This is because of the differences in the surface area-to-volume ratio; Amount of exposed steel: if steel is exposed (in the case of tyre chips and shreds), there is a likelihood that the leaching of manganese and iron will be faster than that from whole tyres in which the steel is not exposed; Chemical environment: leaching of metals is likely to be more rapid under acidic conditions, while leaching of organic compounds is likely to be more rapid under basic conditions; Permeability of soil: leaching is likely to be faster when soils are permeable; Distance from groundwater table: the greater the vertical distance from the groundwater table, the less likely the contamination of groundwater; Distance from tyre storage site: the further the downstream distance from the tyre storage site, the lower the contaminant concentration in the soil and groundwater; Contact time with water: the longer the tyres are in contact with water, the greater the risk of groundwater contamination; Vertical water flow through soil: the greater the water flow through the soil (e.g., from rainfall), the greater the dilution of contaminants; Horizontal groundwater flow: the greater the groundwater flow, the greater the spread of the contaminant plume; and Leached compounds at site: levels of manganese and iron are higher in groundwater when steel is exposed.
(ي) المركبات المغسولة في الموقع: تصبح مستويات المغنيسيوم والحديد مرتفعة في المياه الجوفية عند تعرض الفولاذ. وقد تكون مستويات الألومنيوم والزنك والمركبات العضوية مرتفعة في المياه الجوفية، ومستويات الزنك والكادميوم والرصاص مرتفعة في التربة.