Storm Waters Research Articles

IMPROVEMENT OF THE TECHNOLOGICAL PROCESS OF THE RESERVOIR PRESSURE MAINTENANCE SYSTEM

When preparing Wells, the technology of pumping the produced water into the well is used to maintain pressure.from the point of view of Occupational geology, all waters in oil and gas fields are divided into different categories. Own waters, or otherwise residual waters, are pressurized waters that form in the oil and gas reservoir. This type of reservoir water is the main type of groundwater. To maintain the pressure in the oil and gas reservoir, natural (fresh or weakly mineralized) and flowing(drainage) waters, mainly in the reservoir (85%), fresh ( 10 %) and Storm (5 %) waters, can be pumped. More than 1 billion m3 of water flows into the layer, including 700-750 million m3 of fresh water. Field location projects should take into account the fact that in parallel with the growth of oil production in oil production wells, there is an increase in waterlogging, therefore, the water supply system should be designed and built taking into account the 100% utilization of all professional wastewater from Field oil treatment plants in the reservoir pressure maintenance system (CPF). The pumped water must be in harmony with the layer. The presence of mechanical impurities is sometimes associated with a violation of water stability. This can be a consequence of irreversible chemical reactions, accompanied by the ingress of solid salts from saturated solutions.

Using the Daphnia magna Transcriptome to Distinguish Water Source: Wetland and Stormwater Case Studies.

A major challenge in ecotoxicology is accurately and sufficiently measuring chemical exposures and biological effects given the presence of complex and dynamic contaminant mixtures in surface waters. It is impractical to quantify all chemicals in such matrices over space and time, and even if it were practical, concomitant biological effects would not be elucidated. Our study examined the performance of the Daphnia magna transcriptome to detect distinct responses across three water sources in Minnesota: laboratory (well) waters, wetland waters, and storm waters. Pyriproxyfen was included as a gene expression and male neonate production positive control to examine whether gene expression resulting from exposure to this well‐studied juvenoid hormone analog can be detected in complex matrices. Laboratory‐reared (<24 h) D. magna were exposed to a water source and/or pyriproxyfen for 16 days to monitor phenotypic changes or 96 h to examine gene expression responses using Illumina HiSeq 2500 (10 million reads per library, 50‐bp paired end [2 × 50]). The results indicated that a unique gene expression profile was produced for each water source. At 119 ng/L pyriproxyfen (~25% effect concentration) for male neonate production, as expected, the Doublesex1 gene was up‐regulated. In descending order, gene expression patterns were most discernable with respect to pyriproxyfen exposure status, season of stormwater sample collection, and wetland quality, as indicated by the index of biological integrity. However, the biological implications of the affected genes were not broadly clear given limited genome resources for invertebrates. Our study provides support for the utility of short‐term whole‐organism transcriptomic testing in D. magna to discern sample type, but highlights the need for further work on invertebrate genomics. Environ Toxicol Chem 2022;41:2107–2123. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Urban Growth Development Using Group Method of Data Handling

Urbanization has significantly increased over the last two centuries. In year 1800 only 2% of people lived in cities, while in year 1900 this percent increased to 12%. Recent studies indicate that in year 2008 more than 50% of the world population lived in urban areas, with this percentage expected to reach 75% by year 2030. Urban land cover occupies only 2% or 3% of the earth surface, yet it has been recognized that urban growth is associated with many socioeconomic and environmental problems. For example, impervious surfaces that result from urbanization dramatically increase peak discharges associated with storm and snowmelt events, which in turn makes more likely downstream flooding as storm waters exceed stream channel capacities. Urbanization is a very important aspect in country’s development, that’s why this thesis presents urban growth development in Port Harcourt city. The thesis proposed a model in predicting the urban expansion in terms of population growth and land use expansion. The model was trained on a satellite imagery of greater Port Harcourt city. The satellite imagery covers Port Harcourt, Obio/Akpor, Eleme, Etchem, Oyibo, and Omumma local government area in Rivers state. The model was trained using group method of data handling. The result of the model shows a greater change in land use for grater Port Harcourt City, it also shows that by 2035, there will be an increase in pollution for about 5,449,213. The is to say that greater Port Harcourt city will have over 5 million population increase.

