Low Water Treatment Research Articles

Research Progress in Application of Low Temperature Plasma Technology for Wastewater Treatment

As a new advanced oxidation technology, low temperature plasma integrates strong oxidizing particles, ultraviolet light decomposition, wet oxidation and other technologies. Compared with other technologies, it has the advantages of no selectivity, no secondary pollution, and mild reaction conditions. At present, low temperature plasma technology has made some achievements, but there are some limitations in the actual scale water treatment application.The mechanism of low temperature plasma oxidation needs to be further studied. The reaction and active factors produced by low temperature plasma in the process of water treatment are very complicated, and there is no uniform conclusion on the reaction mechanism. The stability of plasma discharge depends not only on the parameters of power supply equipment and solution, but also on the design of reactor. How to design a reasonable, efficient and mass transfer reactor by combining various influencing factors is also the future research direction.The combination of low temperature plasma water treatment technology with various advanced oxidation technologies should be strengthened.

Intraspecific variation in morphology, physiology, and ecology of wildtype relative to horticultural varieties of red maple (Acer rubrum)

Wildtype and horticultural varieties of red maple seedlings had different morphologies and physiological responses to water stress and abundances of an insect herbivore when grown in a common garden. Horticultural varieties of trees (cultivars) are selected for desirable and consistent morphologies relative to wildtype trees, but the ways by which morphology influences intraspecific physiological and ecological responses are unclear. In this study, we compared morphology, gas exchange and water use efficiency, and stem herbivory for seedlings of wildtype red maple (Acer rubrum) and two cultivars, ‘Summer Red’ and ‘Brandywine,’ grown together in a common garden. Seedlings also received high and low water treatments. Overall, wildtype seedlings grew taller, had fewer, larger leaves, intermediate rates of photosynthesis, and lower abundances of the scale insect Melanapsis tenebricosa, relative to the cultivars. Summer Red seedlings had more leaves, leaves with red coloration throughout the growing season, and the highest rates of photosynthesis, although photosynthesis was higher in green relative to red leaves. Brandywine seedlings tended to be intermediate in morphology, exhibited smaller differences between the high and low water treatments, and had higher leaf water use efficiency than Summer Red seedlings in April and June but similar water use efficiency in September. Total seedling water use efficiency, measured in September, was highest for wildtype seedlings. Both cultivars had more scale insects than wildtype seedlings under well-watered conditions. These differences among types of red maple aid in understanding how intraspecific variation in tree appearance—and the en masse planting of a single cultivar in cities—affects physiological and ecological responses, the provision of ecosystem services, and the condition of planted trees.

