![]() Published work demonstrates that there are variations over time even in the monitoring results for single road. ![]() glyphosate) and de-icing salts (chloride).Īnnual average daily traffic (AADT) (no. Other less frequently measured water quality parameters are: faecal indicator bacteria (FIB), toxicity, polycyclic aromatic hydrocarbons (PAHs), herbicides (e.g. It is acknowledged that the contribution of N and P from traffic-related sources in runoff is less significant than that from surrounding land uses, such as agriculture and farming (e.g. Nutrient constituents: nitrates ( ), nitrites ( ), ammonium ( ), total Kjeldahl nitrogen (TKN), total nitrogen (TN), phosphate ( ) and total phosphorus (TP). Metal constituents: most frequently cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn) and, less frequently, aluminium (Al), the metalloid arsenic (As) and iron (Fe) (e.g.: Du et al. ![]() The following constituents may be found in road runoff:Ĭonventional water quality parameter: such as total suspended solids (TSS), total dissolved solids (TDS), dissolved organic carbon (DOC), total organic carbon (TOC), chemical oxygen demand (COD), biochemical oxygen demand (BOD), oil and grease (O&G), hardness as CaCO 3, temperature and pH. The composition and the concentration of pollutants in road runoff are affected by several factors such as the rainfall pattern, road material and construction, vehicles characteristics, ambient conditions and environmental aspects (e.g. It is generally accepted that at least 10 stormwater events from independent rainfall/runoff events, expressing seasonal variability, must be monitored to calculate a robust SMC for a given site/location ( Hvitved-Jacobsen et al. The laboratory analysis of the samples provides the concentrations for the selected parameters that are used to calculate the EMCs and SMCs, as well as the pollutants loads. ![]() For a given site, the most precise method to characterise road runoff pollutant is to carry out road runoff monitoring studies, including automatic rainfall and flow measurements, and sequential runoff sampling. Parameters such as the event mean concentration (EMC), defined as the concentration of one rainfall and runoff event in mass per volume, site median concentration (SMC), defined as the average concentration of several events for the same site and pollutant load are used to describe road runoff quality (e.g. The knowledge of the characteristics of road runoff pollution together with the evaluation of the vulnerability of the water bodies support the decision to implement mitigation measures such as the construction of treatment systems that are used widely (e.g. The findings support practitioners and researchers all over the world, pointing out directions, and gaps to be filled, regarding the management of road runoff discharges and use of prediction tools. It was concluded that none of the tools could predict the road runoff pollutant concentrations, except for the country where it had been calibrated. The results for the site median concentration (SMC) of total suspended solids (TSS), Zn, Cu, Pb and Cd showed coefficients of determination (R 2) from 0.0004 to 0.2890 for the different pollutants and tools. Four tools from the USA and Europe were selected and tested at 22 road sites located in regions with annual precipitation values ranging from 500 to 1,000 mm, from seven European countries. The present work reviewed and evaluated international tools for road runoff quality prediction, in order to assess if an existing tool could be suitable for wide usage by stakeholders in Europe. Therefore, prediction tools can be a valuable method to manage road runoff discharges and protect the environment. The best method to characterise road runoff is by monitoring, which is not always possible due to human or material constraints. Pollutants discharged by roads may impact water bodies and soils.
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