Download Advanced in the toxic effects of petroleum water accommodated

Advance in the toxic effects of petroleum water accommodated
fraction on marine plankton
Zhibing Jiang, Yijun Huang, Xiaoqun Xu, Yibo Liao, Lu Shou, Jingjing Liu, Quanzhen Chen,
Jiangning Zeng
Laboratory of Marine Ecosystem Biogeochemistry, Second Institute of Oceanography, SOA,
Hangzhou 310012, China
Abstract: Recently, the impact of petroleum pollution on marine plankton has been
complemented by a great concern. This review summarizes the reports about toxic effects of oil
water accommodated fraction (WAF) on marine phytoplankton, zooplankton and early life stage
of animal. For the oil WAF, toxicants are mainly composed of the aromatic hydrocarbons, such as
the benzene hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) with 2–5 rings. The oil
WAF, especially the PAHs, can be accumulated in plankton due to their great lipophilic abilities,
and thus elicites various deleterious effects. Toxicological tests show that marine plankton is very
sensitive to the petroleum WAF, as the order of median effective/lethal concentration is merely
μg/L or mg/L. There are species and developmental stages differences of plankton tolerance to
petroleum WAF, and the toxicity of different oil WAF is various. Generally, its toxicity enhances
with increasing carbonic chain length and benzene ring number. Many studies on the acute and
sub-acute toxic effects of oil WAF have been done, however few researches on its chronic toxic
effects has been carried out till now. Besides, most reports focused on the levels from molecule to
individual, though very little work of petroleum toxic effects has ever been performed on the
marine plankton population or community levels. Therefore, it is necessary to continue these
studies in future.
Key words: petroleum pollution; water accommodated fractions; polycyclic aromatic
hydrocarbons (PAHs); phytoplankton; zooplankton; early life stage
1. Introduciton
With the rapid economic development and energy demand, petroleum import amount is
growing dramatically in China. Marine petroleum transportation and harbor throughput increase
year after year, causing the frequency oil spill accident. Besides, oil pollution discharge from ship
and crude oil exploration gradually increase. So the risks of marine oil pollution become more and
more serious [1]. The import amount of crude oil was about 200 million in China in 2008
according to the statistics, above 90% of which was transported by sea. The realization of China’s
Petroleum Strategy Reservation Plan and the increase of crude oil demand in future will accelerate
the oil transportation amount by sea. Therefore, the risks of marine oil pollution will continuously
climbing in China, and the problem of marine ecological safety can not be optimistic. China
marine environmental quality communique in 2008 [2] showed that oil still was the one of three
main pollutant (the other two were nitrogen and phosphorus) in coastal areas, especially in some

Corresponding author.
Email address: [email protected] (J. Zeng).
important half blocked bay with less water exchange. This ecological risk due to the long term
accumulation of oil pollution is severe and can not be ignored [3].
Marine phytoplankton, as the most important primary productivity, can offer food to
zooplankton and larvae and juvenile fish [4]. Zooplankton can influence or control the primary
productivity by top-down effects [5] in return, and its population dynamic change can influence
the biomass of other marine animals like fish by bottom-up effects [6]. Once the community of
plankton changed by the effects of oil pollution, the structure, stability and function of marine
ecological system can be changed as well [7]. It is necessary and crucial to study the impact of oil
pollution to marine plankton in view of the serious oil pollution of coastal areas in China and the
ecological system function and status of marine plankton. Current researches focus on the impact
of crude oil water accommodated fraction (WAF) to marine phytoplankton [8–11], zooplankton
[12,13], and animals in early life stages [14,15]. This paper summarized the research results about
the influence of oil WAF on marine plankton both at home and abroad, and prospected the study
points in future, to further promote the quantified evaluation of the damage by oil pollution to
marine ecology.
