Substrate Depth Research Articles

Sustainable Growth of Medicinal and Aromatic Mediterranean Plants Growing as Communities in Shallow Substrate Urban Green Roof Systems

To date, the evaluation of the performance of Mediterranean native plants under urban green roof conditions has been limited to monoculture studies. However, plants grow naturally in plant communities and therefore it is of interest to evaluate their growth under realistic conditions, including interactions among plant species. The present study aims to evaluate the growth, flowering, and self-reproduction capacity of three artificially created plant communities consisting of native Mediterranean plants, as exemplified in Greece under shallow green roof substrate depths (8 and 15 cm) and two irrigation regimes (high, 20% ETo and low, 10% ETo). The plant communities (PC) were designed to resemble xerophytic vegetation found either in Chania, Crete (PC-1), as a combined pattern with plants from Attica, Crete, and the Cyclades (Kythnos) (PC-2), or to resemble the coastal vegetation of Attica and Cyclades (Kythnos) (PC-3). Each of the three artificial plant communities (PC-1, PC-2 and PC-3) consisted of nine species and subspecies. The deeper substrate significantly improved the growth, flowering and survival of most plant taxa. The irrigation regime was not significant for all species except one, indicating that minimal amounts of irrigation are required. Four species did not manage to bloom while 15 species were able to self-reproduce.

Impact Deposition Behavior of Al/B4C Cold-Sprayed Composite Coatings: Understanding the Role of Porosity on Particle Retention.

This study explores the role of porosity in the impact deposition of a ceramic-reinforced metal-matrix (i.e., Al/B4C) composite coating fabricated via cold spraying. The Johnson-Holmquist-Beissel constitutive law and the modified Gurson-Tvergaard-Needleman model were used to describe the high strain-rate behavior of the boron carbide and the aluminum metal matrix during impact deposition, respectively. Within a finite element model framework, the Arbitrary Lagrangian-Eulerian technique is implemented to explore the roles of reinforcement particle size and velocity, and pore size and depth in particle retention by examining the post-impact crater morphology, penetration depth, and localized plastic deformation of the aluminum substrate. Results reveal that some degree of matrix porosity may improve particle retention. In particular, porosity near the surface facilitates particle retention at lower impact velocities, while kinetic energy dominates particle retention at higher deposition velocities. Altogether, these results provide insights into the effect of deposition variables (i.e., particle size, impact velocity, pore size, and pore depth) on particle retention that improves coating quality.

Contribution of a groundwater-influenced hinterland drainage system to the restoration of salmonid spawning grounds at the upper river Danube

Groundwater-influenced ditches, so called hinterland drainage systems (HDS), accompany many heavily modified water bodies (HMWBs). Herein, we evaluate the usefulness of including HDS as functional habitats in river restoration approaches by assessing their role as salmonid recruitment areas in HMWBs. We tested the functionality of spawning grounds in a groundwater-influenced HDS compared to the quality of those not influenced by groundwater (OHB 1 and OHB 2), based on bioindication using brown trout eggs. Eggs were placed in each compartment of a two-layered container of 20 cm diameter and 30 cm total depth (known as the HydroEcoSedimentary Tool or HEST) pre-filled with sediment, mimicking hyporheic conditions. A total of 81 HESTs were evenly distributed across the three sites to assess egg and larvae mortality whilst exposed at two substrate depths (5–10 cm and 17–22 cm). In addition, key physico-chemical variables such as dissolved oxygen, temperature, pH, turbidity, electric conductance and substratum composition were analyzed. Mean egg mortality in the HDS was 33% lower than in both non-groundwater-influenced spawning grounds, whereas mean larval mortality was highest in the HDS (95%) compared to 74% at OHB 1 and 66% at OHB 2. The exposure depth of eggs had a significant influence on mortality, with more dead eggs and larvae in the deeper substrate layers, most likely attributed to an increase of fine sediment and a decrease of oxygen availability over time. Particularly the HDS revealed high mortality rates of larvae since it had a 17% lower mean oxygen level compared to the other spawning grounds. These findings suggest that if additional measures such as substratum restoration were undertaken to increase oxygen availability within HDS, these groundwater-dominated ditches could be incorporated as part of an efficient river restoration strategy.

