Urban Aquatic Systems Research Articles

Nanoparticles of dust as an emerging contaminant in urban environments.

Due to very high mobility in the environment and penetration ability into living organisms, nanoparticles (NPs) of urban dust pose a potential threat to human health and urban ecosystems. Currently, data on the chemical composition of NPs of urban dust, their fate in the environment, and corresponding risks are rather limited. In the present work, NPs of deposited urban dust have been comprehensively studied for the first time; NPs isolated from 78 samples of dust collected in Moscow, the largest megacity in Europe, being taken as example. The elemental composition, potential sources as well as environmental, ecological, and health risks of NPs of urban dust are assessed. It is found that dust NPs are extremely enriched by Cu, Hg, Zn, Mo, Sb, and Pb, and can serve as their carrier in urban environments. No regularities in the spatial distribution of elements have been found, probably, due to high mobility of dust NPs. High ecological and health risks caused by dust NPs are demonstrated. Source apportionment study has evaluated one natural and two anthropogenic sources of elements in NPs of urban dust; the contribution of natural and anthropogenic sources being comparable. It is also shown that dust NPs may be considered as an important carrier of trace elements in urban aquatic systems. Additionally, the risks associated with NPs and bulk samples of dust have been compared. The observed risks associated with NPs are significantly higher.

Urban drainage channels as a pathway for microplastics in riverine systems: A case study of Delhi, India

ABSTRACT Urban drainage channels act as significant routers of microplastics (MPs) originating from terrestrial to aquatic systems. In the present study, contamination of MPs (250–5,000 μm size) has been investigated in an interlinked urban aquatic system comprising Najafgarh drain, corresponding secondary drains, and Yamuna River in Delhi, India. A range of 100–4,300 MPs/m3 (pre-monsoon) and 100–6,700 MPs/m3 (post-monsoon) were detected in secondary drains, which meet the Najafgarh drain through its course in the city. Najafgarh drain showed an average abundance of 771 and 343 MPs/m3 during pre- and post-monsoon season, respectively. The discharge of MP-laden wastewater from the Najafgarh drain into the Yamuna River created a rise in MP abundance in the river at the drain’s downstream location. Thus, revealing that secondary drains play a significant role in MP channelization to the Najafgarh drain and subsequently Yamuna River. White MP fragments were dominating in the study area. Chemical characterization revealed 11 types of MP polymers, with a predominance of polyethylene. Considering the knowledge gap in MP database of interconnected urban aquatic systems in India, this study might help in providing baseline information and encourage more studies addressing the magnitude of this problem for predicting long-term environmental risks.

Identification, occurrence, concentration and composition profile of fiproles in municipal wastewater treatment plants

Although fipronil and several of its transformation products are ubiquitous in aquatic environments, limited information is available on the structural identities, detection frequencies, concentrations and composition profiles of fiproles (fipronil and its known and unknown transformation products) in municipal wastewater treatment plants (WWTPs). In this study, a suspect screening analysis was applied to identify and characterize fipronil transformation products in 16 municipal WWTPs from three cities in China. In addition to fipronil and its four transformation products (fipronil amide, fipronil sulfide, fipronil sulfone and desulfinyl fipronil), fipronil chloramine and fipronil sulfone chloramine were detected for the first time in municipal wastewater. Moreover, the cumulative concentrations of six transformation products were 0.236 ng/L and 3.44 ng/L in wastewater influents and effluents, and accounted for one-third (in influents) to half (in effluents) of fiproles. Of those transformation products, two chlorinated byproducts (fipronil chloramine and fipronil sulfone chloramine) were major transformation products in both municipal wastewater influents and effluents. Notably, the log Kow and bioconcentration factor (evaluated by EPI Suite software) of fipronil chloramine (log Kow = 6.64, and BCF = 11,200 L/kg wet-wt) and fipronil sulfone chloramine (log Kow = 4.42, and BCF = 382.9 L/kg wet-wt) were greater than that of their parent compound. Considering the persistence, bioaccumulation potential and toxicity, the high detection rates of fipronil chloramine and fipronil sulfone chloramine in urban aquatic systems need to be specifically considered in future ecological risk assessments.