1. The composition and main toxic substances of marine petroleum WAF
Petroleum (crude oil) is a complex mixture that consisted of hydrocarbon (including alkanes,
cycloalkanes and aromatic hydrocarbons) and non-hydrocarbon (including resin and asphalt). A
series process of physics, chemistry and biology diversifications happen after crude oil entering
the ocean, including spread, evaporation, dissolution, emulsification, disperse, absorption,
sedimentation, biological decomposition and photo-oxidation [16]. These oil substances will be
partially physically transferred and biologically decomposed, and the rest will dissolve in the
seawater. Different kinds of crude and refined oil have different compositions, water solubilities
(generally  200×10−6 mg/L [17]), and WAF components. However, WAF is mainly constitute of
BTEX (the general term of benzene, toluene, ethylbenzene and xylene), alkylation of benzene
homologues, polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbon and some
unresolved complex mixtures (UCMs) through chromatogram [18]. The mainly toxic substances
are some aromatic hydrocarbons, such as BTEX and PAHs. The PAHs in WAF are mostly 2–5
rings [18] and the PAHs with  6 rings are little, because the rest PAHs with more rings can not
dissolve in water for their highly lipophilic ability (high logKow value). Heterocyclic compounds
of N, P, S in petroleum also has contribution on the toxicity, such as thiophene and its alkylated
homologues, quinoline, acridine and other components with high water solubility and toxicity
[19]. And these heterocyclic compounds can be gradually accumulated in the process of oil
weathering [20]. But, generally speaking, the heterocyclic compounds are much less than BTEX
and PAHs in oil [21], so they are relatively lowly toxic in the total toxicity. The resin and asphalt
are hard for the living organism absorption, due to their high molecular weight (700–1000 of resin
and 1000–10000 of asphalt [22]). So they are also less toxic to marine plankton. The PHAs with >
2 rings mainly have chronic toxic effects to the environmental damage and organism hurt [23,24],
for they are difficultly decomposed [25]. The BTEX and the naphthalene with 2 rings and its
homologues have acute toxic effects, due to their high concentration and water solubility and
easily volatile that can not stay long in the water [25].
2. The toxic effects of oil WAF to marine phytoplankton
Different kinds of oil WAF have different toxicity to phytoplankton, and generally, the longer
the carbon chain is, the more benzene ring has, and the more toxic the oil is. The order of
toxicity (Table 1) to phytoplankton usually is ortho xylenes > toluene [10], benzo (a) pyrene (5
rings) > pyrene and fluoranthene (4 rings) > anthracene and the phenanthrene (3 rings) >
naphthalene (2 rings) > BTEX (1 ring) [10,26–29], heavy oil > light oil [30,31], aromatic
hydrocarbons > alkanes [31]. Besides, different phytoplankton species has different tolerance to
oil WAF toxicity, representing different median effective concentration (EC50) of growth
(Table1). Phytoplankton community happen abnormal succession under the stress of oil pollution
that the dominant degree of less tolerant species gradually decreases, even vanishes, while more
tolerant species gradually become the dominant ones [8,9,31–33]. The field investigation after
oil spill accident of “TASMAN SEA” tanker showed that diversity of phytoplankton community
decreased around the pollution area, and species number and cell density reduced to 1/2 of
pre-accident, especially diatom, the dominant species in population, its species number climbed
down from 40 to 18. Contrarily, the species number of dinoflagellates did not change [1].
Table 1
EC50 of growth inhibition for different phytoplankton species under different toxicants exposure
Species
Toxicant
72h-EC50
Pheodactylum tricornutum
Phenanthrene
154 ± 3.1 μg/L
Anthracene
123 ± 5.5 μg/L
Fluoranthene
103 ± 9.1 μg/L
Pyrene
119± 1.2 μg/L
Phenanthrene
47 ± 5.5 μg/L
Anthracene
39 ± 2.4 μg/L
Fluoranthene
18 ± 2.9 μg/L
Pyrene
24 ± 2.0 μg/L
Fluoranthene
1031 μg/L
Pyrene
260.3 μg/L
Benzo(a)pyrene
55.24 μg/L
Cyclotella caspia
Fluoranthene
0.20 mg/La
[29]
Chlorella uvlgaris
0# Fuel oil WAF
12.11 mg/L
[30]
0# marine fuel oil WAF
12.22 mg/L
Heavy fuel oil WAF
18.73 mg/L
BTEX
62.91% WAF a
mixture of aromatics with C9-C11
28.59% WAF a
Raw naphtha
27.84% WAF a
Light naphtha
28.59% WAF a
Heavy naphtha
4.91% WAF a
mixture of aromatic hydrocarbons of C9
4.79% WAF a
mixture of C6-C8 hydrocarbons, paraffin and isoparaffin
19.92% WAF a
Toluene
34.10–114.00mg/L
Naphthalene
3.90–7.30 mg/L
Ortho xylenes
1.69–3.03 mg/L
Skeletonema costatum
Thalassiosira pseudonana
Tetraselmis chuii
Zooxanthella
croadriz
tica,
P.
