Filter Sheets Research Articles

Toxicity of 6-gingerol and Cymbopogon citratus against Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae): Mortality, detoxifying enzymes, and morphological ultrastructure alterations in lice

Pediculus humanus capitis (head louse), which causes pediculosis capitis, remains a global health concern. Plant products are efficient alternative pediculicides for treating the human ectoparasite P. h. capitis which is resistant to permethrin. The study evaluates the toxicity and mechanisms of 6-gingerol and Cymbopogon citratus leaf extract on P. h. capitis. Pediculus humanus capitis adult stages were exposed to three different dosages of 6-gingerol and C. citratus crude leaf extract on filter sheets for 5, 10, and 30 min, respectively. The biochemical approach was used to assess the activity of detoxifying enzymes including acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. Scanning electron microscope (SEM) was used to investigate the ultrastructure of the morphological body of lice. After 30 min, 6-gingerol and C. citratus leaf extract killed P. h. capitis completely. Bioassay periods significantly affected lice mortality (P < 0.05). The LC50 values for 6-gingerol and C. citratus extract were 1.79 μg/cm2 and 25.0 μg/cm2, respectively. 6-Gingerol and C. citratus leaf extract significantly lower AChE and GST activity (P < 0.05). Cymbopogon citratus also caused morphological ultrastructure changes in P. h. capitis, including an irregularly formed head, thorax, abdominal respiratory spiracles, and belly. 6-Gingerol and C. citratus leaf extracts could be used as an alternate pediculicide to decrease P. h. capitis populations.

Characterization of particulate matter in a multizonal residential apartment: transport, exposure, and mitigation

Spatio-temporal monitoring in a multizonal apartment focussing on inter-zonal transport, multizonal exposure, and characterization of mitigation techniques (portable air cleaner, air conditioners, natural ventilation, and filter sheets).

Implementation of an automated process for Limnospira indica harvesting and culture medium recycling for space applications

Future long-term space exploration missions require the implementation of circular life support systems for the supply of water, oxygen and food from mission wastes. Therefore, separation systems dealing with multi-phasic streams need to be addressed. The BioHarvest (BHV) study focused on solid/liquid separation in space with the aim to demonstrate the continuous separation and harvesting of the cyanobacterium Limnospira indica from its culture broth under axenic conditions. The cyanobacterium biomass is intended to be used for further food processing while the broth free of organic matter and resupplied with nutrients should be directly recycled into the photobioreactor (PBR). In this study, an automated breadboard model based on a two-step process was built. First, a Biomass Harvesting Unit (BHU) separates the biomass produced in the PBR from the culture medium with dead-end filtration. Second, the Medium Filtration Unit (MFU) further treats the culture medium to retain the dissolved organic compounds using crossflow filtration. The performances of BHU and MHU met the requirements in batch mode and in short continuous mode: the BHU was able to retain all the biomass and the MFU could retain more than 90% of organic matter while being permeable to nutrients. The productivity of the MFU was also very good, with a high permeation flux allowing treating the targeted 80 L of culture per day. However, continuous operation of the BHV technology could not be achieved in the long term due to biomass accumulation as a sticky cake with a high specific resistance on the BHU filter, despite backwashing cycles and intense vibrations. Future work shall therefore focus on this critical step, to improve process performance by preventing fouling of the filter sheets.

Source characterization of PM10 using CMB receptor modeling for the western industrial area of India