Precipitation and discharge changes drive increases in Escherichia coli concentrations in an urban stream

Determining the driving factors of E. coli dynamics and predicting future E. coli changes in urban aquatic systems are important for regulating water quality. In this study, data from 6985 measurements of E. coli from 1999 to 2019 in an urban waterway Pleasant Run in Indianapolis, Indiana (USA) were statistically analyzed by Mann-Kendall and multiple linear regression to assess the long-term trends in E. coli concentrations and to project E. coli concentrations under future climate change scenarios. E. coli concentrations monotonically increased over the last two decades, with the value increasing from 111 Most Probable Number (MPN)/100 mL in 1999 to 911 MPN/100 mL in 2019. E. coli concentrations have exceeded the Indiana standard of 235 MPN/100 mL since 1998. E. coli showed peak concentration in summer and higher concentration in sites with combined sewer overflows (CSOs) relative to those without. Precipitation had both direct and indirect impacts on E. coli concentrations meditated by stream discharge. Multiple linear regression results showed that annual precipitation and discharge accounted for 60 % of E. coli concentration variability. Based on the observed precipitation-discharge-E. coli concentration relationship, the projected results showed that, in the highest emission representative concentration pathways (RCP) 8.5 climate scenario, E. coli concentrations in the 2020s, 2050s, and 2080s will be 1350 ± 563 MPN/100 mL, 1386 ± 528 MPN/100 mL, and 1443 ± 479 MPN/100 mL, respectively. This study illustrates that climate change can impact E. coli concentrations by altering temperature, precipitation patterns, and stream flow in an urban stream and predicts an undesired future situation under a high CO2 emission scenario.

Fate of antimony contamination generated by road traffic – A focus on Sb geochemistry and speciation in stormwater ponds

Although antimony (Sb) contamination has been documented in urban areas, knowledge gaps remain concerning the contributions of the different sources to the Sb urban biogeochemical cycle, including non-exhaust road traffic emissions, urban materials leaching/erosion and waste incineration. Additionally, details are lacking about Sb chemical forms involved in urban soils, sediments and water bodies. Here, with the aim to document the fate of metallic contaminants emitted through non-exhaust traffic emissions in urban aquatic systems, we studied trace element contamination, with a particular focus on Sb geochemistry, in three highway stormwater pond systems, standing as models of surface environments receiving road-water runoff. In all systems, differentiated on the basis of lead isotopic signatures, Sb shows the higher enrichment factor with respect to the geochemical background, up to 130, compared to other traffic-related inorganic contaminants (Co, Cr, Ni, Cu, Zn, Cd, Pb). Measurements of Sb isotopic composition (δ123Sb) performed on solid samples, including air-exposed dusts and underwater sediments, show an average signature of 0.07 ± 0.05‰ (n = 25, all sites), close to the δ123Sb value measured previously in certified reference material of road dust (BCR 723, δ123Sb = 0.03 ± 0.05‰). Moreover, a fractionation of Sb isotopes is observed between solid and dissolved phases in one sample, which might result from Sb (bio)reduction and/or adsorption processes. SEM-EDXS investigations show the presence of discrete submicrometric particles concentrating Sb in all the systems, interpreted as friction residues of Sb-containing brake pads. Sb solid speciation determined by linear combination fitting of X-Ray Absorption Near Edge Structure (XANES) spectra at the Sb K-edge shows an important spatial variability in the ponds, with Sb chemical forms likely driven by local redox conditions: “dry” samples exposed to air exhibited contributions from Sb(V)–O (52% to 100%) and Sb(III)–O (<10% to 48%) species whereas only underwater samples, representative of suboxic/anoxic conditions, showed an additional contribution from Sb(III)–S (41% to 80%) species. Altogether, these results confirm the traffic emission as a specific source of Sb emission in surface environments. The spatial variations of Sb speciation observed along the road-to-pond continuum likely reflect a high geochemical reactivity, which could have important implications on Sb transfer properties in (sub)surface hydrosystems.

