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Abstract: This study compares the effectiveness of two different thickness of green roof substrate with respect to nutrient and heavy metal retention and release. To understand and evaluate the long term behaviour of green roofs, substrate columns with the same structure and composition as the green roofs, were exposed in laboratory to artificial rain. The roofs act as a sink for C, N, P, zinc and copper for small rain events if the previous period was principally dry. Otherwise the roofs may behave as a source of pollutants, principally for carbon and phosphorus. Both field and column studies showed an important retention for Zn and Cu. The column showed, however, lower SS, DOC and metal concentrations in the percolate than could be observed in the field even if corrected for run-off. This is most probably due to the difference in exposition history and weathering processes. [Copyright &y& Elsevier]

The quality of stored roof runoff in terms of pesticide pollution was assessed over a one-year period. Two tanks, located at a rural and suburban site, respectively, were sampled monthly. The two studied collection surface were respectively a tile slope roof and a bituminous flat roof. Four hundred and five compounds and metabolites were screened using liquid and gas chromatography coupled with various detection systems. Principal Component Analysis was applied to the data sets to elucidate patterns. At the rural site, two groups of compounds associated with two different types of agriculture, vineyard and crops, were distinguished. The most frequently detected compound was glyphosate (83%) which is the most commonly used herbicide in French vineyards. At the suburban site, quantified compounds were linked to agriculture rather than urban practices. In addition, all samples were contaminated with mecoprop which is a roof-protecting agent. Its presence was attributed to the nature of roofing material used for rainwater collection. For both sites, the highest number and concentrations of compounds and metabolites were recorded at the end of spring and through summer. These results are consistent with treatment periods and higher temperatures. [Copyright &y& Elsevier]

The zinc and copper content of roof runoff could originate from different sources such as dry and wet deposition and the corrosion of the material. The zinc runoff rate from a galvanized surface depends on the corrosion products formed during the dry days, the rain intensity and roof slope, which determinates the contact time. In the present study the contact time dependence of zinc rate and the re-dissolution of the zinc were investigated with steeping tests and a pilot study. The average zinc runoff measured in the first 2.81 of runoff was 3.8 mg m-2 11.1-8.4 mg m-2), while in the following samples 1.2 mg m-2 were detected. These results are in accordance with the 5-10 mm, and 40-60 s contact time laboratory steeping test, respectively, which are realistic. The estimated specific yearly zinc runoff rate was 0.7 g m-2 y-1, while the dry and wet deposition rate of copper was 0.009 mg m-2 d-1 and 0.053 mg m-2 storm-1 respectively. The re-dissolution of the zinc from the evaporated then re-filled samples of leaching tests with high initial zinc content was just 60% after 60 min. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) were measured in atmospheric deposition and roof runoff in Beijing, China from May to October 2009. Serious N pollution caused by summer rainfall was found in Beijing. N was mainly transported in dissolved from, while P was predominantly found in its particle form. Bulk deposition potentially accounted for as much as 70%, 71%, 97%, and 45% of total nitrogen (TN), dissolved nitrogen (DN), total phosphorus (TP), and dissolved phosphorous (DP) loads in roof runoff, respectively, indicating that atmospheric deposition predominantly contributes to roof runoff pollution in Beijing. Moreover, wet deposition was an important source of TN, DN, and DP, while dry deposition was the main source of TP. N and P concentrations in roof runoff decreased as the amount of rainfall increased. The monthly loads of N and P in roof runoff were linearly and positively correlated with the amount of rainfall, indicating that the amount of rain is an important factor that influences the N and P loads in roof runoff. The positive relationship between N and P fluxes (load divided by the dry weather period; mg/m²d) and the mean daily rainfall intensity (amount of rainfall divided by the dry weather period; mm/d) suggest that N and P loads in roof runoff can be estimated by measuring the amount of rainfall and the antecedent dry weather period. [ABSTRACT FROM AUTHOR]

