This dataset consists of one data file (spreadsheet) from a 1 year large tank herbicide degradation experiment in seawater, containing 4 different light and sediment treatments. Each tab contains concentration data at each time point for a single herbicide under each of the four light and sediment conditions.
The aim of this study was to conduct a year-long degradation experiment using concentrations of commonly detected herbicides in a series of replicate open tanks. We included different light conditions and natural sediments in treatments to improve the ecological relevance and applicability for inclusion by regulators and resource managers in future risk assessments.
Methods:
This study describes a series of outdoor open tank experiments to measure the degradation of herbicides under conditions more natural than those applied in standard flask tests. These tests were conducted in large open tanks with water circulation over the course of a year under both fully dark and light conditions (partially shaded, natural diurnal cycle) and in the presence and absence of natural sediments. Intertidal sediments, containing no detectable concentrations of herbicides (see Results) were collected from the intertidal zone of low tide from Cockle Bay, Magnetic Island, Queensland (19°10' S, 146° 49' E). Each of the sediment treatments contained 3.8 kg sediment following the removal of large sediments > 2 mm by sieving. To allow for periodic sediment sampling without disruption of sediment communities, the sediments were distributed into a single large and 11 small dishes in each tank which could be removed without disturbing the majority of the sediment. The large dish (25 cm x 22 cm 5 cm) were filled with 3.0 kg of sediment (wet weight) and the small ceramic dishes (6.5 cm diameter) 70 g sediment. Physical and chemical information on the seawater and sediments used the open tank experiment may be found in Mercurio et al. (2016).
The open fibreglass tanks (120 l) were situated in an outdoor glasshouse in two stacked rows of 10 (20 in the top rows and 20 in the bottom rows). The top 20 tanks were partially shaded (70%) and exposed to a natural diurnal cycle (maximum of ~700 µE photons m-2s-1) over the course of the experiment (Li-250A light meter, Li-Cor, Lincoln, USA). The bottom row was fully shaded (no light penetration) at all times. Evaporation was minimised with loose-fitting clear acrylic lids on the top row and fully opaque foam on the bottom row and water continuously circulated in each tank using Turbelle Nanostream pumps. After every sampling period evaporation losses were replenished with equal volumes of MilliQ freshwater. Logged temperatures averaged 28°C (range 21-37°C) in the light and 26°C (21-32°C) in the dark.
Herbicides included:
Atrazine, Diuron, Hexazinone, Tebuthiuron, Metolachlor, 2,4-D,
Water samples were taken periodically and analysed by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) as per Mercurio et al. Herbicide persistence in seawater simulation experiments. PLoS ONE 10(8): e0136391.
Uncertainty in the analytical method for repeated injections into the LC-MS results in a concentration uncertainty of approximately ± 0.2 µg/L. Only concentrations greater than the limit of reporting (LOR) were used to calculate half-lives (t1/2). The limit or reporting was designated as 5 x the detection limit = 1 µg/L to maximise accuracy of the estimations.
Reductions in the concentration of herbicides were plotted to predict the persistence of each herbicide (its 'half-life'). Half-lives for zero order kinetics were obtained by plotting the concentration vs time: t1/2 = 0.5 C0/k0, where C0 is the initial concentration and k0 is the slope.
The emergence of the three herbicide breakdown products were also quantified: Desisopropyl Atrazine, Desethyl Atrazine from Atrazine and 3,4-dichloroaniline from Diuron.
Format:
- Herbicide_persistence_open_tank_10052016.xlsx (1.6 MB): Excel spreadsheet containing 8 sheets, one sheet for each herbicide and one for temperature logger measurements.
