Ea3000 elemental analyzer

The physicochemical characteristics of soils subjected to the different remediation strategies were determined at the beginning (day 0) and the end (day 126) of the experiment. The moisture content and electrical conductivity (EC) were measured, using a TPY-7PC soil analyzer (Zhejiang Top Technology Co.; Ltd., Zhejiang, China). Total carbon (TC), total organic carbon (TOC), and total nitrogen (TN) were determined, using an EA3000 Elemental Analyzer (Euro Vector S.P.A.; Italy). Total phosphorus (TP) was measured, using the molybdenum–antimony anti-spectrophotometric method [30 ].

Three cryoconite samples from each time point were analyzed for TOC, IC, and TN. All eight cryoconite samples from each time point were analyzed for solid phase nitrogen and phosphorus speciation. Dried cryoconite samples (105°C, overnight) were analyzed for total organic carbon (TOC) and total nitrogen (TN) on a Eurovector EA3000 Elemental Analyzer. Detection limits for TOC and TN were 100 μg C g⁻¹ and 100 μg N g⁻¹ respectively, with coefficients of variation for duplicate analyses of 9.5 and 5.3%. Exchangeable NH⁺₄, NO⁻₃, and NO⁻₂ in wet cryoconite were extracted using a 2M KCl method (Telling et al., 2011 (link)). Extracts were analyzed on a Bran and Luebbe Autoanalyzer 3. Results were converted to dry weights after weighing cryoconite before and after oven drying. The average coefficients of variation for duplicate NH⁺₄ and NO⁻₃ analyses were 35.7 and 37.8%, respectively. Potentially bioavailable and residual phosphorus (P_residual) in dried cryoconite were analyzed using a three stage sequential digestion method using (1) 1 M MgCl₂, (2) 0.1 M NaOH and (3) acid persulfate. Extracts were analyzed on a Shimadzu mini UV-vis spectrophotometer. The average coefficients of variation for duplicate cryoconite samples for the MgCl₂, NaOH, and persulfate digestion steps were 10.1, 6.2, and 10.3%, respectively.

Nanometal fluids of different mass fractions were prepared, and the surface tension and oil–water interfacial tension of different concentrations of fluids were tested by a spinning drop interfacial tensiometer TX-500C (Shanghai Geology Instrument Institute, Shanghai, China). All of the interfacial tension measurements were conducted at 25 °C under atmospheric pressure. The thermal catalytic cracking effect of nanometal fluids on Bohai heavy oil at different heating rates was carried out using the Q50 thermogravimetric analyzer (TGA, TA Instruments, New Castle, DE, USA), under a nitrogen atmosphere. A Q2000 differential scanning calorimeter (DSC, TA Instruments, New Castle, DE, USA) was applied to investigate the thermal behavior of the heavy oil. A EA3000 elemental analyzer (EuroVector, Pavia, Italy) was used to determine the content of carbon and hydrogen in the heavy oil.