Unmanaged vegetated roofs hydrological performance in subtropical areas: An investigation in São Paulo, Brazil

Extensive vegetated roofs are Nature-based Solution with the ability to manage rainwater runoff in densely built spaces. Despite the large amount of research demonstrating its water management abilities, its performance is poorly quantified under subtropical climates and when using unmanaged vegetation. The present work aims at characterizing the runoff retention and detention of vegetated roofs under the climate of São Paulo, Brazil, accepting the growth of spontaneous species. By using real scale prototypes under natural rain, a vegetated roof hydrological performance was compared with a ceramic tiled roof. By using models with different substrate depths under artificial rain, changes in the hydrological performance were monitored for different antecedent soil moisture contents. Results from the prototypes showed that the (i) extensive roof attenuated from 30 % up to 100 % the peak rainfall runoff; (ii) delayed the peak runoff from 14 up to 37 min and (iii) retained from 34 % up to 100 % the total rainfall. Furthermore, results from the testbeds indicated that (iv) when comparing two rainfalls with same depths, the one with longer duration can saturate more the vegetated roof and thus undermine more its ability to retain water; and (v) when not managing the vegetation, the vegetated roof's soil moisture content loses correlation with the substrate depth, as plants will also develop more and will more effectively restore the substrate retention capacity. Conclusions point to extensive vegetated roofs as a relevant sustainable drainage system in subtropical areas, but demonstrate that its performance is highly dependent on structural factors, weather factors and level of maintenance. Such findings are expected to be useful for practitioners dimensioning these roofs as well as for policy makers towards a more accurate standardization of vegetated roofs in subtropical regions and Latin American developing countries.

Analysis of Preferential Flow in Artificial Substrates with Sedum Roots for Green Roofs: Experiments and Modeling

The occurrence of preferential flow in vegetated artificial substrates can weaken the stormwater management performance of green roofs. To explore preferential flow, various plant–substrate combinations that involved two Sedum species (Sedum sarmentosum and Sedum lineare) and two artificial substrates for three depths of 6, 10, and 14 cm were established. Artificial substrates without plants were either perlite-based (namely, PAS) or vermiculite-based (namely, VAS), and they were also set as controls. Thereafter, solute breakthrough experiments were conducted, followed by inverse and forward modeling in Hydrus-1D. Skewness coefficients of all solute breakthrough curves were non-zero, suggesting a prevalence of preferential flow. The Nash–Sutcliffe efficiency coefficients during calibration and validation were greater than 0.7. The obtained hydraulic parameters were different among various vegetated PAS and pure PAS without plants, but appeared the same for the VAS case. Rainfall intensity, plant species, and substrate depth, and the interaction of plant species and substrate depth all had significant effects on PAS preferential flow outflow and index (PFI). Substrate depth had a significant effect on VAS preferential flow and PFI. Since a 10 cm-PAS with S. lineare had the smallest PFI of 43.16% in simulation scenarios, its use may better control preferential flow in green roofs.

Optimizing growth chamber conditions for maintaining Arcticlichen‐dominatedbiocrusts

Optimizing growth chamber conditions for Arctic lichen biocrusts will create new opportunities to assess and prioritize reclamation techniques given the challenges associated with conducting arctic field work. Our study is the first to examine growth chamber conditions for optimizing survival and growth of Arctic lichen biocrusts, as measured by changes in lichen cover. We assessed effects of substrate crossed with substrate depth, substrate sterilization, lichen inoculation and community composition, and watering frequency in four concurrent experiments over 6 weeks on survival of arctic biocrusts collected from Diavik Diamond Mine Inc., Northwest Territories, Canada. Mixed species declined less thanFlavocetraria cucullata, and substrate affectedF. cucullatasurvival over time. Live lichen cover declined least with a 3‐day watering frequency and substrate depth of 1 cm. Sterilization did not affect lichen survival, and no contamination was observed over 6 weeks. Our results highlight the challenges of maintaining and growing lichens under controlled conditions, as only a few treatments showed increases in cover. Our research shows that even short‐term growth chamber experiments have potential to screen reclamation treatments prior to field assessments, permitting reclamation scientists to optimize limited time and resources while in the field.

