Our research aim was to apply UV/Vis spectrophotometric techniques for the rapid monitoring of the quality of water sourced from on-farm root vegetable washing processes. To achieve this goal, the quality assessment of the washing water and wastewater at different stages of the technological processes was performed using physicochemical, biological, and UV/Vis absorbance measurements as well as statistical methods, such as principal component analysis (PCA) and partial least squares (PLS) regression. Limit values of UV/Vis absorbance at specific wavelengths were predicted in order to adapt them for routine testing and water quality monitoring at the farm packhouses. Results of the lab analyses showed, that the main problems of the water quality were caused by suspended solids (470–3400 mg L−1), organic substances (BOD5 215–2718 mg L−1; COD 540–3229 mg L−1), nitrogen (3–52 mg L−1), phosphorus (1–6 mg L−1), and pathogenic microorganisms (TVC > 300 cfu mL−1, E. coli 5.5 × 103–1.0 × 104 cfu mL−1, intestinal enterococci 2.8 × 102–1.5 × 104 cfu mL−1, coliform bacteria 1.6 × 103–2.0 × 104 cfu mL−1). Suspended solids exceeded the limit values by 10–50 times, organic matter by 10–25 times, dissolved organic carbon by 3–5 times, nitrogen by 3–7 times, total phosphorus by 3–12 times, and microorganisms by 3–10 times. UV/Vis limit values calculated were as follows: A210 nm—3.997–4.009 cm−1, A 240 nm—5.193–5.235 cm−1, A254 nm—4.042–4.047 cm−1, A320 nm—7.387–7.406 cm−1, and A 660 nm—3.937–3.946 cm−1. UV/Vis measurements at A320 nm are proposed for the routine water quality monitoring.

No abstract

Growing volume of washed vegetables in Europe and Lithuania means that more drinking water is consumed and more wastewater is produced. Farmers, who engage in washing vegetables, face the problems of wastewater treatment, wastewater storage and utilization. Wastewater released to the environment from their farms would meet hygiene and environmental protection criteria. The aim of the study was to assess the contamination of the root vegetable wash water and to evaluate the possiblity of cleaning of wastewater in the land-based treatment system consisting of one constructed wetland and two biological ponds. The contamination of wastewater, produced by washed root vegetables, in Lithuanian farms was measured according to suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen and total phosphorus. Pollution of the wash water and wastewater was evaluated comparing the mean values with legislative limit values and with typical sewage contamination values. In all farms wastewater of initial root vegetables washing was treated in settling basins. Wastewater of one carrots washing farm was treated in the land-based wastewater treatment system consisting of surface flow constructed wetland and two biological ponds. Efficiency of the wastewater treatment in this system was according to suspended solids 90%, BOD7 -97%, CODCr -92%, total nitrogen -98% , total phosphorus -97%. The result shows, that the natural wastewater treatment system is suitable for farms, that wash and produce vegetables, but before releasing wastewater to the environment, it has to be settled.

Forest ecosystems of different tree species participate actively in climatic and biotic processes, such as photosynthesis, plant and soil respiration, therefore knowledge of soil respiration, especially of CO2 emissions to the atmosphere is of great importance. The aim of the study was to determine soil respiration rate of stands of deciduous (Betula pubescens Ehrh., Quercus robur L.) and coniferous (Larix eurolepis Henry, Thuja occidentalis L.) tree species as well as impact of abiotic (soil temperature, humidity, electrical conductivity, pH) and biotic (abundance of undergrowth, shrub, herbs) factors. Measurements of CO2 emissions, temperature, moisture and electrical conductivity were performed in-situ in the stands of different tree species with portable ADC BioScientific LCpro+ system and digital electrochemical device “Wet” (Delta-T). Soil samples were collected for the physicochemical analysis simultaneously. Chemical analysis of soil samples was done at the lab of the Environmental Research of the Aleksandras Stulginskis University by standard methods. Soil respiration was highest in the stand of Thuja occidentalis and lowest in the stand of Betula pubescens. Soil respiration intensity of the tree stands increased as follow: Thuja˂ Quercus˂ Larix˂ Betula. In the coniferous tree stands, the soil respiration was lower on average 27% comparing to deciduous tree stands. Soil respiration rate increased with increase of herbaceous vegetation cover and temperature. Soil respiration rate was mostly influenced by abundance of herbaceous vegetation (r = 0.91) of all biotic factors investigated, while soil temperature (r = 0.75) of abiotic factors. 60 years old stands of different tree species formed specific conditions what influenced different soil respiration rates.