Data Dictionary:
Common:
- Time (days): Time in days from the start of the experiment
- Sample replicate: Up to four replicate tanks were used containing herbicides and these were incubated under different light and sediment conditions
Atrazine:
- Dark no sediment Atrazine: Concentration of Atrazine remaining in open tanks under dark conditions without sediment
- Dark no sediment desethyl atrazine (DEA): Concentration of desethyl atrazine (DEA) remaining in open tanks under dark conditions without sediment
- Dark no sediment desisopropyl (DIA): Concentration of desisopropyl (DIA) remaining in open tanks under dark conditions without sediment
- Dark with sediment Atrazine: Concentration of Atrazine remaining in open tanks under dark conditions with sediment
- Dark with sediment desethyl atrazine (DEA): Concentration of desethyl atrazine (DEA) remaining in open tanks under dark conditions with sediment
- Dark with sediment desisopropyl (DIA): Concentration of desisopropyl (DIA) remaining in open tanks under dark conditions with sediment
- Light no sediment Atrazine: Concentration of Atrazine remaining in open tanks under light conditions without sediment
- Light no sediment desethyl atrazine (DEA): Concentration of desethyl atrazine (DEA) remaining in open tanks under light conditions without sediment
- Light no sediment desisopropyl (DIA): Concentration of desisopropyl (DIA) remaining in open tanks under light conditions without sediment
- Light with sediment Atrazine: Concentration of Atrazine remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
- Light with sediment desethyl atrazine (DEA): Concentration of desethyl atrazine (DEA) remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
- Light with sediment desisopropyl (DIA): Concentration of desisopropyl (DIA) remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
Diuron:
- Dark no sediment Diuron: Concentration of Diuron remaining in open tanks under dark conditions without sediment
- Dark no sediment 3,4-dichloroaniline: Concentration of 3,4-dichloroaniline remaining in open tanks under dark conditions without sediment
- Dark with sediment Diuron: Concentration of Diuron remaining in open tanks under dark conditions with sediment
- Dark with sediment 3,4-dichloroaniline: Concentration of 3,4-dichloroaniline remaining in open tanks under dark conditions with sediment
- Light no sediment Diuron: Concentration of Diuron remaining in open tanks under light conditions without sediment
- Light no sediment 3,4-dichloroaniline: Concentration of 3,4-dichloroaniline remaining in open tanks under light conditions without sediment
- Light with sediment Diuron: Concentration of Diuron remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
- Light with sediment 3,4-dichloroaniline: Concentration of 3,4-dichloroaniline remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
Hexazinone:
- Dark no sediment Hexazinone: Concentration of Hexazinone remaining in open tanks under dark conditions without sediment
- Dark with sediment Hexazinone: Concentration of Hexazinone remaining in open tanks under dark conditions with sediment
- Light no sediment Hexazinone: Concentration of Hexazinone remaining in open tanks under light conditions without sediment
- Light with sediment Hexazinone: Concentration of Hexazinone remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
Tebuthiuron:
- Dark no sediment Tebuthiuron: Concentration of Tebuthiuron remaining in open tanks under dark conditions without sediment
- Dark with sediment Tebuthiuron: Concentration of Tebuthiuron remaining in open tanks under dark conditions with sediment
- Light no sediment Tebuthiuron: Concentration of Tebuthiuron remaining in open tanks under light conditions without sediment
- Light with sediment Tebuthiuron: Concentration of Tebuthiuron remaining in open tanks under light conditions with sediment
- Sample lost: missing data because the sample was lost
Metolachlor:
- Dark no sediment Metolachlor: Concentration of Metolachlor remaining in open tanks under dark conditions without sediment
- Dark with sediment Metolachlor: Concentration of Metolachlor remaining in open tanks under dark conditions with sediment
- Light no sediment Metolachlor: Concentration of Metolachlor remaining in open tanks under light conditions without sediment
- Light with sediment Metolachlor: Concentration of Metolachlor remaining in open tanks under light conditions with sediment
24D:
- Dark no sediment 24D: Concentration of 2,4-D remaining in open tanks under dark conditions without sediment
- Dark with sediment 24D: Concentration of 2,4-D remaining in open tanks under dark conditions with sediment
- Light no sediment 24D: Concentration of 2,4-D remaining in open tanks under light conditions without sediment
- Light with sediment 24D: Concentration of 2,4-D remaining in open tanks under light conditions with sediment
Temperatures:
- Date Time, GMT+10:00: data and time when temperature was logged
- Logger: Temperature logger number
- Temp, °C: temperature logged
- Minimum: minimum temperature for each logger
- Maximum: maximum temperature for each logger
- Mean: mean temperature for each logger
References:
Mercurio P, Mueller JF, Eaglesham G, O'Brien J, Flores F, Negri AP. 2016. Degradation of herbicides in the tropical marine environment: Influence of light and sediment. PLoS ONE in press.
Data Location:
The original data is saved in the eAtlas enduring data repository: data\NERP-TE\4.2_Herbicide-effects\