This paper presents the outcomes of a study which focused on evaluating roof surfaces as stormwater harvesting catchments. Build-up and wash-off samples were collected from model roof surfaces. The collected build-up samples were separated into five different particle size ranges prior to the analysis of physico-chemical parameters. Study outcomes showed that roof surfaces are efficient catchment surfaces for the deposition of fine particles which travel over long distances. Roof surfaces contribute relatively high pollutant loads to the runoff and hence significantly influence the quality of the harvested rainwater. Pollutants associated with solids build-up on roof surfaces can vary with time, even with minimal changes to total solids load and particle size distribution. It is postulated that this variability is due to changes in distant atmospheric pollutant sources and wind patterns. The study highlighted the requirement for first flush devices to divert the highly polluted initial portion of roof runoff. Furthermore, it is highly recommended to not to harvest runoff from small intensity rainfall events since there is a high possibility that the runoff would contain a significant amount of pollutants even after the initial runoff fraction. [ABSTRACT FROM AUTHOR]

This study deals with the assessment of roof runoff waters from the region of Gdansk collected during the winter season (2007/2008). The chemical analysis includes 16 chemical variables: major ions, PAHs and PCBs measured at 3 sampling sites for 6–14 rain events. Although the data set is of limited volume the statistical data treatment using self-organizing maps (SOM) reveals the main factors controlling roof runoff water quality even for a data set with small dimension. This effort for explanation of the identified factors by the possible emission sources of the urban environment and air-particulate formation seems to be very reliable. Additionally to the roof runoff water quality factors the rain events patterns are found: “background” group of events and groups formally named “PAHs”, “PCBs” and “air-borne particles” – dominated events. The SOM classification results give an opportunity to uncover the role of roof “impact” on the runoff waters. Rain runoff water quality is described by four latent factors and the “roof” impact is uncovered. [Copyright &y& Elsevier]

Abstract: Release of copper from a naturally aged copper roof on a shopping centre building in a suburban site of Stockholm has been measured during different rain events after its interaction with the internal drainage system and storm drains made of cast iron and concrete. Concentrations of copper removed by means of urban storm water from a nearby parking space have been determined for comparison. Predictions and measurements of the chemical speciation of released copper are discussed compared to the total concentration, and to threshold values for freshwater and drinking water. The results clearly illustrate that the major part of the released copper from the roof is readily retained already during transport through the internal drainage system of the building, a pathway that also changes the chemical speciation of released copper and its bioavailable fraction. Most copper, not retained by cast iron and concrete surfaces, was strongly complexed to organic matter. The median concentration of free cupric ions and weak copper complexes was less than, or within the range of reported no effect concentrations, NOECs, of copper in surface waters. The parking space contributed with significantly higher and time-dependent concentrations of total copper compared to measured concentrations of copper from the roof after the interaction with the drainage system. Most copper in the surface runoff water was strongly complexed with organic matter, hence reducing the bioavailable fraction significantly to concentrations within the NOEC range. Dilution with other sources of urban storm water will reduce the released concentration of copper even further. The results illustrate that already the internal drainage system and the storm drains made of cast iron and concrete act as efficient sinks for released copper which means that any installation of additional infiltration devices is redundant. [Copyright &y& Elsevier]

Abstract: Scientific reports concerning chemical and microbiological contaminant levels of rainwater runoff from rooftop collection in both urban and rural areas are reviewed. This alternative source of water has been documented to often contain substantial amounts of contaminants. Studies describing levels of heavy metal contamination specific to runoff from rooftop catchment areas containing exposed metal surfaces are discussed. Depending upon the intended use, scientific evidence is also accumulating that various treatments and disinfections will be required prior to release of roof-runoff water either into surface waters or for more direct consumer usage. For microbial contamination, current proposed standards and guidelines regarding this type of water source are shown to vary widely worldwide. Scientific literature reveals a lack of clarity regarding water quality guidelines and health related standards for certain types of rooftop runoff. Studies suggests that rainwater collection systems which are properly designed, maintained, and treated may provide a valuable supplement to existing water supplies by reducing demand on community water supplies/infrastructure costs, enhancing effective management of storm water runoff, and increasing restoration of underground reservoirs through controlled infiltration. [Copyright &y& Elsevier]

