Organochlorines Bulletin 3
June 1996, Ref. INFO 4
Bulletin 3 provides an update on the Organochlorines Programme initiated by the Ministry for the Environment on 1 July 1995. Articles and items are presented on:
- Survey of organochlorines in the New Zealand environment
- The objectives of the Organochlorines Programme
- Trials on organochlorine destruction technologies
- Persistent organic pollutants (POPs)
- Key achievements of the first year of the Organochlorines Programme
Survey of organochlorines in the New Zealand environment
Introduction
The environmental survey of organochlorines in the New Zealand environment is the first stage of the Organochlorines Programme. This article provides a progress report on the survey.
Overview
The organochlorine compounds being studied comprise dioxins, PCBs, and a range of persistent organochlorine pesticides including DDT, aldrin, dieldrin, chlordane, and pentachlorophenol (PCP). The objectives of the survey are:
- To assess background organochlorine contamination levels within New Zealand ecosystems;
- To support the development of national environmental standards and guidelines for the substances studied.
The Organochlorines Programme as a whole comprises the study of human and environmental levels of organochlorine substances, the characterisation of risk, and the development of national environmental standards and guidelines.
The progress of the programme is being monitored by the Organochlorine Consultative Group.
Sampling Programme
The survey involves the collection of air, soil, water, sediment and biota samples from around New Zealand. Assessment of the data collected will enable comparisons to be made with similar overseas studies.
River Water Sampling Sites
- Waipa R. at Whatawhata
- Waingongoro R. at SH45
- Manawatu R. at Opiki
- Tukituki R. at Tamumu Bridge
- Ruamahanga R. at Waihenga
- Waimakariri R. at old H/W Bridge
- Taieri R. at Sutton Stream
- Mataura R. at Parawa
- Rangitaiki R. at Te Teko
- Wanganui R. at Te Maire
- Mohaka R. at Raupunga
- Ruamahanga R. at SH2
- Haast R. at Roaring Billy
- Halswell R. at McCartneys Bridge
- Taieri R. at Allanton
- Mataura R. at Seaward Downs
River Water Sampling
River water samples were collected monthly between January and March 1996 (i.e. on three occasions) from 13 rivers at 16 sites.
(Table 1) representing 12.7 % of the total New Zealand catchment. The rivers were carefully selected as being representative of New Zealand's waterways. They range from pristine to those which receive a variety of domestic, industrial and agricultural wastes.
Each sample consisted of ten litres of river water. Typically this was collected from four positions across the width of the river. At each position, one winchester (2.5 litre volume) of sample was collected.
The actual sample analysed was a composite sample prepared from the three monthly samples. A comprehensive sample preparation procedure was applied to ensure a representative composite sample was taken for analysis. Sampling was undertaken by the National Institute of Water and Atmospheric Research (NIWA).
River Biota Sampling
The collection of river biota (eel and trout) was also undertaken by NIWA, with the assistance of Fish & Game Council anglers in some areas. Sampling was carried out from the same river and sampling locations indicated in Table 1.
Eel were successfully collected from all sites. In contrast, it proved unexpectedly difficult to to catch the required number of trout at some sites. Another attempt will be made when the trout fishing season re-opens in October 1996.
Analysis of river biota is being undertaken on a freeze-dried composite sample prepared from a number of individual taken from each site.
Soil Sampling
For the soil sampling programme, the country was divided into eight strata on the basis of climate, geology and geographical (regional council) boundaries. Thirty-six soil samples were collected (in most cases by Landcare Research Ltd) from each of these strata based on five identified land types:
- Pristine land (indigenous forest and grassland generally in national parks);
- Pasture on hill country;
- Pasture on flat land;
- Parkland in provincial centres (near urban areas);
- Parkland in metropolitan centres (near to urban and commercial/light industrial areas in Auckland and Christchurch).
Sites for sampling from agricultural lands were selected using a random number generator and a grid referenced map. Metropolitan and provincial samples were collected from local parks and reserves; suitable sites were identified in consultation with city and district council staff.