Introduction: Receptor models use the chemical characterisation of particulate matter to distinguish the source and analyse the source contributions. The main aim of this study is to carry out source apportionment of PM10 for industrial locations of Vapi and Ankleshwar in Gujarat, using the Chemical Mass Balance (CMB) receptor model.&#x0D; Materials and methods: At six distinct locations of Ankleshwar and Vapi, respirable dust samplers were used to collect particulate matter on quartz filter sheets for the current study. Filter papers containing PM10 mass were subsequently examined for Water Soluble Ions (WSIs), major and trace elements, elemental and organic carbon followed by source apportionment study.&#x0D; Results: Using CMB, the contributions obtained for Ankleshwar are 27.85% for crustal or soil dust, 26.31% for fossil fuel combustion, 21.06% for vehicle emissions, 14.20% for secondary aerosols, 9.30% for biomass, and 1.20% for industrial emissions. CMB for Vapi revealed the chief source signatures as fossil fuel combustion including industries contributing 35%, crustal or soil dust contributing 22.90%, biomass burning contributing 19.12%, vehicular emissions contributing 16.18%, and secondary aerosols contributing 6.79%.&#x0D; Conclusion: By applying the CMB model, the primary source is found to be crustal or soil dust followed by burning fossil fuels, vehicular emissions, and secondary aerosols for Ankleshwar and Vapi, respectively. A quantitative assessment of source contributions to particulate matter is required to create emission control measures. The findings of this study will be beneficial for the environmental management of particle concentrations in the study region.

Light Intensity Control Using Polaroids

Abstract: In today’s era of illuminating devices, there are a wide variety of devices available in aesthetics but the none with variable intensity of light. Using the basic principle of polarization of light using a Polaroid filter or polarizer, the designing of a light intensity control was done. The polarizing angle of the filter decides the intensity of the light that would pass through the filters. According to the principle of propagation of light, the electric and magnetic vibrations of a light wave occur perpendicularly to each other. A light wave that is vibrating in more than one plane is known as unpolarized light. The light emitted by the sun, by a lamp or a tube light are all unpolarized light sources. The other kind of wave is a polarized wave. A Plane polarized light vibrates on only one plane. The process of transforming unpolarized light into the polarized light is known as polarization. Using the same principle and with the use of a LDR (light dependent resister) as a sensor to sense the intensity of the surrounding light and then rotate the polaroid filter sheets accordingly using a stepper motor for the required change in intensity. The sensing and sending of feedback and subsequent rotation of the Polaroid filter sheets would be automated by ATMEGA32 microcontroller and L293D. Keywords: Polaroids, LDR, Light Variation, ATMEGA32, L293D

Can Wet Aggregate Stability and Texture Regulate Organic Carbon Stock in Alluvial Soils of East Champaran (Bihar)?

Aims: Here in this experiment, the investigation was done for the relationship among the various soil health parameters i.e., soil organic carbon (SOC), soil texture, and wet aggregate stability (WAS).&#x0D; Place and Duration of Study: Sample: Collection of soil samples were done from 0-15 cm depth from East Champaran is situated in Bihar and is located at 26038’N and 84054’E in the year 2019-2020.&#x0D; Methodology: Soil texture: 14g (+/- 0.1g) of sieved soil was added to a 50 ml centrifuge tube holding 42 ml of a dispersant 3% sodium hexametaphosphate solution follwed by 2 hr shaking and 0.053 mm sieved. Water stable aggregates: Each 0.25-mm sieve contained 4g of air-dried, 2-mm aggregate soil. Each sample's precise weight was recorded. The soil samples were dispersed for 3 minutes with 100 mL distilled water and then for 10 minutes with a 2 g/L sodium hexametaphosphate solution. Pre-weighed filter sheets were used to filter both solutions. Each filter paper was weighed after being oven-dried at 105°C.&#x0D; Soil organic carbon: The amount of soil organic carbon (SOC) was calculated using the Walkley and Black technique (1934).&#x0D; Results: Wet aggregate stability and soil organic carbon storage were shown to have a strong positive connection. Soil carbon stock in soils of East Champaran varied between 5.27-19.60 Mg ha-1 with an average of 12.98 Mg ha-1. WAS ranged from 3.82 to 36.43% with a mean of 16.11%. The results revealed that WAS increased with increase in SOC stock. This experiment also revealed that clay (%) and silt (%) directly affect WAS and hence enhance SOC storage.&#x0D; Conclusion: So, it can be concluded that WAS and soil texture directly and positively impact SOC storage in soils of East Champaran, Bihar.