Investigation of the potential of native wetland plants for removal of nutrients from synthetic stormwater and domestic wastewater

Constructed floating wetlands (CFWs) promote the growth of plants in buoyant structures where nutrients can be assimilated into biomass, and thus offer an alternative treatment that is potentially more economically viable than conventional constructed wetlands (CWs). This study examined the hydroponic growth of native Australian plants including Baumea rubiginosa (BR) and Phragmites australis (PA) in a synthetic water mix representing both stormwater and municipal waste water, and their total nitrogen (TN) and total phosphorus (TP) uptake rate over a 35-week period. With increases in the nutrient levels in synthetic waters, the overall dry weight of both roots and shoots, and the accumulated TN and TP values removed from the system, all increased. For both storm and waste waters, BR was found to have a higher overall shoot weight compared to that for the PA. In waters with relatively high nutrient levels, BR was found to have a lower overall root weight compared to that for the PA. The %TN accumulated in all plant root tissue was found to be greater than the shoot tissue and consequently the TN removal efficacy by PA (species with a relatively high growth rate of roots) was high in comparison to that by BR (species with a relatively high growth rate of shoots). The TP removal efficacy by BR was higher than that of PA. These results show that CFWs with native plant species could be used to reduce the nutrients levels in both stormwater and wastewater under a Mediterranean climate condition.

Runoff control simulation and comprehensive benefit evaluation of low-impact development strategies in a typical cold climate area

With the acceleration of urbanization, the proportion of surface imperviousness is increasing continuously in cities, resulting in frequent waterlogging disasters. In this context, storm water management, based on the low-impact development (LID) concept, offers an effective measure for the management of urban storm waters. First, the storm water management model (SWMM) was built for a typical cold climate city (Changchun) in China. Next, the two-stage calibrated model was employed to explore the surface runoff and storm sewer control effects of four LID combination plans. Finally, these plans were put through a “cost-benefit” evaluation through an analytic hierarchy process. According to the results, after using four LID plans, the reduction rates of peak runoff exceeded 40% and the problem of overflow load of the storm sewage was significantly mitigated. The infiltration-oriented Plan I proved to be the optimal plan, with the lowest proportions of the overflow nodes and full-load pipe sections in each return period, as well as with maximum overall performance. This study offers technical and conformed methodological support to cold cities for the prevention and control of waterlogging disasters and recycling of rainwater resources.

Blue lines and blues infrastructures: Notes on water, race, and space

In Detroit, Michigan, the urban poor fear they are being displaced and replaced by water. As part of the city’s recent redevelopment efforts, planners have proposed creating green and blue infrastructure zones to manage urban flooding and mitigate the volume of overflow storm and sewer waters that pollute the Great Lakes each year. The areas slated for these water retention zones are the same marginal neighborhoods where Black residents face frequent foreclosures due to water debts and mass shutoffs from water and sewer services. This paper explores how water materializes and mediates uneven landscapes of livability, as well as new modes of living in common among those excluded from the urban commons. I introduce the concepts of “bluelining” and “blues infrastructures” in order to think through the contested assemblages of water, race, and space at the margins of urban life.

Elimination of flow rate restriction for system of storm water sewage with the help of drag-reducing polymers

The flow-rate restriction for storm sewage network is substantiated. Possible causes of flooding of territories by storm water in the case of emergency and methods of storm waters management are considered. The article is devoted to an increase in throughput of storm sewage networks with the help of in-line storm water detention tank installed at the beginning of storm sewage network and dragreducing polymers (DRP). It is proposed to introduce DRPs in the form of solution directly into the sewage network through a storm-water inlet or through a sewer manhole. The introduction is conducted from a tank (cistern) in which there is a device for preparing an aqueous solution from the raw materials of DRP. For a square (in horizontal plane) catchment, in the case of point-type water drainage, the numerical simulation of the work of a system of storm water sewage with the help of DRP has been carried out.