Performance of constructed wetlands with different water level for treating graphene oxide wastewater: Characteristics of plants and microorganisms

Constructed wetlands (CWs) have been expected advantages in emerging pollutant removal, but with less known on their characteristic when treating wastewater containing graphene oxide (GO). In present study, we investigated characteristics of Iris pseudacorus, microorganisms, and pollutant removal in CWs with 60 cm and 37 cm water level (termed HCW and LCW). Plants in LCW had higher chlorophyll content and lower activities of antioxidant enzyme (superoxide dismutase, catalase, peroxidase) as well as malondialdehyde content. Substrate enzyme activities were affected by time and CW type. LCW increased only dehydrogenase activities, while HCW increased catalase, urease, neutral phosphatase, and arylsulfatase activities. Sequencing analysis revealed that microbial community showed higher richness and diversity in LCW, but this dissimilarity could be eased by time-effect. Proteobacteria (25.62–60.36%) and Actinobacteria (13.86–56.20%) were stable dominant phyla in CWs. Ratio of Proteobacteria/Acidobacteria indicated that trophic status of plant rhizosphere zone was lower in LCW. Nitrospirae were enriched to 0.16–0.68% and 0.75–1.42% in HCW and LCW. The enrichment of phyla Proteobacteria and Firmicutes in HCW was attributed to class Gammaproteobacteria and genus Enterococcus. GO transformation showed some reductions in CWs, which could be affected by water depth and substrate depth. Overall, HCW achieved nitrogen and phosphorus removal for 48.78–62.99% and 95.01%, which decreased by 8.41% and 7.31% in LCW. COD removal was less affected reaching 93%. This study could provide some new evidence for CWs to treat wastewater containing GO.

Investigation of moss species selection and substrate for extensive green roofs

This study investigates the potential of moss species for extensive green roofs to achieve very shallow substrate, low maintenance and low cost green roofs. The performance of four moss species (Didymodon constrictus, Eurhynchium hians, Polytrichum commune and Racomitrium japonicum) were assessed using three kinds of substrate: (a) a mixture of clay soil and compost, b) baked black soil and c) river sand for two years in Chiba, within the Tokyo region of Japan. The individual species were grown in monoculture in 4 cm depth of substrate in trays on a rooftop without supplemental irrigation using an onsite propagation method. Although all four species became dormant in conditions of high temperature and little rain, it was possible for all to establish and survive. R. japonicum showed the greatest coverage among the four species, reaching 70%–80% cover in the first four months. P. commune performed almost as well but took over a year to reach consistently high coverage. E. hians coverage fluctuated greatly in response to drought events. D. constrictus had low coverage overall but grew slightly more in the clay/compost soil; P. commune did poorly in sand substrate; R. japonicum and E. hians showed no consistent differences in how they were affected by substrate type. After two years only R. japonicum and P. commune had high enough coverage to consider further investigation. R. japonicum is already used in green roofing and wall applications. This study suggests that while some mosses show high performance across substrate types, others can be used on green roofs to achieve high cover, but only after determining a suitable substrate type. These results can inform moss species selection for green roofs in Japan, however, this methodology can be applied in other regions to establish moss green roofs. An onsite propagation method can be used to establish moss green roofs but further research is needed to identify means of increasing onsite growth rates for more species.

Compound minirhizotron device for root phenotype and water content near root zone