Pyrethroid insecticides in urban catch basins: A potential secondary contamination source for urban aquatic systems

Pesticide contamination is a threat to many aquatic habitats, and runoff from residential homes is a major contributor of these chemicals in urban surface streams and estuaries. Improved understanding of their fate and transport can help identify areas of concern for monitoring and management. In many urban areas, runoff water congregates in numerous underground catch basins before draining into the open environment; however, at present essentially no information is available on pesticide presence in these systems. In this study, we collected water samples from a large number of underground urban catch basins in different regions of California during the active pest management season to determine the occurrence and profile of the widely used pyrethroid insecticides. Detectable levels of pyrethroids were found in 98% of the samples, and the detection frequency of individual pyrethroids ranged from no detection for fenpropathrin to 97% for bifenthrin. In the aqueous phase, total pyrethroid concentrations ranged from 3 to 726 ng/L, with a median value of 32 ng/L. Pyrethroids were found to be enriched on suspended solids, with total concentrations ranging from 42 to 93,600 ng/g and a median value of 2,350 ng/g. In approximately 89% of the samples, whole water concentrations of bifenthrin were predicted to have toxic units >1 for sensitive aquatic invertebrates. The high detection frequency of bifenthrin and overall pyrethroid concentrations, especially for particle-bound residues, suggest that underground urban catch basins constitute an important secondary source for extended and widespread contamination of downstream surface waters by pesticides such as pyrethroids in urban regions.

Photochemical and microbial alteration of chromophoric dissolved organic matter (CDOM) in aquatic ecosystems associated with different sources