Aquifer Storage and Recovery Using Saline Aquifers: Hydrogeological Controls and Opportunities

Aquifer storage and recovery (ASR) is a valuable tool for managing variations in the supply and demand of freshwater, but system performance is highly dependent upon system-specific hydrogeological conditions including the salinity of the storage-zone native groundwater. ASR systems using storage zones containing saline (>10,000 mg/L of total dissolved solids) groundwater tend to have relatively low recovery efficiencies (REs). However, the drawbacks of low REs may be offset by lesser treatment requirements and may be of secondary importance where the stored water (e.g., excess reclaimed, surface, and storm waters) would otherwise go to waste and pose disposal costs. Density-dependent, solute-transport modeling results demonstrate that the RE of ASR systems using a saline storage zone is most strongly controlled by parameters controlling free convection (e.g., horizontal hydraulic conductivity) and mixing of recharged and native groundwater (e.g., dispersivity and aquifer heterogeneity). Preferred storage zone conditions are moderate hydraulic conductivities (5 to 20 m/d), low degrees of aquifer heterogeneity, and primary porosity-dominated siliclastic and limestones lithologies with effective porosities greater than 5%. Where hydrogeological conditions are less favorable, operational options are available to improve RE, such as preferential recovery from the top of the storage zone. Injection of large volumes of excess water currently not needed into saline aquifers could create valuable water resources that could be tapped in the future during times of greater need.

The effect of water table decline on soil CO2 emission of Zoige peatland on eastern Tibetan Plateau: A four-year in situ experimental drainage

Water table decline is a major threat to soil organic carbon in peatlands worldwide principally because it may largely increase soil CO2 emission (SCE). This study is to determine the response of SCE to water table decline in the Zoige peatland of Tibetan Plateau, which has experienced rapid decline of water table due to climate change and anthropogenic drainage. We conducted a field in situ drainage experiment consisting of low (plots surrounded by 50cm deep ditches), intermediate (20cm deep) and high (intact) water table levels. The experiment lasted for about four years, during which we measured SCE rate and associated variables including soil temperature and moisture with a higher frequency in the growing season (May–September) than the non-growing season (October–April). Experimental drainage decreased water table height by ca. 12cm and 15cm (relative to the intact) and soil moisture (at 5cm soil) by 6% and 12% (relative to 45% in the intact) on average in intermediate and low water table treatments, respectively, but it did not affect soil temperature during the experimental years.The effect of drainage on SCE varied with season. In the non-growing season, the drainage effect was non-significant in each measurement possibly because the low-temperature effect overrode the drainage effect on SCE. In the growing season, the drainage mostly increased the emission except for several cases, in which a negative effect was observed. The negative effect of drainage could be due to the low soil moisture (<25%) in the drained treatments. Provided that the magnitude and the duration of the SCE increase were greater than those of the decrease, it can be estimated that drainage increased SCE by 17% and 20% on average in the low and the intermediate water table treatments, respectively, over the experimental years. Our results suggest that water table decline may facilitate net carbon emission and hence decrease soil carbon storage in the Zoige peatland. We call for artificial filling of the ditches that were historically created by both human beings and storm waters to increase water table in the Zoige peatland.

Toxicity of effluents from gasoline stations oil-water separators to early life stages of zebrafish Danio rerio

Used petroleum hydrocarbons and gasoline stations runoff are significant sources of polycyclic aromatic hydrocarbons (PAHs) to aquatic ecosystems. Samples of the final effluent of oil-water-separators were collected at gasoline stations in the metropolitan region of Recife, Brazil, before release to sewage or rainwater systems. Effluent soluble fractions (ESF) were prepared and bioassays were performed according to the Fish Embryo Toxicity Test. The test involved exposing zebrafish Danio rerio embryos to dilutions of the ESFs for 96 h, with daily examination of lethality and sublethal morphological effects integrated through the General Morphology Score (GMS), based on the achievement of developmental hallmarks. Frequencies of abnormalities were recorded after exposures. ESF LC50-96h (lethal concentration to 50% of exposed embryos) in the most toxic effluent achieved 8.9% (v/v), equivalent to 11 μg phenanthrene equivalents L−1. GMS scores indicated significantly delayed embryo-larval development at ESF dilutions of 10% and 20% from effluents of all gas stations. Major abnormalities detected after the 96 h exposure included the presence of a yolk sac not fully absorbed coupled with the lack of an inflated swim bladder, lack of both pectoral fins, and the failure to develop a protruding mouth. Effective equivalent PAH concentrations that induce a 50% frequency of larvae without an inflated swim bladder (EC50) were 4.9 μg phenanthrene L−1, 21.8 μg naphthalene L−1, and 34.1 μg chrysene L−1. This study shows that PAHs in ESFs from gas stations oil water separators are toxic to zebrafish, contributing to the toxicity of urban storm waters.

