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1.
鲁西平原微咸水资源的开发意义 总被引:1,自引:0,他引:1
鲁西平原处于黄泛平原的尾闾地段,常受旱涝盐咸多种危害。本文分析了浅层微咸水的形成、水质及动态特征,对水质、水量进行了评价,探讨了开发利用微咸水的可能性及灌溉效益。农业上开采浅层微咸水,无疑对扩大地下水资源及促进鲁西平原水、土环境的良性循环有重大意义。 相似文献
2.
3.
采煤塌陷地积水对土壤氮素矿化过程的影响 总被引:1,自引:0,他引:1
煤炭开采导致大面积的土地塌陷,使大量耕地出现常年积水或季节性积水,对塌陷地土壤氮素矿化过程产生一定影响。采集了某矿采煤塌陷地土壤样品,进行好气和淹水培养条件下间歇淋洗培养实验,研究了塌陷地积水对土壤氮素矿化过程的影响。经过62d的培养,40d左右氮素的矿化过程趋于稳定,淹水培养条件下土壤氮素最终累积矿化量为68.99mg/kg,约为好气培养条件的10倍,且淹水培养条件下土壤氮素矿化势可达69.472mg/kg,均矿化速率为5.210mg/(kg·d),说明淹水对土壤氮素矿化过程有显著的促进作用。将实验所得累积矿化量分别代入简单指数模型及双因子指数模型进行拟合,发现简单指数模型能有效模拟好气和淹水培养条件下土壤氮素矿化过程,并获得了2种培养条件下土壤氮素矿化过程的模型参数。 相似文献
4.
Vinicius F. Farjalla André M. Amado Albert L. Suhett Frederico Meirelles-Pereira 《Environmental science and pollution research international》2009,16(5):531-538
Background, aim, and scope Dissolved humic substances (HS) usually comprise 50–80% of the dissolved organic carbon (DOC) in aquatic ecosystems. From
a trophic and biogeochemical perspective, HS has been considered to be highly refractory and is supposed to accumulate in
the water. The upsurge of the microbial loop paradigm and the studies on HS photo-degradation into labile DOC gave rise to
the belief that microbial processing of DOC should sustain aquatic food webs in humic waters. However, this has not been extensively
supported by the literature, since most HS and their photo-products are often oxidized by microbes through respiration in
most nutrient-poor humic waters. Here, we review basic concepts, classical studies, and recent data on bacterial and photo-degradation
of DOC, comparing the rates of these processes in highly humic ecosystems and other aquatic ecosystems.
Materials and methods We based our review on classical and recent findings from the fields of biogeochemistry and microbial ecology, highlighting
some odd results from highly humic Brazilian tropical lagoons, which can reach up to 160 mg C L−1.
Results and discussion Highly humic tropical lagoons showed proportionally lower bacterial production rates and higher bacterial respiration rates
(i.e., lower bacterial growth efficiency) than other lakes. Zooplankton showed similar δ13C to microalgae but not to humic DOC in these highly humic lagoons. Thus, the data reviewed here do not support the microbial
loop as an efficient matter transfer pathway in highly humic ecosystems, where it is supposed to play its major role.
In addition, we found that some tropical humic ecosystems presented the highest potential DOC photo-chemical mineralization
(PM) rates reported in the literature, exceeding up to threefold the rates reported for temperate humic ecosystems. We propose
that these atypically high PM rates are the result of a joint effect of the seasonal dynamics of allochthonous humic DOC input
to these ecosystems and the high sunlight incidence throughout the year. The sunlight action on DOC is positive to microbial
consumption in these highly humic lagoons, but little support is given to the enhancement of bacterial growth efficiency,
since the labile photo-chemical products are mostly respired by microbes in the nutrient-poor humic waters.