The study of phenotype plays a significant role in plant growth and development. In plant phenotype, the growth state and size distribution of roots are crucial to plant growth and development. Exploring the variation of root development and root zone water content is conducive to improving planting technology with efficiency. Whereas, commercial root phenotype monitoring devices on the market are expensive and sophisticated. This study aims to develop a compound minirhizotron device to acquire images of tomato root system and monitor water content near the root zone. The device mainly included core controller module, transmission module, image acquisition module and moisture monitoring module. The device could realize image acquisition of root system at multiple positions and monitoring of water content near root zone under the condition of less damage to root system. Through image processing, parameters such as root length and root diameter could be calculated. Results indicated that tomato roots at the depth of 6–10 cm from the substrate surface were more densely distributed, and root density decreased with increasing substrate depths. And furthermore, total root length showed a gradual downward trend with the downward movement of the substrate layer. In addition, the closer to the vertical downward straight line from the tomato cultivation site, the greater the root diameter within the monitoring range. In the monitoring results of water content near root zone, the closer to the ground, the higher monitored substrate water content. The overall results showed that the compound minirhizotron device could aquire both root system images and water content near root zone stablely and for a long-term, which could improve the efficiency of planting and irrigation technology.

Influence of vegetation type and climatological conditions on evapotranspiration from extensive green roofs

Evapotranspiration (ET) is the key hydrologic process governing the capacity of a green roof to retain rainfall as it regenerates available water storage space in the green roof substrate (soil) between rainfall events. In this field study, the impact of climatological conditions, vegetation type, and substrate depth on ET rates were evaluated from experimental, modular extensive green roofs installed in three climate regions in Canada: Calgary AB (Prairies), London ON (Great Lakes/St. Lawrence), and Halifax NS (Atlantic/ Maritime). Daily ET rates and cumulative ET over two field seasons were quantified for two substrate depths (10 and 15 cm), substrate only treatments (no vegetation), and four vegetation treatments (monoculture treatments of Sedum spurium, Sporobolus heterolepis, and Aquilegia canadensis, and a mixed species treatment consisting of the three aforementioned species). 73 %, 67 % and 33 % of the cumulative rainfall was returned to the atmosphere via ET over the two field seasons in Calgary, London and Halifax, respectively. Importantly, ET rates were shown to be a strong function of substrate moisture content as well as atmospheric forcing with the relative importance of each varying between the different cities. ET rates were typically greater in the mixed species treatment in comparison to the three monoculture treatments (Sedum spurium, Sporobolus heterolepis, and Aquilegia canadensis) and for deeper substrate depths, although ET rate enhancement with substrate depth was comparatively small. This study provides valuable insights on the impact of climatological conditions and green roof design parameters (i.e., vegetation type and substrate depth) on ET rates.

Linear breakwater reefs of the greater Caribbean: Classification, distribution & morphology.

Geomorphic differences among Caribbean reefs have long been noted. These differences are considered to reflect the presence of reefs in different stages of development, following an incomplete recovery from rapid deglacial sea-level rise. But the possibility that these reflect real developmental differences caused by variation in wind, wave, and climate regime, has never been fully considered. Here, for the first time, we quantify the geomorphology and distribution of Greater Caribbean reefs using satellite images in Google Earth and public-domain bathymetry. To do this, we first standardise their classification based on shallow geomorphology, substrate depth, and physiographic setting, and then count and categorise the total number of reefs. These data show a total of 1023 linear breakwater reefs with a combined length of 2237 km. Of this total length, 80% are fringing reefs, 16% are barriers and 4% are faros and atolls. In terms of categories, there are 16 reef subtypes present, but only 9 are common. Their distribution, however, is not uniform. In particular, flat-subtypes form 60% of breakwater reefs in southern regions, but are less common in northern regions where crest-subtypes dominate (80%). To distinguish the geomorphology of these common reef subtypes, we collect size- and length-related morphometric data from their main reef zones. These data reveal that flat and crest subtypes also have morphometric differences: flat subtypes have well-constrained morphologies with statistically consistent unimodal morphometrics characterised by large back-reef zones, smaller and steeper reef fronts, and more sinuous and persistent crestlines. Crest subtypes, by contrast, have multimodal morphometrics suggesting less consistent morphologies (or unresolved subtypes), and are characterised by crestlines with lower sinuosity, more variable back-reef and reef-front areas, and slopes. These differences in geomorphology and distribution imply that flat- and crest-subtypes are neither successional stages of a single reef type, nor a genetically related sequence of types, but distinct reefal geoforms with different modes of development. In subsequent work we will explore what controls these differences.

