共查询到20条相似文献,搜索用时 421 毫秒
1.
Adsorption and desorption of 137Cs by acid sulphate soils from the Nakhon Nayok province, South Central Plain of Thailand located near the Ongkarak Nuclear Research Center (ONRC) were investigated using a batch equilibration technique. The influence of added limestone (12 and 18 tons ha?1) on 137Cs adsorption–desorption was studied. Based on Freundlich isotherms, both adsorption and desorption of 137Cs were nonlinear. A large portion (98.26–99.97%) of added 137Cs (3.7?×?103?7.03?×?105 Bq l?1) was sorbed by the soils with or without added lime. The higher lime treatments, however, favoured stronger adsorption of 137Cs as compared with soil with no lime, which was supported by higher K ads values. The addition of lime, the cation exchange capacity and pH of the soil increased and hence favoured the stronger adsorption of 137Cs. Acid sulphate soils with a high clay content, medium to high organic matter, high CEC, and predominant clay types consisting of a mixture of illite, kaolinite, and montmorillonite were the main soil factors contributing to the high 137Cs adsorption capacity. Competing cations such as NH4 +, K+, Na+, Ca2+, and Mg2+ had little influence on 137Cs adsorption as compared with liming, where a significant positive correlation between K ads and soil pH was observed. The 137Cs adsorption–desorption characteristics of the acid sulphate soils studied exhibited a very strong irreversible sorption pattern. Only a small portion (0.09–0.58%) of 137Cs adsorbed at the highest added initial 137Cs concentration was desorbed by four successive soil extractions. Results clearly demonstrated that Nakhon Nayok province acid sulphate soils have a high 137Cs adsorption capacity, which limits the 137Cs bioavailability. 相似文献
2.
The adsorption of some heavy metals onto the walls of harvested, washed, and dried non-living biomass cells of different Pseudomonas strains was studied at optimum experimental conditions using a simplified single component system. The Langmuir adsorption model was found to be a suitable approach to describe the system via multi-step processes. Isotherms measured at 30.0°C and pH 5.5 with [M]total = 10-100 mM for tight, reversible Cr6+(aq), Ni2+(aq), Cu2+(aq) and Cd2+(aq) binding by the cell walls of the investigated biomass fit the Langmuir model and give the pH-independent stoichiometric site capacities νi and equilibrium constants Ki for metal binding at specific biomass sites i = A, B, C, and D. Tight binding sites A, B, and D of the non-living biomass are occupied by CrVI, sites A and C by NiII, sites A and D by CdII, and only site B by CuII. It is concluded that νi is a stoichiometric parameter that is independent of the magnitude of Ki for binding site i and that the studied heavy metals selectively and tightly bind at different biomass sites. 相似文献
3.
Ulf Roar Aakenes 《Chemistry and Ecology》1995,10(1):61-69
The principles and operation of a gamma radiation sensor mounted on oceanographic buoys are described. the sensor has proved rugged in severe weather conditions and has satisfactory detection limits and accuracy. Continuous monitoring of artificially produced γ-emitters such as 137Cs, 134Cs, 131I, 133I, 132Te, naturally occuring emitters such as 40k and 214Bi in open sea conditions can provide important information in critical situations. 相似文献
4.
Mingxing GAO Yingying LI Hong YANG Yucheng GU 《Frontiers of Environmental Science & Engineering》2016,10(1):1-10
Pymetrozine is a selective insecticide with a unique chemical structure and mode to control hemipteran and homopteran. While pymetrozine has brought great benefits to crop production by killing insects, its residues in soil may have a detrimental effect on environment. Therefore, it is of great importance to investigate its behaviors in soil. In this study, the sorption and desorption of pymetrozine on six Chinese soils were investigated using a batch equilibrium approach to understand its mobile behavior in the soils. Both sorption and desorption isotherms of pymetrozine were in good agreement with the Freundlich model. The sorption coefficient KF varied between 3.37 and 58.32 mL∙g−1 and the sorption isotherms were nonlinear, with 1/n ranging from 0.57 to 0.91. A regression equation was proposed to predict the sorption of pymetrozine on six different soil samples: log KF = 4.3708 − 4.5709 × log (pH in 0.01mol·L−1 CaCl2) + 0.4700 × log OC% + 0.0057 × sand (%) + 0.0022 × CEC(clay), with R2 = 0.9982. The organic carbon content of soil positively affected the sorption of pymetrozine, but soil pH had a negative effect on the sorption. Additionally, effects of CaCl2 concentration, soil to solution ratio and pesticide form were investigated. The sorption was promoted with an increase in soil to solution ratio and a decrease in CaCl2 concentration. The possible variation of the five formulated products of pymetrozine was also investigated. 相似文献
5.