水分和种植密度对干热河谷车桑子生长性状及种内相互关系的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 水分和种植密度对干热河谷车桑子生长性状及种内相互关系的影响 DOI: 10.5846/stxb202002130246 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2018YFD0200502）；绵阳师范学院生态安全与保护四川省重点实验室开放基金项目（ESP1901）；绵阳师范学院科研启动项目（QD2019A04） Effects of water and planting density on the growth characteristics and intraspecific relationships of Dodonaea viscosa in a dry-hot valley Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:水分是干热河谷植物生长过程中最主要的限制因子，种植密度增加也会引起植物生长的资源限制，两者交互作用下植物生长性状及种内关系的变化特征还不清楚。以干热河谷优势植物——车桑子为研究对象，根据元谋干热河谷年均生长季降雨量设置3种水分梯度：高水分、中水分和低水分，同时在各水分梯度下设置4个种植密度：1、2、4、9株/盆，探究水分、种植密度及其交互作用对车桑子生长性状、生物量分配及种内相互作用的影响。结果表明：（1）低水分条件下，车桑子生长和水分生理受到抑制，但车桑子在较低的叶水势下依然能够保持较高的相对含水量；（2）干旱胁迫显著降低了车桑子总生物量和单株生物量，显著增加了枯叶生物量比例，低水分和中水分条件下，增加种植密度对总生物无显著影响；而高水分条件下，增加种植密度显著提高了车桑子总生物量；（3）低水分显著增加了茎、叶生物量的异速生长指数，将更多生物量分配到叶，而种植密度增加显著降低了茎、叶生物量的异速生长指数，增加了茎的生物量分配；（4）通过相对邻体效应的计算，各处理条件下，车桑子种内关系均表现为竞争作用，并且，这种竞争作用的强度随水分的减少和密度的增加而增加。在高密度条件下（9棵/盆），增加水分不会减轻种内竞争作用。综上，水分和种植密度均会对车桑子个体的生理生长产生影响，在植被恢复过程中，应考虑水分和种植密度对车桑子个体产生的资源限制作用。 Abstract:Water is the most important limiting factor in the growth of plants in dry-hot valleys; furthermore, the increase in planting density also causes resource limitation in plant growth. However, the interactive effects of water and planting density on plant growth characteristics and intraspecific relationships are not clear. In this study, Dodonaea viscosa, a dominant species in dry-hot valleys was used as the research subject. According to the rainfall during the growing season of Yuanmou dry-hot valley, D. viscosa was planted with three water levels (high water, medium water, and low water) and at four densities (1, 2, 4, and 9 plants/pot) to explore the influence of water, planting density, and their interaction on growth, biomass accumulation, and intraspecific interaction of D. viscosa. The results showed that (1) under the low-water treatment, the growth and water physiology of D. viscosa were inhibited, but the relative water content was still high when the leaf water potential decreased greatly. (2) Drought stress significantly reduced the total biomass and individual biomass and significantly increased the proportion of litter biomass. Under the low-water and medium-water treatments, the increase in planting density had no significant effect on total biomass, whereas under the high-water treatment, the increase in planting density significantly improved total biomass of D. viscosa. (3) The allometric exponent of stem biomass and leaf biomass was significantly greater under the low-water treatment, which indicated relatively more biomass was allocated to leaves, and the allometric exponent decreased under high-planting density. (4) The intraspecific relationship of D. viscosa exhibited a competitive effect, and the intensity of the competitive effect increased with decreased water content and increased with an increase in planting density. Under the high-density treatment (9 plants/pot), increasing water content did not reduce the competitive effect. In conclusion, both water and planting density affected the growth and physiological characteristics of D. viscosa. In the process of vegetation restoration, the effect of water and planting density on resource constraints of D. viscosa should be considered. 参考文献 相似文献 引证文献

Efecto de la composición iónica sobre el crecimiento y la supervivencia de camarón blanco Litopenaeus vannamei cultivado en agua de pozo de baja salinidad

El cultivo de camarón blanco Litopenaeus vannamei en agua con baja salinidad (1,2 ± 0,5 g L-1) y con diferente composición iónica afecta el desempeño de los organismos en cultivo. El efecto de cultivar en agua de baja salinidad con diferente contenido de iones fue evaluado en crecimiento y supervivencia del camarón. Cuatro pozos de diferente composición iónica del agua fueron seleccionados en el Río Sinaloa, Guasave, México, localizados en: (T1) 25,43°N, 108,44°W; (T2) 25,48°N, 108,37°W; (T3) 25,60°N, 108,40°W y (T4) 25,64°N, 108,51°W. El diseño experimental fueron 4 tratamientos con 3 réplicas. También se cultivó camarón en agua de mar (Tm= 34 ± 1,4 g L-1) como control. El camarón cultivado en Tm y T1 alcanzaron peso promedio superior a 12 g y tasa de supervivencia del 78%, con diferencias significativas a los demás tratamientos de agua de baja salinidad. El factor de condición obtenida con agua de baja salinidad (T1= 0,654) fue similar al registrado para Tm (0,670), donde las proporciones iónicas (Na/K y Mg/K) fueron similares en ambos. Esta última observación sugiere que las proporciones de los principales iones (Na+, K+, Mg2+ y Ca2+) juegan un papel relevante para el desarrollo de los organismos bajo cultivo. Cuando la relación iónica fue similar a la del agua de mar, se obtuvieron organismos con el mejor desarrollo, indicando que la proporción de iones mayores fueron importantes para el crecimiento y desempeño del camarón en cultivo.

