The biological impacts of urban runoff waters

INTRODUCTION. My work with the Middlesex University Urban Pollution Research Centre has been conducted in the following areas: 1 Biological Monitoring of Urban Waters (Publications 1, 3, 5, 6, 25) Conventional biological methods and hydrobiological indices used for assessing water quality have been tested in urban streams and rivers and their limitations exposed. The impact of river engineering and physical disturbance on the substrate during storm events has been shown to influence significantly the index scores in addition to pollution impacts. The recommendation to compare biological with physico-chemical assessment of water quality has also been adopted by the National Rivers Authority. A model to predict the community diversity index score for urban stream macro invertebrate biota from recorded physico-chemical parameters was satisfactory for fairly clean waters and for moderate levels of pollution but not for serious levels of pollution (1). Reference streams and ponds in Trent Country Park on the fringe of North London were used for comparison with studies of the biota of urban waters (3,5). A system of river classification using a hydrobiological score system was proposed to complement the existing National Water Council system which was essentially based on chemical criteria (6). A study of the use of indicator organisms to monitor the impact of localised discharges of urban surface runoff and storm sewer overflows was commissioned by the Water Research Centre, the results of which are reported in paper no. 14. A review of the use of macroinvertebrates and plants as bioindicators in urban aquatic systems is included in publication 25. 2 Aquatic Ecotoxicology (Publications 3, 4, 5, 6, 7, 9, 11, 12, 14, 21, 24, 26, 28, 32, 34) 2.1 Heavy Metals Innovative methods have been developed for assessing heavy metal bioaccumulation in selected macro invertebrate species in urban waters. Traditionally, toxicity tests have been conducted in controlled laboratory conditions which do not simulate the natural environment. The use of caged macro invertebrates secured to the substrate in rivers, enables a more realistic determination of bioaccumulation and mortality rates to be made. The impact of storm events and chronic exposure to contaminated water and sediment has been investigated. At a time when new ecotoxicological tests are being introduced to the UK and the EC, the research has considerable potential application as a test for heavy metal impacts and the determination of environmental standards in freshwater. (The research has been sponsored by the Water Research Centre). VI Tissue concentrations of lead, cadmium, copper and zinc in selected macroinvertebrates collected from semi-rural and urban streams and ponds are reported in papers 3, 4 and 5. The relationship between urbanisation and macro invertebrate tissue, sediment and water metal concentrations and their spatial trends along the Salmon's Brook in North London is discussed in publication 6 and compared with the results from the A veiro Lagoon and its feeding rivers in North Portugal in paper 7. Tissue metal bioaccumulation in popUlations of caged Gammarus pUlex, Asellus aquaticus and Lymnea peregra in relation to ambient sediment and water metal concentrations, metal species bioavailability and organism feeding behaviour are discussed in publication 9. A comparison of mortality and metal uptake in aquatic macroinvertebrate species in field studies and laboratory experiments and a recommendation to reduce the length and lethal limit of the traditional 96 hour LC50 test is made in papers 11, 21, 24 and 32. The impact of storm sewer overflows from a sewage treatment works on caged macro invertebrates exposed to the discharges and to the receiving waters immediately downstream is reported in publications 12, 14 and 24. Principal component analysis was used to determine combinations of caged Aselius aquaticus tissue, sediment and water metal concentrations, precipitation volumes and antecedent dry periods which explained much of the variation in organism mortality and weight (28, 34). 2.2 Hydrocarbons (Publications 15 - 20, 29) Caged macro invertebrate species have also been used to determine hydrocarbon bioaccumulation in an urban stream and the Welsh Harp reservoir, a site of special scientific interest. Sediment and water hydrocarbon concentrations and macro invertebrate community diversity have been monitored along the stream and in the reservoir to investigate the impact of an oil boom. The development of biological and chemical techniques in this unique study of an urban freshwater wetland has led to considerable interest and further publications are planned. (The research has been sponsored by English Nature, formerly the Nature Conservancy Council). Publications 15 and 16 describe a baseline study of the ecotoxicological impacts resulting from oil pollution on the Welsh Harp and one of its receiving streams. Sediment and water concentrations of alkanes and P AHs and the tissue concentrations and temporal and spatial trends in selected caged macro invertebrates and fish are reported in publications 17, 18 and 19. The bioaccumulation of hydrocarbons by macro invertebrate species in laboratory tests and the corresponding mortality rates and their comparison with the results of field studies and controlling factors are discussed in publication 20. The results of the study are summarised in paper 29. vii 3 Aquatic Macrophyte Pollution Control (Publications 10, 13, 22, 23, 27, 31, 33, 35) Heavy metal uptake by the reedmace Typha latifolia, an aquatic plant species, has been investigated in urban wetlands and in greenhouse based studies. The research has shown a high level of tolerance by Typha to heavy metals and its biofiltration ability and creation of a sediment metal sink. It has led to the introduction of Typha in pioneering designs of constructed wetlands for highway runoff treatment in the UK. (The research is ongoing and is receiving sponsorship from industry and PCFC). A comparison of the water pollution control performance of Typha latifolia in the UK and Eicchomia crassipes in China is discussed in publication 10. Further details of the study of metal uptake in Typha latifolia and its associated sediment in the Welsh Harp and two ornamental ponds and a comparison with the results of a greenhouse based metal dosing experiment are given in papers 13 and 27 and summarised in 23 and 31. An analysis of the metal and hydrocarbon uptake and biofiltration ability of different species of aquatic macrophyte in an experimental pond receiving runoff from a car park in Washington State, USA is described in report 33