Soil samples were collected as a series of discrete soil cores. Fifty-four soil cores were taken from flat land and hill country pasture collected from two independent areas ('sampling stations') within each strata. Similarly, samples from pristine lands consisted of 27 cores collected from a single sampling station. For provincial and metropolitan centres, samples were collected as a composite of cores taken from four parks or reserves.
With all soil material collected, a comprehensive sample preparation procedure was followed to ensure a fully representative composite sample was taken for analysis.
Air Sampling
A total of 54 ambient air samples are being collected from 10 sites over a 12-month period. These sites include baseline/pristine environments (Baring Head, Nelson Lakes National Park), agricultural environments (Taranaki hill country and Canterbury farms) as well as provincial towns and cities and major metropolitan centres (Auckland city, South Auckland, Hamilton, Masterton, Greymouth, Christchurch).
Sampling began in March 1996 and is being carried out continuously over a 20-day period for each month resulting in the filtering of approximately 4,000 m3 of air. Any contaminants are adsorbed on to filter material.
Estuarine Sampling
Sampling from estuarine ecosystems involves the collection of a total of 26 sediment and shellfish (cockle) samples from 12 estuaries. The estuaries selected for sampling range from pristine to estuarine catchments of urban, industrial and agricultural areas. The estuaries are:
Parengarenga Harbour; Whangarei Harbour; Manukau Harbour; Hellyers Creek, Waitemata Harbour; Kawhia Harbour; Tauranga Harbour; Wairau Estuary; Whanganui Inlet; Moutere Inlet; Avon Heathcote Estuary; Otago Harbour; New River Estuary.
In general the estuarine samples were collected by Regional Council staff.
Quality Assurance Project Plan
The sampling of environmental matrices for chemical contaminants can be a complex task. A quality assurance project plan (QAPP) was prepared in consultation with the respective sampling agencies. The purpose of the QAPP was to provide all sampling teams involved in the study with detailed information for each phase of the sampling programme which ensured that standardised procedures were applied throughout.
Information was provided on the sampling sites, sample size and identification, the collection procedure, measures to prevent field contamination, sample packaging and shipping, and quality assurance and quality control requirements including requirements for detailed field documentation.
Analytical Programme
The Institute of Environmental Science & Research (ESR) provided all sampling teams with pre-cleaned sample collection jars, solvents and related items necessary for the collection of samples. Analytical work for the environmental survey has been contracted as set out in Table 2.
Further Information
The next Bulletin will provide an update on the findings of the survey of organochlorines in the New Zealand environment.
Table: Laboratory Arrangements for Contaminant Analysis
| Contaminant | Principal Laboratory | Quality Control Laboratory |
|---|---|---|
| Dioxins, PCBs | ESR | Ministry of Environment & Energy, Ontario |
| OC Pesticides | ESR | Food & Horticultural Research |
| Chlorophenols | Food & Horticultural Research | ESR |
| Total Organic Carbon | Landcare Research |
The Objectives of the Organochlorines Programme
- To develop Resource Management (RM) Act national environmental standards
for dioxins in the media of air, soil and water; and where necessary,
environmental guidelines or standards for selected organochlorine
contaminants (e.g. PCP, chlordane, PCBs, dieldrin and DDT). To help
achieve this objective:
- Information will be obtained on ambient levels of dioxins and other key organochlorine contaminants in New Zealand ecosystems and an assessment made of their likely significance in terms of environmental impacts; and,
- Information will be obtained, where practicable, on the level of dioxins and other key organochlorine contaminants in the New Zealand human population and in food products, and an assessment made of their likely significance in terms of human health.
- To facilitate the commercial application in New Zealand of technologies
that safely and effectively destroy organochlorine wastes. To help
achieve this objective:
- Selected technologies will, if required, be trialled and evaluated in conjunction with interested parties;
- RM Act consent requirements will be identified.
- To identify and develop as far as practicable, the elements of an
integrated management strategy for dioxins and organochlorine wastes
in New Zealand. To help achieve this objective:
- Potential sources and continuing emissions of dioxins and other key organochlorines will be identified and prioritised;
- The extent of chemical holdings of organochlorines will be estimated.
- To facilitate informed public input to Government decisions on the
management of organochlorines in the New Zealand environment. To help
achieve this objective the Ministry for the Environment will:
- be guided by the Organochlorines Consultative Group;
- disseminate key information, facilitate an understanding of the issues among interested parties, and consult effectively during the process of policy development.
