Soil biological characteristic,nutrient contents and stoichiometry as affected by different types of remediation in a smelter-impacted soil

ABSTRACT

In order to evaluate the ecological risk reductions of copper (Cu) and cadmium (Cd) and the change of nutrient contents and stoichiometry in a smelter-impacted farmland in Guixi, Jiangxi Province, China, with ～ 800?mg Cu kg^?1 soil and 0.8?mg Cd kg^?1 soil, an three years in situ experiment was conducted. The field trial consisted of 4 ×?5?m plots in a completely randomised block design. Hydroxyapatite was added at 10?g kg^?1 soil and Sedum plumbizincicola, Elsholtzia splendens, and Pennisetum sp. were planted. Post-treatment soil and plant samples were collected annually and analysed for Cu and Cd bioaccessibility, soil carbon: nitrogen: phosphorus (C:N:P), and the stoichiometries of soil β-glucosidase (BG), N-acetylglucosaminidase (NAG), and acid phosphatase (AP) activity levels. The results indicated that the hydroxyapatite treatments significantly reduced Cu and Cd bioaccessibility as well as the ratio of C:P and N:P. Moreover, BG, NAG, and AP activity levels all increased relative to those in untreated soil. Plants may also influence soil BG, NAG, and AP activity. This study demonstrated that in situ Cu and Cd stabilisation by hydroxyapatite and phytoextraction is ecologically safe and can alter soil mineral nutrient ecological stoichiometry and enzyme activity.     

Modeling oil dispersion under breaking waves. Part II: Coupling Lagrangian particle tracking with population balance model

Environmental Fluid Mechanics - Oil dispersion under a deep-water plunging breaker of height 0.15 m was studied by coupling the Lagrangian particle tracking code (NEMO3D) with the...     

太湖流域水供给服务供需时空演变分析

太湖流域是我国经济发展最快、人口最密集的地区之一。受土地利用和降水条件变化的影响,太湖流域水供给服务供需关系也发生着变化。通过分别设置1995～2015年太湖流域不同降水条件和土地利用变化情景,利用Invest模型定量评估水资源供给量,同时利用空间离散法定量评估水资源需求量,并进一步分析供需赤字和盈余区域的时空变化。结果表明:1995～2015年随着土地利用变化,尤其是建设用地的扩张(20年来涨幅达106%),水资源需求占供给量的比重由73%升至90%,需要依赖外来客水的县域面积占整个流域的比重由19%升至33%;2015年在不同降水条件下供需关系变化更为明显,降水量越少,供需赤字的县域越多,在干旱年份整个流域需求量占供给量的117%,供给量已不能满足需求量,且赤字县域的面积占整个流域的47%。两种情境下,太湖流域东北部水供给服务供需关系均比西南部紧张。作为影响太湖流域水资源供需变化的主要因素,土地利用和降水条件变化分别通过影响需求量和供给量改变供需关系。     

Broadband UV spectroscopy system used for monitoring of SO2 and NO emissions from thermal power plants

A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO₂) and nitric oxide (NO) from a 220-ton h^?1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO₂ and NO from the CFB boiler fluctuated in the range of 750–1300 mg m^?3 and 100–220 mg m^?3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO₂ and lower for NO. The relatively high emission concentrations of SO₂ were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.     

低C/N比水产养殖废水生物脱氮实验研究

随着短程硝化-反硝化理论研究的发展,在低C/N比条件下,实现污水的生物脱氮处理已成为可能。为此,设计了水产养殖用水的三级生物膜短程硝化-反硝化处理工艺,并对该工艺在去除模拟水产养殖废水主要污染物的作用进行了初步研究。研究结果表明,在进水pH值7.5~8.5,温度为28~32℃,溶解氧为0.5~1 mg/L,游离氨浓度为5~10 mg/L的条件下,模拟废水的COD、NH4+-N和TN的平均去除率分别达到94.4%、91.6%和70.1%;并且低C/N比对出水氨氮NH4+-N的去除率影响不大,NO2--N的平均浓度控制在5.2 mg/L以下,低于鱼类的耐受浓度。表明该短程硝化-反硝化工艺设计,可用于低C/N比水产养殖废水主要污染物的生物处理,尤其是可消除NO2--N对水产养殖的潜在威胁,基本达到养鱼回用标准。     

动电修复不同形态重金属污染土壤效果研究

以钢铁厂附近废地的重金属土壤为对象,研究了动电修复技术去除重金属效果与其各化学形态的关系,讨论了电能消耗。结果表明,同一种重金属,其动电去除效率顺序为交换态碳酸盐结合态Fe-Mn氧化结合态有机结合态残留态,即吸附性越弱的形态,其去除率越高,如交换态去除率95%;吸附性越强的形态,其去除率越低,如有机态和残留态去除率低于29%;对于不同重金属,高移动性和弱吸附性的重金属较弱移动性和强吸附性的重金属去除效果好,即各形态的Cd、Cu和Zn的去除率明显高于相应形态Pb的去除率;能耗分析表明,实验时间超过96 h后,在电能有较大消耗的同时,重金属去除率却提高不明显。     

Modelling pollutants dispersion and plume rise from large hydrocarbon tank fires in neutrally stratified atmosphere