H. Florou 《Chemistry and Ecology》1996,12(4):253-258
This study deals with 137Cs dispersion and behaviour in the Aegean and Ionian Sea based on work done during the period 1984-1994, as a brief general review. Sea water, sediment and marine biota were analysed and measured by gamma spectrometry and the activity concentrations of 137Cs were evaluated with consideration to the sources of pollution. According to 137Cs levels the period is distinguished into three sub-periods, the pre-Chernobyl, the early Chernobyl influence and the late Chernobyl influence period. During the early period of the Chernobyl accident the 137Cs levels in the Greek marine environment increased roughly up to an order of magnitude if compared with the pre-accident ones. Since 1988, the late impact of the accident is focused mainly in the North Aegean Sea, at the Dardanelles mouth, due to the Black Sea outflow. 相似文献
6.
Several investigations were carried out on biotic and abiotic samples to determine the difference between Chernobyl and preChernobyl environmental radiocontamination of the Adriatic Sea. Special emphasis was put on the determination of 137Cs which resulted in the most abundant radionuclide in a wide variety of samples (sea water, sediment, pelagic and benthic species). Attention was also given to the neutron activation products 110mAg and 134Cs that were first discovered in the Adriatic ecosystem after the Chernobyl event in particular, although the 110Ag fallout deposition over the area was neglected in comparison to that of 137Cs, its bioaccumulation in macroalgae and molluscs was much higher suggesting some particular physiological accumulation mechanism. 相似文献
7.
Kun DING Xianghua WEN Liang CHEN Daishi HUANG Fan FEI Yuyang LI 《Frontiers of Environmental Science & Engineering》2014,8(5):693-702
As low oxygen and high ultraviolet (UV) exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea (AOA) in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR (q-PCR) and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria (AOB), and characterize the community structures of AOA in the samples. The number of AOA cells (9.34 × 10^7-2.32× 10^8 g^-1 soil) was 3.86-21.84 times greater than that of AOB cells (6.91 × 10^6-1.24 × 10^8 g^-1 soil) in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall's correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance. 相似文献
8.
Crude-oil-inundated soils were collected from the Agbada oil field in the Niger Delta region of Nigeria 2 months after the recorded incidence of oil spillage. The soils were taken on the second day of reconnaissance from three replicate quadrats, at surface (0-15 cm) and subsurface (15-30 cm) depths, using the grid sampling technique. The total extractable hydrocarbon content (THC) of the polluted soils ranged from 1.24 × 102 to 3.86 × 104 mg/kg at surface and subsurface depths (no overlap in standard errors at a 95% confidence level). Greenhouse trials for possible reclamation were later carried out using 10-100 g of (NH4)2SO4, KH2PO4 and KCl (NPK) fertilizer as nutrient supplements. Nitrogen as NO3-N and potassium were optimally enhanced at 2% (w/w) and 3% (w/w) of the NPK supplementation, respectively. Phosphorus, which was inherently more enhanced in the soils than the other nutrients, maintained the same level of impact after treatment with 20 g of NPK fertilizer. Total organic carbon (%TOC), total organic matter (%TOM), pH, and percentage moisture content all provided evidence of enhanced mineralization in the fertilizer-treated soils. If reclamation of the crude-oil-inundated soils is construed as the return to normal levels of metabolic activities of the soils, then the application of the inorganic fertilizers at such prescribed levels would duly accelerate the remediation process. However, this would be limited to levels of pollution empirically defined by such THC values obtained in this study. 相似文献
9.