Protecting Natural Water Infrastructure in Espírito Santo, Brazil

After years of attempting to address rising turbidity in its water supplies with engineering solutions, Vitória, the capital of the Brazilian state of Espírito Santo, is turning to watershed conservation. Degradation in the watershed of the Santa Maria da Vitória River, from which Vitória obtains almost 40% of its water supplies, has resulted in a significant increase in water treatment costs; investments in improved filtration have only managed to slow. To reduce erosion in the watershed, a program of Payments for Environmental Services (PES) is being implemented, initially in a micro-watershed that has been identified as contributing disproportionately to sediment loads. This paper estimates the impact of watershed degradation on Vitória’s water treatment costs and undertakes a cost–benefit analysis of the benefits of watershed conservation. These interventions will benefit both downstream water users, in the form of lower water treatment costs, and upstream landholders, in the form of higher income from farming activities and payments for conservation.

Efficiency and Applicability of Low Cost Home-based Water Treatment Strategies in a Rural Context

Efficiency and Applicability of Low Cost Home-based Water Treatment Strategies in a Rural Context

Zinc Sulfide Prepared Through Zno Sulfuration: Characterization and Photocatalytic Activity

P-nitrophenol (PNP) is a toxic organic pollutant and it is difficult to remove from wastewater by means of conventional treatment processes. Therefore, effective and low cost alternative water treatment technologies are required. In the last years there has been a growing interest in advanced oxidation processes involving semiconductor mediated photocatalysis because the process mineralizes many toxic organic pollutants to carbon dioxide and water at ambient temperature under UV light.The aim of this work is to synthetize ZnS photocatalyst starting from formerly ZnO prepared with different precursors such as zinc sulphate and zinc nitrate by means of precipitation method. ZnS was then obtained by sulfuration of ZnO particles. The sulfuration step was carried out at 450°C in presence of N2 gaseous stream containing H2S at 5 vol%. The prepared photocatalysts were characterized from chemical-physical point of view using different techniques (XRD, BET, UV-vis DRS, Raman).The photocatalytic tests were carried out in a recirculating batch cylindrical photoreactor irradiated by a UV-LEDs strip (nominal power of 12W/m and wavelength emission peak at about 365 nm) surrounding the external surface of the reactor. The experimental results evidenced that the optimal sample is ZnS obtained from the sulphuration of ZnO synthetized by zinc sulphate. In particular, this sample was able to achieve about 51% PNP degradation after 240 min of UV light irradiation.

Variable Influences of Water Availability and Rhizobacteria on the Growth of Schizachyrium scoparium (Little Bluestem) at Different Ages.

There is significant interest in understanding the role of plant growth-promoting rhizobacteria (PGPR) in alleviating different types of plant stress. Schizachyrium scoparium (little bluestem) is a moderately drought tolerant, perennial bunchgrass native to North America. The goal of this experiment was to evaluate whether the addition of a bacterial root isolate in the Pseudomonas genus promoted the growth of S. scoparium with changes in water availability. Pseudomonas are common rhizobacteria and have been shown to improve plant growth. It was hypothesized that plants inoculated with the PGPR strain would have greater growth and health, and would be less affected by shifts in water availability. Pseudomonas strains were isolated from the roots of native S. scoparium plants. After germination, S. scoparium seedlings were subjected to four treatment groups: low water; high water; low water with PGPR; and high water with PGPR. The experiment was run three times with plants at different starting ages; 14-, 28-, and 70-day-old plants. The effects of the water and PGPR treatments were variable between the experimental trials. There were no significant effects of the water treatments on plant growth in Trial 1 (14-day-old plants) or Trial 2 (28-day-old plants), however, there was a significant negative effect of the high watering treatment on the shoot length and biomass in Trial 3. High water availability was significantly associated with greater plant health in Trial 1, but appeared to reduce plant health in Trials 2 and 3. The PGPR treatment appeared to promote root growth and biomass in Trial 2, and was associated with greater plant health in all three trials, especially when paired with the low water treatment. Results from a permutational MANOVA indicate that plant growth was significantly different between the trials due to differences in the starting age of the plants and the duration of the experiments. Thus, methodological choices, such as plant life history stage and experiment duration, may affect the response of plants to PGPR in the rhizosphere. This research provides an insight into the interactions between PGPR and water availability on the growth and health of native plants.

