Environmental concerns have increased the interest in winery wastewater remediation and reuse. These practices require more detailed understanding of wastewater composition to ensure optimum usage, and to minimize the risk of long term soil degradation and grape contamination. Particulate organic matter is an important contributor to the carbon burden in winery wastewaters. This article investigates the molecular structure of particulates from the most common winery wastewater treatment processes via infrared spectroscopic and thermochemolysis-gas chromatography/mass spectrometry techniques. Study of the organic composition of both influent and effluent particles enabled further insight into which compounds could prove problematic during treatment and on discharge. The yield and molecular structure of desorbed or “guest” compounds were found to strongly correlate with those produced during pyrolytic cracking. These “guest” compounds and macromolecular fragments form a continuum whose separation is based on molecular size. Polyphenolic and lignin derived compounds tended to survive the water treatment processes within assemblages of microbial detritus. No evidence was found for particles adsorbing and concentrating other unrelated organics such as anthropogenic chemicals from winery wastewaters. Any release of particulates will require careful management to prevent localized accumulation of recalcitrant compounds to toxic levels.
A method is described for rapid and reliable determination of ultra-trace concentrations of mercury in plant and soil samples by cold vapour inductively coupled plasma-optical emission spectrometry (CV-ICP-OES). Under the established optimum conditions, a detection limit of 3 ng g− 1 was achieved. Rapid decomposition of soil and plant samples were achieved with microwave digestion with a 3:1 HNO3:HCl mixture for only 10 min, enabling close to 100% recovery of mercury. Choice of sample storage condition and nature of sample (dried, wet or frozen) had significant influence on mercury concentrations found in plant and soil samples. Storage of samples as frozen, followed by digestion without drying or on as received basis gave optimum recovery of mercury in the samples. Verification of the effectiveness of the CV-ICP-OES method for reliable mercury determination in plants and soil with microwave digested certified soil and spiked plant samples gave close to 100% and 95–103% recoveries, respectively. The CV-ICP-OES method was successfully applied to the determination of mercury in plant and soil samples from a local Australian forest. The mercury concentrations found in plants range from 23.5 to 78.5 ng g− 1, while those found in soils range from 30.1 to 61.7 ng g− 1.