Lee W. Cooper Jacqueline M. Grebmeier I. L. Larsen Scott S. Dolvin Andrew J. Reed 《Chemistry and Ecology》1998,15(1):27-46
Extensive surveys of sediment burdens of radiocaesium, specifically 137Cs, and other radioactive contaminants in the Arctic during the 1990's, indicate that almost all anthropogenic radionuclides buried on continental shelves adjacent to Alaska are derived from global bomb fallout. the 137Cs (half-life: 30.2y) activities observed in surface (0-4 cm) marine sediments however, vary widely, albeit much less than the expected current inventory resulting from bomb fallout at this latitude (∼100mBq cm-2). This observed geographical variation provided the opportunity to evaluate physical and biological mechanisms that may affect caesium biogeochemistry on Arctic continental shelves. We investigated whether high biological productivity in portions of the Bering and Chukchi Seas is effective in removing dissolved radiocaesium from the water column, and whether biological production in overlying water affects total radiocaesium inventories in sediments. Based upon C/N ratios in the organic fraction of shallow sediments, we found no evidence that higher inventories or surface activities of radiocaesium are present in areas with higher deposition of particulate organic matter. Based upon stable carbon isotope ratios of organic matter in sediments, we found no evidence that terrestrial runoff contributes proportionally to higher surface activities, although terrestrial runoff may affect total inventories of the radionuclide. Radiocaesium content of surface sediments was significantly correlated with total organic carbon content of sediments and the proportion of sediments in the finest sediment fractions. Because high current flow can also be expected to influence distributions of those sedimentary parameters, we conclude that re-distribution of 相似文献
10.
Jos L. Mateos Paloma Fern ndez Del Pino Francisco J. Guti rrez Ma ero Marí a Ruiz Palomino Juan J. Colon Jos A. Lucas Garcí a Agustí n Probanza 《Chemistry and Ecology》2000,17(2):125-152
Microbial communities (phospholipid fatty acid pattern, bacterial growing strategies, eco-physiological index (EPI) and total bacteria counts, as a number of heterotrophic cuhurable bacteria), substrate-induced respiration (SIR), and nitrogen mineralization were studied in three Mediterranean soils at three different depth levels (A, B and C). Soils were experimentally treated with a final concentration of 1000 ppm of trace metals (Cu2+, Zn2+, Al3+, Fe2+, Pb2+, Ni2+, Mn2+, Cr3+ and Cd2+). Soils were stored in 571 plastic containers for one year, and watered with 1001 during this period. Leachate was recovered through a bottom tap. Samples of the three depths were studied. Soil microbial communities showed different effects to other studies presented in the literature, but carried out on non-Mediterranean soils. Dramatic differences were found between treated soils and untreated ones, but not between soils or horizons. the treated soil displayed a decrease in CFUs, SIR N-mineralization and EPI together with a dominance of r-growing strategists. the relative moles percent of several PLFAs, especially 15:0, 16: 1ω7, cy17: 0, br18:0 and 18: 1ω7 decreased because of the pollution of soils, whereas 10Me16, 18:2ω6, cy19:0, i16:0 and br17:0 showed higher values than in untreated soils. 相似文献
11.
The objective of this experiment was to study the effects of malic, tartaric, oxalic, and citric acid on the adsorption and desorption characteristics of Cd by two typical anthropic soils (lou soil and irrigation-silted soil) in North-west China. Cadmium adsorption and desorption were studied under a range of temperatures (25°C, 30°C, 35°C, 40°C), organic acid concentrations (0.5–5.0 mmol·L-1), and pH values (2–8). The results showed that the Cd adsorption capacity of the lou soil was significantly greater than that of the irrigation-silted soil. Generally, Cd adsorption increased as the temperature increased. In the presence of NaNO3, the adsorption of Cd was endothermic with ΔH values of 31.365 kJ·mol-1 for lou soil and 28.278?kJ·mol-1 for irrigation-silted soil. The endothermic reaction indicated that H bonds were the main driving force for Cd adsorption in both soils. However, different concentrations of organic acids showed various influences on the two soils. In the presence of citric acid, chemical adsorption and van der Waals interactions were the main driving forces for Cd adsorption rather than H bonds. Although the types of organic acids and soil properties were different, the effects of the organic acids on the adsorption and desorption of Cd were similar in the two soils. The adsorption percentage of Cd generally decreased as organic acid concentrations increased. In contrast, the adsorption percentage increased as the pH of the initial solution increased. The exception was that adsorption percentage of Cd increased slightly as oxalic acid concentrations increased. In contrast, the desorption percentage of Cd increased with increasing concentrations of organic acids but decreased as the initial solution pH increased. 相似文献
12.