Mycelium-composite panels for atmospheric particulate matter adsorption

Mycelium composites grow in a symbiotic relationship with the substrate forming entangled networks of branching fibers. The structure of mycelium resembles filter sheets used in air filtration systems. Owing to their porous character, mycelium composites have been studied and developed as sound absorbent materials, insulation materials, and fire-resistant materials. Herein, we investigated the potential utilization of the filter-like, porous characteristics of mycelium for adsorbing atmospheric particulate matter (PM).First, we compared the PM adsorption performance of mycelium composites grown on four different substrates (hemp, rice straw, lacquer tree wood chips, and oak wood chips) with a widely used architectural exterior material, a stone panel (Pocheon granite). Second, we examined the micro-morphology of the mycelium composite panel surfaces by capturing images at 200x and 1000x using scanning electron microscopy. Third, we examined the water absorption rate of the mycelium composite panels with different substrates.The PM adsorption performance of the mycelium composites were superior to that of the Pocheon granite. The PM adsorption performance of the mycelium composite panels varied depending on the type of the substrate. However, the relationship between the micro-morphology of the surface and the PM adsorption performance could not be defined. We also observed that the mycelium composite panels with the higher PM adsorption performance exhibited a higher rate of water absorption. This study shows that mycelium composite panels have potential to be developed as atmospheric PM adsorbing material.

Reduction of radiocesium in Shiitake (Lentinula edodes) bed logs and fruit bodies by culture with nanoparticle insoluble Prussian blue dispersion liquid and cesiumsorb filter sheet

Reduction of radiocesium in Shiitake (Lentinula edodes) bed logs and fruit bodies by culture with nanoparticle insoluble Prussian blue dispersion liquid and cesiumsorb filter sheet

Application of breakthrough curve analysis and response surface methodology for optimization of a hybrid separation system consisting of fixed-bed column adsorption and dead-end depth filtration

This work investigates the performance and optimization of a hybrid process consisting of a fixed-bed adsorption (FBA) column and a dead-end filtration (DEF) cell for the removal of methylene blue (MB) from water. Granular activated carbon and cellulose acetate depth filter sheets were used as adsorbent and filter medium, respectively. Effects of four operation parameters (initial concentration, feed flowrate, bed length, and filter type) on the MB removal rate (RR) were investigated using breakthrough data analysis and response surface methodology. This RR (mass of MB removed per second) captures the removal capacity and separation rate, simultaneously. The maximum RR was found theoretically equal to 3.875 s−1 at the optimized conditions of initial concentration =39.86 mg/L, flowrate = 1.15 L/min, bed length =29.95 cm, and filter type = OS100, and validated with the experimental data with 99% agreement. The performance of the hybrid process operating at the optimal operation conditions was found to be superior to those of the individual FBA column and DEF cell. After 100 s from the process commencement, the RR obtained with the hybrid process was about 64% higher than that obtained with the FBA column and 30% higher than that obtained with the DEF cell.

Effect of filtration on elimination of turbidity and changes in volatile compounds concentrations in plum distillates

The purpose of this study was to investigate the effect of alcoholic strength by volume (ASV) and storage conditions on turbidity in plum brandies. Different types of filter sheet were also tested for their effects on turbidity, as well as on the chemical composition and organoleptic characteristics of the distillates. The raw materials used were two plum distillates with initial ASVs of 76.77% v/v and 81.92% v/v. The distillates were diluted to alcohol contents of 37.5%, 40% and 50% v/v and stored under various conditions for 64 days. Filtration was performed using two depth filter sheets, with nominal retention rates of 0.40–0.48 μm and 0.80 μm, or with an activated carbon-based filter sheet. The lowest turbidity was observed in samples stored at ambient temperature with an ASV of 50% v/v. Reducing the alcohol content and storage temperature caused turbidity to increase. Samples prepared from distillate with an initial alcohol content of 76.77% v/v were characterized by significantly higher turbidity than those produced from spirit with an initial ASV of 81.92% v/v. Lowering the storage temperature resulted in a larger decrease in the concentration of volatile compounds after filtration. Use of an activated carbon filter sheet caused the greatest decrease in the majority of volatiles. Use of a filter sheet with a nominal retention rate of 0.80 μm led to the greatest improvement in the organoleptics of the tested plum distillates.