Benthic species patterns in and around the Cape Canyon: A large submarine canyon off the western passive margin of South Africa

Although submarine canyons are internationally recognized as sensitive ecosystems and reported to be biological hotspots, regional studies are required to validate this consensus. To this end, hydrographic and benthic biodiversity data were collected during three cruises (2016-2017) to provide insights on the benthic patterns within South African canyon and non-canyon offshore areas. A total of 25 stations, sampled at 200-1000 m depth range, form the basis of the multivariate analysis. Diversity gradients were calculated and then differences were compared across substrate types and depth zones represented within 12 canyon and 13 non-canyon stations. Significant differences in both substrate and depth were evident, despite measures being highly variable. This observation of varying diversity in different substrates is in line with previous studies. No clear pattern was observed for species diversity (delta+). However, non-canyon stations overall showed a higher diversity in comparison to canyon stations. A notable peak in diversity is observed in canyon areas in the 401-500 m depth zone. Species richness followed an opposing pattern, as it decreased with depth and was consistently higher in canyon areas. These results align with the well-defined influence of depth-related variables on the distribution of taxonomic groups and the substrate available, at various scales. The eutrophic characteristic of the Benguela region may have attributed to the insignificant diversity differences between canyon and non-canyon stations. To assess the benthic species structure in canyon and non-canyon areas, we converted the 108 benthic species into a gamma+ matrix. We then modelled the biological response to predictor variables (substrate and depth). Although the canyon and non-canyon areas have an overlapping species composition, the main effects (canyon vs. non-canyon, depth, and substrate) showed significant differences. Thirteen species were characteristic of canyon areas, whilst only three distinguished non-canyon areas. The region has a long history of anthropogenic activities, so the observed benthic profiles may already be altered. The current study therefore provides the first detailed taxonomic description and analysis of benthic species profiles in the Cape Canyon, and advances important baseline information necessary for understanding the ecological importance of the Cape Canyon.

Substrate composition impacts long-term vegetation development on blue-green roofs: Insights from an experimental roof and greenhouse study

Green roofs provide ecosystem services and can promote biodiversity in urban areas. Blue-green roofs have an additional water storage compartment under the substrate to reduce roof water runoff, thereby also reducing drought stress which is beneficial for green roof vegetation. In order to study which blue-green roof design supports the highest plant diversity, we assessed the effect of different substrates and seed mixtures on vegetation development in a short-term greenhouse experiment and long-term blue-green roof experiment. A ten-week full-factorial greenhouse experiment was performed for six substrate composition and four seed mixture treatments. On an experimental blue-green roof, we annually surveyed plants from 2013 to 2021 in nine different treatments (five replicates each), that varied in substrate composition, substrate depth and seed mixture that was initially applied. Two treatments resembled conventional non-green roofs (100% gravel) and conventional extensive Sedum green roofs. The results of the greenhouse experiment showed that seed mixture is more important than substrate composition in shaping the initial species richness and species composition. However, on the experimental roof the substrate composition was an important determinant of species richness and species composition long-term. Plant species richness on the experimental roof was lowest in the gravel treatment (resembling conventional non-green roofs), and highest in treatments where locally collected soil was used, likely due to additional species that appeared from the seed bank present in the transplanted soil. Soil was never completely covered with vegetation on unfertilized substrates that contained 20% or less dense and organic materials. Plant species richness on conventional Sedum roof substrate was higher on the experimental blue-green roof compared to an adjacent non-blue roof, highlighting that blue-green roofs can promote biodiversity more than conventional green roofs. For future construction of blue-green roofs in our region, we recommend the addition of 30% locally collected soil to a 6 cm deep lightweight substrate to maximize long-term plant cover and plant species richness.

