Fertilizer Characterization:  Isotopic Data (N, S, O, C, and Sr)

Abstract

A detailed isotopic characterization (delta15N(Ntotal), delta15N(NO3), delta18O(NO3), delta34S(SO4), delta18O(SO4), (delta13C(Ctotal), and 87Sr/86Sr) of 27 commercial fertilizers used in Spain is presented in this paper. Results together with a compilation of fertilizer isotopic published data are used for two purposes: (i) to identify the origin of the primary constituents and raw materials used in fertilizer manufacture and relate these data with their heavy metals and rare earth elements (REE) contents; (ii) to compare the fertilizer isotopic signatures with natural values and other anthropogenic pollutants and evaluate the usefulness of multi-isotopic analyses to trace fertilizer contaminations in future study cases. Isotope data permit us to know, in most cases, the origin of the primary constituents of fertilizers, and the 87Sr/86Sr ratio distinguishes the origin of the phosphate content--phosphorites or carbonatites--which in turn implies a qualitatively defined and potentially contaminant presence of REE and heavy metals in fertilizers. Delta15N, delta34S, and 87Sr/86Sr have already been used to trace fertilizer contaminations. Their utility can be improved by the coupled use of delta15N(NO3)-delta18O(NO3) and delta34S(SO4)-delta18O(SO4) to evaluate the fractionation processes that can affect contaminants. Moreover, multi-isotopic analyses, using heavy isotopes, allow us to see beyond the fractionation effects to the fertilizer stable isotope signatures and a better distinction from other anthropogenic contaminants.

Lombards on the Move – An Integrative Study of the Migration Period Cemetery at Szólád, Hungary

“…They were also closely comparable to data from other European loess landscapes that typically range between about 0.7090 and 0.7100–0.7110 [80]–[83]. Given the consistent offset towards Sr isotope values of common fertilizers, the relatively low and very uniform Sr isotope values of the soil leachates from agricultural fields (0.7085±0.0002 (2 SD)) are likely to have been influenced by fertilizers [[83], [84] (∼0.7084±0.0010 (2 S.D. ))], and were therefore not given any consideration in the interpretation of the data gathered from the human remains.…”

Dietary Heterogeneity among Western Industrialized Countries Reflected in the Stable Isotope Ratios of Human Hair

“…The small number of higher δ 15 N values detected in Western Europe did not originate from a single geographic region; rather, they came from six different countries (Heinola, Finland; Mirambeau, France; Aosta, Italy; Dingli, Malta; Almada, Portugal; Medina del Campo, Cangas de Onis, Hostalric, Bilbao, and Toledo, Spain; and Sheffield, England). These samples might represent individuals with diets with unusually high animal protein consumption, consumption of elevated amounts of marine fish, or consumption of foodstuff derived from organic farming where manure is used as fertilizer [59].…”

“…Similarly, the type of fertilizers used will impact the isotope values of the crops. Large ranges in δ 34 S values (up to 30‰) of fertilizers exist due to their varied geochemical origins and manufacturing methods [59]. Given that all these processes could be acting at different geographic scales alone or in conjunction, it is very difficult to ascribe a single factor or combination of factors that would explain the isotopic difference in δ 34 S values of hair from Western Europe and the USA.…”

Stable Isotope Ratios as Biomarkers of Diet for Health Research

“…Because nitrogen assimilation discriminates against 15 N, plants may have lower δ 15 N values than soil nitrogen when nitrogen availability is high (and plants can be isotopically “choosy”) (41). The synthetic, inorganic fertilizers used in conventional agriculture have δ 15 N values close to that of atmospheric N 2 (0‰) (6, 152), and conventionally grown crops typically have similar δ 15 N values, approximately −5‰ to +5‰ (7). In contrast, organic fertilizers have higher and more variable δ 15 N values (6), a difference that can aid in determining the authenticity of organically-labeled produce (7).…”