Knowledge Gaps: AbioticKnowledge Gaps: AbioticFactors and Ecosystem-Wide

Effects Prof. Richard Handy

School of Biomedical & Biology Sciences, University of Plymouth UKUniversity of Plymouth, UK.

rhandy@plymouth.ac.uk

NNI USA workshop: 6-7th October 2009, Arlington, Virginia

ContentsContents

T l i h ff il / di• Translating the effects on soils/sediments, primary producers, herbivores, carnivores, into

l i l l ffa population or ecosystem level effect.• Terrestrial and aquatic ecosystems.• Physico-chemistry and ecosystems.• Experimental ApproachesExperimental Approaches

Soils and Sediments

• At the base of the ecosystemL k ft th di t / il• Look after the sediments/soils.

AntibacterialAntibacterial Activity is I lInversely Related to

Particle Size

Neal, Ecotoxicology (2008) 17:362–371

Silver NPs:Silver NPs: Behaviour in

N t lNatural Estuarine Sediments

Bradford et al. (2009) ES&T

Silver NPs: No Effect on

NaturalNatural Microbes in

E iEstuarine Sediments

Muhling et al. (2009) Marine Environmental Research

Algae, Fungi, Terrestrial Plantsg , g ,Navarro et al. (2008) Ecotoxicology, 17:372–386

Unknown Effects on Nutrient Cycling, Water Depuration & Biomass ProductionWater Depuration & Biomass Production

Navarro et al. (2008) Ecotoxicology, 17:372–386

Dietary Exposurey p• Dietary bioavailability and uptake measurements are

needed.• Gut chemistry and NP adsorption onto epithelia.• Relate by feeding habit and gut anatomy, not by particle

h i t lchemistry alone.• Herbivores, carnivores, tropical, temperate.• Food webs: species sensitivity with/without• Food webs: species sensitivity with/without

biomagnification.• Gut function is about energy acquisition by animals.• Use bioenergetics to link individual with population level

effects.• Trade offs animals preserve growth at the expense of• Trade offs-animals preserve growth at the expense of

locomotion/behaviour and reproduction.

Uptake of NPs Across

EpitheliaBloodEpitheliaMucusUnstirred waterBulk water

Unstirred layer

p t e aNa+

N +

Na+Cl-Cl-

Cl-

Na+

Na+

Cl-

Cl-Na+

Cl-

ATP

HCO3-

3Na+

2K+Cl-

Cl-HCO3-

Tight junction

Ca2+

Ca2+ Me+Me+

Me+Me+

Me+

Me+

Handy et al., 2008.

Na+

Na+

Na+

Na+ Cl

Cl-

Cl-

Na+

Na+H+

CO2 CO2CA

ATPH+

ClHCO3

CO2CO2

CACa2+ Me+Me+

Me+

CH3-XCH3-XCH3-X

CH3-XCH3-X

Diffusion

Ecotoxicology, 17, 396–409

Na+

Na+Na+

Cl-

Ca2+

Ca2+

HS HS

HS

HS

Cl-HS

HSER/Golgi

vesicularTransport of NPs

Cl-

6 -18 mV

Na+ Ca2+ Mg2+

Mucous layer Donnan potential

1-3 mVTransepithelial potential

Dietary TiO :Dietary TiO2: Growth & Food

I k bIntake by Rainbow Trout

Ramsden et al (2009) Ecotoxicology 18:939-951Ecotoxicology, 18:939 951

No statistical differences between treatments (ANOVA, P > 0.05)

Dietary TiO2: Titanium Increases in Some Internal Organs But DynamicInternal Organs-But Dynamic.

Effect of Dietary Copper on Metabolic Rate of TroutC b ll t l (2002) CJFASCampbell et al. (2002) CJFAS

20

25

ol g

-1 h

-1)

15

umpt

ion

(um

o

5

10

Controlf oxy

gen

cons

u

0 200 400 600 800 1000 1200 1400 16000

ControlCopper

Rat

e of

Swimming Activity (bodylengths h-1)

Relationship Between Activity Level and Potential Mortalityand Potential Mortality

(after Priede 1977)

5

6

me

1.0

lity

%

S

3

4

age

tim 0.1

0.01 mor

talS

M

1

2

Perc

ent

0.001

oten

tial

0

0.02

0.08

0.14 0.

2

0.26

0.32

0.38

0.44 0.

5

0.56

0.62

0.68

0.74 0.

8

0.86

0.92

0.98

P

0.0001 Po

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Metabolic rate relative to scope

Space and Time Effects in Ecosystems: Loss of p yBiological Clock in Trout After Dietary Copper.