Sustainable removal of pernicious arsenic and cadmium by a novel composite of MnO2 impregnated alginate beads: A cost-effective approach for wastewater treatment

There is a dire necessity of developing low cost waste water treatment systems, for the efficient removal of noxious heavy metals (and metalloids) such as Arsenic (As) and Cadmium (Cd). Magnetic biopolymer (CABs-MO) was synthesized by the entrapment of nanocrystalline MnO2 in the polymeric microcapsules of calcium alginate (CABs). Batch experiments were conducted under constant pH (6.5), temperature (25OC), different initial concentrations (30–300 mg L−1) and contact times (0–48 h) to study the adsorption isotherms and removal kinetics of pristine (CABs) and hybrid biopolymer (CABs-MO) for the removal of As and Cd. The pseudo-equilibrium process was mathematically well explained by the pseudo-second-order kinetic (R2 ≥ 0.99) and Langmuir isotherm model (R2 ≥ 0.99) with the highest monolayer sorption capacity of 63.6 mg g−1 for Cd on CABs-MO. The As removal rate was maximum up to 6.5 mg g−1 after 12 h of contact period in a single contaminant system than in the mixed contaminant (As + Cd) system (0.8 mg g−1), though the effect was non-significant for Cd (p < 0.05; t-test). The performance of the 10 mM HCl as a regenerating agent was superior (for As in comparison to Cd, p < 0.05; t-test) compared to distilled water (DW) through three to five regeneration cycles. Therefore, the obtained results clearly validate the feasibility of CABs-MO as a potential promising adsorbent for removing metal contaminants from the wastewater. Further research is required to study the decontamination of emerging contaminants with such novel composite beads characterized by varied physico-chemical properties.

A Comparative Analysis of Physicochemical Composition of Selected Spring Water in the Bale Eco-region, South East Ethiopia

Spring water chemical behaviors in various locations and environmental degradation are being among the most recent dynamic issues. In this study, spring water sources of the Rira and Burkitu streams of remote rural areas were considered as holy and healthy water by the local communities. However, the quality of the water is not yet analyzed and still very low attentions are paid by the concerned governmental stakeholders towards characterizing the mineral constituents in order to confirm the existing perceptions. This study focused on comparing water quality of two springs exists in the two extreme altitudinal difference (from upper mountain (Rira spring) and lower altitude (Burkitu spring)) flowing through undisturbed ecosystem in the Bale Ecoregion. Water samples were taken following depth integrated composite samples from the two streams in 2015. The samples were taken to Ethiopian Public Health Organization, Addis Ababa. The spring water samples’ physicochemical characteristics were compared by one way ANOVA and a piper diagram and evaluated against WHO drinking water quality standards. Laboratory investigations revealed that “Burkitu” spring water has a special physique that makes it advantageous water. Turbidity, PO4, F-, and NH4+1 content of Rira and Burkitu spring water were 0.11 and 1.06 (NTU), 0.08 and 0.1 (mg/L), 0.43 and 0.42 (mg/l) 0.19 and 0.18 (mg/l) but not significantly different at P value less than 0.05 in that order respectively. Significantly different parameters at P value less than 0.01 were filterable residue at 180°C, CaCO3, Hardness, silica, Na+, K+, Ca, Mg, NO3, and HCO3 content of Rira and Burkitu springs were 56 and 222, 10 and 180, 36 and 188, 28.18 and 33.51, 6.1 and 8.2, 0.6 and 1.3, 11.22 and 54.51, 1.95 and 12.65, 6.17 and 1.19, 12.2 and 219.6 in that order respectively. pH and NO2 of the springs were significantly different at P value less than 0.05. The most dominant hydro chemical facies explaining the quality were Ca and Na in which Ca2+> Na+. Moreover, the water fit Ethiopian drinking water standard saving the lives of those rural communities with low and cheap water treatment.

