基于统计模型的养殖鱼塘溶解氧预报技术研究

根据武汉市2009-2011年的养殖鱼塘溶解氧数据和对应的气象要素,通过多元逐步回归分析构建鱼塘的溶解氧含量预报预测模型,并在武汉和荆州进行了验证。结果表明:一般鱼塘溶解氧在5-9月期间较低,低值一般出现在清晨6-7时,且较低值出现与天气相关,即闷热型天气突降大雨易导致溶解氧值降低。溶解氧量预报预测模型R2均在0.7以上,拟合效果良好。     

Vertical Water Circulation Capabilities of an Electric Paddle Wheel Aerator and Dissolved Oxygen Loss Due to Daytime Aeration

ABSTRACT

Vertical water circulation by the paddle wheel aerator was determined by measuring dissolved oxygen profiles in a 3.6-m deep watershed pond during daylight hours, using aerated and non-aerated treatments. The paddle wheel aerator circulated the well-oxygenated surface water to the pond bottom, producing a uniform dissolved oxygen profile in the aerated treatment, while the non-aerated treatment maintained high dissolved oxygen concentrations near the surface with low dissolved oxygen concentrations near the pond bottom. The aerated treatment contained 35.6% less dissolved oxygen than the non-aerated treatment after four hours as a result of operating the aerator during the daytime. The paddle wheel aerator, with a shallow (10 cm) paddle immersion, is effective in vertically circulating water in deeper ponds. However, substantial loss of dissolved oxygen may result from operating the aerator on days with high rates of photosynthesis.     

南方种养结合模式对冬季稻田净碳交换和不同土层活性碳氮转化的影响

为探讨不同利用模式下的冬季稻田土壤活性碳氮变化和系统净碳交换变化特征。本研究对冬闲(F)、单种黑麦草(R)、单种紫云英(M)、种黑麦草养鸡(RC)以及种紫云英养鸡(MC)的冬季稻田土壤微生物量碳氮、可溶性碳氮及系统净碳交换量进行了定量分析。结果表明,1)RC和MC短期内增加了系统净碳排放,在早稻播种前,白天总体表现为碳汇(RC为817.38 g/m²,MC为472.90 g/m²);且所有处理对CH₄表现为弱汇(3.06~22.88 mg/m²)。2)R和M固碳量显著高于F和RC、MC处理。3)RC,MC,R和M与F相比显著提高了土壤活性碳氮含量。4)虽然RC和MC土壤微生物量碳平均值低于R和M,但其土壤可溶性碳含量平均值更高。5)R, M, RC, MC提高了土壤有机碳含量,增加了土壤碳汇。综上所述,种养结合既提高了土壤活性碳氮,同时增加了冬季稻田系统固碳量。     

Organic amendments decomposability influences microbial activity in saline soils

Organic amendments with contrasting biochemical properties were investigated by conducting an incubation experiment in soils irrigated with different levels of saline water. Soil samples were taken from a long-term experimental field plots irrigated with normal water and saline water having electrical conductivity (EC) 6 and 12 dS m^?1, respectively. Finely ground biochar, rice straw (RS), farm yard manure (FYM) and glucose were added at two rates (1% and 2.5% carbon basis) and incubated for 8 weeks at 25°C. Cumulative respiration (CR), microbial biomass carbon and available nutrients (nitrogen and phosphorus) were negatively correlated with EC, irrespective of the source and amount of added carbon (C). Compared with non-saline soil, at EC 12, relative decrease in CR was lowest with glucose (21.0%) followed by RS (32.0%), FYM (46.0%) and biochar (55.0%). Dissolved organic carbon was positively correlated with salinity and its concentration was higher in treatments with higher rate of C addition (2.5% C). This study showed decomposability of organic amendments and their rate of addition determines microbial activity in saline soils. Further, lower nitrogen (N) release from amendments under saline conditions limits microbial ability to utilize available C for satisfying their energy needs.     