Impact of substrate depth and fertilizer type on growth, production, quality characteristics and heavy metal contamination of tomato and lettuce grown on urban green roofs

Urban farming on rooftops is a contemporary approach that combines the benefits of green roofing with food production within the city sprawl. The present study aims at assessing plant growth, nutritional value, and consumer safety of two vegetables, lettuce (Lactuca sativa L.) and tomato (Solanum lycopersicum L.) grown on urban green roof. Treatments included: (a) two substrate depths (7.5 and 15 cm) and (b) three types of fertilization (granulated complex fertilizer [GF], slow nitrogen release complex fertilizer [SR], and liquid fertigation [LF]). Measurements included plant growth, total fresh yield, dry weight, and quality characteristics such as nutrient content, nitrate accumulation in lettuce and firmness, and total soluble solids [TSS] in tomatoes. Production safety was evaluated through tissue analyses of the edible parts for heavy metal residues. Results showed that 15 cm substrate depth improved the total yield for both vegetables, and the firmness of tomato fruit, compared to 7.5 cm depth. Fertilization type had no impact on tomato productivity but GF increased TSS in tomato fruits while LF enhanced lettuce yield. The deeper substrate increased N, P, K, Ca, Mg in lettuce leaves but only P and Mn in tomato fruits. In contrast, fertilization type affected leaf nutrient levels in lettuce, where N, P, and Mg were increased using LF. In tomato, the LF increased the fruit P, K, Ca, Mg, and Fe concentration. LF increased the concentration of nitrates in lettuce to levels exceeding the maximum safety limits according to the European Food Safety Authority (EFSA) but not according to EU regulation No 1258/2011. The leaf Mn concentrations in lettuce were higher than the health limits for young children in all measured samples irrespective of the experimental treatments. Selenium (Se) exceeded the health limits in tomato fruits for adults and toddlers using SR but only for toddlers using LF, while GF maintained the Se content below the safety levels. Lead (Pb) and aluminium (Al) were high for both vegetables but did not exceed the EFSA safety limits for adults. However, Pb exceeded the EU Commission Regulation No 420/2011 limit, for both vegetables and fertilization treatments. Washing the leaves of lettuce reduced only Fe and Al concentration but the remaining elements were unaffected. In conclusion, our results suggest that lettuce and tomato of adequately high quality for human consumption can be produced on urban green roofs with shallow substrate depths ranging from 7.5 to 15 cm but, further research is needed to ensure production safety.

Impact of substrate depth and irrigation regime on growth, flowering and physiological indices of Greek sage (Salvia fruticosa Mill.) grown on urban extensive green roof systems

The broad application of extensive green roofs in the Mediterranean region is hindered by the stressful climatic conditions of the summer period, which is characterized by drought and heat extremes that challenge plant survival and growth. The use of native plants can provide a sustainable solution in overcoming these challenges. The aim of the present study was twofold: Firstly, to investigate the growth and flowering of the native Greek sage (Salvia fruticosa Mill.) when grown as part of an extensive green roof phytocommunity under two different substrate depths (either 8 cm or 15 cm) and two levels of irrigation (either high or low). Secondly, to determine several physiological indices in order to quantify the water stress tolerance response of Greek sage when grown under the above-mentioned green roof conditions with the imposition of three drought periods (20–25 July, 22–31 August, 23 September–10 October 2014). The deeper substrate (15 cm) promoted growth regardless of the level of irrigation and the number of flowers was favored by the deeper substrate with the higher water regime treatment. Although the shallow substrate depth and the low irrigation regime reduced growth and flowering, all plants survived. The imposition of drought stress periods resulted in a gradual decrease of total soluble sugars, proline and electrolyte leakage. Chlorophyll fluorescence (Fv/Fm) fluctuated between the three drought periods and SPAD increased in the drought period that was imposed during fall. During the first drought period, plants subjected to the shallow depth (8 cm) and irrigated with the low water regime, accumulated more sugars and had a higher chlorophyll fluorescence. By contrast, plants growing in the deeper substrate depth of 15 cm provided moderate sugars, but the lowest chlorophyll fluorescence. In the second drought period, the only index that varied between treatments was proline, which was increased for the plants growing in the shallow substrate depth and irrigated with the high-water regime. The lowest proline concentration occurred in plants growing in the deeper substrate depth receiving low irrigation. SPAD increased on the third drought period for plants growing in the deeper substrate. It was concluded that Greek sage can be successfully grown in extensive green roof systems with minimal inputs of water resources even at substrate depths of 8 cm. Out of the tested physiological indices, none could be employed as a standalone indicator of the Greek sage water stress magnitude.

