低表观气速间歇曝气AGS-SBR系统处理实际生活污水

实验选用3个SBR反应器接种污水厂活性污泥,R1采用高表观气速（SGV）连续曝气,R2采用低SGV连续曝气,R3采用低SGV间歇曝气,在低碳氮比的实际生活污水中培养好氧颗粒污泥,探究不同SGV曝气条件对好氧颗粒污泥的形成及系统处理效果的影响.经过120d的培养,R1、R2和R3中颗粒粒径分别为（754±78）,（812±86）,（1183±93）μm,R3的脱氮除磷效果优于R1和R2.结果表明,应用低SGV间歇曝气策略在低碳氮比实际生活污水中培养的好氧颗粒污泥脱氮除磷性能良好,且系统中反硝化聚磷菌（DPAO）占聚磷菌（PAO）比例为24.75%.     

生物体微塑料提取方法比选研究

微塑料（<5mm）在淡水、海洋以及陆生生物体内被广泛检出,但由于提取方法不一致,限制了现有数据之间的可比性.本研究比选了4种消解方法对鱼胃等7种组织的消解效率,并通过显微镜检查、重量、傅里叶变换红外光谱（FT-IR）和拉曼光谱综合评估不同提取方法对10种环境微塑料形态、重量和光谱特征的影响.结果显示,消解效率依次为10% KOH > RIPA组织裂解液+蛋白酶K > 蛋白酶K > 30% H₂O₂.另外,4种消解处理后PA（聚酰胺）颗粒重量均显著增加,H₂O₂处理后PU（聚氨酯）颗粒颜色略有变化,可生物降解塑料溶于10% KOH,而其他塑料处理前后重量和形态均未变化;4种消解处理前后所有塑料的红外光谱与拉曼光谱均未发生改变.综合以上,推荐以10% KOH为消解液,50℃、180r/min温育振荡6h作为分离提取生物组织微塑料的首选方案.     

Improvements on physical conditions of bauxite residue following application of organic materials

Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant growth. Organic materials were demonstrated as effective ameliorants to improve the physical conditions of bauxite residue. In this study, three different organic materials including straw (5% W/W), humic acid (5% W/W), and humic acid-acrylamide polymer (0.2% and 0.4%, W/W) were selected to evaluate their effects on physical conditions of bauxite residue pretreated by phosphogypsum following a 120-day incubation experiment. The proportion of 2-1 mm macro-aggregates, mean weight diameter (MWD) and geometric mean diameter (GWD) increased following organic materials addition, which indicated that organic materials could enhance aggregate stability. Compared with straw, and humic acid, humic acid-acrylamide polymer application had improved effects on the formation of water-stable aggregates in the residues. Furthermore, organic materials increased the total porosity, total pore volume and average pore diameter, and reduced the micropore content according to nitrogen gas adsorption (NA) and mercury intrusion porosimetry (MIP) analysis, whilst enhancing water retention of the residues based on water characteristic curves. Compared with traditional organic wastes, humic acid-acrylamide polymer could be regarded as a candidate according to the comprehensive consideration of the additive amount and the effects on physical conditions of bauxite residue. These findings could provide a novel application to both Ca-contained acid solid waste and high-molecular polymers on ecological rehabilitation at disposal areas.     

南方崩岗区铁路工程弃渣场水土保持防治措施研究

在借鉴南方崩岗区水土保持综合治理经验的基础上,基于现场调查和资料分析,以龙岩至武平铁路为例,研究南方红壤区铁路工程在崩岗侵蚀背景下的弃渣场水土保持防治措施,旨在为同地区铁路工程弃渣场水土保持防治措施提供解决思路。     

Estimation of annual potential evapotranspiration at regional scale based on the effect of moisture on soil respiration

Potential evapotranspiration (PET) is an important component of water cycle. For traditional models derived from the principle of aerodynamics and the surface energy balance, its calculation always includes many parameters, such as net radiation, water vapor pressure, air temperature and wind speed. We found that it can be acquired in an easier way in specific regions. In this study, a new PET model (PETP model) derived from two empirical models of soil respiration was evaluated using the Penman-Monteith equation as a standard method. The results indicate that the PETP model estimation concur with the Penman-Monteith equation in sites where annual precipitation ranges from 717.71 mm to 1727.37 mm (R² = 0.68, p = 0.0002), but show large discrepancies in all sites (R² = 0.07, p = 0.1280). Then we applied our PETP model at the global scale to the regions with precipitation higher than 700 mm using 2.5° CMAP data to obtain the annual PET for 2006. As expected, the spatial pattern is satisfactory overall, with the highest PET values distributed in the lower latitudes or coastal regions, and with an average of 1292.60 ± 540.15 mm year⁻¹. This PETP model provides a convenient approach to estimate PET at regional scales.     