Conclusions HS may be an important source of energy for aquatic bacteria in humic waters, but it is probably not as important as a substrate
to bacterial growth and to aquatic food webs, since HS consumption is mostly channeled through microbial respiration. This
especially seems to be the case of humic-rich, nutrient-poor ecosystems, where the microbial loop was supposed to play its
major role. Highly humic ecosystems also present the highest PM rates reported in the literature. Finally, light and bacteria
can cooperate in order to enhance total carbon degradation in highly humic aquatic ecosystems but with limited effects on
aquatic food webs.
Recommendations and perspectives More detailed studies using C- and N-stable isotope techniques and modeling approaches are needed to better understand the
actual importance of HS to carbon cycling in highly humic waters. 相似文献
5.
6.
Soonchul Kwon Maohong Fan Herbert F. M. DaCost Armistead G. Russell 《环境科学学报(英文版)》2011,23(8):1233-1239
Olivine, one of the most abundant minerals existing in nature, is explored as a CO2 carbonation agent for direct carbonation of
CO2 in flue gas. Olivine based CO2 capture is thermodynamically favorable and can form a stable carbonate for long-term storage.
Experimental results have shown that water vapor plays an important role in improving CO2 carbonation rate and capacities. Other
operation conditions including reaction temperature, initial CO2 concentration, residence time corresponding to the flow rate of CO2
gas stream, and water vapor concentration also considerably affect the performance of the technology. 相似文献
7.
The nitrogen (N) distribution and cycling of atmosphere-plant-soil system in the typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow Calamagrostis angustifolia wetland (MMCW) in the Sanjiang plain were studied by a compartment model. The results showed that the N wet deposition amount was 0.757 gN/(m2·a), and total inorganic N (TIN) was the main body (0.640 gN/(m2·a)). The ammonia volatilization amounts of TMCW and MMCW soils in growing season were 0.635 and 0.687 gN/m2, and the denitrification gaseous lost amounts were 0.617 and 0.405 gN/m2, respectively. In plant subsystem, the N was mainly stored in root and litter. Soil organic N was the main N storage of the two plant-soil systems and the proportions of it were 93.98% and 92.16%, respectively. The calculation results of N turnovers among compartments of TMCW and MMCW showed that the uptake amounts of root were 23.02 and 28.18 gN/(m2·a) and the values of aboveground were 11.31 and 6.08 gN/(m2·a), the re-translocation amounts from aboveground to root were 5.96 and 2.70 gN/(m2·a), the translocation amounts from aboveground living body to litter were 5.35 and 3.38 gN/(m2·a), the translocation amounts from litter to soil were larger than 1.55 and 3.01 gN/(m2·a), the translocation amounts from root to soil were 14.90 and 13.17 gN/(m2·a), and the soil (0-15cm) N net mineralization amounts were 1.94 and 0.55 gN/(m2·a), respectively. The study of N balance indicated that the two plant-soil systems might be situated in the status of lacking N, and the status might induce the degradation of C. angustifolia wetland. 相似文献
8.
二氧化钛纳米颗粒(TiO2NPs)的广泛应用使其环境释放量不断增加,从而影响到土壤氮的转化过程.然而,目前关于TiO2NPs对湖滨沼泽土壤氮矿化的影响机制尚不明确.因此,本研究以典型沼泽土壤为研究对象,通过室内培养实验研究不同剂量TiO2NPs处理(0 mg·kg-1(CK)、10 mg·kg-1(A10)、100 mg·kg-1(A100)、250 mg·kg-1(A250)、1000 mg·kg-1(A1000))对土壤理化性质、酶活性和氮矿化过程的影响,探讨TiO2NPs输入对土壤氮矿化过程影响的内在机制.结果表明:①不同剂量TiO2NPs处理显著降低了土壤pH和总有机碳(TOC)含量(p<0.05),A100、A250和A1000处理显著降低了硝态氮(NO3--N)含量(p<0.05).②A250和A1000处理显著抑制了过氧化氢酶活性(p<0.05);培养7 d,不同剂量TiO2NPs处理均显著促进了脲酶活性(p<0.05),抑制了脱氢酶活性(p<0.05);随着培养时间延长,TiO2NPs处理对脲酶和脱氢酶活性的抑制作用逐渐减弱,表明TiO2NPs的负面作用会随时间减弱.③不同剂量TiO2NPs处理对氨化速率没有显著影响(p>0.05),A250、A1000处理对硝化和矿化速率有显著抑制作用(p<0.01).④土壤氮矿化速率与土壤pH、总磷(TP)、NO3--N含量呈显著正相关,与脲酶、过氧化氢酶活性呈显著负相关.TiO2NPs主要通过改变沼泽土壤NO3--N含量影响氮矿化过程.本研究可为湖滨湿地保护和TiO2NPs环境风险评估提供理论依据. 相似文献
9.