城市非点源污染向水生生态系统中输入大量的溶解有机物(DOM)，对生态系统健康产生重要影响. 有色可溶性有机物(CDOM)是广泛分布于自然水体中的一类成分和结构复杂、含有多种高活性化学官能团的大分子聚合物，是DOM的重要组分，对水生生态系统健康、能量流动及生物地球化学循环有重要影响. 光化学反应和微生物代谢过程被认为是控制水体CDOM转化、降解和循环的主要影响因素. 然而，对城市化如何影响CDOM组成以及光化学和微生物如何相互作用影响城市水体CDOM动态的理解是不足的. 因此，为评估光化学过程和微生物代谢对不同城市水体CDOM降解与转化的贡献，解析不同城市水体CDOM光化学/微生物降解作用机理，本研究在英国伯明翰选择3类具有典型DOM来源的水体样本，通过实验室9 d受控培养实验，对比分析光化学以及微生物影响下CDOM来源和组成的变化. 结果表明：(1)城市河流由于接受上游污水排放及较短的水力滞留时间，含有丰富的芳香性碳，其CDOM光化学活性明显高于湖泊，光化学降解率为16.60%;(2)城市湖泊CDOM受人类活动影响，自生源类荧光成分富集，生物活性高，在微生物培养过程中CDOM增加了62.16%，而相较于城市湖泊，非城市湖泊由于接受周围景观土壤输入的大量腐殖质类CDOM，光照对其降解转化作用较为明显; (3)光化学过程促进了陆源CDOM中大分子类腐殖质物质降解成为生物活性高的小分子化合物，刺激微生物代谢生成类蛋白质类有机物; 以类蛋白质组分为主导的CDOM在光照过程中被转化为难降解状态，生物活性降低，CDOM微生物代谢过程被抑制. 研究成果为城市水体不同CDOM来源及活性差异特征研究提供了新的思路，有助于城市河流的可持续开放与管理.;Urban non-point source pollution contributes large amounts of dissolved organic matter (DOM) to aquatic ecosystems and has a significant impact on ecosystem health. Chromophoric dissolved organic matter (CDOM) is a group of macromolecular polymers with complex composition and structure, containing a variety of highly reactive chemical functional groups, which are widely distributed in natural waters. It has an important impact on aquatic ecosystem health, energy flow and biogeochemical cycling. Photochemical reactions and microbial metabolic processes are the main controlling factors on the transformation, degradation and cycling of CDOM in water bodies. However, understanding how urbanization source input impacts CDOM quantity and quality and how photochemical and microbial interact to affect CDOM dynamic are deficient. To assess the contribution of photochemical processes and microbial metabolism to the degradation and transformation of different sources of CDOM in urban waters, and to elucidate the mechanisms of photochemical/microbial degradation of different sources of CDOM in aquatic systems (non-urban lake with humic, mostly terrestrial CDOM; urban lake with autochthonous biological production CDOM; urban river with mixed humic and protein-like CDOM), this study compares and analyses the changes in the sources and composition of CDOM under the influence of photochemistry and microorganisms in a controlled 9-day laboratory incubation experiment in three water bodies with typical urban characteristics, selected in Birmingham, UK. Changes in CDOM concentration, optical properties and chlorophyll concentration were measured at the initial and end of incubations. The results show that: (1) due to the acceptance of upstream sewage discharge and shorter hydraulic retention times, the CDOM of urban rivers is dominated by aromatic substances, with the highest photochemical degradation rate of 16.60%; (2) the CDOM of urban lakes, which is affected by human activities, is dominated by autochthonous substances, and could be increased by 62.16% via microbial metabolism, while compared to urban lakes, non-urban lakes have a more pronounced effect of light on their degradation and transformation due to receiving a large input of humus-like CDOM from the surrounding landscape soils; (3) the photochemical process could degrade terrestrial humic-like substances into small molecular compounds with high biological activity, which could stimulate microbial metabolism to produce protein-like CDOM, however, photochemical degradation could inhibit microbial metabolism by transform the autochthonous protein-like CDOM into a refractory state. The study provides a novel perspective for the differences in the sources and activities of CDOM in different urban aquatic systems and the changes in CDOM characteristics during photochemical and microbial processes.

Are fluorometric, taxonomic, and functional indicators of phytoplankton community structure linked to environmental typology of urban ponds and lakes?

ABSTRACTPhytoplankton bioindicators were used to assess environmental conditions in urban aquatic systems in a large Canadian city. Sampling was conducted during summers 2010 and 2011 in 20 urban waterbodies on the Island of Montreal (Quebec, Canada). We evaluated 4 indicators: (1) fluorometric estimates of the chlorophyll concentration of the total phytoplankton and of 4 spectral groups, (2) species richness, and (3) biovolumes of taxonomic and (4) functional groups of the microphytoplankton. We assessed how these indicators changed among types of urban waterbodies and determined the limnological features and/or management practices driving their spatial variation. Principal component analysis captured 48% of total environmental heterogeneity, and K-means clustering analyses defined 5 relevant types of waterbodies. Overall, 96 microphytoplankton species (γ diversity) were recorded, and species richness (α diversity) per waterbody varied from 1 to 27. Chlorophyll concentration of the total phytoplankton and the green algae spectral group, as well as the total biovolume of microphytoplankton, dinophytes, and of 2 functional groups (large flagellates, large colonies of green algae, and cyanobacteria) differed among waterbody types. Phytoplankton indicators based on in situ fluorometry and microphytoplankton biovolume of functional and taxonomic groups were fairly coherent and showed potential for monitoring. Implications of our findings are discussed in light of guiding future management practices to sustain biodiversity, ecological integrity, and water quality of urban waterbodies.