Recyclable polyvinyl alcohol sponge containing flower-like layered double hydroxide microspheres for efficient removal of As(V) anions and anionic dyes from water.

Layered double hydroxides (LDHs) are very promising adsorbents for the removal of anionic pollutants from water. However, the low adsorption efficiency and recycling difficulty of conventional LDH powders are obstacles to practical applications. Herein, a novel Zn/Fe-LDH composite sponge was successfully fabricated using a simple in-situ hydrothermal method. Characterization studies revealed that the composite sponge contained flower-like Zn/Fe LDH microspheres uniformly dispersed throughout a poly vinyl alcohol (PVA) sponge matrix. The specific surface area of the Zn/Fe-LDH composite sponge was 42.5 m2 g-1, approximately 5 times higher than the pristine PVA sponge (8.9 m2 g-1). Adsorption experiments revealed that Zn/Fe-LDH composite sponge exhibited a much higher adsorption ability for As(V) anions and methyl orange (MO) compared with a Zn/Fe-LDH powder or the pristine PVA sponge. The maximum adsorption capacity for As(V) was found to be 85.7 mg g-1. Furthermore, the Zn/Fe-LDH composite sponge showed high thermal stability, good mechanical stability and easy recoverability, thereby allowing reuse. Results guide the development of improved, low cost water treatment materials.

Stabilization of High-Organic-Content Water Treatment Sludge by Pyrolysis

Water treatment sludge from algal blooms were analyzed and compared with general water treatment sludge as the pyrolysis temperature was varied from 300 °C to 900° C. Elemental analysis showed that the water treatment sludge in the eutrophication region has ~12% carbon content, higher than that (8.75%) of general water treatment sludge. X-ray diffraction (XRD) analysis of both types of sludge showed that amorphous silica changed to quartz and weak crystalline structures like kaolinite or montmorillonite were decomposed and changed into stronger crystalline forms like albite. Fourier transform infrared spectroscopy (FT-IR) peaks of humic/fulvic acid that indicated the affinity to combine with heavy metals disappeared above 700 °C. Toxicity characteristic leaching procedure (TCLP), conducted to determine the heavy metal leaching amount of pyrolyzed water treatment sludge, showed the lowest value of 5.7 mg/kg at 500 °C when the humic acid was not decomposed. At 500 °C, the heavy metal leaching ratio to the heavy metal content of high organic content water treatment sludge and low organic content water treatment sludge were 1.87% and 3.19%, respectively, and the water treatment sludge of higher organic content was more stable. In other words, pyrolysis of water treatment sludge with high organic content at 500 °C increases the inorganic matter crystallinity and heavy metal leaching stability.

Characteristics of Multifunctional Polymer and Its Use for Low Pressure Boiler Water Treatment - Its Application to Marine Boilers

Characteristics of Multifunctional Polymer and Its Use for Low Pressure Boiler Water Treatment - Its Application to Marine Boilers

Removal of nitrogen from low pollution water by long-term operation of an integrated vertical-flow constructed wetland: Performance and mechanism

The efficiency of nitrogen removal and its mechanism, aquatic organism distribution characteristics and regeneration capability of zeolite from an integrated vertical-flow constructed wetland (IVFCW) for low pollution water treatment were evaluated after steady and continuous operation for eight years. After running for eight years, better than average COD and NH4+-N removal were observed in the IVFCW. The NH4+-N removal rate in this system was controlled by ammoxidation and adsorption and ion exchange of zeolite. The low total nitrogen (TN) removal efficiency was due to NO3−-N accumulation and zeolite desorption. In addition, this phenomenon indicated that because of poor organic carbon sources, nitrification was stronger than denitrification, consistent with the distribution of the functional genes for nitrification and denitrification. The biological activity in this system was abundant, especially that of spirogyra and navicula. The saturated adsorption capacity of zeolite was as high as 1.35 mg g−1 with a desorption rate of <20%. There were no obvious differences among the effects of aeration, water cleaning, drained reoxygenation and steam stripping for zeolite regeneration (adsorption capacity of >50%). However, the drained reoxygenation performance of was better due to zero energy consumption and regeneration in situ.

