Odour Threshold Investigation 2012 - Bay of Plenty Regional Council

Kevern 56 undertook several surveys (20/8/93, 10/9/93 and 17/9/93) using a Jerome
Model 621 sensor with a H 2 S detection range of 0-50 ppb. Measurement points
were at irregular intervals along the State Highway from Kawerau to Rotorua.
Results showed that the H 2 S level around Rotoehu/Rotoma were below 5 ppb.
Kevern noted that samples taken at the Waitangi Soda Springs on 10 September
were high (up to 45 ppb) compared to the values recorded on 17 September and
attributed this to possibly a contamination of the measurement cell from high
readings recorded in Rotorua earlier in the day. Elevated levels were found in the
Kawerau, Tikitere and Rotorua areas (15->50 ppb).
4.2.4 Tauranga Harbour
Monitoring of ambient H 2 S associated with decomposing sea lettuce 57 has shown
concentrations that are at adverse human health effect levels. Two sites in
Tauranga Harbour, Ongare Point and Ngakautuakina Point, were selected for
monitoring of H 2 S based on reported odour issues and health concerns raised by
local residents. When the material was disturbed, both sites recorded values greater
than ~288,000 μg/m 3 . Values recorded ~1 m above the surface ranged from 2.88
mg/m 3 to 14.4 mg/m 3 .
A summary of the ambient values from this section are shown in Table 4.1. For the
purposes of comparison all H 2 S volume measurements have been converted to
weight-based measurements (see Section 1). It should be noted that the results
obtained by different measurement methods may not be directly comparable
(sampling inlet position has been noted where known). No allowance has been
made for the different measurement sampling and averaging times.
The summary table shows that a wide range of concentrations can be experienced
depending on location. Also at any given location there can be variations of several
orders of magnitude in the values monitored, most likely due to variations in
emissions and/or meteorological conditions.
56 Kevern, R., 1993, BOPRC Internal memorandum, Ambient Hydrogen Sulphide Monitoring around
Lake Rotoma, File Reference 1370 03 0077, 5p.
57 BOPRC, 8 December 2009, Tauranga Harbour sea lettuce - hydrogen sulphide monitoring, Agenda
Report to Regulation Monitoring & Operations Committee.
18 Environmental Publication 2012/06–A review of odour properties of H 2 S Odour Threshold Investigation 2012