Treatability studies on PCP and dioxin contaminated soils
Overview
This article reports on the results of treatability trials on pentachlorophenol (PCP) and dioxin contaminated soils. Two treatment technologies were applied in sequence, namely, thermal desorption followed by chemical decomposition (see later explanation on technologies).
The work comprised the first of a two phase evaluation of the potential of these technologies to remediate soil contaminated with PCP and dioxins from New Zealand sawmills. The second phase, which involves a pilot scale plant, is scheduled to run between June and September 1996.
The treatability trials were undertaken by the owners of the technologies, ADI Services Ltd. (ADI) at their Melbourne laboratory, with specialised dioxin analyses by ESR Ltd., Wellington. The trials were commissioned by the Ministry for the Environment in conjunction with three New Zealand timber companies: Carter Holt Harvey Ltd, Fletcher Challenge Forests, and the Forestry Corporation of New Zealand.
Laboratory Treatability Trial
PCP and dioxin were thermally desorbed (heated to remove the contaminants) from the sample of soil and then chemically decomposed. This was carried out in a small scale version of the thermal desorption and chemical decomposition technologies.
Soil Sample
A 16 kg sample of PCP/dioxin contaminated soil from a New Zealand sawmill was forwarded to the Melbourne laboratories of ADI.
Homogeneous material of up to 1 mm suitable for the laboratory trials was prepared by sieving, to remove rock fragments, and air dried to around 10% moisture content.
Equipment
The majority of trials were conducted in a 450 ml stainless steel reactor modified to allow for:
- Operation at atmospheric pressure under inert nitrogen gas;
- Rapid heating to a maximum of 350 C;
- Distillation into an ice/salt cooled (-20 C) trap (followed by a further condensate trap at ambient temperature and two activated carbon traps ensuring total containment of distilled contaminants);
- Slow anchor paddle stirring of the soil.
Two other trials were conducted in a custom built glass barrel thermal desorber. Continuous processing conditions were simulated by slow rotation and the rapid heating of soil to varying temperatures of up to at least 450 C in the presence of air or an inert gas.
Experimental design
A total of 44 thermal desorption trials were completed using a variety of physical conditions and chemical additives. The laboratory work was directed towards the development of process conditions and recipes suitable for pilot plant application.
The experiments consisted of placing 100 g of soil and additives into the thermal desorber equipment, displacing air with nitrogen, rapidly heating to the required temperature, maintaining that temperature for a set period and then rapidly cooling.
The equipment was dismantled and the soil sample and liquid condensate removed from the cold trap for analysis. The reactor, connecting tubing and condensate traps were rinsed thoroughly with solvents to recover all traces of condensed organics for analysis.
The following thermal desorption variables were examined: temperature; time; water content; alkali additive; catalyst additive; accelerant additive.
Analysis
PCP and OCDD determinations were carried out routinely at the ADI laboratory. Detection limits were in the range of 1-10 ng/g and 10-50 ng/g respectively. Specialised high resolution GCMS analysis of samples selected for the measurement of individual dioxin congeners was carried out at the ESR laboratory.
Results
The thermal desorption of PCP and dioxin contaminated soil were optimised:
- At temperatures of 400 - 450 C for 30 minutes;
- By the addition of 5 - 10% alkali earth.
The best alkali earth additive to use (a range of 3 alkali earths were trialled in addition to NaOH, NaHCO3, and Na2CO3) was determined from the following criteria:
- Ability to adsorb water from soil (energy costs decrease with less water in the distillate);
- The elimination of chlorophenols from the distillate;
- Soil handling properties;
- Cost and availability.
The thermal desorption process, using the most appropriate recipe, produced a residual sterile soil, suitable for backfill on site, containing less than 10 ng/g of chlorophenols and less than 5 ng/g of dioxins. The toxic equivalents (I-TEQ) for the soil was reduced to 0.08 ng/g.
In a second stage ADOX reaction, the destruction of dioxins present in the thermally desorbed condensate was demonstrated to a level in excess of 99.999%.