Emission and fate modelling framework for engineered nanoparticles in urban aquatic systems at high spatial and temporal resolution

The combination of emission and fate modelling improves the exposure assessment of engineered nanoparticles in complex urban systems.

Variation in nitrate isotopic signatures in sewage for source apportionment with urbanization: a case study in Beijing, China

Nitrate (NO3-) pollution is a severe problem in urban aquatic systems especially within megacity undergoing rapid urbanization, and mostly, sewage is supposed as the prevailing NO3- source. A dual isotope approach (δ 15N-NO3- and δ 18O-NO3-) was applied to explore the variation in NO3- isotopic signatures in sewage processed by wastewater treatment plants (WWTPs) in Beijing from 2014 to 2015. We found that the raw and treated sewage owned the different NO3- isotopic signatures, including δ 15N from 1.1 to 24.7‰ and δ 18O from 1.6 to 22.8‰ in raw sewage, as well as δ 15N from 6.1 to 22.8‰ and δ 18O from 1.6 to 13.2‰ in treated effluents. The WWTP processing would result in the enrichment of NO3- isotopic compositions in discharged effluents with NO3- concentrations increasing. Besides, advanced sewage treatment technology with more pollutant N reduction may raise the heavier NO3- isotopic compositions further. The NO3- isotope value ranges of urban sewage and manure should be separated, and the seasonal and tighter NO3- isotope value ranges are supposed to improve the accuracy of source apportionment. The NO3- isotope value ranges conducted in this study might provide useful information for tracing NO3- sources towards the implementation of efficient water pollution control in Beijing.

Landscape and morphometric controls on water quality in stormwater management ponds

Stormwater management ponds (SWMPs) are used to mitigate the adverse effects of urbanization on water quality, and are increasing in numbers in the urban landscape. Given that these novel urban environments are becoming more ubiquitous and are being used as habitat by myriad flora and fauna, it is important to understand what controls water quality in SWMPs. We sampled 50 SWMPs and associated forebays in Southern Ontario, Canada for water quality to investigate the role of morphometric and landscape characteristics in determining water quality under baseflow conditions. SWMPs were characterized by extremely variable water quality, which was highly degraded compared to natural ponds. We found significant differences in water quality among varying ponds types, including ponds with different forebay designs and those without forebays. Ambient pond water quality was correlated with variables such as watershed imperviousness contributed by roads, sewershed area, and rainfall amount. We found that pond morphometry influenced nutrient concentrations, and that pond length, width, length: width ratio and surface area: perimeter ratio had the highest correlation with water quality. Over 80 % of SWMPs were found to show thermal structure, which often resulted in low dissolved oxygen, particularly at the sediment-water interface. These results will improve understanding of these new urban aquatic systems, including their suitability as habitat, and help managers improve pond nutrient removal efficiency.

Influences of natural and anthropogenic factors on surface and groundwater quality in rural and urban areas

Although water constitutes 71% of the earth's surface, only 0.3% of it is available as fresh water for human use. Moreover, the quality of fresh water in ground and surface systems is of great concern, as potable water needs to have appropriate mineral content. Ground and surface water quality in rural and urban environments is affected by both natural processes and anthropogenic influences. Because of this, water is becoming scarcer as the population increases across the world. Natural processes leading to changes in water quality include weathering of rocks, evapotranspiration, depositions due to wind, leaching from soil, run-off due to hydrological factors, and biological processes in the aquatic environment. These natural processes cause changes in the pH and alkalinity of the water, and also phosphorus loading, increase in fluoride content and high concentrations of sulphates. Anthropogenic factors affecting water quality include impacts due to agriculture, use of fertilizers, manures and pesticides, animal husbandry activities, inefficient irrigation practices, deforestation of woods, aquaculture, pollution due to industrial effluents and domestic sewage, mining, and recreational activities. These anthropogenic influences cause elevated concentrations of heavy metals, mercury, coliforms and nutrient loads. This paper studies the effects of natural processes and human influences in rural and urban aquatic systems. Pollution due to environmental parameters such as heavy metal pollution, heavy metals and bacterial and pathogenic contamination of both urban and rural areas is discussed in detail.