Treating urban stormwater in constructed wetlands in Kalmar, Sweden, for improved water quality and biodiversity

Stormwaters’ heavy loads of nutrients, metals and oil etc, via urban ditches / streams, are increasingly treated in engineered shallow wetlands/ponds. Such approaches are still only remedying a minor part of affected storm waters, urban streams, and freshwater and marine recipients. In Kalmar, a middle-sized Swedish town at the Baltic Sea, &gt; 10 such wetlands / ponds are established for reduction of such heavily polluted waters. Aiming at determining the effectiveness in reduction of nutrients and metals, and the facilitation of the aquatic biodiversity (primarily in the wetlands), monitoring programs were initiated. Regular in/outflow water sampling, water flow and biology, were followed for 1-2-3 years (varied with parameter) after construction in two of these wetlands. Skälby Dämme, constructed 14 years ago (2000), showed ca 40 % nutrient reduction figures, less for TSS and metals, while Hagbygärde Dämme, constructed two years ago (2012), attained only much lower results. Reasons for this difference might be that Hagbygärde is less surrounded by forested land, also that less than one year had elapsed before evaluation commenced, while two-three years in Skälby. More recent monitoring in Skälby Dämme is also compared with. Moreover, this kind of wetlands/ponds is shown to favour the biodiversity of benthic invertebrates, (aquatic) plants and birds, although with trends to decline in species richness some years after the initial colonization period.

CURRENT STATE OF THE ECOSYSTEM OF THE LAKE SABYNDYKOL

The ecological condition of an ecosystem of the lake Sabyndykol is analysed, the hydrological and hydrochemical characteristic of a reservoir is given. Biological diversity of phytoplankton, phytobenthos, zooplankton, zoobenthos, fish fauna, coastal and water vegetation is revealed. Ground deposits of lake ecosystem are considered. The processes of instruction and shallowing of a reservoir which have amplified recently are considered. It is proved that the drain of flood and storm waters from the nearby settlement leads to water pollution. The cattle grazing on the lake coast promotes violation and destruction of coastal vegetation. Practical recommendations of nature protection character are suggested.

Polymer-modified pervious concrete for durable and sustainable transportation infrastructures

Pervious concrete is widely considered as an optimal material to manage storm waters in built environments as well as to provide several other environmental benefits. Despite the broad capabilities pervious concrete pavements have exhibited a high failure rate so far. Causes are mainly related to poor design, inadequate construction techniques including compaction, and heavy vehicular traffic. Performance of pervious concrete can be furthermore improved by modifying the cement matrix through polymer modifications, for instance. Polymers could indeed have the capability of improving mechanical performance, particularly flexural strength, without reducing drainability and void content.Four polymers have been tested in the present research and preliminary analyses on polymer-modified cement grouts and mortars were conducted during the first phase of the study; polymer-modified pervious concrete mixes were then prepared and further tested to evaluate the inclusion of polymers depending on the type and content.Results showed a delayed curing of polymer-modified mixes as well as an increased mechanical resistance and durability to raveling and freeze-thaw cycles; polyvinyl acetate polymer demonstrated to be a very good option.

The effects of Asian summer monsoons on algal blooms in reservoirs

An important characteristic of lakes and reservoirs in the East Asian summer monsoon region is the dramatic seasonal difference in hydrologic inputs, with annual rainfall commonly concentrated in a few heavy rain events. In this study, we surveyed the monthly variations of phytoplankton density in 3 large deep reservoirs and 7 small shallow reservoirs and analyzed the effect of large precipitation events on phytoplankton. During heavy rains, stream phosphorus concentrations increased sharply, and phosphorus loadings into reservoirs were not continuous but episodic shock loadings. In deep stratified reservoirs, however, the concentrations of phosphorus and chlorophyll a were much lower than expected from the high total phosphorus levels in the storm runoff. Inflowing storm waters laden with phosphorus flowed into metalimnetic layers because deep reservoirs had strong thermal stratification and the storm water was cooler than the epilimnion. The result was the formation of an ecosystem resilient to phosphorus shock loadings during monsoon. Nutrients in the metalimnion seemed to be dispersed gradually toward the epilimnion, and phytoplankton reached maximum densities, called “monsoon blooms,” after the monsoon. By contrast, shallow reservoirs with short hydraulic residence times had lower chlorophyll a concentrations during the monsoon season because the high flushing rate was the major limiting factor of phytoplankton growth. In conclusion, summer monsoon is the major determinant of phytoplankton density in reservoirs of the East Asian region, but their responses can vary widely depending on hydrologic characteristics.