tricornutum,
Nitzschia closterium
minutissima, S. costatum, C. uvlgaris,
Reference
[26]
[27]
[28]
[31]
[10]
Platymonas subcordiformis

Phenanthrene
0.60–1.92 mg/L
Unmarked letter indicated 72h-EC50; a: exposure duration for 24 h
Both laboratory researches and field investigations showed that low concentration of WAF in
seawater had less influence on phytoplankton, even could promote its growth [9,34,35]. The
stimulative effects were related to the bacteria in water and algae itself [34,35]. The bacteria
would decompose the oil WAF to the algae utilized carbon. And some species of phytoplankton,
such as Chlamydomonas, Chlorella, Navicula, Nitzschia and Cyclotella, could decompose WAF
by themselves and realize the biological transformation [29,36,37], consequently achieve the
biological restoration of oil pollution area. But if the oil concentration was too high, it could
restrain the algae growth [11,38,39]. Therefore, it is worthy of being discussed that how much the
concentration was low or high need the experiments to judge. Whether the degrees of oil pollution
in China can influence coastal phytoplankton community, and if the influence exits, how much the
influence is in different seasons, and whether such influence can cause the decreasing species
diversity, dominance change, or community abnormal succession.
Oil WAF accumulated in the phytoplankton cells [40], suppressed their photosynthesis by
reducing the primary photochemical yield, electron transport capacity, the activity of release
oxygen center and photosystem II. Meanwhile respiration of phytoplankton enhanced, compelling
the increase of energy expenditures [41]. WAF also could block the absorption of CO2 and
nutrients, leading to the decreasing chlorophyll a and reduce of primary productivity [33,42]. Oil
WAF would destroy the cell structure and membrane system of microalgae [43], disturb the
operation of anti-oxidation defence system [41,44], stop the synthesis of nucleic acid and protein
[45], even induce the cell abnormality [29,46] and gene mutation [28]. Researches showed that oil
WAF would damage DNA structure or cause the DNA adduct formation of microalgae
cells[28,47], prevent the replication of DNA, thus cells could not divide or proliferate, leading to
the augment of cell size [33,48]. But Wang et al. [49] found that oil WAF did not make the
granularity of Chaetoceros curvisetus increase, and the reasons needed the further study.
3 The toxic effects of oil WAF to marine zooplankton
Generally, the toxicity of oil WAF enhances with the increment of carbon chain and benzene
ring (Table 2 and 3). The order of toxicity to the same species of zooplankton were
dimethylnaphthalene > methylnaphthalene > naphthalene [50,57], pyrene and fluoranthene >
anthracene and philippines > naphthalene [51,54], and kerosene > gasoline > diesel oil > crude oil
[15]. But Wang et al. [53] found that the toxicity of anthracene and philippines was stronger than
pyrene and fluoranthene, as artemia nauplii being the study object. Besides, the tolerance of
zooplankton to oil WAF has the species differences as well as growth and development stage
differences. For example, the median lethal concentration (LC50) of naphthalene and its
homologue to Oithona davisae [57] was greatly higher than to Paracartia grani [50], the LC50 of
fluoranthene to nauplius, adult and egg of Tisbe battagliai were 68.3, 101.1 and 86.2 μg/L,
respectively [52]. On the aspect of acute lethal, oil WAF can cause the activity decrease and
non-polarity narcotic coma, even to death, by affecting the lipid membrane fluidity of
zooplankton, and interrupting operation of physiological and biochemical system[58–60]. On the
other aspect of sub-acute and chronic lethal, oil WAF will disturb zooplankton feeding, spawning,
hatching, growth, development and behavior (Table 2), consequently bring out the long negative
effect to the population activity and continuity. Bejiarano et al. [62] took the experiments that
Amphiascus tenuiremis was exposed in South Louisiana crude oil for three generations, and they
found that the population exhibited abnormal growth and development, and the reproduction and
population yield both greatly reduced. Currently, there are few researches about the chronic
toxicity of oil WAF to zooplankton and its effect to the population and community. So assessment
of population damage caused by oil pollution was lack of basis. The toxicity experiments are quite
needed to study the effects to the full lifecycle, and the mesocosm experiment are highly
demanded to research the response of population and community level to oil pollution. It is not
difficult to measure the toxicity of whole lifecycle of zooplankton, for their short generations and
being easily controlled.