About the technologies
Thermal desorption
Thermal desorption at temperatures ranging from around 300 C to 600 C (depending on both the soil matrix and contaminants) is a widely accepted and practised first stage remediation technology for the removal of organic contaminants from soils and other materials. ADI are currently developing the means to treat soils contaminated with chlorinated substances. The approach being taken involves thermal desorption followed by chemical decomposition processes.
First, the soil is heated under controlled conditions so that the organochlorine contaminants are volatilised from the soil matrix, then condensed and stored. (At elevated temperatures, dioxins can be produced from PCP. However research by ADI has shown that addition of sodium bicarbonate to the soil seems to enhance both desorption and suppress the formation of dioxins).
In a second stage, the concentrated organochlorine condensate is decomposed in a chemical reactor. The US EPA has approved such combined treatment technologies for use on the remediation of several PCP contaminated sites in the USA.
Various technologies can be applied to destroy the organochlorines in a second stage reactor such as Base Catalysed Dechlorination (BCD) or Accelerated Decomposition of Organic Halides (ADOX).
Base Catalysed Dechlorination
The BCD process was developed and patented by researchers working for the US EPA. Its principal application to date has been the treatment of polychlorinated biphenyls (PCBs) in transformer oils. The BCD technology offers a viable alternative to the high temperature incineration (HTI) of contaminated oils. ADI is one of several companies to acquire rights to the BCD process.
Essentially the BCD process uses a common alkali such as sodium hydroxide and a special hydrocarbon oil to act as a hydrogen donor. In conjunction with a proprietary carbon-based catalyst, decomposition and dehalogenation of the organochlorines occurs at temperatures around 350 C.
The ADOX reaction
The ADOX reaction was discovered by ADI during extensive research and development to support the commercialisation of the BCD process. It differs from the BCD process in that ADOX uses a proprietary organic accelerant, any hydrocarbon oil, and no carbon catalyst is added. In the presence of sodium hydroxide, ADOX causes simultaneous carbon-chlorine/carbon-carbon bond rupture of aromatic organochlorine molecules at temperatures ranging from 250 to 350 C.
The comparative decomposition rates for the ADOX process are at least 10 to 50 times faster than for the BCD process and this in itself represents a commercially significant advantage. Also, unlike the BCD process, the ADOX process does not involve sequential dehalogenation where more volatile (and potentially more toxic) organohalides are produced as intermediates. The ADOX process converts organohalides directly into carbon and inorganic chloride ions, typically as sodium chloride. ADI has patents pending on ADOX.
Organochlorines Consultative Group
- Howard Ellis, Ministry for the Environment (Chair)
- Dr Simon Buckland, Ministry for the Environment
- Jim Waters, Ministry of Health
- Dr Bill Jolly, MAF Regulatory Authority
- Paul Dell, Local Authorities
- Mark de Bazin, Timber industry
- Peter Sligh, Pulp and paper industry
- Dr Jim Barnett, Agricultural sector
- Tony Petley, AGCARM, NZCIC, Waste Disposal industry
- Norm Thom, CAE, IPENZ, NZIC, WMINZ
- John Hohapata, Adviser on iwi
- Jocelyn Keith, National Council of Women
- Michael Szabo, ECO
- Simon Towle, ECO
- (Incineration industry to be appointed)
Technical specialists
- Dr Michael Bates, ESR Communicable Disease Centre
- Dr Don Hannah, ESR Wellington Science Centre
Keeping an eye on POPs
Introduction
Persistent organic pollutants (POPs) is a term applied to a group of organic chemicals. POPs is an issue that is rising rapidly on the global environmental agenda. Their unique chemical characteristics, the significance of which are only now being more fully appreciated, has led to POPs being distributed around the globe as ubiquitous environmental contaminants.
What are POPs ?
POPs share four essential characteristics:
- Environmentally persistent – resist physical, biological and chemical degradation;
- Toxic – toxicity and ecotoxicity assessments have indicated concerns about their risks to human health or the environment;
- Bioaccumulative – characterised by low water solubility and high lipid solubility, leading to their bioaccumulation and biomagnification;
- Semi-volatile – enabling them to move long distances through the atmosphere before deposition occurs.