Assessment of microbial populations within Chicago area nearshore waters and interfaces with river systems.

The Chicago area locks separate and control water flow between the freshwaters of Lake Michigan and the network of Illinois waterways. Under extreme storm conditions, however, the locks are opened and storm waters, untreated waste, and runoff are released directly into the lake. These combined sewer overflow (CSO) events introduce microbes, viruses, and nutrients such as nitrogen and phosphorous into nearshore waters which likely affect the native species. We collected surface water samples from four Chicago area beaches – Gillson Park, Montrose Beach, 57th Street Beach, and Calumet Beach – every two weeks from May 13 through August 5, 2014. Sampling was conducted with four biological replicates for each sampling date and location, resulting in 112 samples. Each community was surveyed through targeted sequencing of the V4 16S rRNA gene. Technical replicates were also sequenced and are included in this dataset. Taxa were identified using Mothur. Raw sequence data is available via NCBI׳s SRA database (part of BioProject PRJNA245802).

Analysis of the Physicochemical Burden of Oyo State Fish Pond, Ibadan, Southwest Nigeria

Physicochemical characteristics of the Oyo State fish pond (OYSFP) was analysed to assess the water quality status in relation to the fish produced in the pond for human consumption. The pond was originally designed to control storm waters from the high lands around but was later converted for the purpose of commercial fish production and other uses by the State Government. The pond is a recipient of tributaries of wastewaters from Premier Hotel (PHWW), Coca Cola bottling plant (CCWW), University of Ibadan Teaching Hospital (UCHWW) and Bodija Residential area (BDJWW). Results of the physico-chemical parameters showed most of the parameters were higher than the maximum permissible limits for surface waters and discharge of wastewaters into surface waters. Premier Hotel wastewater (PHWW) had the lowest pH value of 6.41 and the most acidic of all the wastewaters sampled. OYSFP recorded the lowest dissolved oxygen value of 2.03mg/L and the highest BOD, COD, nitrate, TS and conductivity values of 78.04mg/L, 235.26mg/L, 78 mg/L, 1428.50, 947μS/cm respectively. The highest sulphate value of 248 mg/L was recorded for BDJSW, this was probably due to runoffs from vegetable gardens along the stream bearing inorganic fertilizers. Other macroscopic observations showed that PHWW was slimy to touch, fowl smelling, dark in colour and had animal life forms such as maggots and flying insects residing in it. CCWW was brownish in colour and slightly smelly and fishes were sighted. OYSFP was dark, muddy, fowl smelling, the surface was covered by aquatic weeds predominantly water hyacinth. UCHWW was transparent, foamy, slimy, slightly smelly and no animal life was sighted in it. BDJWW was clear, no odour, animal life forms including fish and surface arthropods were sighted. Results of physicochemical parameters reported in the present study indicate contamination in OYSFP and fish produced there may not be suitable for human consumption.

Experimental study on the effects of fine sand addition on differentially compacted pervious concrete

Pervious concrete provides a sound solution for managing storm waters in built environments where the water runoff as well as the natural recharge of the groundwater are important issues. The use of pervious concrete is also commonly related to other environmental benefits such as the Urban Heat Island reduction, traffic noise absorption, and pollutant filtering. Despite the broad capabilities, comprehensive standards are still limited and many issues have not yet been completely fixed. For example, compaction is often underestimated and one of the common compaction effort is provided by hand-rolling; however, different compaction energies, techniques, or timing can significantly affect mechanical and functional properties of the material. Performance can be furthermore improved by adding a small amount of fine sand, as suggested by many; sand can lead towards better raveling and skid resistance, also improving the maximum flexural strength. On the other hand, too much sand and improper compaction energy may lead to an excessively low void content and reduced drainability features. Compaction and sand addition should be therefore analyzed more in details.The present research aimed at (1) evaluating the effect of differential levels of compaction energy and (2) analyzing the influence of fine sand addition into several pervious concrete mixtures.Results suggested that adding small amounts of fine sand (around 5% of the total aggregate weight) to pervious concrete mixtures provided better mechanical and surface properties, and a consequent reduction of drainability. However, the correct balance of mechanical and hydrological properties can be achieved due to both accurate mix-design and proper compaction plan.