Table 2
EC50 of feeding, spawn and hatch for different copepod species under different toxicants exposure
Species
Toxicant
EC50
EC50
Feeding rate
Paracartia grani
1264 μg/L
Naphthalene
1,2-dimethylnaphthalene
Acartia tonsa
μg/L a
―
Fluoranthene
Tisbe battagliai
146
a
EC50
Clutch size
2096
254
Hatching rate
μg/L a
―
μg/L a
87.58
Reference
[50]
―
μg/L b
77.87 μg/L b
μg/Lb
Phenanthrene
―
253.98
Pyrene
―
61.89 μg/L b
59.67 μg/L b
Fluoranthene
34.0 μg/L c
66.9 μg/L d
63.4 μg/L e
180.37
[51]
μg/Lb
[52]
A: 24h-EC50; b: 48h-EC50; c: Exposure time = 2–4 d; d: 6d-EC50; e: Exposure time >4 d
Table 3
LC50 of different zooplankton species under different toxicants exposure
Species
Life stage
Toxicant
48h-LC50*
A. tonsa
Adult
Fluoranthene
120.14 μg/L
Phenanthrene
105.87 μg/L
Pyrene
>129.45 μg/L
Naphthalene
2523 μg/L a
P. grani
T. battagliai
Artemia salina
Mysidopsis bahia
M. bahia
Adult
Nauplii
1,2-dimethylnaphthalene
161
Fluoranthene
68.3 μg/L b
101.1 μg/L
Egg
86.2 μg/L c
Larvae (24–48 h)
―
Phenanthrene
[51]
[50]
μg/L a
Adult
II–III instar nauplii
Reference
[52]
c
1320.7±19.8 μg/L a
Anthracene
1009.5±37.5
Fluoranthene
1430.5±13.4 μg/L a
Pyrene
1770.6±213.1 μg/L a
Anthracene, Fluoranthene, and Pyrene
535, 63.8, and 24.8 μg/L
2#
548 μg/L
Fuel oil (TPAHs) WAF
[53]
μg/L a
Arabian Light Crude oil (TPAHs) WAF
139 μg/L
Prudhoe Bay crude oil (TPAHs) WAF
157 μg/L
Weathered Guadalupe oil WAF (TPHs)
0.92 (0.71–1.14) mg/L d
[54]
[55]
M. bahia
<1d
Ampelisca abdita
Juvenile
Oithona davisae
Nauplii
Adult
Calanus sinicus
―
Fluoranthene
[56]
67 (59–76) μg/L e
Naphthalene
4422 (3942–4961) μg/L a
1,2-Dimethylnaphthalene
771 (759–784) μg/L
Naphthalene
>10 mg/L a
1,2-Dimethylnaphthalene
1346 (1047–1732) μg/L a
Daqin crude oil WAF
19.8 mg/L
Diesel oil WAF
15.8 mg/L
70#
6.1 mg/L
Gasoline WAF
Kerosene WAF

31 (22–41) μg/L e
[57]
a
[15]
3.5 mg/L
Unmarked letter indicated 48h-LC50; a: 24h-LC50; b: Exposure time > 4 d; c: 6 d-LC50; d: 7d-LC50; e: 96h-LC50; WAF: Water
accommodated fraction; TPAHs: Total polycyclic aromatic hydrocarbons; TPHs: Total petroleum hydrocarbons
Traditionally considering, PAHs with more benzene rings and higher molecular weight are
not much in the water, due to the low solubility [18], and usually sinking to the seafloor with
organic matters. However, lately researches showed that PAHs still stay in the seawater for a
relatively high concentration [32,63]. Oil WAF mostly are strongly lipophilic [58], so the organic
compounds (especially PAHs) of WAF can be accumulated in the body of marine zooplankton
with high body fat [64] by utilizing the routes of feeding and surface contact [65,66], which is
definitely no good to the zooplankton. Even if exposed in the low concentration of oil WAF,
zooplankton also will behave abnormally that feeding rate is decreasing [13,50,52] while oxygen
consumption is increasing [67]. Then the content of carbohydrates, protein and fat, and the
activity of electronic energy transfer system are affected, and the balance of energy budget is
broken [68], thus leading to the abnormal growth and development, and the decrease of growth
and breeding rate [51,62,69].