Modelling the impact of thermal adaptation of soil microorganisms and crop system on the dynamics of organic matter in a tropical soil under a climate change scenario

No consensus currently exists about how climate change should affect the status of soil organic matter (SOM) in the tropics. In this study, we analyse the impact of climate change on the underlying mechanisms controlling SOM dynamics in a ferralsol under two contrasting tropical crops: maize (C4 plant) and banana (C3 plant). We model the effect of microbial thermal adaptation on carbon (C) mineralisation at the crop system scale and introduce it in the model STICS, which was previously calibrated for the soil-crop systems tested in this study. Microbial thermal adaptation modelling is based on a reported theory for thermal acclimation of plant and soil respiration. The climate is simulated from 1950 to 2099 for the tropical humid conditions of Guadeloupe (French Antilles), using the ARPEGE model and the IPCC emission scenario A1B. The model predicts increases of 3.4 °C for air temperature and 1100 mm yr⁻¹ for rainfall as a response to an increase of 375 ppm for atmospheric carbon dioxide concentration in the 2090-2099 decade compared with the 1950-1959 decade. The results of the STICS model indicate that the crop affects the response of SOM to climate change by controlling the change in several variables involved in C dynamics: C input, soil temperature and soil moisture. SOM content varies little until 2020, and then it decreases faster for maize than for banana. The decrease is weakened under the hypothesis of thermal adaptation, and this effect is greater for maize (−180 kg C ha⁻¹ yr⁻¹ without adaptation and −140 kg C ha⁻¹ yr⁻¹ with adaptation) than for banana (−60 kg C ha⁻¹ yr⁻¹ and −40 kg C ha⁻¹ yr⁻¹, respectively). The greater SOM loss in maize is mainly due to the negative effect of warming on maize growth decreasing C input from residues. Climate change has a small effect on banana growth, and SOM loss is linked to its effect on C mineralisation. For both crops, annual C mineralisation increases until 2040, and then it decreases continuously. Thermal adaptation reduces the initial increase in mineralisation, but its effect is lower on the final decrease, which is mainly controlled by substrate limitation. No stabilisation in SOM status is attained at the end of the analysed period because C mineralisation is always greater than C input. Model predictions indicate that microbial thermal adaptation modifies, but does not fundamentally change the temporal pattern of SOM dynamics. The vegetation type (C3 or C4) plays a major role in SOM dynamics in this tropical soil because of the different impact of climate change on crop growth and then on C inputs.     

Vegetation competition model for water and light limitation. I: Model description, one-dimensional competition and the influence of groundwater

Vegetation growth models often concentrate on the interaction of vegetation with soil moisture but usually omit the influence of groundwater. However the proximity of groundwater can have a profound effect on vegetation growth, because it strongly influences the spatial and temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. In two papers we describe the behavior of a coupled vegetation-groundwater-soil water model including the competition for water and light. In this first paper we describe the vegetation model, compare the model to measured flux data and show the influence of water and light competition in one dimension. In the second paper we focus on the influence of lateral groundwater flow and spatial patterns along a hillslope. The vegetation model is based on a biophysical representation of the soil-plant-atmosphere continuum. Transpiration and stomatal conductance depend both on atmospheric forcing and soil moisture content. Carbon assimilation depends on environmental conditions, stomatal conductance and biochemical processes. Light competition is driven by tree height and water competition is driven by root water uptake and its water and oxygen stress reaction. The modeled and measured H₂O and CO₂ fluxes compare well to observations on both a diurnal and a yearly timescale. Using an upscaling procedure long simulation runs were performed. These show the importance of light competition in temperate forests: once a tree is established under slightly unfavorable soil moisture conditions it can not be outcompeted by smaller trees with better soil moisture uptake capabilities, both in dry as in wet conditions. Performing the long simulation runs with a background mortality rate reproduces realistic densities of wet and dry adapted tree species along a wet to dry gradient. These simulations show that the influence of groundwater is apparent for a large range of groundwater depths, by both capillary rise and water logging. They also show that species composition and biomass have a larger influence on the water balance in eco-hydrological systems than soil and groundwater alone.     