Runoff from urban catchments depends largely on the amount of impervious surface and the connectivity of these surfaces to the storm sewer drainage system. In residential areas, pervious lawns can be used to help manage stormwater runoff by intercepting and infiltrating runoff from impervious surfaces. The goal of this research was to develop and evaluate a simple method for estimating the reduction in stormwater runoff that results when runoff from an impervious surface (e.g., rooftop) is directed onto a pervious surface (e.g., lawn). Fifty-two stormwater runoff reduction tests were conducted on six residential lawns in Madison, Wisconsin during the summer of 2004. An infiltration-loss model that requires inputs of steady-state infiltration rate, abstraction (defined here as surface storage, vegetation interception and cumulative total infiltration minus steady-state infiltration during the period prior to steady-state), and inundated area was evaluated using experimental data. The most accurate results were obtained using the observed steady-state infiltration rates and inundated areas for each test, combined with a constant abstraction for all tests [root mean squared (RMS) difference = 1.0 cm]. A second case utilized lawn-averaged steady-state infiltration rates, a regression estimate of inundated area based on flow-path length, and lawn-specific abstractions based on infiltration rate (RMS difference = 2.2 cm). In practice, infiltration rates will likely be determined using double-ring infiltration measurements (RMS difference = 3.1 cm) or soil texture (RMS difference = 5.7 cm). A generalized form of the model is presented and used to estimate annual stormwater runoff volume reductions for Madison. Results indicate the usefulness of urban lawns as a stormwater management practice and could be used to improve urban runoff models that incorporate indirectly connected impervious areas. [ABSTRACT FROM AUTHOR]

The buildup of roof pollutants in an urban area of Shanghai, China was investigated by conducting 16 experiments between November 2007 and October 2008. Concentrations of Cu, Zn and Cd in runoff from three types of roof (concrete, aluminum and glass) exceeded USEPA National Recommended Water Quality Criteria. The solid/liquid partition of the selected metal elements was consistent for the three roof types: Al, Fe, Zn and Pb were present mainly in the particle-bound form, while the total loading of Cd was nearly 100% in the dissolved form. Atmospheric dry precipitation accounted for most of all pollutant loadings for all roof types, while roof material made only a minor contribution to the loadings. All pollutant accumulation rates except for COD showed a seasonal trend with peaks in spring (March∼May) and winter (December∼February) and troughs in summer (June∼August) and autumn (September∼November). Our results showed that a linear equation is the most reliable of commonly used buildup models to simulate the total phosphorus (TP) and total suspended solids (TSS) buildup processes on aluminum roofs and glass roofs. This study provided novel information about roof runoff in Shanghai, China, in terms of pollution status, pollution source and pollutant buildup processes, thereby aiding in rainwater utilization and non-point pollution control. [ABSTRACT FROM AUTHOR]

Deposition, leaching and chemical transformation are processes that affect roofing tile and roof runoff water. Leaching experiments, with artificial rainwater in the laboratory, showed the presence of Na+, K+, Mg2+, Ca2+, Cl−, NO3 −, SO4 2−, with a ratio of Ca2+ and SO4 2− suggesting gypsum dissolution. X-ray fluorescence (XRF) of the exposed roof tile showed depletion such as Mg, Al, Si, P, Ti and K at the surface of the tile and an enrichment of Fe and Mn which hinted at a process akin to laterite formation. However, calcium appeared to be enriched at the surface as gypsum (confirmed by X-ray diffraction) and to a lesser extent calcite, which is characteristic of deposits on building surfaces in cities. [ABSTRACT FROM AUTHOR]