Development of a hematocrit-insensitive device to collect accurate volumes of dried blood spots without specialized skills for measuring clozapine and its metabolites as model analytes

Dried blood spots have been used as alternatives to traditional plasma and serum samples. We have now developed new devices, named volumetric absorptive paper disc (VAPD) and mini-disc (VAPDmini), to collect accurate volumes of dried blood spots in a simple manner and without the need for additional instruments. VAPD consists of a filter paper disc and a filter paper sheet with holes slightly larger than the disc. The disc is fixed in one such hole without direct contact with the filter sheet. VAPDmini is a scaled-down version of the same device. When several drops of whole blood are applied, the disc becomes saturated and any excess sample is absorbed by the surrounding filter sheet. Accuracy and precision of sampling were assessed by determining the levels of clozapine and its metabolites as target analytes by liquid-liquid extraction and high-performance liquid chromatography with coulometric detection. In addition, differences in analyte recovery were within ±15% for all analytes in samples with 30–60% hematocrit, suggesting that VAPD and VAPDmini are insensitive to hematocrit for the analytes tested. The devices were also validated for analyte concentrations in the range 50–1000 ng/mL, and the limit of detection and lower limit of quantification were 5–17 ng/mL and 15–51 ng/mL, respectively. Intra- and inter-day precision ranged from 3% to 13%, whereas accuracy ranged from a −14% to 12% bias. Analytes were stable in the devices for at least 2 weeks at room temperature. Collectively, these results indicate that sampling using VAPD and VAPDmini is comparable to conventional hole punch sampling of entire dried blood spots, even for samples obtained from patients treated with clozapine. Importantly, the devices were also found to be suitable for sample self-collection.

Use of Sorbents to Increase Beer Foam Stability

ABSTRACTLong-lasting creamy foam is an important quality parameter for various types of beers. Foam stability depends on both foam-stabilizing and foam-damaging compounds, and lipids are considered to be the main foam-damaging compounds. The aim of this work was to validate a technologically and economically feasible method for stabilizing beer foam using sorption. Among eight materials tested for their foam stabilizing effects (activated carbon, Florisil, polytetrafluoroethylene, montmorillonite, filter sheet, steel dust, cotton, and polyethylene), three were selected for further study to verify their effects on color, bitterness, and the sensory profile of a commercial lager beer. The results showed that the foam stabilizing effect of sorbents were positively correlated with their surface areas. The most promising sorbents (activated carbon, Florisil, and polytetrafluoroethylene) were effective at low doses (50 mg/L) and short contact times (5 min), and did not affect the color, bitterness, or sensory profile of the beer. At the low dose required and the price of sorbents, their single use in combination with other process aids and subsequent filtration should be economically feasible.

Effect of cultivation pH on the surface hydrophobicity of Bacillus subtilis spores

Bacillus subtilis spores are often used as biological indicators (BI) to monitor decontamination processes with gaseous hydrogen peroxide. Results in practical inactivation validation tests, however, vary considerably with no available explanation so far. This study reports on the effect of cultivation pH on spore surface hydrophobicity. Surface hydrophobicity is suspected to have an impact on the decontamination of technical surfaces such as packaging material when gaseous, condensing hydrogen peroxide is applied. It is the aim of this study to examine the impact of different cultivation pH levels on surface hydrophobicity and resistance of B. subtilis spores. Submersed cultivation of B. subtilis in bioreactors at controlled conditions with different static pH levels led to contact angles ranged between 50° and 80°, which was analyzed with water on a homogeneous layer of spores on a filter sheet. Resistance of spores was also affected by the cultivation pH. The results show that the culturing conditions during BI production should be controlled to obtain BI with specified characteristics in inactivation validation tests.

