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991.
Estimation of Nitrogen and Phosphorus in Effluent from the Striped Catfish Farming Sector in the Mekong Delta,Vietnam 总被引:1,自引:0,他引:1
In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish
(Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8°33′–10°55′N, 104°30′–106°50′E), South Vietnam. The sector accounted for 687,000 t
production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial
and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were
similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge
levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish).
Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged
31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned
directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish
farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta
compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P
discharged in the production of a tonne of production was estimated. 相似文献
992.
Matthieu Guillemain Johan Elmberg Michel Gauthier-Clerc Grégoire Massez Richard Hearn Jocelyn Champagnon Géraldine Simon 《Ambio》2010,39(2):170-180
Animal populations are exposed to large-scale anthropogenic impact from e.g. climate change, habitat alteration and supplemental
stocking. All of these may affect body condition in wintering dabbling ducks, which in turn may affect an individual’s survival
and reproductive success. The aim of this study was to assess whether there have been morphometric changes in Mallard (Anas platyrhynchos) and Teal (Anas crecca) over the last 30 years at a major wintering site. Body mass and condition increased from the 1950s–1960s to the 2000s in
both species. The increase in body mass amounted to as much as 11.7%, with no corresponding change in body size. Improved
body condition was maintained from early to mid-winter, but then converged with historical values for late winter. Our interpretation
is that increasingly benign ambient winter conditions permit ducks to maintain better energetic “safety margins” throughout
winter, and that converging spring departure values may be related to evolutionary flight energetic optima. The observed changes
are consistent with large-scale climate amelioration and local/regional habitat improvement (both anthropogenic). 相似文献
993.
采用SummA罐采集样品,自动进样器进样,三级冷阱预浓缩样品,全二维气相色谱/飞行时间质谱法(GC×GC/TOFMS)测试分析,以较长的非极性柱Rxi-5MS(60m×320μm×1.0μm)作为第一维柱,较短的中等极性柱DB-17MS(2.0×0.1mm×0.1μm)作为第二维柱,对环境空气中的VOC成分进行了定性定量分析。通过考察方法的线性范围、精密度、加标回收率、检出限与《空气和废气监测分析方法》(四版)给出的两个方法比较,证实该方法特性不仅满足方法学要求,而且能够更加准确快速监测环境空气中VOC。 相似文献
994.
K.M.S. Sundaram 《Journal of environmental science and health. Part. B》2013,48(3):541-579
Abstract Two formulation concentrates of the insecticide, RH‐5992 [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyI) hydrazine], an aqueous flowable (2F) and an emulsion‐suspension (ES), were diluted with water to provide spray mixes containing dosage rates ranging from 35 to 150 g of the active ingredient (AI)/ha. The mixes were sprayed in a laboratory chamber, onto balsam fir branch tips collected from field trees and greenhouse‐grown seedlings. Droplet spectra and spray mass recovery were determined on artificial samplers. Simulated rainfall of two different intensities was applied at different rain‐free periods, and rain droplet sizes were determined. Foliar washoff of RH‐5992 was assessed after application of different amounts of rain, and the increase in soil residues was evaluated. A direct relationship was indicated between the amount of rainfall and RH‐5992 washoff. The larger the rain droplet size, the greater the amount washed off. Longer rain‐free periods made the deposits more resistant to rain. Regardless of the amount of rainfall, rain droplet size and rain‐free period, foliar deposits of the 2F formulation were washed off to a greater extent than the ES formulation. The increase in soil residues due to foliar washoff was greater for the 2F than for the ES formulation. The deposits of the emulsion‐suspension were consistently more resistant to rain‐washing than those of the aqueous flowable formulation. 相似文献
995.