Considering the short length of building roofs, a theoretical analysis of the first flush of roof runoff was conducted based on the kinematic wave and pollutant erosion equations. This mathematical derivation with analytical solutions predicts pollutant mass first flush (MFF), mean concentration of initial runoff (MCIF), mean concentration of roof runoff (MCRR) with diversion of initial portion and residual mass available on the bed surface (RS) after the entire runoff under the condition of constant excess rainfall. And the effects of the associated influencing factors (roof length, roof gradient, roof surface roughness, rainfall intensity, rainfall duration, and erosion coefficients) on them were discussed while the values of parameters referred to the previous studies. The results showed that for roofs whose length is shorter than 20 m, both the increase in roof length and roof gradient and the decrease in roof surface roughness result in larger MFF and MCIF and smaller MCRR and RS, which is beneficial to water reuse and pollution reduction. The theoretical relationship between the first flush and the influencing factors may aid the planning and design of roof in terms of rainwater utilization or diffuse pollution control. [ABSTRACT FROM AUTHOR]

Pollutants originating with roof runoff can have a significant impact on urban stormwater quality. This signifies the importance of understanding pollutant processes on roof surfaces. Additionally, knowledge of pollutant processes on roof surfaces is important as roofs are used as the primary catchment surface for domestic rainwater harvesting. In recent years, rainwater harvesting has become one of the primary sustainable water management techniques to counteract the growing demand for potable water. This paper presents the outcomes of an in-depth research study into particulate matter build-up and wash-off for roof surfaces. In this research, particulate matter was considered as the indicator pollutant where the processes related to other pollutants can be predicted based on the understanding generated for particulate matter. The study outcomes confirm that the build-up process on roof surfaces is comparatively similar to road surfaces. However, particle loads collected from roofs were significantly less compared to road surfaces and much finer in texture. Wash-off from roofs also showed significant similarities to wash-off from roads. A relatively high concentration of particulate matter was noted during the initial part of storm events. Furthermore, the amount of particulate matter remaining on the roof surfaces was significantly high for less intense rain events. [Copyright &y& Elsevier]

Abstract: Summer sampling of storm runoff generated from areas of roofs and hardstanding situated on four dairy/beef farms has provided novel information regarding its microbiological and chemical quality. All farm hardstandings generated runoff that was contaminated with respect to those pollutants (faecal coliforms, FC, and faecal streptococci, FS, major nutrients, organic carbon) that are ubiquitously associated with faecal matter and urine. The separate analysis of roof runoff indicated that these can contribute significant concentrations of FS, phosphorus (P) and potentially toxic elements such as zinc (Zn), and suggests a level of ‘background’ contamination originating from wash-off of bird droppings and in the case of Zn galvanised surfaces. On average hardstanding runoff showed enhanced concentrations of >4 orders of magnitude for FC and 2–3 for major nutrients and carbon relative to roof runoff. Organic forms of nitrogen (N) and P contributed significantly (averaging >40%) to the total dissolved fraction in both roof and hardstanding runoff. Part of the substantial variability in composition of runoff samples could be attributed to differences between farms as well as the timing of sample collection during individual storms. Where situations allowed, a comparison of water upstream and downstream of the farmyard demonstrated they acted as a source of multiple contaminants not only during hydrologically active storm events but also during dry periods. Contamination pathways included a combination of both point (e.g., septic overflows) and non-point (e.g., seepage from livestock housing) sources. Farmyards situated within intensive livestock farming areas such as SW Scotland, would be expected to have significant local and accumulated downstream impacts on the aquatic environment. Localised impacts would be particularly important for headwaters and low order streams. [Copyright &y& Elsevier]

The article discusses a study which aims to estimate measurements of the average runoff from the roofs of six houses in an urban environment. A model developed for estimating the evaporation of rainfall intercepted by forest canopies was applied using values of the mean rates of wet canopy evaporation and rainfall derived for forests and an estimate of the roof storage capacity derived from data collected from a previous study. The study concludes that the process of evaporation from an urban roof is sufficiently similar to that from a forest canopy for forest evaporation models to be used to give a useful estimate of urban roof runoff.