Performance of activated carbon-impregnated cellulose filters for indoor VOCs and dust control

An activated carbon-impregnated cellulose filter was fabricated, and the capacity to remove dust and volatile organic compounds was evaluated in a laboratory. The adsorption capacities for benzene, toluene, ethyl benzene and m-xylene gases were compared by an adsorption isotherm test conducted as a preliminary test, showing that m-xylene and benzene were the most and least favorable for adsorption onto activated carbon, respectively. Cellulose filters were made with four levels of activated carbon contents, and dust removal was performed with all of the filters showing 99 % and higher efficiencies stable with a small variation during the experiment. Activated carbon content of 5 g in the unit filter area (125 g/m2) was found optimum for benzene, toluene, ethylbenzene and m-xylene removal, as it appeared that higher than 5 g activated carbon content was unnecessary for the improvement of its capacity. With increasing benzene, toluene, ethylbenzene and m-xylene loading, the highest removal rates were determined as 0.33–0.37 mg/cm2 s for as short as 0.0046 s of air filter residence time. The rapid removal was possible because of the high surface area of the activated carbon-impregnated cellulose filter provided by powdered activated carbon, which is distinguished from the granular form in conventional activated carbon towers. As fixed within a cellulose scaffolding structure, the powdered activated carbon performed excellent benzene, toluene, ethylbenzene, and m-xylene adsorption (98.9–100 %), and at the same time, particular matters were removed in average 99.7 % efficiency after being filtered through the cellulose filter sheet.

Experimental investigation of air pressure affecting filtration performance of fibrous filter sheet

ABSTRACTUnderstanding the effect of air pressure on their filtration performance is important for assessing the effectiveness of fibrous filters under different practical circumstances. The effectiveness of three classes of air filter sheets were investigated in laboratory-based measurements at a wide range of air pressures (60–130 KPa). The filtration efficiency was found most sensitive to the air pressure change at smaller particle sizes. As the air pressure increased from 60 to 130 KPa, significant decrease in filtration efficiency (up to 15%) and increase in pressure drop (up to 90 Pa) were observed. The filtration efficiency of the filter sheet with largest fiber diameter and smallest solid volume fraction was affected most, while the pressure drop of the filter sheet with smallest fiber diameter and largest solid volume fraction was affected most. The effect of air pressure on the filtration efficiency was slightly larger at greater filter face air velocity. However, the effect of air pressure on the pressure drop was negligible. The filtration efficiency and pressure drop were explicitly expressed as functions of the air pressure. Two coefficients were empirically derived and successfully accounted for the effects of air pressure on filtration efficiency and pressure drop.

Growth of the Native Xerophyte Convolvulus cneorum L. on an Extensive Mediterranean Green Roof under Different Substrate Types and Irrigation Regimens

The possibility of using Convolvulus cneorum L., a native Mediterranean xerophyte, with compact dome-like canopy and extended blooming period, on extensive green roofs in areas with semiarid Mediterranean climate was investigated in a 27-month experimental period, which included three summers (the dry season of the year). The aim was to preserve the local character and biodiversity, as well as to reduce water consumption and construction weight. Convolvulus cneorum rooted cuttings were planted in the beginning of July 2011 in experimental modules on a fully exposed flat roof at the Agricultural University of Athens, with a green roof infrastructure (substrate moisture retention and protection of the insulation, drainage element, and filter sheet). Two types of substrate with 10 cm depth were used, one with soil, i.e., grape marc compost:perlite:soil:pumice (3:3:2:2, v/v) and a lighter one without soil, i.e., grape marc compost:perlite:pumice (3:3:4, v/v). Two irrigation frequencies were applied during the dry periods, i.e., every 5 days (normal) and 7 days (sparse) in 2011 and 2012 and every 4 days (normal) and 6 days (sparse) in 2013. The chemical properties of the two substrates were similar, while their physical properties differ slightly as the substrate that contained soil was holding more water at saturation and it had lower saturated hydraulic conductivity and higher easily available water (EAW). The substrate type affected growth since plant height and diameter, shoot number, and aboveground dry weight were promoted by the soil substrate. Irrigation frequency did not affect plant growth. However, plants cultivated on soil substrate and irrigated normally had the highest growth, particularly compared with plants in soilless substrate under sparse irrigation. Flowering was abundant in April (spring) and in the first year flower number was promoted by the soil substrate. During the dry periods, sparse irrigation resulted in increased stomatal resistance one day before irrigation, indicating that water availability was marginal for the plants, while normal transpiration rate was restored the day after irrigation. According to photosystem II photochemical parameters measured one day before and the morning after an irrigation event, no evidence of damage to the photosynthetic apparatus was recorded in any of the treatments. In general, after 27 months of culture, plant size and roof coverage was appearing more or less similar in all the experimental treatments, therefore the combination of the lighter soilless substrate with sparse irrigation is highly suggested for C. cneorum cultivation on Mediterranean green roofs.