4. The toxic effects of oil WAF to marine fauna in early life stage
The early life stage of marine animals refers to the animals’ development from the fertilized
egg to planktonic larvae. The fertilized eggs and planktonic larvae of marine animals, for their
special ecological status and economic function, are classified as another group of zooplankton in
this paper. Large quantities of oil WAF can be accumulated in the yolk of fertilized eggs [59,70,71]
for its strong lipophilic ability [58]. Thus, there are high concentrations of PAHs in the original
embryonic development stages of marine fauna. When the animals began to develop and the
embryo assimilated the necessary nutrients from the yolk sac, PAHs began to disperse inevitably
into the embryo, affecting its physiological and biochemical processes of early development [72],
then affecting embryo development, and organ differentiation and formation [70,73,74]. Since
early life stage of marine fauna involved most of life processes, including cleavage, growth, basic
metabolism and synthesis, organ differentiation, formation and development etc., it was more
sensitive to pollution in the early life stage than any other life stages. Therefore, it was considered
as the most important and crucial stages of life. Base on it, the fertilized eggs and larvae are
widely used in marine toxicity test (Table 4 and 5).
Table 4 and 5 showed that most kinds of fertilized eggs, embryos, and larvae of marine fauna
was sensitive to the oil WAF, because their unit of LC50 and EC50 were only μg/L or mg/L.
Different origins, efflorescence degrees [70] and kinds [54,8,77] of oils were different in their
toxicities. But generally, the toxicity of oil WAF to the embryos and larvae enhances with the
increasing of carbon chain and benzene rings. Also the tolerances of embryos and larvae to oil
WAF were different among species and developmental stages [8,54,77]. Besides the lethal effects,
more serious circumstances was that oil WAF could also cause the conformation deformities and
developmental abnormalities to the early life stages of marine animals. Take the larval fish for
example [70], oil WAF would cause the reduced hatching rate, developmental malformations
(such as spinal curvature and yolk sac edema), membrane phase delay, decrease or loss of feeding
and swimming ability, growth inhibition, interference with nervous system function, decreased
immunity, as well as increased risk of predation, etc.; As in the case of shellfish [54,73,74], it
could result in reduce or deformity of D-veliger, failure of larval metamorphosis, inhibition of
growth and development, etc. (Table 5). Carls et al. [70] studies showed that > 0.4 μg/L of TPAH
concentrations could multiple the occurrence frequency of yolk sac edema, and > 0.7 μg/L of it
could lead to reduced of fish body length, and rapidly increased of yolk sac edema and spinal
deformities. These sub-acute or chronic toxic effects were bound to influence the maintenance and
continuance of marine animal populations.
