Using high-frequency phosphorus monitoring for water quality management: a case study of the upper River Itchen, UK

Citizen scientists filling knowledge gaps of phosphate pollution dynamics in rural areas

In situ monitoring is fundamental to manage eutrophication in rivers and streams. However, in recent decades, the frequency and spatial coverage of regulatory monitoring have often been reduced due to funding and infrastructure limitations. This reduction has made it impossible to provide adequate coverage for most water bodies. In this study, trained citizen scientists filled spatial and temporal gaps in agency monitoring across a major catchment in rural England. By integrating data from citizen scientists, regulatory agencies, and the local water company, it was possible to demonstrate the opportunities for hypothesis-based citizen scientist monitoring to identify continuous and event-driven sources of phosphate pollution. Local citizen scientists effectively covered important spatial gaps, investigating river conditions both upstream and downstream of suspected pollution point sources, improving the identification of their temporal dynamics. When combined with long-term monitoring data from regulatory agencies, it became possible to identify areas within the catchment that exhibited increased phosphate concentrations during periods of low river discharge (summer). Inter-annual trends and anomaly detection suggested that continuous pollution sources dominated over event-driven sources in many sub-basins, allowing for the prioritisation of mitigation actions. This study highlights the opportunity for citizen scientists to fill gaps in regulatory monitoring efforts and contribute to the improved management of eutrophication in rural catchments.

Innovative receiving phase for Chemcatcher® passive sampler for phosphorus in the water environment: Calibration of sampling rate by water temperature and pH

Passive sampling is a technique for monitoring orthophosphate (PO4-P) in the water environment. Compared with traditional grab sampling followed by PO4-P quantification, kinetic-type passive samplers such as Chemcatcher® express representative concentrations of PO4-P as time-weighted average concentrations (CTWA). They can also potentially evaluate much lower PO4-P concentrations, but the available receiving phases of Chemcatcher® used for PO4-P were extremely limited. We developed a new receiving phase, the PSfZS sheet, comprising a zirconium sulfate-surfactant micelle mesostructure and polysulfone matrix. We examined its performance in terms of PO4-P sorption characteristics, PO4-P selectivity, and PO4-P sampling rate (Rs). Its capacity was adequate (12.0 μg-P/cm2) and selectivity for PO4-P uptake was good. The Rs for PO4-P increased with increasing water temperature (8.1-29.1 °C) and decreasing pH (4.1-9.7) in a laboratory calibration, and ranged from 5.27 × 10-2 L/d to 1.66 × 10-1 L/d. We placed the samplers in a municipal wastewater treatment plant, a shallow eutrophic lake, and an oligotrophic caldera lake. The Rs in the deployment sites was calibrated by monitored water temperature and pH. The estimated CTWA of PO4-P in the municipal wastewater treatment plant was similar to the averaged concentration of soluble reactive phosphorus determined by multiple grab samplings. In the lake deployments, we found that the new sampler can quantify CTWA values of PO4-P below 10 μg/L, and thus it provides more technical monitoring options and contributes to the conservation and management of the water environment.

Effect of seasonal variation on the occurrences of high-risk pharmaceutical in drain-laden surface water: A risk analysis of Yamuna River

The occurrence of pharmaceutical residues in the aquatic ecosystem is an emerging concern of environmentalists. This study primarily investigated the seasonal variation of high-priority pharmaceutical residues in the Yamuna River, accompanied by 22 drains discharge from different parts of Delhi. Five sampling sites were selected for analyzing high-priority pharmaceuticals along with physico-chemical and biological parameters for 3 season's viz. pre-monsoon (PrM), monsoon (DuM), and post-monsoon (PoM), respectively. The maximum occurrences were detected during the PoM, compared to the PrM and DuM seasons. The maximum concentration of BOD, COD, and Phosphate was detected at the last sampling station (SP-5). Similarly, all targeted pharmaceuticals concentration were maximum at the last sampling point i.e. Okhla barrage (SP-5, max: DIC = 556.1 ng/l, IBU = 223.4 ng/l, CAR = 183.1 ng/l, DIA = 457.8 ng/l, OFL = 1726.5 ng/l, FRU = 312.2 ng/l and SIM = 414.9 ng/l) except at Barapulla downstream (SP-4, max: ERY = 178.1 ng/l). The mean concentrations of Fecal coliform (FC) ranged from 1700 to 6500 CFU/100 ml. The maximum colonies were detected in PrM season (6500 CFU/100 ml) followed by PoM (5800 CFU/100 ml) and least in DuM (1700 CFU/100 ml). Risk quotient (RQ) analysis of high-priority pharmaceuticals indicated high ecotoxicological risks exposure (>1) from DIC, DIA, OFL, and SIM in all seasons at all the sampling sites. However, lower risk was predicted for IBU, CAR, ERY, and FRU, respectively. This risk assessment indicated an aquatic ecosystem potentially exposed to high risks from these pharmaceutical residues. Moreover, seasonal agricultural application, rainfall, and temperature could influence the levels and compositions of pharmaceutical residue in the aquatic ecosystem. Hence, attention is required particularly to this stream since it is only a local lifeline source for urban consumers for domestic water supply and farmers for cultivation.

The fractionation of phosphorus in UK chalk stream surface waters and its relevance to the regulation and management of water quality

The regulatory management of river water quality requires measurements of phosphorus that are operationally viable and meaningful in terms of insight into its effects. This need is a particular concern in globally rare and ecologically sensitive chalk streams. P data pertaining to rivers are commonly limited to soluble reactive P; other fractions of P may be of concern but are not routinely monitored. This study seeks to establish the nature and extent of non-regulated forms of P in UK chalk streams. Whilst soluble reactive P in two southern English chalk streams was found to comprise the majority of reactive P in surface waters in the majority of samples, 15-20% of the total reactive P was within other size fractions greater than 0.22 μm. The contribution of reactive P to the total P was highly variable. We conclude that, with some adjustments, the established method of regulatory monitoring of P in UK rivers is viable and valuable. In cases where the levels of reactive P are not consistent with ecological status and/or expected outcomes of programmes of measures, we recommend that targeted analysis of non-regulated forms of P is undertaken as a means to guide and focus management interventions.

Water quality assessment and pollution source apportionment in a highly regulated river of Northeast China

Dams and sluices break down the river continuum, alter the river hydrological regime, and intercept the migration processes of nutrients and pollutants. The regulation of dams and sluices will have great impacts on water quality characteristics in the river basin. In this study, variable fuzzy pattern recognition model (VFPR), principal component analysis/factor analysis (PCA/FA), and the absolute principal component score-multiple linear regression (APCS-MLR) were used to assess the water quality and identify the potential pollution sources in a highly regulated river of Northeast China. A set of water quality variables at three stations were measured from January 2015 to August 2017. The water quality assessment results showed that there were spatial and temporal variations of water quality and the total nitrogen (TN) and fecal coliforms (F. coli) were the major pollution factors of the study river section. Four pollution sources, including industrial effluent source, domestic sewage source, meteorological factor and atmospheric deposition source, and agricultural non-point source, were identified in dry and wet seasons using the PCA/FA method. The APCS-MLR results showed that the industrial effluent source was the main pollution source in dry seasons and had a decrease in wet seasons. While the mean contribution of the domestic sewage source had an increase in wet seasons, influenced by the sewage overflow and the flushing of pollutants during the extreme precipitation, the construction of dams decreased the flow obviously in wet seasons and increased in dry seasons. The increase in pollutants caused by storm runoff and the reduction of dilution water in the river channel could be the main reason for the water quality degradation in wet seasons.