On-site infiltration may be considered as a promising way of managing rainwater runoffs in urban areas, provided the hydrological and ecological conditions allow infiltration, and provided there is adequate treatment of the contaminants to avoid a risk of soil and groundwater pollution. The aim of this study was to evaluate the feasibility of the application of a new technical infiltration system equipped with clinoptilolite as an artificial barrier material for the treatment of the copper roof runoff of the Academy of Fine Arts in Munich, Germany. During the 2-yr sampling period, 30 rain events were examined. The cover material of the roof and the drainage system was responsible for the high copper concentrations in the roof runoff. The rain height and the rain intensity were of great significance regarding the establishment of the copper runoff rate. The technical infiltration system applied was able to reduce the copper from the roof runoff by a factor up to 96%. The mean measured copper concentration in percolation water was lower than the critical value of 50μg/l set by the German Federal Soil Protection Act and Ordinance, indicating no risk for soil and groundwater contamination. [Copyright &y& Elsevier]

Runoff waters are one of the forms in which precipitation reaches the ground and surface waters. They are formed when rain or melting snow washes the surfaces of roofs, highways, agricultural areas or tree canopies. Pollutants present in runoff waters can constitute a potential danger to aquatic ecosystems. This paper reviews techniques and equipment for collecting runoff water. It discusses storage and preparation of samples for analysis (errors made on the stage of sampling, type of a sampled fraction - important step of analysis). This work presents bibliographic information about a wide range of inorganic and organic compounds in various form of runoff water (as a result of washing out pollutants from such surfaces as: highways, building roofs, and agricultural areas). [ABSTRACT FROM AUTHOR]

In order to estimate the detention effect (storage and peak flow attenuation) of a sedum green-roof, a comparison between the response of an impervious roof (runoff coefficient C = 1) and a green-roof has been carried out. Precipitation and runoff data from several controlled experiments (with wet initial conditions, i.e. approximately at field capacity) on a sedum green-roof were used for the analysis. For events with variable rain intensity, the green-roof's attenuation effect was as high as 65% for design storms. In contrast, events with constant intensity had increases in peak flows of up to 5%. The lowest detention volumes were observed for the experiments with constant rain intensity, for which a maximum of 29% of the rain volume was detained, whereas for rain events with variable intensity the detention volume was up to 52%. Simulations (using PondPack), based on a real case study, showed that green-roofs can be implemented in combination with other structural best management practices (BMPs) to obtain a desired detention. They can be used to reduce the size of other structural BMPs, and can occupy unused space that is readily available. [ABSTRACT FROM AUTHOR]

There has been a growing interest, especially in developing countries, in rooftop rainwater harvesting as an alternative source of drinking water. This paper reviews the available information on the water quality of rooftop rainwater harvesting systems. Various factors that affect the physico-chemical and microbiological quality of harvested water are discussed. Different contaminants including heavy metals and trace organic pollutants in the roof runoff reported from different parts of the world are compared. The review shows that the quality of harvested water from roof catchments often does not meet the drinking-water guideline values. Most of the studies reveal that harvested water is heavily contaminated microbiologically by a variety of indicator and pathogenic organisms unless special care is taken during collection and storage of rainwater. Heavy metals and trace organics could also pose problems in some cases. The review thus indicates that the purity of rainwater harvested from rooftops should not be taken for granted, and analysis of the harvested water especially for microbiological contamination should be undertaken. Appropriate treatment of collected rainwater would be necessary to make the harvested rainwater fit for drinking. The review also shows the need for further research on proper design and maintenance strategies to minimise contamination of roof-collected rainwater supplies. [ABSTRACT FROM AUTHOR]

Large, uncoated copper and zinc roofs cause environmental problems if their runoff is infiltrated into the underground or discharged into receiving waters. Since source control is not always feasible, barrier systems for efficient copper and zinc removal are recommended in Switzerland. During the last few years, research carried out in order to test the performance of GIH-calcite adsorber filters as a barrier system. Adsorption and mass transport processes were assessed and described in a mathematical model. However, this model is not suitable for practical design, because it does not give explicit access to design parameters such as adsorber diameter and adsorber bed depth. Therefore, for e.g. engineers, an easy to use design guideline for GIH-calcite adsorber systems was developed, mainly based on the mathematical model. The core of this guideline is the design of the depth of the GIH-calcite adsorber layer. The depth is calculated by adding up the GIH depth for sorption equilibrium and the depth for the mass transfer zone (MTZ). Additionally, the arrangement of other adsorber system components such as particle separation and retention volume was considered in the guideline. Investigations of a full-scale adsorber confirm the successful application of this newly developed design guideline for the application of GIH-calcite adsorber systems in practice. [ABSTRACT FROM AUTHOR]

