and water-level fluctuation are the major contributors to variations in water quality. The water chemistry of the impounded Al-Wehda Reservoir showed that Na, Ca, Mg, HCO3, and Cl are the principal ions, reflecting the dominance of carbonate weathering, with some contribution of silicates. The pH values showed a cyclic pattern with highest values observed in the spring seasons. Total dissolved solids (TDS), Ca, Mg, and HCO3 are primarily related to leaching and evaporation, with elevated levels that occurred in the rainy winter months. In contrast, seasonal patterns in Na, K, Cl, and NH4–N contents showed decreased values in winter. Peaks in NO3–N observed in winter are strongly associated with agricultural runoff. Fluctuations in chlorophyll-a level were coincided with low ratio of total nitrogen (TN) to total phosphorus (TP). Seasonal variations in organic matter content were also apparent, with peaks that generally occurred in spring through early fall corresponding with high algal growth. On an annual basis, the vast majority of water quality data have generally declined, particularly, in 2011. However, it is not clear whether these decreases are related to change in management practices within the Yarmouk basin, or protective measures have been implemented. Comparison of in-lake and post-dam water quality from 2009 to 2011 showed variation in concentrations, where Ca, HCO3, NO3–N, Mg, and TDS showed relatively greater post-dam values than in-lake water, whereas pH, Na, Cl, K, COD, BOD5, and chlorophyll-a were consistently lower in post-dam water. This comparison emphasizes the importance of self-purification capacity of Al-Wehda Dam in reducing some contaminants. 相似文献
704.
705.
Semi-arid regions across the globe are fronting water crises, signaling a challenge to ensure future water security. Given the high inter-seasonal rainfall variability and unrestrained groundwater extraction, the precise quantification of groundwater flow components in an aquifer system is a priority. To address this challenge, we used high-resolution remote sensing (RS) data (Landsat and IRS) and GIS modeling (SEBAL, ArcCN) to spatially quantify major groundwater balance (GWB) components, viz., evapotranspiration (ET), rainfall recharge (R), surface runoff (Q), groundwater extraction (PG), irrigation return flow (IRF), and ultimately changes in groundwater storage (ΔS) in a small semi-arid crystalline representative watershed. Results show that a total of ~?230 mm of groundwater is extracted during 2008–2009, creating a negative impact on the groundwater resource, which is further enhanced by limited recharge and high ET. A decrease of approximately 65 mm in groundwater storage is observed in a single hydrological year, and given a very low specific yield, this decrease will introduce large water level decline. The study establishes that declining groundwater level in the watershed is a direct result of over-extraction, and owing to this scenario, efficient irrigation and land use policies are suggested as potential approaches to minimize extraction specifically in the dry season. Our methodology provides a systematic assessment of vital GWB components at a high spatial resolution and an insight on various sustainable mitigation methods. This methodology is useful in the planning and management of groundwater resources, particularly in water-stressed areas. 相似文献
706.
Farghali Mohamed Osman Ahmed I. Mohamed Israa M. A. Chen Zhonghao Chen Lin Ihara Ikko Yap Pow-Seng Rooney David W. 《Environmental Chemistry Letters》2023,21(4):2003-2039
Environmental Chemistry Letters - New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine... 相似文献
707.
Kinetic studies on the NADP-linked glutamate dehydrogenase (GDH) activity in 8 species of marine phytoplankton have been carried out. The pH optima, linearity of reactions, apparent energies of activation, and apparent K
m values for NADPH, NH
4
>+
and -ketoglutarate were determined. Based on these data, an accurate, sensitive enzyme assay procedure is presented which was successfully tested on shipboard during a recent cruise in an upwelling region. Preliminary studies on inhibition and activation of the NADP-linked GDH activity have also been carried out. In addition to NADP-linked GDH activity, NAD-linked GDH activity was discovered in certain species of phytoplankton. The possible physiological roles of NAD-and NADP-linked GDH enzymes are discussed.Contribution No. 911 from the Department of Oceanography, University of Washington. This research was supported by the National Science Foundation Grants GA-34165 and GX-33502. 相似文献
708.
Measurement of a respiratory control ratio is deemed very useful in determination of energy balance in respiration. We have defined and computed a control ratio as the ratio of the rate of oxygen consumption in vivo to the calculated maximum rate of oxygen consumption in vitro as measured by enzymatic electron transport rates. In order for a control ratio to serve a useful purpose in calculating in situ oxygen consumption in a water parcel, the ratio must be fairly constant. Our results indicated that this is precisely so in healthy cultures of the 9 species of phytoplankton studied. The data presented in this communication further point towards the potential for making reasonable estimates of phytoplankton oxygen consumption in an ocean water parcel by directly utilizing in vitro electron transport activity measurements. 相似文献
709.
Mubark Amal E. Eliwa Ahmed A. Zaki Salah A. Mohamed Basma T. 《Journal of Polymers and the Environment》2022,30(10):4178-4192
Journal of Polymers and the Environment - A considerable increase in the importance of vanadium globally and its common uses in many manufacturable alloys made it a target for much scientific... 相似文献
710.
Species differences in accumulation of nitrogen pools in phytoplankton 总被引:12,自引:0,他引:12
The changes in the intracellular concentrations of nitrate, ammonium, free amino acids, protein, DNA, RNA and total nitrogen were measured in batch cultures of seven species of marine phytoplankton as they progressed from being nitrogen sufficient to being nitrogen starved. After several days of nitrogen starvation, either nitrate or ammonium was added to the cultures, and the measurements were continued for 10 to 36 h. By this means it was possible to assess the long-term and short-term changes in cellular nitrogen compounds and how they relate to phytoplankton nitrogen uptake and growth. Considerable species differences were observed in the amounts and kinds of nitrogen compounds which were stored and the degree to which the utilization of these compounds could support growth if the external nitrogen supply is low or variable. Despite the species variation, the results suggest that the concentrations or ratios of a number of intracellular nitrogen compounds can be used to assess the nitrogen deficiency and/or growth rate of natural phytoplankton populations.Contribution No. 1373 from the School of Oceanography, University of Washington and Contribution No. 83006 from the Bigelow Laboratory for Ocean Sciences 相似文献