ECOLOGICAL RISK ASSESSMENT OF A TROPICAL LAKE SYSTEM

Risk analysis of urban aquatic systems due to heavy metals turns significant due to their peculiar properties viz. persistence, non-degradability, toxicity, and accumulation. Akkulam Veli (AV), an urban tropical lake in south India is subjected to various environmental stresses due to multiple waste discharge, sand mining, developmental activities, tourism related activities etc. Hence, a comprehensive approach is adopted for risk assessment using modified degree of contamination factor, toxicity units based on numerical sediment quality guidelines (SQGs), and potentialecological risk indices. The study revealed the presence of toxic metals such as Cr,Cd, Pb and As and the lake is rated under ‘low ecological risk’ category.

ECOLOGICAL RISK ASSESSMENT OF A TROPICAL LAKE SYSTEM

Risk analysis of urban aquatic systems due to heavy metals turns significant due to their peculiar properties viz. persistence, non-degradability, toxicity, and accumulation. Akkulam Veli (AV), an urban tropical lake in south India is subjected to various environmental stresses due to multiple waste discharge, sand mining, developmental activities, tourism related activities etc. Hence, a comprehensive approach is adopted for risk assessment using modified degree of contamination factor, toxicity units based on numerical sediment quality guidelines (SQGs), and potentialecological risk indices. The study revealed the presence of toxic metals such as Cr,Cd, Pb and As and the lake is rated under ‘low ecological risk’ category.

Charging for stormwater in South Africa

The social, economic and environmental impacts of poor water quality on South Africa’s urban aquatic systems are increasingly being highlighted by the media. Improving the water quality in these systems will require catchment-wide strategies, including the monitoring and management of point and non-point source pollution collected in stormwater. Significant costs may be incurred; however, international experience suggests that these are outweighed by the benefits. Municipalities across South Africa charge their citizens for potable water and sewerage. Stormwater management, however, is generally funded through municipal rates. Competition with other pressing needs frequently results in the stormwater departments being significantly under-funded – at times only receiving a tenth of what is required for water quantity management. Internationally, an increasing number of cities have introduced a direct charge for stormwater management in order to secure the funding required to manage stormwater and its associated water pollution, and to serve as a disincentive to polluting practices on the part of landowners. In order to ensure adequate funding for stormwater management in South Africa, municipalities need to consider charging for stormwater management either based on an Equivalent Residential Unit (ERU) or Residential Equivalent Factor (REF), combined with an appropriate discount scheme for on-site stormwater management. Preliminary indicative rates have been calculated for municipalities across South Africa using the Damage Avoidance Cost (DAC) approach. The results indicate that the amount that municipalities could and should charge varies widely, from ZAR30 (2010) to ZAR110 (2010) per residential unit per month, depending on climatic zone and level of treatment. Keywords: stormwater management, damage avoidance cost, stormwater utilities

Diversity of Mercury Resistant Escherichia coli Strains Isolated from Aquatic Systems in Rio de Janeiro, Brazil

Escherichia coli may harbor genetic mercury resistance markers which makes this bacterial species a promising alternative for bioremediation processes. The objective of this study was to investigate phenotypic and genetic characteristics related to diversity and mercury resistance among 178 Escherichia coli strains isolated from residential, industrial, agricultural, and hospital wastewaters and recreational waters at Rio de Janeiro city. Genetic and conventional methods were carried out in order to determine mercury resistance. Random amplification of polymorphic DNA (RAPD-PCR) and denaturing gradient gel electrophoresis (DGGE) were used to investigate genetic variability. RAPD data revealed a high degree of polymorphism among E. coli mercury resistant strains and showed reproducibility and good discriminative results. DGGE typing detected diversity within the merA gene fragment. Our findings represent an improvement in epidemiological studies of HgR E. coli and support the evidence of nonclonal nature of mercury resistant E. coli strains circulating in rural and urban aquatic systems in Rio de Janeiro city.

