Dynamics of soil inorganic nitrogen and their responses to nitrogen additions in three subtropical forests, south China

Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine （Pinus massoniana） and pine-broadleaf mixed forests, both originated from the 1930＇s clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH4^＋-N and NO3-N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4^＋-N in the mature forest. In contrast, inorganic N （both NH4^＋-N and NO3^--N） in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.     

Fe2+EDTA液相对NO的络合作用

对Fe~(2 )EDTA溶液络合NO过程的影响因素的探讨,是“液相络合-铁还原-酸吸收”回收法脱除烟气中NOx技术研究的基础。用鼓泡反应器和模拟烟气,在实验室研究了Fe2 EDTA溶液络合NO的过程,探讨了Fe2 EDTA溶液络合NO过程的影响因素,以及该过程的反应平衡常数。结果表明:Fe2 EDTA溶液对NO的络合能力随时间延长而减弱;Fe2 EDTA溶液对NO的络合容量随着烟气中O2含量的增加和络合温度的升高而降低,随络合液中Fe2 EDTA浓度增加而呈直线增加;pH值为8左右时,Fe2 EDTA溶液对NO的络合容量最大;Fe2 EDTA溶液络合NO的反应平衡常数在实验条件下为105~106L·mol-1数量级,其值随温度升高而降低。     

水体中亚硝酸盐的光降解

一定浓度的亚硝酸盐溶液经太阳光模拟器照射一定时间后,观测溶液中亚硝酸盐的含量变化.改变溶液条件（介质、pH）和光照条件（时间、光强）等实验条件,同时进行黑暗对照实验,探求影响亚硝酸盐光解的因素和规律.结果表明,在光照的8 h内,时间越长亚硝酸盐的降解率越大,基本符合一级反应动力学曲线;光照强度越大亚硝酸盐的降解程度越大...     

Redistribution of zinc, cadmium, and lead among soil fractions in a sandy calcareous soil due to application of poultry litter

This study was conducted to evaluate, using soil columns, the mobilization and redistribution of heavy metals (Zn, Cd, and Pb) among different soil fractions by soluble organic ligands within poultry litter. Uncontaminated soil was amended with Zn, Cd, and Pb to achieve concentration levels of 400, 8, and 200 mg kg⁻¹ soil, respectively. Columns repacked with this amended soil were leached with distilled water, 0.01 M EDTA, 0.01 M CaCl₂, or poultry litter extract (PLE) solutions. After leaching, the soil samples in the columns were sequentially extracted for exchangeable (EXC), carbonate (CARB) organic matter (OM), Mn oxide (MNO), Fe oxide (FEO), and residual (RES) fractions. Considerable mobilization of Zn, Cd, and Pb occurred in soil during EDTA leaching. Leaching with PLE and CaCl₂ solutions significantly decreased Zn and Cd concentrations in the EXC, CARB, and OM fractions. These solutions significantly decreased Pb concentration in the EXC fraction, while PLE solubilized more Pb from EXC fraction than CaCl₂. Thus, the applied poultry litter may change Zn, Cd, and Pb fractions in metal-amended soil and possibly enhance metal mobility.     

寻求解决乌鲁木齐市空气污染的途径

针对乌鲁木齐市最突出的环境问题——冬季采暖期空气污染,从主客观二方面进行了原因分析,并结合“十一五”和2020年环境保护目标,从7个方面分析论述了解决乌鲁木齐市空气污染的途径,使多年困扰乌鲁木齐市的空气污染问题有望从根本上得到解决。     

严惩环境污染犯罪观念之反思

目前,中国重大环境污染事故频发,严重危害了公民居住的环境甚至是公共安全,在社会上引起了广泛影响,民众要求严惩环境污染犯罪的观念也日益盛行。从客观上来讲,严惩环境污染犯罪有一定的意义,但此种观念的蔓延也可能带来一系列的副作用,因此有必要对此种观念进行深刻反思。通过对环境污染犯罪进行综合分析可以发现,导致此类犯罪的原因是多方面的,因而预防该类犯罪的方法也应当是多元的,仅仅严惩是起不到防治环境污染犯罪效果的。     

十三烷基苯磺酸钠和辛基酚聚氧乙烯醚二元复配溶液的定量分析

采用向十三烷基苯磺酸钠（STBS）和非离子表面活性剂辛基酚聚氧乙烯醚（OP-10）二元复配溶液中添加β-环糊精（β-CD）的方法,降低STBS和OP-10之间定量检测时的相互干扰。实验结果表明：添加β-CD时,可提高STBS的检测准确性,降低STBS对OP-10的检测干扰;在二元复配溶液中,STBS和OP-10的方法回收率分别在100.8%~102.0%,97.4%~102.2%之间,检测误差分别在2.0%和2.6%以内;Cl^-,SO₄^2-,Na⁺,Ca²⁺的存在对二元复配溶液中STBS和OP-10的检测干扰可忽略;将该方法应用于地层水水样中,仍可准确定量分析STBS和OP-10的含量。     

应用散射光浊度法分析水中机械杂质

用散射光浊度法测定水样中机械杂质含量，灵敏度和准确度均高于目视法，且适用性强。     

阴离子洗涤剂分析中标准物质的比较初探

通过对用分析纯十二烷基苯磺酸钠配制成阴离子洗涤剂标准物质与国家标准十二烷基苯磺酸钠溶液比较，二者无显著性差异，具有同等的效果。     

An ecological risk assessment model for a pulsed contaminant emission into a wetland channel flow

As a continuation of the modelling on ecological degradation and hydraulic dispersion of pollutant emission into an idealized two-dimensional free-surface wetland flow (Zeng, L., Chen, G.Q., 2009b. Ecological degradation and hydraulic dispersion of contaminant in wetland. Ecol. Model., doi:10.1016/j.ecolmodel.2009.10.024), an ecological risk assessment model for the typical case of a pulsed contaminant emission into a realistic three-dimensional wetland channel flow is presented in this paper for the fate of cross-sectional mean concentration under environmental dispersion. An environmental dispersion model for the mean concentration is devised as an extension of Taylor’s classical analysis on dispersion in fluid flows. The velocity distribution and the environmental dispersivity in the fully developed steady flow through the wetland is found and illustrated with limiting cases covering various known solutions for the porous media flow between parallel plates, flow in a shallow wetland, sweeping flow in a densely vegetated wetland, and single phase flow in a channel. Obtained by Aris’s method of moments, the environmental dispersivity is shown characterized with multi-scale asymptotic time variations with stem dominated stage, transitional stage, and width-depth-stem dominated stage. Based on the solution for the evolution of contaminant cloud in the wetland channel flow, critical length and duration of the contaminant cloud with concentration beyond given environmental standard level are concretely illustrated for typical pollutant constituents in wastewater emission. Under the same emission intensity and environmental standard, the duration of contaminant cloud in the wetland channel is revealed shorter than that in a free surface wetland, due to the lateral effect.