Assessment of Urban Water Supply System Based on Query Optimization Strategy

As a complicated water treatment system project, an urban water supply plays a significant role in enhancing ecological civilization construction, promoting social-economic sustainable development, and improving the living environment of humans. This paper has the goal of improving water treatment efficiency and reducing water treatment cost based on comparative studies by applying two types of distributed database query optimization methods, including the system for a distributed database (SDD-1) and all reduction algorithms. The approach involves the components of partial relations and deletes the database components that are unrelated to a query, using only attributes related to a query. Thereby, the realization process becomes simple, with a small amount of transmitted data. The results show that the validity and convenience of all reduction algorithms involve the whole query process. An algorithm is independent of the chart of static characteristics and can realize all reduction states without depending on analyzing the benefits from intermediate semijoin results, which will ultimately contribute to reductions in the transmission of useless data in the network and communication costs. Implementation of the query optimization strategy can improve water treatment efficiency, reduce water treatment cost, lower water treatment expense, and implement effective communication.

Effects of climate change on water savings and water security from rainwater harvesting systems

Climate change presents major uncertainties in future safe water access especially in rural communities that are already faced with water insecurity. For Uganda, rainwater harvesting has become a major adaptation strategy to ensure the attainment of safe water access for all. However, climate change effects on rainwater harvesting potential remains largely unexplored. Therefore, this paper assesses climate change effects on water savings and water security from rainwater harvesting systems for Kabarole district, Uganda. The top performing Global circulation models (GCMs), used in this study included; MIROC5, BCC-CSM-1-M, CNRM-CM5, ACCESS1-0, HADGEM2-ES and HADGEM2-CC using projections for 2025–2055 (2040s) and 2060–2090 (2070s) periods. Seasonal analysis used the 4 seasons for Uganda, namely; the 2 dry seasons of December, January, February (DJF) and June, July, August (JJA) and the 2 rainy seasons of September, October, November (SON) and March, April, May (MAM). Although there are conflicting model predictions, generally, the models agree that water savings and security will reduce in DJF and MAM and increase in JJA and SON seasons. MAM rain season will be most affected with water savings and security projected to reduce by more than 50% in the 2070s period. Therefore, households should harness the increased water savings in JJA and SON to cater for the predicted reduction in water savings in MAM and DJF seasons especially for the 2070s period. A larger tank of 5 m3 along with at least 50 m2 roof size combined with a low cost household water treatment is thus recommended.

An irrigation control system with a web-based interface for the management of Eucalyptus planting stock in a nursery

Efficient nursery irrigation is a key factor for the production of high-quality forestry planting stock. Conventional timer-based irrigation systems used by most forestry nurseries have some drawbacks that, if not properly managed, can lead to over-irrigation and water wastage, leaching of nutrients and contribute to increased incidences of pests and/or diseases. A practical method to accurately measure media water content and control irrigation more carefully could prevent some of these issues. To evaluate the potential use of an automated irrigation system, commercially available Decagon EC-5 dielectric soil water content sensors were laboratory-calibrated against the gravimetric method using coir/pine bark/vermiculite, coir/perlite and pine bark media to measure water content of nursery seedling containers. Using Eucalyptus dunnii seedlings raised in polystyrene seedling containers to test the irrigation system, a datalogger was programmed to control irrigation for low (0.22–0.26 m3 m−3), medium (0.26–0.32 m3 m−3) and high (0.32–0.41 m3 m−3) watering treatments. The measurements were displayed in near real-time using a web-based system, which allowed for system checking and from which data could be downloaded. The Decagon EC-5 sensors were successfully calibrated for all media (R2 > 0.97) and provided a better estimation of media water content than the manufacturer-supplied calibration equation better-suited for soils. The automated irrigation system effectively maintained the specified media water content for E. dunnii seedlings. The high watering treatment seedlings had the highest growth rates, although this treatment also had increased leaching of nutrients. By contrast, the low watering treatment seedlings showed the lowest growth rates, although these seedlings seemed to be more robust and tolerant of water stress. This study showed that the automated irrigation system, based on measurements of the media water content, can be successfully used in scheduling irrigation for Eucalyptus seedlings, leading to potential water savings.