Removal of pathogens from greywater using green roofs combined with chlorination

Greywater is an important alternative water resource which could be treated and reused in buildings, reducing the freshwater demand in drought affected areas. For the successful implementation of this solution, it is important to ensure the microbial safety of treated greywater. This study examined the microbiological quality of treated greywater produced by an emergent nature-based technology (green roofs) and a chlorination process. Specifically, the effect of substrate, substrate depth, and vegetation on the removal of total coliforms, Escherichia coli, and enterococci in experimental green roofs treating greywater was examined for a period of about 12 months. In addition, the ability of chlorination to inactivate the abovementioned pathogen indicators was evaluated and their potential regrowth was examined. Results shown that green roofs filled with 10 cm of perlite reduce total coliform concentration by about 0.4 log units while green roofs filled with 20 cm of vermiculite reduce total coliform concentration by about 1.2 log units. In addition, the use of vegetation in green roofs improves the removal of pathogenic bacteria by about 0.5 log units in comparison with unvegetated systems. In all cases, the effluents of green roofs failed to satisfy the criteria for indoor reuse of treated greywater for non-potable uses such as toilet flushing without a disinfection process. The addition of 3 mg/L of chlorine in the effluent provided safe greywater microbiological quality for storage periods of less than 24 h, while longer periods resulted in the significant regrowth of pathogens. In contrast, a chlorination dose of 7 mg/L completely secured inactivation of pathogen indicators for periods of up to 3 days.

Substrate and moisture content effects on pupation of the black soldier fly (Diptera: Stratiomyidae)

The black soldier fly (BSF)Hermetia illucens (L.) (Diptera: Stratiomyidae) is a beneficial insect species of great environmental and economic potential. Previous studies showed that providing a suitable pupation substrate can accelerate BSF pupation and increase pupation rate. However, the effect of substrate moisture content and the possible interactions between substrate type and moisture content on BSF pupation have not been investigated. In this study, we tested the effects of two pupation substrates (vermiculite and wood chips) and nine moisture levels (dry, 18.8, 37.5, 56.3, 75.0, 93.8, 112.5, 131.3, and 150.0%) on BSF pupation rate and depth. Substrate type and moisture content both affected BSF pupation rate and depth. Compared with the ‘no substrate’ treatment, neither substrate reduced BSF prepupal mortality without adding water, but the presence of dry substrate increased pupation rate by more than 8%. Within the range used in this study, moisturising substrates reduced BSF prepupal mortality by up to 88% for vermiculite and 95% for wood chips, and increased pupation rate by up to 9% for vermiculite and 6% for wood chips. In all substrate treatments more than 99% of the pupae were found in the top 4 cm, and more than 85% were found in the top 2 cm depth. The tendency of BSF to pupate deeper than 2 cm depended on substrate type and moisture content, and the effect of moisture content on pupation depth followed a parabolic trend. Based on our data, the proportions of BSF pupae presenting deeper than 2 cm would be the highest when the moisture content is around 20% for vermiculite and 70% for wood chips. Our results provide clues for selecting suitable substrate, moisture content, and substrate depth to facilitate BSF pupation.

Impact of structural factors on green roof runoff – A field investigation and statistical analysis

• Unit area runoff decreases slightly with the increase of roof area but this effect is not statistically significant. • Plant richness and substrate type did not affect the runoff from the GRs. • Substrate depth was the only structural factor which demonstrated a statistically significant effect on the runoff per unit area. • No interactions between the four factors that affect the hydrological process of GRs were statistically significant. Green Roofs (GRs) are a type of Blue Green Infrastructure, growing in popularity due to their ability to provide numerous benefits. Designers and modelers of GRs typically make the assumption that GRs are homogeneous, which means that for different roof areas and the same structural factors such as substrate depth and composition, they have the same runoff per unit area. Based on this assumption, the measured data from small scale GRs in the laboratory can be applied to large GRs in the field. However, this assumption of homogeneity has not been sufficiently verified. To investigate this gap, an outdoor experiment was carried out from April 25 to December 1, 2021. Thirty-six GRs were constructed following an orthogonal experimental design with four primary structural factors investigated (i.e., substrate type (ST), substrate depth (SD), plant richness (PR), and roof area (RA)). Rain and runoff data were recorded and N -way ANOVA was used to evaluate the impact of the structural factors. Results showed that there were no statistically significant interactions between the structural factors that affected the GR runoff. The order of influence of the individual parameters, determined by the F value statistical metric was: SD > RA > ST > PR. However, substrate depth was the only structural factor which significantly affected the runoff per unit area of GR. Plant richness and substrate types showed no statistically significant effect on the GR runoff. The results of this study indicate that the implicit assumption: GRs are homogeneous, is acceptable.

