[SYSTEM]
You are answering a single information-extraction question. Use ONLY the supplied source material. Do not use prior knowledge. Give a clear, concrete answer with the specific number, name, year, or value asked for.

[USER]
--- SOURCE ARTIFACT (M3-L4 — corrected card) ---
# Table 096 — **TABLE III. PHOSPHORUS IN OFFSHORE WATER**
Position: 3 miles south of Eddystone Lighthouse. Depth: 67 m. Date: 23 July 1947.
Units: **mg P per m³**

PDF page: 378

```csv
Depth (m),Inorganic,Total,Organic
5,2.2,11.6,9.4
10,5.0,12.3,7.3
20,3.0,12.6,9.6
**30**,6.5,12.6,**6.1**
**40**,7.4,11.8,**4.4**
60,6.8,13.1,4.3
65,6.78,14.2,7.4
35 cm above sea floor,8.4,14.7,6.73
6 cm above sea floor,8.8,24.0,16.2
```

--- END ARTIFACT ---

Question:
In Vol 27, Table III lists the organic phosphorus concentration in offshore water 3 miles south of the Eddystone Lighthouse on 23 July 1947. The table reports depths at 30 metres and 40 metres but does not include a 35-metre row. What would you estimate the organic phosphorus concentration was at 35 metres? Show the bracketing values and your interpolation method.

Answer concisely. Cite the row/cell/section you used.