以有机磷农药-草甘膦为目标污染物,利用光电芬顿方法对其进行降解研究。研究汇总考察了电流强度、初始pH、Fe2+浓度、草甘膦初始浓度、光种类及通入背景气体种类对草甘膦降解效果的影响。实验结果表明:电流强度越大,草甘膦初始浓度越低,草甘膦降解效果越好;草甘膦在pH=2.0~3.0的酸性体系中降解效果最好;Fe2+浓度升高,草甘膦降解效果增强。在电流为0.36 A、初始pH=3.0、Fe2+浓度为1.0 mmol·L-1、通入100 mL·min-1 O2条件下,以365 nm紫外光照射的光电芬顿反应降解初始浓度为84.5 mg·L-1的草甘膦溶液,处理360 min后溶液矿化率可达64.5%。 相似文献
10.
Jeanette D. Gaultier Annemieke Farenhorst 《Journal of environmental science and health. Part. B》2013,48(3):255-264
The objective of this study was to quantify 2,4-D (2,4-dichlorophenoxyacetic acid) mineralization in soil profiles characteristic of hummocky, calcareous-soil landscapes in western Canada. Twenty-five soil cores (8 cm inner diameter, 50 to 125 cm length) were collected along a 360 m transect running west to east in an agricultural field and then segmented by soil-landscape position (upper slopes, mid slopes, lower slopes and depressions) and soil horizon (A, B, and C horizons). In the A horizon, 2,4-D mineralization commenced instantaneously and the mineralization rate followed first-order kinetics. In both the B and C horizons, 2,4-D mineralization only commenced after a lag period of typically 5 to 7 days and the mineralization rate was biphasic. In the A horizon, 2,4-D mineralization parameters including the first-order mineralization rate constant (k 1), the growth-linked mineralization rate constant (k 2) and total 2,4-D mineralization at the end of the experiment at 56 days, were most strongly correlated to parameters describing 2,4-D sorption by soil, but were also adequately correlated to soil organic carbon content, soil pH, and carbonate content. In both B and C horizons, there was no significant correlation between 2,4-D mineralization and 2,4-D sorption parameters, and the correlation between soil properties and 2,4-D mineralization parameters was very poor. The k 1 significantly decreased in sequence of A horizon (0.113% day?1) > B horizon (0.024% day?1) = C horizon (0.026% day?1) and in each soil horizon was greater than k 2. Total 2,4-D mineralization at 56 days also significantly decreased in sequence of A horizon (42%) > B horizon (31%) = C horizon (27%). In the A horizon, slope position had little influence on k 1 or k 2, except that k 1 was significantly greater in upper slopes (0.170% day?1) than in lower slopes (0.080% day?1). Neither k 1 nor k 2 was significantly influenced by slope position in the B or C horizons. Total 2,4-D mineralization at 56 days was not influenced by slope positions in any horizon. Our results suggest that, when predicting 2,4-D transport at the field scale, pesticide fate models should consider the strong differences in 2,4-D mineralization between surface and subsurface horizons. This suggests that 2,4-D mineralization is best predicted using a model that has the ability to describe a range of non-linear mineralization curves. We also conclude that the horizontal variations in 2,4-D mineralization at the field scale will be difficult to consider in predictions of 2,4-D transport at the field scale because, within each horizon, 2,4-D mineralization was highly variable across the twenty-five soil cores, and this variability was poorly correlated to soil properties or soil-landscape position. 相似文献