Pesticide residues in waters of the Great Barrier Reef by yhi13010

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									Pesticide residues in waters of
 the Great Barrier Reef region

            Jon Brodie
A brief history…….
•   Superficial analysis in early 1990s suggested no pesticides still in common use
    are capable of reaching the reefs of the GBR.
•   Studies in Atherton Tablelands, Johnstone, lower Burdekin and Bundaberg
    catchments in 1990s onwards show common presence of herbicide residues of
    a number of compounds (Hunter, Ham, Armour and colleagues).
•   Presence of herbicide residues in coastal sediments, seagrasses and waters
    along much of the GBR coast (Haynes et al., 2000a; Duke et al., 2005
    Bengston Nash et al., 2005; McMahon et al., 2005).
•   Experimental toxicity studies show the ‘effect concentration’ of the herbicides of
    concern to mangroves, seagrass, algae and corals (e.g. Haynes et al., 2000b;
    Seery et al., 2006; Jones, 2005; Jones et al., 2003; Negri et al., 2005; Bell and
    Duke, 2005).
•   Loads of herbicides being discharged to GBR estimated in Mackay Whitsunday
    and lower Burdekin regions (Mitchell et al., 2005; Lewis et al., 2007).
•   Use of passive samples in rivers and GBR lagoon to detect long-term
    contamination (e.g. Shaw and Muller, 2005).
Monitoring of the
Great Barrier Reef
 Catchment Area
Recent catchment studies
• Paddock and stream scale studies in Burnett (Stork et al)
• Stream scale studies in Mackay Whitsunday (Rohde et al),
  Tully (Bainbridge et al), Burdekin (Davis et al) summarised in
  Lewis et al 2009
• Fitzroy river work (Packett et al 2009)
• Paddock scale work lower Burdekin (Davis et al)
• Passive samplers in rivers (GBRMPA MMP, Mueller et al)
• Stream studies in Burnett (yet to be published)
 Herbicide
runoff GBR
waterways




 Lewis et al. (2009)
          Herbicide runoff linked to
             different land uses
    Land Use                  Herbicides detected

   Sugar cane         Diuron, atrazine, ametryn, hexazinone

      Urban                          Diuron

   Grain crops                      Atrazine

     Grazing                      Tebuthiuron

   Horticulture               Atrazine, hexazinone

Plantation forestry                Simazine
                                                                  EMC                  EMC      Hexazin    EMC
                                                       Diuron              Atrazine
              Site               Year      Flow (ML)                (µg/                 (µg/       one      (µg/
                                                           (kg)                 (kg)
                                                                     L)                   L)        (kg)      L)
                                2005/06     138,200      46       0.33        80       0.58       2.7      0.02
   West Barratta Creek          2006/07     150,500      79       0.52       116       0.77       2.2      0.01
                                2007/08     176,000      44       0.25        70       0.40       1.0      0.01
                                2005/06     254,600      63       0.25        72       0.28        +        -
     Haughton River             2006/07     530,000      39       0.07        26       0.05      BDL        -
                                2007/08     256,000      16       0.06        25       0.10      BDL        -
                                2001/02a    126,000     470       3.73        75       0.60       28       0.22
      Pioneer River             2004/05     207,000     310       1.50        95       0.46       45       0.22
                                2006/07     415,000     470       1.13       310       0.75       140      0.34
                                2002/03a    21,000       26       1.24       BDL        -        BDL        -
       Sandy Creek              2004/05     67,000      180       2.69        40       0.60       36       0.54
                                2006/07     130,000     200       1.54        66       0.51       73       0.56
                                2004/05     65,000       17       0.26       3.7       0.06       2.5      0.04
     O'Connell River            2005/06     61,000       30       0.49       6.6       0.11       4.9      0.08
                                2006/07     27,000       31       1.15        20       0.74       2.5      0.09


aMitchell   et al. 2005;



EMC: Event mean concentration
               Catchment summary

Easily detectable residues of atrazine and diuron (+others
including ametryn, hexazinone and metolachlor) are found
in the waterways draining sugarcane land use

Tebuthiuron found in waterways draining grazing land use

ANZECC and ARMCANZ guidelines have been exceeded
for atrazine and diuron in some freshwater samples
                            Burdekin




                 Mackay Whitsunday

Flood plumes
               28 January, 2005
      Aqua                 Terra
9th February 2007   11th February 2007
                    Plume monitoring

•   Marine samples collected in river flood plumes adjacent
    to the Tully/Murray, Burdekin/Townsville, Fitzroy and
    Mackay Whitsunday Regions.

•   More than 100 samples collected in the marine waters
    from these areas over 5 years.

•   Data for diuron presented in contour plots based on
    latest GBRMPA 99% guideline (0.9 µg/L), lowest effect
    levels (0.1 µg/L) and detection limit (0.01 µg/L).
Tully-
Murray
Basin
Diuron
Burdekin-
Townsville
 Region
 Diuron
 Mackay
Whitsunday
 Region
  Diuron
                      Plume summary
Diuron and atrazine (+ others) residues in all river water plumes which drain cane
lands.
Tebuthiuron residues in the plumes of the large dry tropics catchment draining
grazing lands
Residues found a long way offshore (>50 km) in easily detectable concentrations.
Concentrations, at times, above known effect levels (reduced photosynthesis) for
certain species of seagrass and coral zooxanthellae.
Diuron and atrazine display conservative mixing behavior in river water plumes
(which allows the herbicides to travel large distances offshore).
Residues persist in the marine environment (chronic effects).
                Toxic effects to marine plants
• Short-term effects (hours to days) of herbicide exposure show that certain
 species of mangroves, seagrass and corals more sensitive than others
 (Bell and Duke, 2005; Haynes et al., 2000; Jones, Negri and colleagues).
• Certain herbicide products more toxic than others.
• Exposure to diuron concentrations as low as 0.1 µg/L reduces
 photosynthesis in certain species of seagrass (Haynes et al. 2000) while
 0.3 μg/L is the lowest effect concentration to corals (e.g. Acropora
 formosa) (Jones et al. 2003; Jones and Kerswell, 2003) – lowest effect
 level for atrazine in corals is 3 µg/L.
    Toxic effects to marine plants (continued)

•   Synergistic effects of diuron and sediments affects crustose coralline
    algae (Harrington et al. 2005).

•   Link between diuron and mangrove dieback in the Mackay
    Whitsunday area (Duke et al. 2005).

•   Most marine plants appear to be able to recover following short-term
    exposure to herbicides – laboratory studies may not account for
    complex range of environmental and chemical conditions in the
    marine environment (Macinnis-Ng and Ralph, 2003).
                     Conclusions

• Our study shows that herbicide residues in river water
  plumes in the Great Barrier Reef lagoon are at (additive)
  levels which cause reduced photosynthesis potential to
  marine plant communities.
• The chronic effects of long-term persistence of herbicide
  residues in the Great Barrier Reef lagoon may not be
  evident for several years.
• Possible effects of chronic exposure of herbicide
  residues may result in a change in the community
  structure of freshwater wetland, mangrove, seagrass and
  coral reef ecosystems.

								
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