Table 4
LC50 of different marine fauna (Early life stage) species under different toxicants exposure
Species
Life stage
Toxicant
96h-LC50
Reference
Palaemonetes pugio
Larvae (< 48 h)
Fluoranthene
2.53 (2.14–2.58) μg/L
[71]
Benzo(a)pyrene
1.02 (0.83–1.26) μg/L
Melanotaenia fluviatilis
Egg
Bass Strait crude oil (TPHs) WAF
1.28 (1.0–1.6) mg/L
Naphthalene
0.51 (0.4–0.7) mg/L
[75]
Homarus americanus
Larvae
Fluoranthene
317 (166–378) μg/L
Clupea Pallasi
Egg
Less-weathered Alaska North Slope crude oil WAF
53.3 ± 3.6 μg/L
Anthracene, Fluoranthene, and Pyrene
4260, 58.8, and >11900 μg/L
Mulinia lateralis
egg
Sparus macrocephalus
Pagrasomus major
larvae
0#
(15–20 mm)
20#
Diesel oilWAF
Diesel oil WAF
[14]
3.02 (1.95–4.47) mg/L
3.55 (2.51–3.98) mg/L
larvae
0#
0.71 (0.54–1.07) mg/L
(18–22 mm)
20#
Diesel oil WAF
Diesel oil WAF
3.16 (2.19–4.57) mg/L
South China Sea crude oil WAF
5.89 (4.07–8.51) mg/L
Shengli crude oil WAF
6.4 (4.9–8.5) mg/L a
Paralichthys olivaceus
13.7 (12.3–15.2) mg/L
S. macrocephalus
10.7 (7.5–15.1) mg/L a
 Unmarked
[54]
a
0.28 (0.23–0.35) mg/L
South China Sea crude oil WAF
larvae (3–5 d)
[70]
a
>13300, 3310, and >9454 μg/L
Larvae and juvenile
Penaeus monodon
[56]
[77]
a
letter indicated 96h-LC50; a: 48h-LC50; WAF: Water accommodated fraction; TPHs: Total petroleum hydrocarbons
Table 5
EC50 of different marine fauna (Early life stage) species under different toxicants exposure
Species
Life stage
Toxicants
Index
48h-EC50
References
Mytilus
Egg–D-veliger
Naphthalene
Percentage of D-veliger
9.92 (9.36–11.77) mg/L
[73]
galloprovincialis
Phenanthrene
224.21 (173.42–298.89) μg/L
Ciona intestinalis
Paracentrotus
Egg–Tadpole larvae
Egg–Pluteus
lividus
M.
Percentage of tadpole
4.28 mg/L
Phenanthrene
larvae
>427.75 μg/L
Naphthalene
Larval growth
558.82 (483.20–645.98) μg/L
418.16 (366.64–512.23) μg/L
Phenanthrene
Eggs–D-veliger
galloprovincialis
P. lividus
Naphthalene
Prestige fuel oil WAF
Percentage of D-veliger
Marine fuel oil WAF
Egg–Larvae
―
Prestige fuel oil WAF
Weathered
Guadalupe
[74]
> 100% WAF
Larval length
Marine fuel oil WAF
M. bahia
17 (16.9–17)% WAF
11 (9–14)% WAF
58 (38–88)% WAF
oil
WAF
Dry weights
0.21 mg/L a
Spinal abnormality
33.5±3.1 / 3.60±0.55 μg/L b
Yolk sac edema
19.6±1.6 / 0.77±0.16 μg/L
Small jaw
22.3±1.4 / 1.00±0.21 μg/L b
Effective swimmers
18.4±1.1 / 2.44±0.29 μg/L b
Dry weight
>11900, 900, and >9454 μg/L c
[55]
(TPHs)
C. pallasi
Egg–Larvae
Less-/more-weathered Alaska North
Slope crude oil (TPAHs)
Mulinia lateralis
Juvenile
Anthracene, Fluoranthene, and Pyrene
2# Fuel
oil (TPAHs) WAF
806
[70]
b
[54]
μg/L c
118 μg/L c
Arabian Light Crude oil (TPAHs)
WAF
>2540 μg/L d
Prudhoe Bay Crude oil (TPAHs) WAF
Hemicentrotus
Egg–Pluteus
Marine heavy fuel oil WAF
0# Diesel
pulcherrimus

Larval growth
oilWAF
2.71 (2.21–3.32) mg/L c
1.87 (1.69–2.06) mg/L
Unmarked letter indicated 48h-EC50; a: 7d-EC50; b: 16d-EC50; c: 96h-EC50; d: 72h-EC50; WAF: Water accommodated fraction;
TPAHs: Total polycyclic aromatic hydrocarbons; TPHs: Total petroleum hydrocarbons
5. The toxicity and detoxification mechanism of oil WAF to marine plankton
Quantitative structure–activity relationship (QSAR) studies show that the toxicity of organic
compounds depends primarily on the accumulation capacity in organisms and the ability to
interact with the receptors [79]. Oil WAF toxicity mechanism to plankton approximately is that:
most WAF are strongly lipophilic, and the fat contents are usually high in the body of marine
plankton [63]. Thus, quantities of these organic compounds (especially PAHs) are accumulated in
marine plankton [22,40,66], affecting the physiology, biochemistry, behavior, reproduction,
growth, development and survival. PAHs with 2–3 rings showed strongly acute toxicity, but
generally no carcinogenic effect, while PAHs with 4–5 rings showed strongly effects of
carcinogenicity, teratogeny and genetic mutation, not the acute toxicity [80]. Currently, the
theories on the carcinogenic mechanism of PAHs are mainly K-region theory, Bay-region theory,
and Di-region theory etc., but all of which have not yet been completely clarified [80].