Addition of a steel pre-filter to improve plate filter-press performance in olive oil filtration

Olive oil is a turbid colloidal dispersion. The most common technique used to clear the oil is filtration. Among filter systems, plate filter-presses are used by small companies because the filters are cheap, and the technique does not impair the sensory and chemical traits of the olive oil. However, plate filter-presses have some disadvantages: their operating capacity is low, they require a lot of man power, and filter sheets trap part of the processed oil. It has been argued in the literature that they can retain minor compounds. Furthermore, there is a cost associated with their disposal. The impact of all of these issues could be reduced by the optimization of filtration cycles. Hence, a new processing arrangement was proposed and tested. This consisted of the insertion of a steel pre-filter into the system, which retained part of the suspension. Consequently, the plate filter-press only retained residual solids and water. The plate filter press with the added pre-filter was able to process about 1.8 times the amount of oil normally processed in a batch. Operative capacity was improved and the amount of oil trapped in the sheets was reduced. Furthermore, the number of the filter sheets required was almost halved, which also halves their purchase and disposal costs. A surface fouling mechanism is seen in the traditional filter press configuration, while in the new configuration particle retention is due to depth fouling. This change in the fouling mechanism demonstrates that the addition of a pre-filtration step leads to the more effective use of filter sheets.

Geosynthetics for waterways and flood protection structures – Controlling the interaction of water and soil

The interaction of water and soil has been both a blessing and a curse in all times within living memory. Water is the origin of life but is also threatening life when appearing unboundedly. Therefore mankind has always worked hard to benefit from water resources on one hand and to deal with the threat of flooding on the other hand. For both, to protect the land and to allow for beneficial uses like irrigation or navigation, often special measures are necessary to keep the water within certain bounds. Structures to achieve a permanently stable situation like irrigation and navigational canals, river training or flood protection measures need suitable material, carefully thought out design and accurate execution. Often a decision has to be made among competitive approaches to optimize such structures. In many cases, geosynthetics can support or improve the functionality and sometimes only with geosynthetics the desired result can be achieved.Geosynthetics can provide strength and flexibility, imperviousness and drainage, durability and robustness or controlled degradation. All these properties can be of use to handle the many occurrences of interaction of water and soil. Surface water has to be guided or to be kept off; percolating water should be controlled to avoid internal erosion effects should be restrained by appropriate filtration. To guarantee well functioning in general, also chemical and biological aspects have to be considered like ochre formation, root penetration and population by any kind of species. The German Federal Waterways Engineering and Research Institute (BAW) has gathered experience with geosynthetics in hydraulic applications since more than 40 years. These years revealed the capabilities of geosynthetic solutions and simultaneously emphasized the need of careful selection, design and execution.A large variety of geosynthetic fabric and structures is available. To control the interaction of water and soil many different attributes are required, e.g. membranes for impervious lining, filter sheets for erosion control, different kinds of mattresses or wrap-around structures, voluminous elements from sandbags to mega containers for protection, training or immediate repair. In many cases geosynthetics can be designed to control the interaction of water and soil according to the individual and local requirements to allow for an excellent execution of waterways and flood protection structures.

