Applying metabolic fingerprinting to ecology: The use of Fourier-transform infrared spectroscopy for the rapid screening of plant responses to N deposition

The potential for metabolic fingerprinting via Fourier-transform infrared (FT-IR) spectroscopy to provide a novel approach for the detection of plant biochemical responses to N deposition is examined. An example of spectral analysis using shoot samples taken from an open top chamber (OTC) experiment simulating wet ammonium deposition is given. Sample preparation involved oven drying and homogenisation via mill grinding. Slurries of a consistent dilution were then prepared prior to FT-IR analysis. Spectra from control, 8 and 16 kg N ha^–1 yr^–1 treatments were then subjected to cross-validated discriminant function analysis. Ordination diagrams showed clear separation between the three N treatments examined. The potential for using Calluna vulgaris (L.) Hull as a bioindicator of N deposition is further evident from these results. The results also clearly demonstrate the power of FT-IR in discriminating between subtle phenotypic alterations in overall plant biochemistry as affected by ammonium pollution.     

Assessment of the maximum allowed acid deposition load at current stage in China

Soil acidification caused by acid deposition has been significant in some forests in southern China. We present an approach for assessing the current stage maximum allowed load (SML) of acid deposition for terrestrial system in the country. The main idea was that soil base cation exchange as a finite buffer to acidity was included in the soil acidity mass balance calculation at current acidification stage. We calculated the SML for five forests in southern China. The usual critical loads for the same forests were also calculated by the steady state mass balance model for comparison. The results showed that the SML is a more tolerant limit than the critical load for the forests with soils not acidified seriously at current stage. However, the SML become a more stringent limit to acid deposition when the forest soils have acidified seriously to very low base cation saturation. In this case the SML assessment is beneficial for the soils recovering from a serious acidified state. Based on a national scale database, the SML mapping for non-agricultural soil system in China was carried out.     

工业园区综合难降解废水深度处理实验研究

某工业园区综合废水处理厂设计规模5.0×104m3/d,原设计出水执行《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级B标准,需将出水标准提高到一级A排放标准.分别采用混凝沉淀法和高级氧化法深度处理二级生化出水.小试试验结果表明:二级生化出水CODcr在62~75 mg/L左右,PAC、Al2(SO4)3及PFS三种絮凝沉淀药剂处理出水CODcr去除效果均不明显,不能稳定达到一级A排放标准.芬顿催化氧化的pH=5,FeSO4+H2O2投加量为(200+100)mg/L;臭氧氧化的O3投加量33 mg/L,其出水CODcr均能达到一级A排放标准.     

亚微米颗粒在Sierpinski海绵模型中热泳沉积研究

亚微米颗粒由于其特殊的粒径尺度,具有很多不同于与传统细颗粒的物理和化学性质,同时极易吸入人体,对人体造成很大危害。谢尔宾斯基海绵模型作为一种理想化的结构模型,具有内比表面积大、多通道等特点。通过建立可工程应用的谢尔宾斯基海绵模型通道,并结合热泳沉积相关数学模型开展计算,可以发现:随着谢尔宾斯基海绵阶数的上升,内部通道的增加是引起亚微米颗粒热泳沉积率上升的主要因素;在海绵通道中运动的亚微米颗粒较之其他粒径的颗粒,更容易受到热泳沉积的影响;同时温差对其热泳沉积影响较为剧烈,呈现线性变化。建立具有工程特征的谢尔宾斯基海绵模型通道,可为研究亚微米颗粒沉积及脱除开辟一条新途径。     

苏州河表层沉积物中总汞测定的研究

采用金汞齐富集-冷原子吸收光谱法直接测定苏州河表层沉积物中的总汞。结果表明:该方法在0.00～200ng范围内呈良好线性关系,检出限为0.005mg/kg(样品以0.2g计)。实际样品测定的RSD为1.24%～4.36%,加标回收率为91.8%～101%。与原子荧光光谱法相比,两种方法测定的结果没有显著差异。     

模拟氮沉降和CO2浓度增加对三江平原小叶章群落土壤总有机碳和氮素含量的影响

利用开顶气室(Open-Top Chamber,OTC),设置当前大气CO2浓度(370μmol.mol-1)、中等CO2浓度(550μmol.mol-1)和高CO2浓度(700μmol.mol-1)3个CO2浓度水平和不施氮(N1,0g N.m-2.a-1)、常氮(N2,5g N.m-2.a-1)、高氮(N3,10g N.m-2.a-1)3个氮素水平。研究了不同N沉降水平下,大气CO2浓度升高对以三江平原小叶章群落土壤有机碳和氮素含量的影响。结果表明:CO2浓度升高结合氮沉降连续运行两个生长季后,湿地土壤总有机碳含量没有显著变化,说明较短时间内大气CO2浓度升高和氮沉降不会使三江平原土壤有机碳含量产生变化。氮沉降引起各个土层的土壤全氮、铵态氮和硝态氮的含量增加,施氮水平越高土壤氮增加越多,但是全氮增加量不明显,铵态氮随施氮量的增加呈现极显著差异水平(P<0.01)。0～10cm,10～20cm土层土壤全氮、铵态氮的含量随着CO2浓度升高呈现出先增大后减小的趋势。土壤硝态氮含量在10～20cm土层含量变化与土壤全氮、铵态氮的变化趋势相同。说明大气CO2浓度一定程度的增加可以增加土壤的氮素含量,但是过量的大气CO2浓度反而会使得土壤氮素含量减少。     