The toxicity mechanisms of BTEX and PAHs to plankton are non-acute anesthesia, adduct
formation, reactive oxygen free radicals, and endocrine disruption [69]. The different components
have different toxic mechanisms. For instance, BTEX and the naphthalene with 2 rings mostly
operate by the anesthesia [59] or Lipid-partitioning mechanisms [81], while PAHs with 3–5 rings
work mainly by the metabolism-driven approach [70], including the generation of reactive oxygen
species (ROS) from cells under the oxidative stress and the toxic intermediates or metabolites
induced by system of cytochrome P-450 monooxygenase (also known as Mix-function oxidase,
d
[78]
MFO) [82,83]. At present, the knowledge about toxicities of PAHs with small ring and multiring
still have uncertainties [84,85], existing additive effects [60] as well as antagonistic and
synergistic effects [69]. In general, BTEX and PAHs into the organisms are formed into the
aromatic rings oxide and ROS by MFO catalyzation, and then come into being aromatic
hydrocarbon dihydrodiol diol derivatives by hydrolysis of hydrase, which can form the
carbocation with electrophilic [86,87], binding to guanine N-2 of DNA molecule forming. Then
DNA adducts are formed by DNA alkylation, leading to the change of the DNA base structure,
consequently resulting in the genetic code change, causing mutations, and finally inducing the
cancer [80]. At the mean while, ROS may damage proteins, lipids, DNA and other biological
macromolecules [88], then bringing about the distortion.
The detoxification processes of oil WAF in vivo are constituted of Phase I reaction and Phase
II reaction. Phase I reaction: the lipophilic oil WAF catalyzed by MFO is transformed into more
polar material by the introduction of the corresponding reactive bases through a series of
oxidation, hydrolysis and reduction reactions, in order to create the conditions for Phase II
reaction. Phase II reaction is to combine the exogenous substances (oil WAF) and its metabolic
intermediates (like aromatic ring oxide) with some endogenous substances, which is catalyzed by
glutathione S-transferase. So oil WAF and its intermediates are more hydrophilic and easily
eliminated from the body. However, PAHs with 4–5 rings, originally as an indirect carcinogen,
can be the metabolic intermediates (PAH epoxide) with carcinogenic effect and the ultimate
carcinogen (dihydrodiol diol epoxy PAH) in this process [80]. It is obvious that the toxicity of oil
WAF can be reduced or eliminated by the bio-transformation on the one hand, but may increase
on the other hand. PAHs can be eliminated out of the body by the fast and effective metabolism
through the active MFO system in vertebrates, but accumulated in the body of invertebrates lack
of MFO system activity [85]. Marine plankton, except the larval fish as vertebrates, most are
invertebrates. Moreover, larval fish are not fully developed. Therefore, the low concentration of
PAHs can also bring about the damage to them [70].
6. Problems and prospect
The low concentration of oil WAF can lead to some species microalgae bloom, for the
phytoplankton has short life cycle and rapid generation turnover. At the mean while, other
consumers, such as the zooplankton with the longer generation alternation, have poor tolerance to
oil pollution. So the biomass need a longer term to recover, resulting in the top-down effects
weakening or loss of control [8,9,42]. In such mismatch effect of circumstances, once the
nutrients and other physical and chemical factors are desirable and adequate, red tide may be
triggered around the oil pollution area [89], such as the outbreak of Huanghua red tide in 1989
[90]. Therefore, we should take full account of the relationship between oil pollution and red tide
outbreaks.