Guidance manual for constructed wetlands.

This Guidance Manual was produced to provide up to date information on the design, costs, construction, operation and maintenance of constructed wetlands used for the treatment of highway runoff. Information is provided on the different types of wetlands and their mode of operation, the design and planting of a wetland system and the retrofitting of treatment structures, the performance and costs of wetlands and their operation and maintenance requirements. The benefits of wetlands in encouraging wildlife and improving the landscape are discussed. The implementation of Sustainable Drainage systems (SuDS) and the use of decision support approaches for selecting SuDS systems are considered. Recommendations are made for future research

Constructed wetlands and links with sustainable drainage systems.

The potential of constructed wetlands with sustainable drainage systems in urban catchments is reviewed. Data from wetland systems used to treat domestic wastewaters were not directly applicable to stormwater treatment due to the differences in inflow regimes and pollutant loading. Urban wetland performance, costs, design, retrofitting, operation and maintenance are considered. The role of urban wetlands in wildlife and landscape enhancement and the benefits to the community are discussed. The implementation of sustainable drainage systems and catchment planning along with decision support systems are reviewed. Constructed wetlands offered considerable potential for the control and treatment of urban stormwater runoff. Recommendations are made for future work

Saline and Alkaline tolerance of wetland plants — what are the most representative evaluation indicators?

The increasing discharge of wastewater containing inorganic salts, sometimes accompanied by high pH, has been a worldwide environmental problem. Constructed wetlands (CWs) are considered a viable technology for treating saline and/or alkaline wastewater provided that saline-alkaline tolerant plant species are selected and applied. The influence of both saline and alkaline stress on four wetland plant species during their seed germination, early growth, vegetative propagation and continued growth stages was evaluated by three experiments. Principal component analysis (PCA) was conducted for selecting representative indicators for evaluating the saline and alkaline tolerance of plants during vegetative propagation and plant growth stages. The saline and alkaline stress inhibited the vegetative propagation and plant growth of all tested plant species to varying degrees, therein the influences of saline-alkaline stress on plants were more marked than saline stress. The length of new roots, Na+ accumulation in plant tissue, Na+/K+ ratios in aerial tissue and the total dry biomass were selected as most representative indicators for evaluating the saline and alkaline tolerance of plants. Iris sibirica and Lythrum salicaria showed better saline and alkaline tolerance ability among tested species and could be grown in CWs for treating saline and/or alkaline wastewater

Twitter and the US stock market: the influence of micro‑bloggers on share prices

With the increased interest in social media over recent years, the role of information disseminated through avenues such as Twitter has become more widely perceived. This paper examines the mention of stocks on the US markets (NYSE and NASDAQ) by a number of financial micro-bloggers to establish whether their posts are reflected in price movements. The Twitter feeds are selected from syndicated and nonsyndicated authors. A substantial number of tweets were linked to the price movements of the mentioned assets and an event study methodology was used to ascertain whether these mentions carry any significant information or whether they are merely noise

Bioaugmented constructed wetlands for denitrification of saline wastewater: a boost for both microorganisms and plants

The inhibition of salt stress on plant and microbial functions has led to the reduction of nitrogen removal capacity of constructed wetlands (CWs) under saline conditions. The mechanisms and effectiveness of bioaugmented CW (Bio-CW) microcosms with a salt-tolerant microbial inoculum were evaluated for nitrogen removal at different salinity levels. The results showed that the denitrification capacity of CWs was improved under saline conditions by adding the salt-tolerant microbial inoculum. At an EC of 15 mS/cm, the removal percentages of ammonia nitrogen (NH -N) and total nitrogen (TN) in Bio-CW microcosms (95.7% and 99.4%) on Day 5 were significantly (p < 0.05) higher than that in unbioaugmented CW (un-Bio-CW) microcosms (68.5% and 76.4%), respectively. The high throughput sequencing data of substrate samples indicated that the microbial community in the CWs was changed by the addition of the salt-tolerant microbial inoculum and the frequency of bacteria with nitrogen removal function was increased in the CWs. Furthermore, both growth and the TN accumulation capacity of plants in Bio-CW microcosms were promoted compared with the un-Bio-CW microcosms. In conclusion, the addition of the salt-tolerant microbial inoculum can enhance the nitrogen removal efficiency of CWs under saline condition via boosting the function of both microorganisms and plants. [Abstract copyright: Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.