Campbell et al. (2002) CJFAS

2500

Control

15

20

25

30

m s

tatis

tic (S

)

m (%

incr

ease

)

1500

2000

0

5

10

15

6 9 12 15 18 21 24 27 30 33 36 39

Period (hours)

Perio

dogr

am

Dis

tanc

e sw

am

0

500

1000

Copper

68

101214

m s

tatis

tic (S

)Time (hours)

0 6 12 18 24 30 36 42 480246

6 9 12 15 18 21 24 27 30 33 36 39

Period (hours)

Perio

dgra

m

Fate, Behaviour and Biological Effect At Ecosystem Level

• No where near enough data to make accurate models!

• Field & mesocosmexperiments (top down).M d l f• Model from component parts/organismsparts/organisms (bottom up).

http://www.hgtech.com/images/MISC/CYCLEHG.GIF

Gold NPs in E iEstuarine

MesocosmsMesocosmsFerry et al., 2009. Nature

Nanotechnology.

Abiotic Factors• Abiotic factors relating to particle behaviour.

H ff t i t f h ( ti )– pH effects on point of zero charge (aggregation)– Ionic strength and divalent ions (“water hardness”)– Dissolved organic matter ligand chemistry– Dissolved organic matter, ligand chemistry.

• Broader hydrological and climate issues– Flow dynamics of rivers, micro-environments with y ,

different chemistry that may “concentrate” NPs.– Topography of sea bed, river bed etc.– Micro-climates; tree canopy, high altitude sites vulnerable

to precipitation; extreme temperatures.– Relationships with particle energy and temporal changes inRelationships with particle energy and temporal changes in

particle chemistry, or size (dissolution/weathering).

TiO2 NP Aggregation in SalinesVevers & Jha (2008) Ecotoxicology (2008) 17:410–420

Cell in Mitosis

Cytoplasmic processes, filopodia

Particulate and organic matter from coastal runoffs

Formation of aerosol, i k t bi d d l

Atmospheric inputs

Concentration of NPs in the surface microlayer

Dilution and transport t Changes in temperature

risk to seabirds and mammals

Toxicity to embryos and plankton

to open ocean

AggregationCoastal

Changes in temperature, ionic strength and natural organic matter with depthToxicity to pelagic species

gg gsediments

Accumulation of NPs

Precipitation to ocean floor

Accumulation of NPsor aggregates at interfaces?

Toxicity to benthos

Mobilisation of NPs by microbes

Ocean floor

Conclusions on Knowledge GapsConclusions on Knowledge Gaps

• Need to employ all our experimental tools– Study real ecosystems, and mesocosm approaches– Data on the individual physical and biological components of

ecosystems are also needed (reductionist approach).– Real wild-type organisms of ecological importance from different

phyla- not just standard OECD/ISO method organisms.• Our knowledge of the effects of NPs on plants is particularly

weak compared to animal biology.• More work on terrestrial systems.• Dietary exposure and food chain studies are neededDietary exposure and food chain studies are needed.• Bioenergetics to link individuals with populations• Abiotic factors relating to particle aggregation chemistry are

h l idnot the only ones to consider.• Micro-climate, micro-environments, hydrology etc.

Environmental Monitoring: What Compartments and Receptors (Organisms) to Prioritise?and Receptors (Organisms) to Prioritise?

• Uncertainty because of the knowledge gaps.• Sediments/soil and sediment dwelling organisms a prioritySediments/soil and sediment dwelling organisms a priority.• Key stone species in food webs.• Standard ecotoxicity test organisms

– The consensus view is that we should continue to use these in Europe (e.g. Crane et al., 2008, Ecotoxicology, 17, 421-437)

• Whole effluent testing/Direct toxicity assessment approaches?• Rapid Screening tools

– Microtox, MARA, etc. Need comparing against higher tier organisms in the laboratory to validate their use with NPs.

– Chemical methods need developing e.g., particle reactivity assays etc.• The usual combination of chemical and biological monitoring

in a tiered approachin a tiered approach• Review and re-visit more frequently as data on novel effects

emerge.

Research Priorities• The knowledge gaps! But which one is the most important?• Soil and sediments.• Food chains; sediments through to man• Food chains; sediments through to man.• Measurement techniques for NPs in complex matrices such as

soil, natural water, tissues.• “Plan B” on measurement; antibody/bioassay approaches

(endocrine disrupters & VTG assay analogy). • Plants and terrestrial ecosystems as one of the big knowledge y g g

gaps; tree canopy effects (air) and soil contamination (root functions of plants).

• More fundamental research rather than applied science so we• More fundamental research rather than applied science, so we don’t make “wrong assumptions” in our thinking.– Toxic mechanisms on key biochemical pathways; photosynthesis,

respiration geochemical cycles (nitrogen water)respiration, geochemical cycles (nitrogen, water).– Control systems in organisms; endocrine, immune, nervous systems.

• NPs as “delivery vehicles” for other contaminants.

Any Questions?Any Questions?