城市排水系统沉积物特性研究

重点阐述了沉积物的来源和组成,沉积物的颗粒粒径、有机物含量(VSS/SS)、颗粒粘性和颗粒密度等物化性质,以及附着于沉积物上的金属污染物的相关特征。其粒度分布范围是D10为1.89～223.21μm,D50为12.38～437.30μm,D90为39.06～1 572.52μm;VSS/SS的范围是1%～38%;密度范围是1.80～2.47 g/cm3。金属污染物主要的附着对象是沉积物中的细小颗粒如生物膜上。以上沉积物性质对于解决排水系统的泥沙淤积问题以及水体污染的控制都具有重要意义。     

维管束植物桂花树叶片对大气氮沉降的吸收研究

本文通过测定维管束植物桂花树叶片的氮含量和氮同位素组成,分析其对大气氮沉降的截留吸收机制。为期一年(2009.03～2010.03)的监测数据显示,桂花树叶片氮含量为1.33%～3.09%,平均值为2.18%;叶片δ15 N为+0.54‰～+3.78‰,均值为+2.29‰。桂花树叶片N%、δ15 N的季节性变化趋势,总体呈现春、冬高,夏、秋低的规律,这与已有的贵阳市雨水监测数据一致。对比不同树冠厚度的叶片样品,发现叶片N%随树冠厚度增加而降低,顶部叶片N%表现为最高(2.39±0.4%),说明桂花树的树冠层对大气氮沉降有明显的截留吸收作用。桂花树顶部叶片δ15 N最偏负,而上覆树冠层最厚的下方叶片的δ15 N最偏正,反映了树冠层在吸收大气氮沉降过程中存在选择性吸收,引起同位素分馏,即树冠层越厚,穿冠水δ15 N越偏正,且分馏程度与树冠厚度成正比,导致下方叶片δ15 N最高。     

铜坑矿区蔬菜和土壤汞污染研究及来源解析

为了深入了解铜坑矿区的汞污染状况,就矿区内蔬菜、土壤中的汞进行了含量研究,指出了矿区汞污染传播途径以及可能造成居民受汞污染的途径,最后针对矿区内不同污染程度的尾砂坝、山地、农田、住宅等不同地区提出了针对性的治理方案。     

Soil fertility dynamics in runoff-capture agriculture, Canary Islands, Spain

In the extremely arid (∼150 mm yr⁻¹) eastern Canary Islands of Lanzarote, Fuerteventura and La Graciosa, agriculture has been sustained for decades by a traditional runoff-capture (RC) farming system known as “gavias”. Although the main goal of these systems is to increase water supply for crops, making unnecessary conventional irrigation, a secondary and equally important factor is that this system allows for sustainable agricultural production without addition of chemical or organic fertilizers. A field study was conducted to assess the impact of long-term agriculture (>50 yr) on soil fertility and to evaluate key factors affecting the nutrient sustainability of RC agricultural production. Soil fertility and nutrient dynamics were studied through chemical characterization of the arable layer (0-25 cm) of RC agricultural plots, adjacent natural soils (control) not affected by runoff and cultivation, and sediments contributed by a series of RC events. Results showed that RC soils have enhanced fertility status, particularly because they are less affected by salinity and sodicity (mean electrical conductivity = 1.8 dS m⁻¹ vs. 51.0 dS m⁻¹ in control soils; mean exchangeable sodium percentage = 11.1% vs. 30.6% in control soils), and have higher water and nutrient holding capacities (mean clay plus silt contents ≈87% vs. 69% in control soils). In general, sediments transported with the runoff and deposited in RC plots (average sediment yield ≈ 46 ton ha⁻¹ yr⁻¹), contain sufficient nutrients to prevent a progressive reduction of essential plant nutrients below natural levels in spite of nutrient uptake and removal by the harvested crop. Average additions of nitrogen, phosphorus and potassium with the runoff sediments were 33.6, 35.3 and 48.8 kg ha⁻¹ yr⁻¹, respectively. Results of this study show how a crop production system can be sustained in the long term by natural hydrological and biogeochemical catchment processes. This system maintains a nutrient balance that is not based on energy-intensive inputs of fertilizers, but is integrated in natural nutrient cycling processes, unlike other tropical farming agroecosystems.