Pb-binding to various dissolved organic matter in urban aquatic systems: Key role of the most hydrophilic fraction

Dissolved organic matter (DOM) from the treated effluent of a wastewater treatment plant and from the river Seine under high human pressure has been separated into three fractions: hydrophobic (containing humic and fulvic substances), transphilic and hydrophilic using a two column array of XAD-8 and XAD-4 resins. The acid base properties and the binding characteristics with respect to Pb ions (using the new electroanalytical technique AGNES, Absence of Gradients and Nernstian Equilibrium Stripping) have been studied and fitted to NICA (Non-Ideal Competitive Isotherm). We evaluated the binding potential of each DOM fraction in order to better predict the speciation of Pb and, later, its bioavailability in the river. The total binding capacity of the different fractions to Pb, as well as the total titratable charge, reaches its maximum value at the most hydrophilic fraction from the treated effluent. Specific properties of the distribution of the complexing sites within each DOM fraction have been exposed by plotting the conditional affinity spectrum (CAS). The addition of these distributions, weighted according to the respective abundance of each organic fraction, allows for a full description of the Pb binding properties of the whole DOM of a sampling site. Despite its weak aromaticity, the hydrophilic fraction from the wastewater treatment plant effluent exhibits a high lead binding affinity, so that at typical environmental pH and free Pb levels (0.1 μg L −1), Pb is mainly bound to the most hydrophilic fraction of the treated effluent (49% of bound Pb at pH 7). This feature may greatly enhance the transport of Pb and highlights that Pb speciation should also consider other fractions apart from humic and/or fulvic acids when studying surface waters under high human pressure.

Let's Not Forget the Biodiversity of the Cities

ABSTRACTCities contain over half of the world's population and are the source of many anthropogenic effects on the world's biota. Close examination of San Juan, Puerto Rico, a tropical city, reveals a significant green infrastructure. The city contains natural and human‐constructed forests, urban aquatic systems with native and introduced species, and a thriving and diverse biota adapted to urban conditions. It behooves tropical ecologists to pay attention to the biodiversity of urban environments to learn lessons about ecological persistence and adaptation to novel anthropogenic environments.

Characterisation of dissolved organic matter in Parisian urban aquatic systems: predominance of hydrophilic and proteinaceous structures

Understanding the nature of organic matter is a necessary first step in assessing contaminant bioavailability and allowing water supply managers to optimise the treatment train in the aim of providing safe and inexpensive drinking water. This study provides further insight into the composition, structure and functional groups of dissolved organic matter (DOM) (both hydrophobic and hydrophilic) from urban aquatic systems by means of various analytical techniques (DAX-8/XAD-4 fractionation, elemental analysis, UV and FTIR spectroscopies, 13C and 15N isotopic analysis, size exclusion chromatography and Pyrolysis-GC-MS). The analytical range chosen for this study constitutes a powerful tool in the characterisation of DOM in urban water. The inclusion of information from one technique to the next might not only serve as a support to each one, but also as a complement. The DOM fraction from treated effluent and, more generally, DOM from urban water (i.e. receiving treated effluent) display a strong hydrophilic characteristic [i.e. low humic substance (HS) content, low SUVA], along with a high distribution in molecular weights observed by SEC and low average molecular weight. Due to the origin of this DOM, proteinaceous structures constitute the main compounds, as observed by FTIR and Py-GC-MS. Such characteristics (i.e. heterogeneity, low average molecular weight and diverse functional groups, which make up a total of N) could explain that DOM from treated effluent displayed a strong reactive potential metals pollutants as previously demonstrated.

Environmental science and research in China: A snapshot of the current state

Environmental science and research in China: A snapshot of the current state