Trace element geochemistry of Nova Scotia (Canada) maple syrup

Abstract

Between 2000 and 2005, 50 sugar maple ( Acer saccharum Marshall, 1785) syrup samples from 16 producers in northern Nova Scotia, were analyzed (for 39 elements) using new techniques and inductively coupled plasma – mass spectrometry. Multidimensional scaling (exploratory statistics) using all samples and chemical data indicates that composition correlates with producer–woodlot, syrup colour (percent transmission), and processing (boiling alone versus reverse osmosis + boiling). Data are subdivided to explore these relationships. Using boiled samples (five producers, 21 samples), producers–woodlots are distinguished by high field-strength (Cr, Hf, and U), rare-earth (La, Pr, and Nd), chalcophile (Cu), alkaline earth (Ba, Ca), and especially alkali elements (Na, K, Rb, and Cs). On average, element concentrations are 1.6 times higher in darkest, boiled-only syrups (n = 6) compared with the lightest boiled syrups (same producers; n = 6). Apparently, dark syrups result from sap that contains low sugar content but similar element concentrations. More boiling to concentrate sugar causes caramelization, resulting in darker syrup and higher element concentrations. Averages for boiled and osmosis-processed syrups suggest that cations with small ionic radius and high charge (3+and 4+) are ∼1.6 times higher in boiled samples. These cations are partially lost by passing through the osmosis membrane. Based on boiled samples, water-soluble alkali metal cations with large ionic radius and low charge (+1) have high continental-crust-normalized concentrations (0.1 times), whereas insoluble cations with smaller ionic radius and higher charge (e.g., Hf, Th, REE) exhibit low (0.0001) concentrations. This pattern apparently reflects element solubility in soil water. Concentrations are ∼10 times those in Nova Scotia wine. Because ∼35 L of sap makes 1 L of syrup, the lower concentration factor in wine may reflect evapotranspiration concentration in grapes. Several elements in syrup (Sn, Cu, Pb, Zn), show producer-related concentration anomalies that probably reflect equipment (tanks, pumps, evaporators) used in processing.