Meng Zhu Yongming Luo Ruyi Yang Shoubiao Zhou Juqin Zhang Mengyun Zhang Peter Christie Elizabeth L. Rylott 《Frontiers of Environmental Science & Engineering》2020,14(4):58
13.
生物炭对土壤中阿特拉津吸附特征的影响 总被引:3,自引:0,他引:3
为探究生物炭对土壤中阿特拉津的吸附特征及影响因素,采用批处理实验研究了灭菌(T1)、5%秸秆生物炭+灭菌(T2)、未灭菌(T3)和5%秸秆生物炭+未灭菌(T4)条件下对土壤中阿特拉津吸附特征及土壤理化性质的影响.结果表明,在最初0—12 h内,不同处理下阿特拉津吸附量均随时间的延长而快速增加,而在12—96 h内增加较为缓慢并逐渐趋于平衡.在96 h时,T2和T4处理下阿特拉津最大吸附量分别达到46.22 mg·kg-1和46.43 mg·kg-1,而未添加生物炭的T1和T3处理则有所降低,分别为44.20 mg·kg-1和43.09 mg·kg-1.准二级动力学模型更好地拟合不同处理下土壤对阿特拉津吸附特征,T2和T4处理下吸附速率常数K分别为0.257 kg·mg-1·h-1和0.339 kg·mg-1·h-1,显著高于未添加生物炭处理的T1和T3处理(K分别为-0.083 kg·mg-1·h-1和-0.261 kg·mg-1·h-1).内扩散模型显示添加生物炭后,土壤对阿特拉津的吸附是一个由边界扩散、内部孔隙扩散等多因素控制的复杂化学过程.添加生物炭可显著提高土壤pH、有机碳、碱解氮、速效磷和速效钾含量,其中土壤有机碳含量与阿特拉津最大吸附量之间存在显著的正相关关系(P<0.05).由此可见,添加生物炭可以提高土壤对阿特拉津的固持能力,减少其淋溶迁移风险,从而达到修复阿特拉津污染土壤的目的. 相似文献
14.
Excess nitrate in Mississippi River water entering offshore areas is reported to contribute to low oxygen (hypoxia) conditions in the Gulf of Mexico. Excessive algal growth driven by the excess nitrogen results in a decrease in dissolved oxygen in bottom water. Reintroduction of Mississippi River waters into a Louisiana coastal wetland has the potential to reduce the amount of nitrate reaching offshore waters. In this study, reduction in the concentration of added NO3- was determined in sediment-water-columns collected from a wetland site in Breton Sound estuary receiving nutrient inputs from the Mississippi River. The capacity of a wetland to process nitrate in floodwater was determined in the laboratory. The rates of NO3- removal (determined from change in nitrate concentration in the floodwater) averaged 97 mg N m-2 d-1 over 16 d for a 1750-mg NO3-N m-2 addition, and 170 mg N m-2 d-1 over 16 d for a 3500-mg NO3-N m-2 addition. The total N2O-N emissions from the 1750- and 3500-mg NO3-N m-2 additions were 19 and 54 mg N m-2 accounting for 1.1% and 1.5% of the applied NO3-N, respectively. Using the acetylene-inhibition technique, the average denitrification rate was determined to be 57 and 87 mg N m-2 d-1 (21 and 32 g N m-2 yr-1) during the most active denitrification period of 5 d after incubation for 1750 and 3500 mg NO3--N m-2 of added nitrate in floodwater, respectively. The total N evolved over 11 d as N2O + N2 was equivalent to 436 and 921 mg N m-2 (24.9% and 26.3%, respectively, of added N). Increasing the amount of NO3- applied to the overlying water increased the rate of NO3- loss and N2O emission significantly. The thickness of the oxidized surface sediment layer was also influenced by the NO3- application to the floodwater with a significant linear correlation between nitrate addition and thickness of the oxidized layer (r = 0.9998, p = 0.01). This study indicates that wetlands receiving diverted Mississippi River water have the potential to process and remove NO3- in the river water, reducing the amount of NO3- reaching to offshore areas. 相似文献
15.