Fine-scale ensemble species distribution modeling of eelgrass (Zostera marina) to inform nearshore conservation planning and habitat management

Baseline data on the distribution and extent of biogenic habitat-forming species at a high spatial resolution are essential to inform habitat management strategies, preserve ecosystem integrity, and achieve effective conservation objectives in the nearshore. Model-based approaches to map suitable habitat for these species are a key tool to address this need, filling in gaps where observations are otherwise unavailable and remote sensing methods are limited by turbid waters or cannot be applied at scale. We developed a high resolution (35 m) ensemble species distribution model to predict the distribution of eelgrass (Zostera marina) along the Atlantic coast of Nova Scotia, Canada where the observational coverage of eelgrass occurrence is sparse and nearshore waters are optically complex. Our ensemble model was derived as a performance-weighted average prediction of 7 different modeling methods fit to 6 physical predictors (substrate type, depth, wave exposure, slope, and two bathymetric position indices) and evaluated with a 5-fold spatially-blocked cross-validation procedure. The ensemble model showed moderate predictive performance (Area Under the Receiver-Operating Characteristic Curve (AUC) = 0.803 ± 0.061, True Skill Statistic (TSS) = 0.531 ± 0.100; mean ± SD), high sensitivity (92.0 ± 4.5), and offered some improvement over individual models. Substrate type, depth, and relative wave exposure were the most influential predictors associated with eelgrass occurrence, where the highest probabilities were associated with sandy and sandy-mud sediments, depths ranging 0 m – 4 m, and low to intermediate wave exposure. Within our study region, we predicted a total extent of suitable eelgrass habitat of 38,130 ha. We found suitable habitat was particularly extensive within the long narrow inlets and extensive shallow flats of the South Shore, Eastern Shore, and Bras d’Or Lakes. We also identified substantial overlap of eelgrass habitat with previously identified Ecologically and Biologically Significant Areas that guide regional conservation planning while also highlighting areas of greater prediction uncertainty arising from disagreement among modeling methods. By offering improved sensitivity and insights into the fine-scale regional distribution of a habitat-forming species with associated uncertainties, our ensemble-based modeling approach provides improved support to numerous nearshore applications including conservation planning and restoration, marine spatial and emergency response planning, environmental impact assessments, and fish habitat protection.

Modeling and evaluation for large amplitude vibration and nonlinear bending of perovskite solar cell

The large amplitude vibration and nonlinear bending analyses for a perovskite solar cell (PSC) in thermal environments are presented through the plate-substrate model. The PSC film is modeled as a thin laminated plate which consists of five plies including ITO, PEDOT:PSS, perovskite, PCBM, and Au. Two kinds of graphene platelets reinforced composite (GPLRC) substrates are considered. The GPLRC substrate is modeled as a porous foundation with finite depth. The foundation stiffnesses are predicted by modified Vlasov model and the equivalent Young’s modulus of the foundation is estimated through a modified Halpin–Tsai model where the porosity coefficient is introduced. The material properties of GPLRC substrates are assumed to be temperature dependent. The thermal effect and plate-foundation interaction are involved in the governing equations which are solved by means of a two-step perturbation approach. The numerical investigations are carried out for the PSC plate rested on GPL/PMMA and GPL/Al substrates. It is shown that the substrate depth and porosity coefficient have substantial influences on the vibration response and nonlinear bending behavior of PSC plates.