Drought stress leads to systemic induced susceptibility to a nectrotrophic fungus associated with mountain pine beetle in Pinus banksiana seedlings.

Conifers have complex defense responses to initial attacks by insects and pathogens that can have cascading effects on success of subsequent colonizers. However, drought can affect a plant’s ability to respond to biotic agents by potentially altering the resources needed for the energetically costly production of induced defense chemicals. We investigated the impact of reduced water on induced chemical defenses of jack pine (Pinus banksiana) seedlings from initial attack by biotic agents and resistance to subsequent challenge inoculation with a pathogenic fungal associate of mountain pine beetle (Dendroctonus ponderosae), Grosmannia clavigera. Applications of phytohormones (methyl salicylate and methyl jasmonate) and G. clavigera were used for initial induction of defenses. Monoterpene concentrations varied with initial induction from fungal and phytohormone application while watering treatment had no effect. Seedlings treated with G. clavigera and methyl jasmonate had the greatest monoterpene concentrations compared to the control and methyl salicylate-treated seedlings. However, the monoterpene response to the challenge inoculation varied with watering treatments, not with prior induction treatments, with lower monoterpene concentrations in fungal lesions on seedlings in the low to moderate watering treatments compared to normal watering treatment. Furthermore, prior induction from phytohormones resulted in systemic cross-induction of resistance to G. clavigera under normal watering treatment but susceptibility under low watering treatment. Seedlings stressed by low water conditions, which also had lower stomatal conductance than seedlings in the normal watering treatment, likely allocated resources to initial defense response but were left unable to acquire further resources for subsequent responses. Our results demonstrate that drought can affect interactions among tree-infesting organisms through systemic cross-induction of susceptibility.

Factors affecting the Faradaic efficiency of Fe(0) electrocoagulation

Electrocoagulation (EC) using Fe(0) electrodes is a low cost water treatment technology that relies on efficient production of Fe(II) from the electrolytic dissolution of Fe(0) electrodes (i.e. a high Faradaic efficiency). However, the (electro)chemical factors that favor Fe(0) oxidation rather than O2 evolution during Fe(0) EC have not been identified. In this study, we combined electrochemical methods, electron microscopy and Fe measurements to systematically examine the interdependent effects of current density (i), anodic interface potential (EA) and solution chemistry on the Faradaic efficiency. We found that Fe(0) oxidation was favored (Faradaic efficiency >0.85) in chloride and bromide solutions at all i, whereas carbonate, phosphate, citrate, and nitrate solutions lead to Faradaic efficiencies <0.1. The anodic reaction (i.e. Fe(0) oxidation or O2 evolution) only depended on i in the sulfate and formate solutions. Experiments in binary-anion solutions revealed that molar ratios of [HCO3−]/[Cl−] near 100 and [NO3−]/[Cl−] near 20 separated the electrochemical domains of Fe(0) oxidation and O2 evolution in the EC system. These molar ratios were supported by experiments in synthetic groundwater solutions. We also found that the EA vs i curves for solutions with poor Faradaic efficiency overlapped but were situated 2–4V vs Ag/AgCl higher than those of solutions with high Faradaic efficiency. Therefore, the position of the EA vs i curve, rather than the EA alone, can be used to determine unambiguously the reaction occurring on the Fe(0) anode during EC treatment.

Effects of Biotic and Abiotic Environmental Stimuli on the Morphology and Biomass Allocation of Mimosa pigra L.

The main focus of this study was to examine the morphology of Mimosa pigra, an invasive weed in response to artificial biotic and abiotic stressors. Seedlings of M. pigra were subjected to stressors such as seed sowing density, leaf defoliation and water regime. Comparatively, morphological performance related to different sowing practices differed significantly (p 0.05) in morphological performance under different levels of water regime. However, seedlings that received low water (LW) treatment showed better growth performance than seedlings that received high water (HW) treatment, which had the lowest morphological traits and biomass allocation.