The aim of the work described here was to investigate the existence of evaporable 137Cscontaining compound(s) in lichen and to suggest a possible way of dealing with a phenomenon during lichen exploitation. A sample of lichen, Cetraria islandica, was submitted to aqueous extraction and the extract was monitored to be 137Cs-radioactive. It was heated according to the experimental schedule and the resulting vapour passed over a layer of activated charcoal. By measuring the decrease in the radioactivity content of the lichen extract after heating and the radioactivity of the adsorbent it was found that a significant amount of the extracted 137Cs could be evaporated and bound to the charcoal adsorbent (40.6%). If not captured, this radiocaesium may lead to air pollution, especially of immediate breathing space. 相似文献
16.
几种电解质对土壤吸附Cu2+的影响 总被引:9,自引:3,他引:9
采用平衡吸附法研究了潮褐土、红壤对Cu^2 的等温吸附以及不同pH和电解质对土壤吸附Cu^2 的影响。结果表明,(1)土壤对Cu^2 的吸附量随平衡溶液中Cu^2 浓度增加而增加,潮褐土CuCu^2 最大吸附量明显比红壤的高,约是红壤的4—5倍。(2)体系pH显著影响土壤对Cu^2 的吸附,随pH升高Cu^2 吸附率增加,基本呈S形曲线变化。(3)随体系电解质浓度的增加,土壤对Cu^2 吸附率的变化趋势因土壤性质及体系中电解质种类、浓度的不同而不同。随KNO3浓度提高,土壤Cu^2 吸附率降低。KCl、KH2PO4对潮褐土吸附Cu^2 的影响与红壤的有些不同,低浓度KCl、KH2PO4抑制潮褐土对Cu^2 的吸附,高浓度KCl、KH2PO4促进潮褐土对Cu^2 的吸附,面对红壤。KCl降低Cu^2 的吸附率,KH2PO4提高Cu^2 的吸附率,但随KH2PO4浓度的提高,其提高幅度逐渐减弱。 相似文献
17.
采用批量平衡法和气相色谱法研究了己唑醇在3种土壤中的吸附-解吸特性.结果表明,己唑醇在3种供试土壤中的等温吸附-解吸曲线能较好地符合Freundlich模型,其吸附常数(Kf)分别为0.791、2.274和43.800,显示3种土壤吸附行为存在较大差异.吸附率与土壤有机质含量(OM)、土壤阳离子交换量(CEC)和粘粒含量呈良好相关性.己唑醇在粘土和壤土中的等温吸附线属于L型等温吸附线,砂土中属S型.己唑醇在土壤中的吸附自由能为-5.186—-8.164 kJ.mol-1,表示吸附机理主要为物理吸附. 相似文献
18.
E. Holm 《Chemistry and Ecology》1996,12(4):265-277
The Baltic Sea is, like the Mediterranean, a marginal sea, which with the Black Sea, were marine environments contaminated from the Chernobyl accident.
Radiocaesium and plutonium isotopes were studied in water, sediment and macroalgae in the Baltic Sea since 1982. the inventory of 137Cs in the Baltic increased from 0.65 PBq to 5.85 PBq following the Chernobyl accident. the corresponding increase for 239 + 240Pu was less significant and yielded 1.5 TBq to a total value of 16.5 TBq.
For plutonium, 98% is trapped in the sediment and the net-exchange of this element through the Baltic straits is very small (1 GBq/year), while for radiocaesium, 45% is in the water phase and there is a net-loss of 60 000 GBq annually into the adjacent water (Kattegatt). 相似文献
Radiocaesium and plutonium isotopes were studied in water, sediment and macroalgae in the Baltic Sea since 1982. the inventory of 137Cs in the Baltic increased from 0.65 PBq to 5.85 PBq following the Chernobyl accident. the corresponding increase for 239 + 240Pu was less significant and yielded 1.5 TBq to a total value of 16.5 TBq.
For plutonium, 98% is trapped in the sediment and the net-exchange of this element through the Baltic straits is very small (1 GBq/year), while for radiocaesium, 45% is in the water phase and there is a net-loss of 60 000 GBq annually into the adjacent water (Kattegatt). 相似文献
19.