Chemistry group:

Iuffredo RaffaelaCastellone GennaroPollio AlessioTortorella Attila

ChemistryChemistry

Chemistry is a brancChemistry is a branchh of physical of physical science that studies the science that studies the

composition, structure, properties composition, structure, properties and change ofand change of the the matter. matter.

We collected samples of the Vipava river at two different poinst, the source and downstream. These samples we took in the lab for analysis. Analyses were carried out by the whole group by ion cromatography. For the mobile phase of the cromatography we used 0,750g of tartaric acid, 0,167g of dipicolinic acid and 1,5g of boric acid weighed on an analytical balance and dissolved into a plastic flask of 1000ml.

Analysis of total carbon and total nytrogen (npoc/ tn )

NPOC/TN is the analysis that shows how the concentration of total carbon and nitrogen.

In an analyzer that uses this method, half of the sample is injected into a chamber where it is acidified , usually with phosphoric acid, to turn all of the inorganic carbon into CO2 as for the following reaction: CO2 + H2O H2CO3 H+ + HCO3

- 2 H+ + CO32-

This is then sent to a detector for measurement. The other half of the sample is injected into a combustion chamber which is raised to between 600-700°C, some even up to 1200°C. Here, all the carbon reacts with oxygen, forming CO2. It’s then flushed into a cooling chamber, and finally into the detector.

Analysis results.

As you read above, we performed analysis of the NPOS, TN, carbonates and cations.

For every analysis we performed, we found out that the analytes’ concentration in Miren’s samplingsight was much higher than the analytes’ concentration in the source’s samplingsight. We called the source’s samplingsight as Vipava 1 and Miren’s samplingsight as Vipava 2. But let’s take a look at the numeric results:

Cations Analysis result

  Vipava 1A Vipava 1B Vipava 2A Vipava 2B

C Li+ 4,13 mg/L 6,11 mg/L 28,80 mg/L 25,35 mg/L

C Na+ 0,75 mg/L 0,89 mg/L 12,02 mg/L 8,72 mg/L

C NH4+ 2,23 mg/L 2,45 mg/L 9,60 mg/L 7,62 mg/L

C K+ 0,53 mg/L 0,53 mg/L 7,71 mg/L 6,01 mg/L

C Ca2+ 0,26 mg/L 0,70 mg/L 8,35 mg/L 7,95 mg/L

C Mg2+ 0,96 mg/L 1,63 mg/L 7,70 mg/L 6,20 mg/L

NPOC and TN analysis

Vipava 1

  1 2 3 avg

NPOC c (mg/L) 1,59 1,55 1,59 1,57

TN c (mg/L) 1,34 1,33 1,33 1,33

Vipava 2

  1 2 3 avg

NPOC c (mg/L) 4,68 4,57 4,54 4,6

TN c (mg/L) 8,77 8,88 8,92 8,86

Carbonate analysis

Vipava 1

n° V HCL C HCl V CO32- C CO3

2- avg C CO32- avg C CO3

2-

1 3,2 mL 0,1 mol/L 100 mL 0,0032 mol/L

0,0032 mol/L 192 mg/L2 3,2 mL 0,1 mol/L 100 mL 0,0032 mol/L

Vipava 2

n° V HCl C HCl V CO32- C CO3

2- avg C CO32- avg C CO3

2-

1 3,7 0,1 mol/L 100 mL 0,0037 mol/L

0,00375 mol/L 225 mg/L2 3,8 0,1 mol/L 100 mL 0,0038 mol/L

Conclusions

As you can see from the tables above, the river’s water has an high carbonate’s concentrations due to the fact that the river starts underground and it passes over carbonate rocks. Carbonate concentrations rise with the flowing of the river, but so do the cations concentrations.

Cations concentrations at the spring of the river are relatively low (<1mg/L), but it rises by an order of magnitude downstream.

Speaking for the NPOC, it approximately three times higher, while the TN gets approximately two times higher.

As we expected the river, flowing gets more substances into itself. This has an effect on pH and electric conductivity: at the spring we have a pH= 7.30 and L= 327 mS/cm while downstream we have pH= 7,86 and L=386 mS/cm.

We expected an higher rising of the electric conductivity, also because of the higher temperature downstream (9,6°C at the spring, 21,4°C, at Miren’s samplingishgt), but we don’t have it perhaps due to an higher anions concentrations that we didn’t measure.