Isolation and characterization of a salt-tolerant denitrifying bacterium Alishewanella sp. F2 from seawall muddy water

A salt-tolerant denitrifying bacterium strain F2 was isolated from seawall muddy water in Dalian City, Liaoning Province, China. Strain F2 was identified by morphological observations, physiological and biochemical characteristics and 16 S rDNA identification. The salt tolerance of strain F2 was verified and the factors affecting the removal ability of strain F2 to nitrous nitrogen (NO2–N) and nitrate nitrogen (NO3–N) in saline conditions were investigated. Strain F2 was identified as Alishewanella sp., named Alishewanella sp. F2. Strain F2 can tolerate NaCl concentrations up to 70 g/L, and its most efficient denitrification capacity was observed at NaCl concentrations of 0−30 g/L. In the medium with NaCl concentrations of 0−30 g/L, strain F2 exhibited high removal efficiencies of NO2–N and NO3–N, with the removal percentages for both NO2–N and NO3–N of approximately 99%. In saline conditions with 30 g/L NaCl, the optimum culture pH, NaNO2 initial concentrations and inoculation sizes of strain F2 were 8−10, 0.4−0.8 g/L and 5−7%, respectively. Strain F2 was highly effective in removing NO2–N and NO3–N in saline conditions, and it has a good application potential in saline wastewater treatment

Saline and Alkaline tolerance of wetland plants — what are the most representative evaluation indicators?

The increasing discharge of wastewater containing inorganic salts, sometimes accompanied by high pH, has been a worldwide environmental problem. Constructed wetlands (CWs) are considered a viable technology for treating saline and/or alkaline wastewater provided that saline-alkaline tolerant plant species are selected and applied. The influence of both saline and alkaline stress on four wetland plant species during their seed germination, early growth, vegetative propagation and continued growth stages was evaluated by three experiments. Principal component analysis (PCA) was conducted for selecting representative indicators for evaluating the saline and alkaline tolerance of plants during vegetative propagation and plant growth stages. The saline and alkaline stress inhibited the vegetative propagation and plant growth of all tested plant species to varying degrees, therein the influences of saline-alkaline stress on plants were more marked than saline stress. The length of new roots, Na+ accumulation in plant tissue, Na+/K+ ratios in aerial tissue and the total dry biomass were selected as most representative indicators for evaluating the saline and alkaline tolerance of plants. Iris sibirica and Lythrum salicaria showed better saline and alkaline tolerance ability among tested species and could be grown in CWs for treating saline and/or alkaline wastewater

Identification and denitrification characteristics of a salt-tolerant denitrifying bacterium Pannonibacter phragmitetus F1

A salt-tolerant denitrifying bacterium F1 was isolated in this study, which has high nitrite (NO -N) and nitrate (NO -N) removal abilities. The salt tolerance capacity of strain F1 was further verified and the effects of initial pH, initial NaNO concentration and inoculation size on the denitrification capacity of strain F1 under saline conditions were evaluated. Strain F1 was identified as Pannonibacter phragmitetus and named Pannonibacter phragmitetus F1. This strain can tolerate NaCl concentrations up to 70 g/L, and its most efficient denitrification capacity was observed at NaCl concentrations of 0-10 g/L. Under non-saline condition, the removal percentages of NO -N and NO -N by strain Pannonibacter phragmitetus F1 at pH of 10 and inoculation size of 5% were 100% and 83%, respectively, after cultivation for 5 days. Gas generation was observed during the cultivation, indicating that an efficient denitrification performance was achieved. When pH was 10 and the inoculation size was 5%, both the highest removal percentages of NO -N (99%) and NO -N (95%) by strain Pannonibacter phragmitetus F1 were observed at NaCl concentration of 10 g/L. When the NaCl concentration was 10 g/L, strain Pannonibacter phragmitetus F1 can adapt to a wide range of neutral and alkaline environments (pH of 7-10) and is highly tolerant of NaNO concentration (0.4-1.6 g/L). In conclusion, strain Pannonibacter phragmitetus F1 has a great potential to be applied in the treatment of saline wastewater containing high nitrogen concentrations, e.g. coastal aquaculture wastewater