Petrochemical industries normally use storage tanks containing large amounts of flammable and hazardous substances. Therefore, the occurrence of a tank fire, such as the large industrial accident on 11th December 2005 at Buncefield Oil Storage Depots, is possible and usually leads to fire and explosions. Experience has shown that the continuous production of black smoke from these fires due to the toxic gases from the combustion process, presents a potential environmental and health problem that is difficult to assess. The goals of the present effort are to estimate the height of the smoke plume, the ground-level concentrations of the toxic pollutants (smoke, SO₂, CO, PAHs, VOCs) and to characterize risk zones by comparing the ground-level concentrations with existing safety limits. For the application of the numerical procedure developed, an external floating-roof tank has been selected with dimensions of 85 m diameter and 20 m height. Results are presented and discussed. It is concluded that for all scenarios considered, the ground-level concentrations of smoke, SO₂, CO, PAHs and VOCs do not exceed the safety limit of IDLH and there are no “death zones” due to the pollutant concentrations.     

Examining the temperature dependence of ethanol (E85) versus gasoline emissions on air pollution with a largely-explicit chemical mechanism

The increased use of ethanol in transportation fuels warrants an investigation of its consequences. An important component of such an investigation is the temperature dependence of ethanol and gasoline exhaust chemistry. We use the Master Chemical Mechanism (MCM, version 3.1, LEEDS University) with the SMVGEAR II chemical ordinary differential solver to provide the speed necessary to simulate complex chemistry to examine such effects. The MCM has over 13,500 organic reactions and 4600 species. SMVGEAR II is a sparse-matrix Gear solver that reduces the computation time significantly while maintaining any specified accuracy. Although we use a box model for this study, we determine and demonstrate in a separate study that the speed of the MCM with SMVGEAR II allows the MCM to be modeled in 3-dimensions. We also verified the accuracy of the model in comparison with smog chamber data. We then use the model with species-resolved tailpipe emissions data for E85 (15% gasoline, 85% ethanol fuel blend) and gasoline vehicles to compare the impact of each on nitrogen oxides, organic gases, and ozone as a function of ambient temperature and background concentrations, using Los Angeles in 2020 as a base case. We use two different emissions sets – one is a compilation of exhaust and evaporative data taken near 24 °C and the other from exhaust data taken at ?7 °C – to determine how atmospheric chemistry and emissions are affected by temperature. We include diurnal effects by examining two day scenarios. We find that, accounting for chemistry and dilution alone, the average ozone concentrations through the range of temperatures tested are higher with E85 than with gasoline by ～7 part per billion volume (ppbv) at higher temperatures (summer conditions) to ～39 ppbv at low temperatures and low sunlight (winter conditions) for an area with a high nitrogen oxide (NOx) to non-methane organic gas (NMOG) ratio. The results suggest that E85's effect on health through ozone formation becomes increasingly more significant relative to gasoline at colder temperatures due to the change in exhaust emission composition at lower temperatures. Acetaldehyde and formaldehyde concentrations are also much higher with E85 at cold temperatures, which is a concern because both are considered to be carcinogens. These could have implications for wintertime use of E85. Peroxy acetyl nitrate (PAN), another air pollutant of concern, increases with E85 by 0.3–8 ppbv. The sensitivity of the results to box size, initial background concentrations, background emissions, and water vapor were also examined.     

Behaviour and dynamics of di-ammonium phosphate in bauxite processing residue sand in Western Australia—II. Phosphorus fractions and availability

Background, aim and scope  

Australia is the largest producer of bauxite in the world, with an annual output of approximately 62 million metric dry tons in 2007. For every tonne of alumina, about 2 tonnes of highly alkaline and highly saline bauxite-processing residue are produced. In Western Australia, Alcoa World Alumina, Australia (Alcoa) produces approximately 15 MT of residue annually from its refineries (Kwinana, Pinjarra and Wagerup). The bauxite-processing residue sand (BRS) fraction represents the primary material for rehabilitating Alcoa’s residue disposal areas (RDAs). However, the inherently hostile characteristics (high alkalinity, high salinity and poor nutrient availability) of BRS pose severe limitations for establishing sustainable plant cover systems. Alcoa currently applies 2.7 t ha⁻¹ of di-ammonium phosphate ((NH₄)₂HPO₄; DAP)-based fertiliser as a part of rehabilitation of the outer residue sand embankments of its RDAs. Limited information on the behaviour of the dominant components of this inorganic fertiliser in highly alkaline BRS is currently available, despite the known effects of pH on ammonium (NH₄) and phosphorus (P) behaviour. The aim of this study was to quantify the effects of pH on NH₃ volatilisation and residual nitrogen (N) in BRS following DAP applications.     

河北省海域承载力多层次模糊综合评价

借鉴有关承载力的研究成果,利用多层次模糊综合评判法对河北省海域承载力进行了评价分析。结果表明:1996—2006年间河北省近海海域承载力一直处于超载状态,但承载状况总体趋于好转;人口和环境污染的加剧、环境治理能力和科技发展水平缓慢、资源供给能力不足是导致河北省海域承载力超载的主要因素。基于此提出了改善河北省海域承载状况的对策建议。