Rain gardens have been recommended as a best management practice to treat stormwater runoff. However, no published field performance data existed on pollutant removal capabilities. Replicated rain gardens were constructed in Haddam, CT, to capture shingled-roof runoff. The gardens were sized to store the first 2.54 cm (1 inch) of runoff. Influent, overflow and percolate flow were measured using tipping buckets and sampled passively. Precipitation was also measured and sampled for quality. All weekly composite water samples were analyzed for total phosphorus (TP), total Kjeldahl nitrogen (TKN), ammonia-nitrogen (NH3-N), and nitrite+nitrate-nitrogen (NO3-N). Monthly composite samples were analyzed for copper (Cu), lead (Pb) and zinc (Zn). Redox potential was measured using platinum electrodes. Poor treatment of NO3-N, TKN, organic-N, and TP in roof runoff was observed. Many Cu, Pb and Zn samples were below detection limit, so statistical analysis was not performed on these pollutants. The only pollutants significantly lower in the effluent than in the influent were NH3-N in both gardens and total-N in one garden. The design used for these rain gardens worked well for overall flow retention, but had little impact pollutant concentrations in percolate. These results suggest that if an underdrain is not connected to the stormwater system, high flow and pollutant retention could be achieved with the 2.54 cm design method. [ABSTRACT FROM AUTHOR]

Abstract: Aim of this study was to evaluate the feasibility of the use of clinoptilolite as a barrier material to eliminate heavy metals from roof runoff. The effect of chemical conditioning with 1M NaCl solution upon the ion exchange capacity and on kinetic of zinc uptake by clinoptilolite has been investigated. According to the batch experiments the modified clinoptilolite has up to 100% higher sorption capacity, regarding Zn than the natural material. The pre-treatment of clinoptilolite results in an acceleration of the ion exchange process up to 40% regarding zinc. In order to define the reasons of this behaviour, both materials, modified and natural, were analysed for: (i) chemical composition, (ii) density, (iii) pore size distribution and (iv) zeta potential. The clogging of the pores, the charge of the grain surface, the pH of the initial metal solution and the ion metal concentration are the factors which are mainly affecting the ion exchange capacity and the rate of zinc uptake by clinoptilolite. [Copyright &y& Elsevier]

Sixteen wooden structures with two roofs each were installed to study runoff quality for four commonly used roofing materials (wood shingle, composition shingle, painted aluminum, and galvanized iron) at Nacogdoches, Texas. Each roof, either facing NW or SE, was 1.22m wide×3.66m long with a 25.8% roof slope. Thus, there were 32 alternatively arranged roofs, consisting of four roof types×two aspects×four replicates, in the study. Runoff from the roofs was collected through galvanized gutters, downspouts, and splitters. The roof runoff was compared to rainwater collected by a wet/dry acid rain collector for the concentrations of eight water quality variables, i.e. Cu2+, Mn2+, Pb2+, Zn2+, Mg2+, Al3+, EC and pH.Based on 31 storms collected between October 1997 and December 1998, the results showed: (1) concentrations of pH, Cu, and Zn in rainwater already exceed the EPA freshwater quality standards even without pollutant inputs from roofs, (2) Zn and Cu, the two most serious pollutants in roof runoff, exceeded the EPA national freshwater water quality standards in virtually 100% and more than 60% of the samples, respectively, (3) pH, EC, and Zn were the only three variables significantly affected by roofing materials, (4) differences in Zn concentrations were significant among all roof types and between all roof runoff and rainwater samples, (5) although there were no differences in Cu concentrations among all roof types and between roof runoff and rainwater, all means and medians of runoff and rainwater exceeded the national water quality standards, (6) water quality from wood shingles was the worst among the roof types studied, and (7) although SE is the most frequent and NW the least frequent direction for incoming storms, only EC, Mg, Mn, and Zn in wood shingle runoff from the SE were significantly higher than those from the NW; the two aspects affected no other elements in runoff from the other three roof types. Also, Zn concentrations from new wood-shingle roofs were significantly higher than those from aged roofs of a previous study. The study demonstrated that roofs could be a serious source of nonpoint water pollution. Since Zn is the most serious water pollutant and wood shingle is the worst of the four roof types, using less compounds and materials associated with Zn along with good care and maintenance of roofs are critical in reducing Zn pollution in roof runoff. [Copyright &y& Elsevier]