Effect of Different Irrigation Methods on Dissolved Organic Carbon and Microbial Biomass Carbon in the Greenhouse Soil

The objective of this study was to investigate the contents and distribution of dissolved organic carbon （DOC） and microbial biomass carbon （MBC） at 0-100 cm soil depth under three irrigation treatments, viz., subsurface, drip and furrow irrigation in the greenhouse soil. The soil samples were collected at different depths （0-100 cm）, and the contents of soil total organic carbon （TOC）, DOC and MBC were analysed. The experiment was conducted for 10 yr, during which period the application of fertilizers and crop management practices were kept identical. The results showed that the contents of TOC, DOC and MBC were significantly affected by different irrigation regimes, decreased with the increase of soil depth. TOC at 0-10 and 80-100 cm soil depths followed the order of furrow irrigation 〉 subsurface irrigation 〉 drip irrigation, whereas at the depth of 10-80 cm followed the order of subsurface irrigation 〉 furrow irrigation 〉 drip irrigation. DOC and MBC contents at 0-100 cm soil depths followed the order of furrow irrigation 〉 drip irrigation 〉 subsurface irrigation, and drip irrigation 〉 furrow irrigation 〉 subsurface irrigation, respectively. The ratios of DOC and MBC to TOC accounted for 4.98-12.87% and 1.48-2.82%, respectively, which were the highest in the drip irrigation treatment, followed were in the furrow irrigation treatment, and the lowest in subsurface irrigation treatment. There were significant positive correlations among the contents of DOC, MBC and TOC in all irrigation treatments. The furrow irrigation facilitated the accumulation of TOC and DOC, while drip irrigation increased the MBC. The content of TOC and the ratios of DOC to TOC were the lowest in subsurface irrigation treatment.     

不同碳输入方式对沿海防护林土壤氮库的影响

为探究凋落物和根系在滨海沙地人工林土壤氮循环中所扮演的角色,设置去除凋落物、切断根系、对照3种处理,分析3种典型沿海防护林(尾巨桉、纹荚相思、木麻黄)土壤氮素对不同碳输入的响应。结果表明：滨海沙地土壤矿质氮含量(2.91－4.49 mg?kg－1)远低于内陆森林土壤;3种人工林土壤矿质氮含量表现为纹荚相思>木麻黄>尾巨桉,其中纹荚相思与尾巨桉土壤矿质氮含量差异显著( P<0.05);不同树种土壤硝态氮( NO－3－N)含量存在显著差异,表现为纹荚相思>木麻黄>尾巨桉。树种对切断根系或去除凋落物的响应不一致,切断根系后纹荚相思和木麻黄土壤NO－3－N含量显著高于对照,对铵态氮( NH＋4－N )含量影响不显著;切断根系和去除凋落物处理后土壤硝化作用均增强,对尾巨桉的影响达显著水平( P<0.05);切断根系和去除凋落物均显著降低尾巨桉和纹荚相思土壤微生物量氮( MBN)含量,对土壤可溶性有机氮( DON)的影响与之相反。土壤NO－3－N与土壤MBN之间存在极显著的负相关关系( r＝－0.671, P<0.01),与土壤DON呈极显著正相关( r＝0.900, P<0.01),土壤DOC与NO－3－N、 NH＋4－N之间分别存在显著的负相关( r＝－0.413, P<0.05)和极显著的正相关关系( r＝0.461, P<0.01)。     

Soluble Phosphorus Released by Poultry Wastes in Acidified Aqueous Extracts

Abstract

Research has shown that measured water‐soluble phosphorus (WSP) from poultry litter might have been less than that released in the field. The effects of acidified extractions on soluble P (SP) concentrations were studied, and a buffer was selected to measure SP at pH 6.0, which is a target value for soil management in Georgia.