Scrutinizing Rhizobia to Rescue Maize Growth under Reduced Water Conditions

Availability of fresh water for crop production is a major concern these days. Therefore inoculation biotechnology has been tried as a tool to support crop growth and yield under water deficit conditions. Thirty rhizobia were isolated from the nodules of three legumes (Lens culinaris, Vigna radiata, and Cicer arietinum) cultivated in arid and semiarid regions of Punjab (Pakistan). Nine fast growing isolates were evaluated for drought tolerance capability with PEG-6000-induced water stress. These nine isolates were assessed for plantgrowth-promoting-activity on maize under drought in gnotobiotic conditions by planting inoculated seeds between filter sheets soaked with each respective inoculum. Drought was imposed by applying PEG solutions of -0.61 and -1.2 MPa osmotic potential and isolates rhizobial strain (RS)-1, RS-3, RS-8, and RS-12 were selected as prominent growth promoters. Selected isolates were evaluated in a pot trial under natural conditions where irrigation was delayed at the vegetative and reproductive growth stages of the maize crop to develop water deficit stress. Improvement in fresh cob yield, root/ shoot length, shoot fresh weight and drought tolerance index was observed. The isolates displayed P-solubilization (RS-1 and RS-12), siderophores (RS-3 and RS-8), oxidase (RS-1), indole acetic acid, catalases, and exopolysaccharides production ability (RS-1, RS-3, RS-8, and RS-12). Isolates RS-1 and RS-3 were identified as Rhizobium phaseoli whereas RS-8 and RS-12 were Mesorhizobium ciceri. Results suggested rhizobia as potential inoculants to maize for improving growth and productivity under drought. However, evaluation in field conditions is required to confirm their capability.

Growth of Native Aromatic Xerophytes in an Extensive Mediterranean Green Roof as Affected by Substrate Type and Depth and Irrigation Frequency

Green roofs could be a way to increase vegetation in the center of old Mediterranean cities. The need for conservation of local character and biodiversity requires the use of native plant species, whereas the deficiency of water, particularly in semiarid regions, requires the use of species with reduced irrigation needs. Moreover, the aged buildings lead to the use of lightweight green roof constructions. Therefore, research was undertaken to investigate the possibility of using three Mediterranean aromatic xerophytes, Artemisia absinthium L., Helichrysum italicum Roth., and H. orientale L., at an extensive green roof in Athens, Greece. Simultaneously, the possibility of using locally produced grape marc compost was investigated. Substrate type and depth and irrigation frequency effects on growth of these species were studied. Rooted cuttings were planted mid-May in plastic containers with a green roof infrastructure fitted (moisture retention and protection of the insulation mat, drainage layer, and filter sheet) and placed on a fully exposed third floor flat roof at the Agricultural University of Athens. Two types of substrates were used, grape marc compost:soil:perlite (2:3:5, v/v) and peat:soil:perlite (2:3:5, v/v, as a control), as well as two substrate depths, 7.5 (shallow) and 15 cm (deep), and two irrigation frequencies, sparse (5 or 7 days in shallow and deep substrate, respectively) and normal (3 or 5 days in shallow and deep substrate, respectively). Increased contents of macroelements, total phosphorus (P) and potassium (K) in particular, were recorded in the compost-amended substrate, whereas both substrates had similar physical properties. Plant growth was recorded from May to October. The deep compost-amended substrate, independent of irrigation frequency, resulted in taller plants with bigger diameter and aboveground dry weight in all species. However, a remarkable result was that shallow compost-amended substrate with sparse irrigation resulted in similar or even bigger plant growth of all plant species compared with deep peat-amended substrate with normal irrigation. Thus, all three species were found suitable for use in Mediterranean extensive or semi-intensive green roofs, whereas the use of grape marc compost in the substrate allowed for less water consumption and the reduction of substrate depth without restriction of plant growth at the establishment phase and the first period of drought.