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Hydrocarbons (aliphatic and aromatic) and metals (heavy metals and major elements) were measured in both atmospheric deposition and roof runoff in central Paris (France). Atmospheric deposition (wet and dry) was collected from December 2001 to October 2002 and roof runoff was sampled on three buildings with different covering materials, i.e., slate tiles and zinc sheets. This paper gives an overview of the results on the flux and distribution points of view for both atmospheric deposition and roof runoff. Results show that atmospheric fluxes of hydrocarbons and major elements increase during cold seasons, due to residential heating occurrence, while heavy metals, whose major sources have constant emission fluxes, exhibit steady atmospheric loads throughout the year. Moreover, hydrocarbon fingerprints reveal mainly biogenic and pyrolytic origins for aliphatic and aromatic hydrocarbons, respectively. The results about roof runoff contamination suggest that the scavenging processes for hydrocarbons and metals are dependent on rainfall amount rather than on the rain event characteristics (number, intensity, duration), and dry deposition weakly contributes to the pollutant loads in roof runoff. Results also highlight that both metallic and slate roofs do not act as a source of hydrocarbons and major elements—exclusively originating from atmospheric deposition—while they act as a source of some heavy metals. Zinc-covered roofs largely release Zn and Ti, while slate roofs mainly release Pb, Ti and Cu. Whatever the material used for roof covering, roof runoff presents high Ni and V loads due to the vicinity of the chimney stacks of heating boilers. [ABSTRACT FROM AUTHOR]

Summary Nanometre-scale electron spectroscopic imaging has been applied to characterize the operation of a copper filtration plant in environmental science. Copper washed off from roofs and roads is considered to be a major contributor to diffuse copper pollution of urban environments. A special adsorber system has been suggested to control the diffusion of copper fluxes by retaining Cu with a granulated iron hydroxide. The adsorber was tested over an 18-month period on facade runoff. The concentrations range of Cu in the runoff water was measured between 10 and 1000 p.p.m. and could be reduced by between 96% and 99% in the adsorption ditch. Before the analysis of the adsorber, the suspended material from the inflow was ultracentrifuged onto TEM grids and analysed by energy-filtered transmission electron microscopy (EFTEM). Copper was found either as small precipitates 5–20 nm in size or adsorbed onto organic and inorganic particles. This Cu represents approximately 30% of the total dissolved Cu, measured by atomic emission spectrometry. To locate where the copper sorption takes place within the adsorber, the granulated iron oxide was analysed by analytical electron microscopy after exposure to the roof run-off water. A section of the granulated iron hydroxide was prepared by focused ion beam milling. The thickness of the lamina was reduced to 100 nm and analysed by EFTEM. The combination of these two techniques allowed us to observe the diffusion of Cu into the aggregate of Fe. Elemental maps of Fe and Cu revealed that copper was not only present at the surface of the granules but was also sorbed onto the fine particles inside the adsorber. [ABSTRACT FROM AUTHOR]