Soluble P concentrations were extracted from poultry wastes at three pHs: 1) at natural pH, using deionized water (DI_w); 2) after titrating DI_w suspensions with 0.5N hydrochloric acid (HCl) to pH end‐points 3.0, 4.0, and 6.0; and 3) at pH 6.0 with buffers of sodium (Na) acetate, potassium hydrogen phthalate (KHP), 2‐(N‐morpholino) ethanesulphonic acid (MES), Na cacodylate, imidazole, N‐(2‐acetamido)‐2‐aminoethansulphonic acid (ACES), N‐(carbamoyl‐methyl) iminodiacetic acid (ADA), bis‐(2‐hydroxyethyl) imino]‐tris‐[(hydroxymethyl) methane (Bistris), and 1,4 piperazine‐bis‐(ethane sulphonic acid) (PIPES).

Total SP increased 60% to 140% in suspensions acidified with HCl to pH 6.0 compared to suspensions at pH≥8. Dissolved unreactive P responded more (2× to 30×) than molybdate reactive P (20–100%). Buffers extracted more soluble minerals than suspensions acidified with HCl, probably because of their complexation ability. The most effective buffer was MES, because its effects seemed mainly due to acidification.     

贵州红枫湖溶解有机质不同分离组分的卤代活性研究

饮用水使用氯化消毒产生的消毒副产物给人类健康带来了极大危害。利用XAD树脂与阴、阳离子交换树脂对贵州红枫湖水体中溶解有机质进行了富集分离,分成腐植酸、富里酸、疏水中性物质及亲水酸性、碱性及中性物质6种组分,比较了各组分在加氯消毒过程中卤代活性的大小及其三卤甲烷的生成情况,揭示了有机组分卤代活性与其结构之间的关系,并探讨了它们可能的来源,提出了相应的控制措施。结果表明,红枫湖水体溶解有机质以富里酸组分为主,占分离出总有机碳的56%。氯化消毒实验发现消毒副产物以三氯甲烷和一溴二氯甲烷为主,富里酸的卤代活性最强。结构分析显示各有机组分的卤代活性与紫外吸光系数和酚羟基含量之间具有显著相关性。6种分离组分的消毒副产物生成量中,富里酸是生成三卤甲烷的主要前驱物质,占消毒副产物总量的76%。有机组分的碳稳定同位素值与C/N比值表明,富里酸主要来自陆源有机物,其余组分兼有陆源和内源两种来源。因此,控制陆源污染是减少红枫湖消毒副产物前驱物的有效途径。     

河岸带土壤溶解性有机质垂直分布特征及其性质研究

河岸带有机质（Soil organic matter,SOM）的迁移转化在有机碳从陆地生态系统向水域生态系统中迁移转化及污染物的迁移转化中起到了重要的作用。以崇明岛典型河岸带为研究对象,分析了不同区域河岸带土壤有机碳（Soil organic carbon,SOC）、土壤溶解性有机碳（Soil dissolved organic carbon,SDOC）垂直分布特征和三维荧光光谱（Excitation—Emission matrix,EEM）特征,探讨了河岸带对土壤溶解性有机质（Soil dissolved organic matter,SDOM）性质及其潜在环境影响。结果表明：表层土壤（0—30cm）SOC储量占采样深度土壤SOC的40％左右,SDOC占SOC的5％左右,从陆上区域到缓冲区域表层土壤SDOC呈累积效应。河岸带有机质主要来自河岸带植物残体及其代谢产物,地下水也可能是河岸带土壤DOM的另一来源,河岸带土壤中大部分类腐殖质被表层矿物质所吸附。在土壤系统中,综合应用荧光指纹指数[荧光指数（Fluorescence index,FI）,生源指数（The index of recent autochthonous contribution,BIX）和腐殖化指数（Humification index,HIX）]可以有效地揭示其来源和特性,但在土壤体系中单独应用指纹指数需审慎。     

Methods for measuring N2O flux from water surface and N2O dissolved in water from agricultural land

A new chamber method and a stripping method were developed for field measurements of the rate of N₂O emission from the water surface and for determinations of dissolved N₂O in water from agricultural land.

These methods were used for the measurement of drainage canal water and flooded water of rice fields during the period of June 1982 to January 1983. The results demonstrate that aquatic systems of agricultural land may provide both source and sink for atmospheric N₂O.