It is this last characteristic which has caused particular international concern. The semi-volatile nature of POPs chemicals means that their toxic impact can occur thousands of miles away from its original site of use or emission.
POPs used in the countries of the tropics, for example, eventually volatilise and are transported by atmospheric circulation to the higher and colder latitudes of the hemisphere where condensation occurs. POPs appear to impact most in the regions of Scandanavia, northern Europe, Canada and the Arctic circle.
The push to control further emissions of POPs, and in the long term to limit their accumulation in northern latitude ecosystems, is coming from countries (such as Canada, Denmark, Sweden, Norway, and Germany) that have studied the impacts these chemicals are having on their environments.
Background
An international meeting of experts was held in Vancouver, June 1994, in order to develop a broad-based and global perpsective on POPs. The meeting examined human health and environmental concerns, as well as the technical, institutional, social and economic issues relevant to effective global management of the pollutants. A number of issues were noted by the conference, including:
- Once released into the environment, POPs cannot be retrieved;
- POPs can build to high concentrations in biota and recycle within the ecosystems;
- POPs have been detected throughout the world, even in remote areas such as Antarctica and the Arctic, where relatively high levels have been found in fish, marine mammals and humans – this is attributed to long-range atmospheric transportion;
- Stockpiles of unwanted POPs exist in the world;
- In recent decades, many wildlife populations have begun to show reproductive abnormalities, immune dysfunction, neurobehavioural impairment, and elevated incidences of cancers and tumours. These are all consistent with the effects predicted from controlled laboratory animal exposures to POPs;
- The developing mammalian foetus and noenate may be particularly vulnerable to POPs exposure. This arises from transplacental and lactational transfer of maternal burdens at critical periods of development, eliciting effects on offspring at levels which have no effect on the adult.
The Vancouver meeting agreed that “there is enough scientific information on the adverse health and environmental impacts of POPs to warrant coherent action at the national, regional and international level. This will include bans, phase-outs and provisional severe restrictions for certain POPs”.
International Action
The United Nations Environment Programme (UNEP) is currently studying ways by which the manufacture, use and emissions of POP chemicals can be minimised.
The Intergovernmental Forum of Chemical Safety (IFCS) is coordinating the preparatory documentation of POPs chemistry, toxicity, transport, and working up possible global, regional and national control mechanisms.
The UNEP Governing Council will consider IFCS recommendations in January 1997. A New Zealand delegation comprising officials from the Ministry of Foreign Affairs and Trade, and the Ministry for the Environment, are participating in IFCS meetings.
New Zealand’s Contribution
The Ministry for the Environment’s Organochlorines Programme is studying nine of the twelve POPs most relevant to NZ, and also includes PCP.
Although not designed with international POPs in mind, the Organochlorines Programme may in due course be of interest to other countries in the development of strategies to control POP residues and emissions.
The NZ approach is to:
- Collect countrywide background data on levels of POPs in the environment, to estimate human dietary exposure and body burdens, and from this information estimate the likely significance of the levels found;
- Take stock of chemical holdings, continuing emissions, hot spots, sinks and potential sources of POPs;
- Develop national environmental standards and guidelines to regulate emissions and clean-up criteria;
- Keep people informed and interested parties involved in decision making;
- Identify relevant technologies to achieve clean-ups;
- Develop as far as practicable a management strategy for organochlorine wastes.
Key achievements in the first year of the Organochlorines Programme:
- Objectives of the Organochlorines Programme defined;
- Consultative Group established; three meetings held;
- Environmental survey designed and peer reviewed by NZ and international experts; implemented with 80% of samples collected and analysed; participation of a Canadian Government analytical laboratory;
- A bibliography compiled of publications on organochlorines in the New Zealand environment;
- Three information bulletins prepared and distributed;
- Organochlorine destruction technology trials proceeding; public seminars held in four centres;
- Contacts established with other country initiatives on POPs;
- Proposal developed for the assessment of human body burdens; involvement of USA Government laboratory obtained.
For further information on any aspect of the Organochlorines Programme contact:
Organochlorines Programme
Ministry for the Environment
PO Box 10362
WELLINGTON
Phone (04) 473 4090
Fax (04) 471 0195