The infiltration of urban roof runoff into well permeable subsurface material may have adverse effects on the ground water quality and endanger drinking water resources. Precipitation water from three different roofs of an industrial complex was channelled to a pit and infiltrated into a perialpine glaciofluvial gravel-and-sand aquifer. A shaft was constructed at the bottom of the pit and equipped with an array of TDR probes, lysimeters and suction cups that allowed measuring and sampling soil water at different depths. A fast infiltration flow was observed during natural rainfall events and during artificial infiltration experiments. For a better understanding of the behaviour of contaminants, experiments were conducted with cocktails of compounds of different reactivity (ammonium, strontium, atratone) and of non-reactive tracers (uranine, bromide, naphthionate), which represent different classes of pollutants. The experiment identified cation exchange reactions influencing the composition of the infiltrating water. These processes occurred under preferential flow conditions in macropores of the material. Measuring concentration changes under the controlled inflow of tracer experiments, the pollution potential was found to be high. Non-reactive tracers exhibited fast breakthrough and little sorption. [Copyright &y& Elsevier]

The rainwater and rainfall runoff of roofs in the central district of Beijing from June to September in 2019 were sampled and analyzed to study the characteristics of the water quality, the first flush effect, and the main influential factors and sources of pollutants. The results showed that the roof runoff was seriously polluted by total nitrogen, ammonia nitrogen, chemical oxygen demand, and total suspended solids whose event mean concentration (EMC) exceeded the fifth level of environmental quality standards for surface water (GB 3838-2002) (the EMC of suspended solids exceeded the second level of discharge standard of pollutants for municipal wastewater treatment plants (GB 18918-2002)). The rainwater was relatively less polluted than the rainfall runoff, but the EMC of ammonia nitrogen and total nitrogen of the rainwater also exceeded the standard in some rainfall events. The first flush intensity of the rainfall runoffs was between weak and medium. The sequence of strength of the first flush of different pollutants was ammonia nitrogen>total suspended solids>chemical oxygen demand>total nitrogen>mercury>zinc>total phosphorus>lead. The concentration of total suspended solids, chemical oxygen demand, and total phosphorus in roof runoff were significantly positively correlated with the length of rainfall and the dry period and negatively correlated with the rainfall intensity. According to the results of principal component analysis, the main pollutant in rainwater was nitrogen emitted by vehicles, and the main pollutants in roof runoffs were suspended solids, organic matters, and phosphorus pollutants released from the aging of roofing materials and the corrosion of metal down pipes.

Because roofs represent a major part of the urban impervious surface, it is hypothesized that roof runoff is an important source of urban stormwater contamination. However, the contribution of different roofing materials to this contamination has only been examined to a limited extent. In this study, a resource and time efficient methodology, which uses some of the principles of a standardized leaching test (CEN/TS16637-2), was developed to identify material-pollutant relationships for sixteen commonly used roofing materials (EPDM, PVC, TPO, EVA, PU and bitumen membranes). Metals were detected in concentrations ranging from several μg/L in the leachate of synthetic materials up to 2.5 mg/L for Zn in the leachate of EPDM materials. Cd and Cr were not detected in any of the leachates. Furthermore, polycyclic aromatic hydrocarbons were detected in most leachates, with phenanthrene and naphthalene being most frequently detected in concentrations up to 4.5 μg/L for naphthalene. Further insights on organic pollutants' leaching from the tested materials were obtained by a non-target GC-MS screening of the leachates. Several commonly used additives such as flame retardants and light stabilizers were detected. Although no information on long-term leaching and material behavior under outdoor conditions could be obtained by the developed methodology, the laboratory test results could be used to benchmark the materials for their potential impact on roof runoff quality by the calculation of material indexes (which summarize the material-pollutant relationships). EPDM and PU roofing materials were identified as the materials having the highest potential to affect roof runoff quality. • All tested roofing materials were found to leach metals and organic substances. • The proposed leaching test is suitable to identify material-pollutant relationships. • Materials were benchmarked based on their leaching behavior. • EPDM and PU roofing materials have the highest potential impact on water quality. [ABSTRACT FROM AUTHOR]

The article offers the author's insights on construction of an observatory in Keighley, West Yorkshire in England. The author states that the run-off roof design was chosen because it is easier to construct and for security purposes. He mentions that the building which is 9 by 7 feet is almost made entirely of timber. He adds that an Uninterruptible Power Supply (UPS) was installed to avoid power cuts.