NIWA (and its predecessor NZOI) have been collecting and analysing sediment from the seafloor around New Zealand and the South Pacific since the late 1950s and the details of these are stored in a database. This database contains station details (such as station id, position, and date) and the sediment analysis (grainsize analysis: % sand, % mud, % carbonate).

This report describes the summer 2014 (Baseline 3) marine benthic monitoring, conducted in late January/early February, and presents a brief description of the benthic invertebrate communities, habitats, sediment types, and sediment contaminant concentrations found at each site. All samples collected were surface samples from either intertidal or subtidal locations. Sampling was conducted at 10 subtidal and 10 intertidal monitoring sites in Porirua Harbour, to quantify and describe benthic communities, sediment characteristics and sediment contaminant levels. Specifically, at the subtidal sites, eight 10 cm diam. x 15 cm deep cores were collected using divers, for macroinvertebrate identification and enumeration and three composite core samples were collected for sediment contaminant and grain size analysis. The surface sediment (0-3 cm) was removed from 5 or 6 smaller cores (7 cm diameter) and these fractions were pooled to produce a composite core sample for contaminant and grain size analysis. One core (13 cm diameter x 15 cm deep) was collected from each intertidal site at low tide from within one 5 m x 5 m grid to determine community composition. A 0.25 m² quadrat was also photographed adjacent to each macroinvertebrate core for later assessment of epifaunal invertebrate community and macroalgal cover. Three samples of surface sediment (0-2 cm) were collected from each site for sediment contaminant and grain size analyses. Three composite samples were prepared, by combining samples from grids A, B, C, D, E (sample 1), from grids F, G, H, I, J (Sample 2), and from grids K, L, M, N, O (Sample 3). All sediment contaminant samples were collected using clean HDPE plastic trowels and trays. Samples were sealed in double zip-lock bags and stored on ice until shipped to the laboratory for processing.

The Greater Wellington Regional Council (GWRC) engaged NIWA to prepare and process estuarine sediment samples collected from Porirua Harbour in late 2010 and manage the analyses of both organic and metal contaminants for comparison with ANZECC sediment quality guidelines. Metal contaminants were analysed by Hill Laboratories and reported elsewhere. NIWA provided analytical data for organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs) and particle size distributions (0-300 μm). This report describes methodology and presents results [including quality assurance (QA) data] for the analyses of OCs, PAHs and particle size distributions for estuarine sediment samples collected from Porirua Harbour in 2010.

This report describes the winter 2013 (Baseline 2) marine benthic monitoring, conducted in early July, and presents a brief description of the benthic invertebrate communities, habitats, sediment types, and sediment contaminant concentrations found at each site. All samples collected were surface samples from either intertidal or subtidal locations. Sampling was conducted at 10 subtidal and 10 intertidal monitoring sites in Porirua Harbour, to quantify and describe benthic communities, sediment characteristics and sediment contaminant levels. Specifically, at the subtidal sites, eight 10 cm diam. x 15 cm deep cores were collected using divers, for macroinvertebrate identification and enumeration and three composite core samples were collected for sediment contaminant and grain size analysis. The surface sediment (0-3 cm) was removed from 5 or 6 smaller cores (7 cm diameter) and these fractions were pooled to produce a composite core sample for contaminant and grain size analysis. One core (13 cm diameter x 15 cm deep) was collected from each intertidal site at low tide from within one 5 m x 5 m grid to determine community composition. A 0.25 m² quadrat was also photographed adjacent to each macroinvertebrate core for later assessment of epifaunal invertebrate community and macroalgal cover. Three samples of surface sediment (0-2 cm) were collected from each site for sediment contaminant and grain size analyses. Three composite samples were prepared, by combining samples from grids A, B, C, D, E (sample 1), from grids F, G, H, I, J (Sample 2), and from grids K, L, M, N, O (Sample 3). All sediment contaminant samples were collected using clean HDPE plastic trowels and trays. Samples were sealed in double zip-lock bags and stored on ice until shipped to the laboratory for processing.

This report briefly describes methodology and presents results for the analyses of contaminants and particle size distributions for catchpit sediment samples. TPH, TOC and heavy metal results were produced by Hill Laboratories. PAH and chemical marker compound results were produced by NIWA.

This report briefly describes methodology and presents results [including quality assurance (QA) data] for the analyses of Wellington Harbour marine sediments for sediment contaminants. Results reported for total organic carbon (TOC), total petroleum hydrocarbons (TPH), organochlorine pesticides, Polycyclic aromatic hydrocarbons (PAH), PAH chemical markers, heavy metals and sediment particle size distributions. TPH, TOC and heavy metal results were produced by Hill Laboratories. Organochlorine pesticides, PAH and PAH chemical marker compound results were produced by NIWA.