Development and evaluation of a culture-independent method for source determination of fecal wastes in surface and storm waters using reverse transcriptase-PCR detection of FRNA coliphage genogroup gene sequences

A method, incorporating recently improved reverse transcriptase-PCR primer/probe assays and including controls for detecting interferences in RNA recovery and analysis, was developed for the direct, culture-independent detection of genetic markers from FRNA coliphage genogroups I, II & IV in water samples. Results were obtained from an initial evaluation of the performance of this method in analyses of waste water, ambient surface water and stormwater drain and outfall samples from predominantly urban locations. The evaluation also included a comparison of the occurrence of the FRNA genetic markers with genetic markers from general and human-related bacterial fecal indicators determined by current or pending EPA-validated qPCR methods. Strong associations were observed between the occurrence of the putatively human related FRNA genogroup II marker and the densities of the bacterial markers in the stormwater drain and outfall samples. However fewer samples were positive for FRNA coliphage compared to either the general bacterial fecal indicator or the human-related bacterial fecal indicator markers particularly for ambient water samples. Together, these methods show promise as complementary tools for the identification of contaminated storm water drainage systems as well as the determination of human and non-human sources of contamination.

Whole-Lake CO2 Dynamics in Response to Storm Events in Two Morphologically Different Lakes

In lentic systems, hydrology can be dramatically altered after storm events, potentially modifying the carbon budget. In particular, rapid increases in the surface water carbon dioxide partial pressure (pCO2) have been observed following such events. Several processes may explain these shifts in lake CO2 dynamics, including vertical mixing, increases in metabolism, and increases in external loading. To evaluate the relative importance of these various processes, we reconstructed the whole-lake daily CO2 budget using concurrent estimates of lake metabolism and daily CO2 mass balance budgets in two lakes with distinct morphometries located in Quebec, Canada. We found that storm events caused variable, but significant, changes in whole-lake CO2 mass. Such events influenced CO2 dynamics indirectly by inducing shifts in lake metabolism, and directly by importing CO2 by the inflowing storm waters. Storm intensity (in terms of total amount of precipitation) influences the balance between these two processes, but the final outcome depends on lake morphometry. Our results suggest that when storms are intense enough to drive lake water renewal rate beyond 1% day−1, external CO2 loadings became the dominant process, overwhelming internal CO2 production. Lakes with slower hydrological turnover, however, are more susceptible to internal regulation and may simply re-allocate CO2 from the hypolimnion to the epilimnion following a storm event. Our results thus suggest that this tightening of the watershed-lake-atmosphere linkage by climatic events is strongly modulated by lake morphometry. These features should be considered when predicting the impact of future climate change on regional C budgets and emissions.

Combination of synchrotron radiation-based Fourier transforms infrared microspectroscopy and confocal laser scanning microscopy to understand spatial heterogeneity in aquatic multispecies biofilms

Understanding the spatial heterogeneity within environmental biofilms can provide an insight into compartmentalization of different functions in biofilm communities. We used a non-destructive and label-free method by combining Synchrotron Radiation-based Fourier Transform Infrared Microspectroscopy (SR-FTIR) with Confocal Laser Scanning Microscopy (CLSM) to distinguish the spatial chemical changes within multispecies biofilms grown from natural storm waters in flow cells. Among the different surfaces tested for biofilm growth and optimal imaging, mylar membranes were most suited and it enabled successful spatial infrared imaging of natural biofilms for obtaining reliable and interpretable FTIR spectra. Time series analysis of biofilm growth showed that influx of water during biofilm growth, results in significant changes in biofilm formation. Early biofilms showed active nutrient acquisition and desiccation tolerance mechanisms corresponding with accumulation of secreted proteins. Statistical approach used for the evaluation of chemical spectra allowed for clustering and classification of various regions of the biofilm. Microheterogeneity was observed in the polymeric components of the biofilm matrix, including cellulose, glycocalyx and dextran-like molecules. Fructan and glycan-rich regions were distinguishable and glycocalyx was abundant in the strongly adhering peripheral regions of biofilms. Inner core showed coexistence of oxygen dimers and ferrihydrite that will likely support growth of Fe (II)-oxidising bacteria. The combined SR-FTIR microspectroscopy and CSLM approach for complex natural biofilms described here will be useful both in understanding heterogeneity of matrix components and in correlating functions of juxtaposed microbial species in complex natural biofilms with physicochemical microenvironment to which they are exposed.