Determination of naproxen, ibuprofen and triclosan in wastewater using the polar organic chemical integrative sampler (POCIS): A laboratory calibration and field application

In this study, the occurrence in wastewater of two non-steroidal  anti-inflammatory drugs (NSAIDs), naproxen and ibuprofen, and one  personal care product, triclosan, was assessed using the polar organic  chemical integrative sampler (POCIS). The samplers were initially  calibrated in the laboratory to obtain sampling rates (Rs) for each target compound followed by deployment in the influent and effluent of  Goudkoppies and Northern Wastewater Treatment Plants (WWTPs), South Africa. Exposure was done for 14 days in 2012. High performance liquid chromatography (HPLC) system with ultraviolet (UV) and fluorescence (FLD) detectors was used to analyse POCIS extracts. Laboratory calibration of POCIS yielded Rs values for the three compounds that were between 0.087 and 0.383l.d-1 in quiescent conditions, and 0.125 and 0.936 l.d-1 in  stirred conditions. From the accumulated amounts in field-deployed  samplers, estimated freely dissolved concentrations of the studied compounds in wastewater influent ranged from 55.0 to 78.4 µg.l-1 and 52.3 to 127.7 µgl.-1 in Goudkoppies and Northern WWTPs, respectively. Average concentrations of these compounds in the treated effluent ranged from 10.7 to 13.5 µgl.-1 in Goudkoppies WWTP, and 20.4 to 24.6 µgl.-1 in Northern WWTP. Analyte removal efficiencies varied between 68 and 86% in Goudkoppies WWTP and 61 and 82% in Northern WWTP. Grab samples processed by SPE method yielded higher analyte concentrations (up to three-fold) as compared to POCIS-derived estimates. This  discrepancy was attributed to SPE's ability to extract both the free  dissolved, and particle sorbed fractions of the contaminants.Keywords: Polar organic chemical integrative sampler, pharmaceuticals and personal care products, wastewater, wastewater treatment plant

Investigating the temporal trends in PAH, PCB and OCP concentrations in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)

The seasonal variability of persistent organic pollutants in Hartbeespoort Dam, South Africa, was investigated using semipermeable membrane devices (SPMDs) as passive samplers. Freely dissolved waterborne  polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were sampled to investigate  seasonal changes in their concentrations. Exposure of the passive  samplers was done for 14 days at the same sampling site in each of the four seasons of the year, in 2011. The SPMD-derived analyte amounts  enabled the calculation of time-weighted averages of free dissolved  waterborne levels of the contaminants. Concentrations ranged from 30.0 ng·l-1 to 51.5 ng·l-1 for PAHs, 38 pg l-1 to 150 pg·l-1 for PCBs, 9.2 to 10.4 ng·l-1 for HCHs and 0.3 to 0.8 ng·l-1 for DDTs, respectively. It was also  noted that the winter season generally exhibited higher contaminant  concentrations for most compounds studied, which likely reflects the  seasonality of their atmospheric deposition. An attempt was also made to identify possible sources of PAH contaminants in the dam by examining PAH ratios. These diagnostic ratios were inclined towards pyrogenic sources of pollution, except for the winter season where both pyrogenic and  petrogenic sources likely contribute to the contamination pattern.Keywords: Hartbeespoort dam, persistent organic pollutants,  semipermeable membrane devices, water-dissolved concentrations, temporal trends

Irrigation water quality and the threat it poses to crop production: evaluating the status of the Crocodile (West) and Marico catchments, South Africa

Ensuring food security is becoming increasingly difficult due to limited freshwater resources. Low-quality irrigation water also poses a severe threat to crop yield and quality. The aim of this study was to evaluate the water quality associated with the Crocodile (West) and Marico catchments, which represent one of South Africa’s most developed regions. Sources of irrigation water include the hypertrophic Hartbeespoort Dam, as well as the heavily impacted Crocodile (West) River. Analysis of historical irrigation water quality data (from January 2005 to December 2015) revealed that the Hartbeespoort and Crocodile (West) irrigation schemes were exposed to calcium sulfate enrichment, likely as a result of extensive mining activities in the Bushveld Igneous Complex. Also, significant differences in water quality parameters occurred between these irrigation schemes and the reference system (Marico-Bosveld Irrigation Scheme), while important salt (chloride and sodium) and nutrient (inorganic nitrogen and orthophosphate (as phosphorus)) concentrations exceeded threshold values provided by irrigation water quality guidelines. The Hartbeespoort and Crocodile (West) irrigation schemes also presented distinctive temporal (long-term and seasonal) patterns in water quality. Seasonal variation in pH levels at the Hartbeespoort Irrigation Scheme is likely caused by excessive algae growth and cyanobacteria blooms (Mycrocystis sp.), which also pose an important threat to human and animal health. Despite mitigation efforts by government and other stakeholders, some of South Africa’s major irrigation schemes remain highly impacted as a result of water quality deterioratio