Assessment of metals in soil extracts and their uptake and movement within Tamarix nilotica at Lake Nasser banks,Egypt

This study aims to determine heavy-metal levels in soil from the banks of Lake Nasser, the ability of Tamarix nilotica to accumulate such metals from soil and hence its potential for phytoextraction. Soil and Tamarix samples were collected from the banks of four bights around Lake Nasser and analysed for Fe, Mn, Ca, Mg, Cr, Cu, Ni, Zn, Cd and Pb by atomic absorption spectrometry, whereas Na and K were measured by atomic emission spectrophotometry. Three different methods of extraction were used for the soil samples. Lead, copper and zinc were equally distributed between the exchangeable phase and Fe/Mn oxide-bound form, while other measured metals were mainly present in the Fe/Mn oxide fraction. With the exception of iron, all metals studied showed total concentrations within the geochemical background values. T. nilotica exhibited elevated concentrations of Na (36.2–48.5?mg?g^?1) and K (2.74–4.33?mg?g^?1) in stems, and relatively high concentrations of Pb, Cd and Co (0.39–1.03?µg?g^?1, 0.24–1.3?µg?g^?1 and 1.94–5.3?µg?g^?1, respectively) are found in plant leaves. Bioaccumulation factors of Na and K (9.3 and 12.63, respectively) were high in T. nilotica stems. While the bioaccumulation of Pb, Cd, Co and Ni (2870.1, 2035.4, 10.5 and 5313.2, respectively) was high in plant leaves, Fe, Mn, Ca and Mg were accumulated relatively equally in plant stems and leaves. T. nilotica was found to secrete high amounts of Na, Ca and K, in addition to small amounts of all accumulated metals except Cd and Cu. These secreted metals appeared as salt crystals (67.5% Na; 25.8% Ca; 5% Mg; 1.5% K and 0.16% trace and minor elements) on the plant surface. The concentrations of all the metals studied in T. nilotica were higher than in the salt crystals. Statistical analysis of the database suggests bioaccumulation of these metals from soil to T. nilotica. This reflects the importance of using T. nilotica as a model in the phytoremediation process as an established environmental clean-up technology.     

A GC method to determine o‐chloroacetophenone residual in soil and vegetable substrates

o‐Chloroacetophenone (CAF) is a peripheral sensory irritant used in open air situations giving rise to human and environmental exposure. An analytical GC method has been developed to determine CAF residual in soil and vegetable substrates at low ppm levels.     

Evaluation of SWAT sub-daily runoff estimation at small agricultural watershed in Korea

A study was undertaken for the prediction of runoff flow from 0.8 ha field-sized agricultural watershed in South Korea using Soil and Water Assessment Tool (SWAT) sub-daily. The SWAT model with sub-daily configuration predicted flow from the watershed within the range of acceptable accuracy. The SWAT sub-daily simulations were carried out for a total of 18 rainfall events, 9 each for calibration and validation. Overall trend and extent of matching simulated flow for the rainfall events in 2007-2008 with measured data during the calibration process were coefficient of determination (R²) value of 0.88 and Nash and Sutcliffe Efficiency (E_NS) value of 0.88. For validation, R² and E_NS values were 0.9 and 0.84, respectively. Whereas R² and E_NS values for simulation results using daily rainfall data were 0.79 and -0.01, respectively, that were observed to be out of acceptable limits for the model simulation. The importance of higher time resolution (hourly) precipitation records for flow simulation were evaluated by comparing R² and E_NS with 15 min, 2 h, 6 h and 12 h precipitation data, which resulted in lower statistics with increases in time resolution of precipitation data. The SWAT sub-daily sensitivity analysis was performed with the consideration of hydraulic parameter and was found as in the rank order of CN2 (curve number), ESCO (soil evaporation compensation factor), GW_DELAY (ground water delay time), ALPHA_BF ( base flow alpha factor), GWQMN ( a threshold minimum depth of water in the shallow aquifer required for return flow to occur) , REVAPMN (minimum depth of water in shallow aquifer for re-evaporation to occur) , LAT_TIME (lateral flow travel time) respectively. These sensitive parameters were evaluated at 10% higher and lower values of the parameters, corresponding to 70.5% higher and 23.2% lower in simulated flow out from the SWAT model. From the results obtained in this study, hourly precipitation record for SWAT sub-daily with Green-Ampt infiltration method was proven to be efficient for runoff estimation at field sized watershed with higher accuracies that could be efficiently used to develop site-specific Best Management Practices (BMPs) considering rainfall intensity, rather than simply using daily rainfall data.