固定化嗜麦芽寡养单胞菌的高效聚磷效果及应用研究

为寻找能循环去除富磷废水的生物材料,以筛选鉴定出的高效聚磷菌—嗜麦芽寡养单胞菌为材料,测定了该菌的生长曲线,并采用钼锑抗比色法测定该菌的聚磷曲线,比较了游离的嗜麦芽寡养单胞菌和海藻酸钙包埋菌小球对不同浓度含磷废水的聚磷效果。结果表明:游离菌处理5、10、15和20mg/L的含磷废水24h后,聚磷率分别达到97.8%,96.3%,85.3%和70.7%;即游离菌处理10mg/L含磷废水,24h即可达到排放标准(TP0.5mg/L)。海藻酸钙包埋菌的小球在处理5、10mg/L的含磷废水时,12h达到最高聚磷率,分别为99.9%和98.9%,在处理15和20mg/L的含磷废水时,48h聚磷率达到最高,分别为98.2%和98.54%。即包埋小球处理10mg/L含磷废水,12h即可达到安全排放;处理10~20mg/L废水时,48h即可达到安全排放。嗜麦芽寡养单胞菌具有良好的聚磷潜力,且固定化菌聚磷效果更好,特别是对低浓度的含磷废水聚磷效果显著。     

去除污水中总磷的两种方法效果比较

利用磁粉和聚合氯化铝联合除磷法和聚合氯化铁除磷法这两种方法,研究了它们对于高含磷污水和低含磷污水中总磷的去除效果,通过计算去除率,对两种方法的去除效果进行了比较,实验中总磷的测定方法采用过硫酸钾消解-钼酸铵分光光度法,实验结果表明:磁粉和聚合氯化铝联合的去除效果较好,对于高磷污水,当磁粉浓度为300mg/L时,去除率最高,达到了87.25%,出水中磷的浓度为9.153mg/L;对于低磷污水,当磁粉的浓度为300mg/L时,去除率最高,为56.01%,出水浓度为0.545mg/L。     

废水生物法除磷技术的新发展

综述了以PAO（聚磷菌）、DPB（反硝化聚磷菌）和磷酸盐还原菌处理含磷废水的原理,并在此基础上探讨了传统聚磷菌厌氧/好氧、厌氧/缺氧/好氧除磷工艺的各种改进和发展以及反硝化除磷的单泥、双泥系统的除磷效能和研究进展。     

牡蛎壳改性花生壳生物炭吸附去除水体中的磷

基于牡蛎壳富含碳酸钙成分,采用800℃高温改性方法制备牡蛎壳改性花生壳生物炭,考察了其对溶液中磷的吸附性能。实验结果表明:牡蛎壳改性后的花生壳生物炭对磷的吸附量显著高于未改性的花生壳生物炭。溶液初始磷浓度为200mg/L,添加0.02g的生物炭,在25℃下反应48h后,牡蛎壳改性花生壳生物炭磷吸附容量为197.3mg/g,约为未改性花生壳生物炭的17倍。     

A~2O工艺应用于化学制药废水脱氮效果研究

采用A~2O生物处理工艺,处理了高浓度制药废水,结果表明:废水进水NH_3-N平均浓度为262.90 mg/L,出水平均浓度为10.82 mg/L,去除率为95.25%;进水TN平均浓度为587.692 mg/L,出水平均浓度为46.61 mg/L,去除率为91.76%;出水平均pH值和碱度分别为8.66和4.62 mg/L。     

给水厂污泥吸附磷的动力学和热力学研究

对某给水厂污泥用含磷为10mg/L的模拟废水进行了吸附性能的研究。结果表明:该给水厂污泥可有效吸附处理含磷废水,吸附量可达0.154mg/g。吸附过程符合二级吸附动力学模型,通过模型计算出了二级吸附速率常数(k2)为11.912310-3g·mg-1·min-1;热力学研究结果表明:吸附过程可以用Freundlich方程描述,相关系数在0.99以上;计算吸附热力学参数:吸附自由能(ΔG)、吸附熵(ΔS)和吸附焓(ΔH),给水厂污泥对磷的ΔH为-83.34kJ·mol-1,ΔG和ΔH均为负值,表明吸附为一自发的放热过程。     

A~2O+絮凝沉淀组合工艺处理高浓度制药废水工程案例分析

采用A~2O生物处理工艺,并结合絮凝沉淀工艺处理了高浓度制药废水。结果表明:废水进水COD、氨氮、总氮、总磷浓度分别为4845.5 mg/L、403.5 mg/L、570.2 mg/L、26.7 mg/L,出水浓度分别171.4 mg/L、2.9 mg/L、17.1 mg/L、1.8 mg/L,完全满足设计出水要求。工程总投资金额约为660万元,废水处理成本约为18.79元/m~3。工程案例及分析结果可为高浓度化学制药废水处理工艺提供借鉴。     

基质和激素处理对树头菜扦插生根的影响

研究不同基质、不同浓度激素处理对树头菜扦插生根的影响,结果表明:混合基质比其他单一基质扦插生根率高,可达86%;不同浓度激素处理中,以NAA-150mg/L为最佳激素浓度,生根率达93%。促进树头菜扦插生根的最佳处理组合为混合基质(珍珠岩:河沙:草炭=1:1:1)、激素NAA最适浓度为150mg/L。     

膨胀石墨负载型TiO2光催化剂的制备及性能研究

本文以钛酸丁酯作为钛源,细磷片膨胀石墨作为载体,制备出了膨胀石墨负载型TiO2光催化剂,通过XRD对样品结构进行了表征;以紫外光为光源,研究了膨胀石墨负载型TiO2光催化剂对偶氮染料甲基橙的去除效果.实验结果表明:在膨化温度900℃,细磷片石墨:钛酸丁酯:混酸:高锰酸钾=20g:3.7g:200ml:3.6g条件下制备的催化剂催化活性较好,对浓度为100mg/L的甲基橙的脱色率可达95%以上.     

豆腐柴扦插繁殖技术研究

以豆腐柴(Premna microphylla)为研究材料,研究了不同基质类型、不同浓度萘乙酸(NAA)对扦插繁殖的影响。实验结果表明:最佳扦插基质为珍珠岩+泥炭(珍珠岩∶泥炭=1∶2),NAA最佳浓度为100 mg/L,其对豆腐柴扦插生根效果最好。     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.