Jayakrishnan Saimandir Madhuban Gopal 《Journal of environmental science and health. Part. B》2013,48(3):292-301
Indoxacarb was applied at 75 and 150 g a.i. ha? 1 for two years to an eggplant (Solanum melongena L.) crop grown in the field plots in order to evaluate its efficacy for management of the lepidopteron pest, shoot and fruit borer. The residues of the insecticide were quantified by high-pressure liquid chromatography (HPLC). The mean initial deposits of indoxacarb on eggplant fruits were found to be 2.60–2.634 mg kg? 1 and 3.64–3.68 mg kg? 1 from the two rates of applications, respectively. They declined with time and reached to non-detectable (< 0.02 mg kg? 1) after 15–20 d. Residues dissipated with a half-life of 3.0–3.8 d from both first and second-year application. A 3 d waiting period for harvest of fruits after insecticide application and processing resulted in the residue levels that were below the Codex maximum residue limit (MRL) of 0.5 mg kg? 1 thereby achieving a maximum safety and minimum risk to consumers. The best combination of chemicals for decontamination of indoxacarb was found to be by washing with a mixture of alkali and potassium permanganate (KMnO4) thereby resulting in the removal of 67.5% and 59.2 % residues for 5 and 10 μ g g? 1 spiking doses, respectively. Major products formed on reaction of indoxacarb with alkali were identified by electron spray ionization chromatography/mass spectrometry (ESI/MS). The per cent reduction on the weight and number basis of treated eggplant plots were compared to those observed in control plots to demonstrate the effectiveness of indoxacarb treatment on shoot and fruit borer population. 相似文献
996.
Isabel C.F. Damin Maria A.E. Santo Rosmari Hennigen Denise M. Vargas 《Journal of environmental science and health. Part. B》2013,48(12):1103-1111
In the present study, a method for the determination of mercury (Hg) in fish was validated according to ISO/IEC 17025, INMETRO (Brazil), and more recent European recommendations (Commission Decision 2007/333/EC and 2002/657/EC) for implementation in the Brazilian Residue Control Plan (NRCP) in routine applications. The parameters evaluated in the validation were investigated in detail. The results obtained for limit of detection and quantification were respectively, 2.36 and 7.88 μg kg?1 of Hg. While the recovery varies between 90–96%. The coefficient of variation was of 4.06–8.94% for the repeatability. Furthermore, a comparison using an external proficiency testing scheme was realized. The results of method validated for the determination of the mercury in fish by Hydride generation atomic absorption spectrometry were considered suitable for implementation in routine analysis. 相似文献
997.
Feng Zhu Zhijian Yao Wenliang Ji Deye Liu Hao Zhang Aimin Li Zongli Huo Qing Zhou 《Frontiers of Environmental Science & Engineering》2020,14(3):51
998.
Joseânia Salbego Débora Seben Leticia Raquel Sippert Luciane Tourem Gressler Jessyka Arruda da Cunha Renato Zanella 《Journal of environmental science and health. Part. B》2020,55(8):749-755
AbstractThis study assessed the hematological, enzymatic and osmoregulatory responses of silver catfish (Rhamdia quelen) exposed to sublethal concentrations (1.125 and 3.750?µg/L) of a commercial thiamethoxam-containing insecticide used on rice crops. Groups of 6 fish per tank (in triplicate, n?=?3, total 54 fish) were exposed for up to 96?h to different concentrations of the compound. After this period, fish were placed in clean water for 48?h. Two fish from each tank (6 per treatment) that had been exposed to the insecticide for 24?h were anesthetized with eugenol and blood was collected to evaluate hematological and biochemical parameters. Blood, liver and muscle were collected for determination of metabolic parameters, plasma cortisol, Cl-, Na+ and K+ levels and H+-ATPase and Na+/K+-ATPase activity in the gill. H+-ATPase activity was higher in fish exposed to 1.125?µg/L insecticide at 24?h compared to control (0.0?µg/L). Differences in cortisol levels were evidenced throughout the experimental period. These results indicated that exposure to the insecticide changed the hematological, biochemical and metabolic profile of the animals, suggesting concern about environmental safety. Therefore, we discourage the use of this pesticide in areas that come into contact with water bodies inhabited by fish. 相似文献
999.
三重四极杆质谱技术测定固体废弃物中多氯联苯 总被引:1,自引:0,他引:1
以二氯甲烷为萃取剂,采用快速溶剂萃取、凝胶渗透色谱净化、三重四极杆质谱技术测定固体废弃物中7种多氯联苯单体,选择十氯联苯为内标物,2,4,5,6-四氯间二甲苯为替代物。质谱采用MRM扫描,优化了目标物质保留时间、母离子和子离子质量数及碰撞能量等参数。方法在0.050 mg/L~2.00 mg/L范围内线性良好,7种多氯联苯单体的检出限为0.194 ng/g~0.355 ng/g(以称取30 g样品、定容至2.0 mL计),标准样品回收率多在60%~105%之间,空白加标样品测定值的相对标准偏差在8.6%~13.0%之间。 相似文献
1000.