The total carbon, total nitrogen, carbon, and nitrogen isotopic compositions of the samples were determined with an improved IRMS (Thermo Finnigan DELTAplusXP) coupled to a FLASH EA (Thermo Finnigan EA1112) via a Conflo III interface (Ogawa et al. 2010).
Total nitrogen (TN) and the nitrogen isotopic composition (δ15N) of the bulk organic matter were <0.48 wt% (mean, 0.3 ± 0.1 wt%) and from +2.2‰ to +6.6‰ (vs. Air), respectively.
The lower total nitrogen concentration and heavier δN-NO3 composition compared to typical wastewater concentrations (Umari et al. 1993; Wakida and Lerner 2005; Katz et al. 2010) and isotopic compositions (Hinkle et al. 2008) are consistent with nitrogen loss either through volatilization of ammonium or denitrification within this OWTS prior to sample collection.
The inset figure includes the total nitrogen for each sampling point and relative composition of organic and inorganic nitrogen.
Rice bran contained more reducing sugar, total nitrogen and vitamins than wheat bran under previous composition analysis (Wang 2013); therefore, it was identified as a preferred carbon source.
Total nitrogen concentrations and δN- NH4 + NO3) isotopic compositions were evaluated to address the combined effects of these processes on nitrogen concentrations in the Civic Center area.
Total nitrogen concentrations and δN- NH4 + NO3) isotopic compositions for samples dominated by ammonium (SMBRP-12 and C-1, April 2010) plot along a mixing line between OWTS sources and native groundwater (SMBRP-2, April 2010).
The composition of NPK fertilizer was 20% total nitrogen (N): 4.6% nitrate nitrogen, 2.5% ammoniacal nitrogen, 12.9% uric nitrogen, 20% phosphorus pentoxide (P2O8) = 8.7% P and 20% K2O (16.6% K .The composition of Kala compost is given as follows: pH 7.6, EC 31 mS/cm, total organic carbon (TOC) 28.04%, total nitrogen (TN%) 2.6 2.8, moisture content 24%.
An ammonium level of 36% of the total nitrogen (36%N-NH4+) was chosen as the base media composition for pH-balanced algal growth.
We also sampled leaves and needles from selected trees to measure their carbon isotope composition (a proxy for water use efficiency) and total nitrogen content.