It was reported that certain single toxicants of oil WAF were usually tested on plankton to
value the biological toxicity, but the conclusions of this method were often different from the real
situation, for the actual toxicities of oil, as a complex mixture of toxic ingredients with different
proportion of each components [18], were far more complex than the single toxicant under the
effects of mixed-toxic additive, antagonistic or synergies [23]. The researchers had disputes on the
combined toxicity of mixed PAHs to plankton. So the complex mechanisms of toxicities are still
needed for the further study, and the methods of QSAR and experimental ecology are necessarily
utilized to verify the results. In addition, WAF toxicological test can also be applied for the more
accurate assessment of petroleum pollution to plankton.
At present, the toxicities of oil WAF on marine plankton mostly focused on the acute or
sub-acute researches, few on the chronic ones. And most of these toxic studies emphasized on the
levels of biochemical, molecular, sub-cells, cells, tissues, organs and individual, few on the
aspects of populations or communities. Actually however, study the impact of toxins on the
individual is to better study the population effects, for the primary objective of ecotoxicology is to
ensure the populations durative and vigor in ecological communities [88]. Therefore, the impact
of oil WAF to the maintenance and activity of marine plankton population are needed to be
emphasized for the future study.
Many works had been taken about the impact of oil pollution to marine plankton in global.
However, few studies were found in China. And different species (populations) of plankton
respond to oil pollution differently. Therefore, it is necessary to continuously carry out the
toxicological response of plankton species, populations and communities to oil WAF in China's
coastal areas, in order to provide the scientific basis for the quantitative evaluation of marine
biological resources and ecological loss caused by the oil spill and oil pollution.
The studies about oil WAF toxic effects on marine plankton mostly were carried out under
the laboratory light conditions, not under the simulated sunlight so far. However, a large number
of studies showed that the ultraviolet radiation from sun significantly enhanced the toxicity of oil
WAF on plankton [26,47,71,74], which was called “phototoxicity”. Obviously, the results of
laboratory experiments without the measurement of UV radiation to predict the oil WAF impact
on marine life often would underestimate the toxic effects of oil pollution under the natural light
and lead to the underassessment of ecological damage caused by oil spills and pollutions.
Acknowledgements
The project was financially supported by National Basic Research Program of China (No.
2010CB428903), Scientific Research Fund of Second Institute of Oceanography, SOA, China
(JG0921, JT0806), National Marine Public Welfare Research Project of China (No. 200805069),
National Special Fund of China (908-01-BC06, 908-02-04-02, 908-ZC-II-04), and SOA Special
Fund of China (No. 2011914).
References:
[1]
Gao Z H, Yang J Q, Wang P G, et al. Theory, method and case study of the ecological risk assessment of
marine oil spill. Beijing: Ocean Press, 2007
[2]
State Oceanic Administration. China marine environmental quality communique in 2008. Beijing: Ocean
Press. 2009
[3]
W G Cai, Lin Q, Jia X P, et al. Integrated model-based analysis on the pollution status of petroleum
hydrocarbons in Kaozhou Bay. Acta Ecologica Sinica, 2005, 25(10): 2669–2675.
[4]
Behrenfeld M J, O’Malley R T, Siegel D A, et al. Climate-driven trends in contemporary ocean productivity.
Nature, 2006, 444: 752–755.
[5]
Yang Y F, Wang Q, Chen J F, et al. Research advance in estuarine zooplankton ecology. Acta Ecologica
Sinica, 2006, 26(2): 576–585.
[6]
Beaugrand G. Brander K M, Lindley J A, et al. Plankton effect on cod recruitment in the North Sea. Nature,
2003, 426: 661–664.
[7]
Duffy J E, Stachowicz J J. Why biodiversity is important to oceanography: potential roles of genetic, species,
and trophic diversity in pelagic ecosystem processes. Mar. Ecol. Prog. Ser., 2006, 311: 179–189.
[8]
Tang S M, Chen X L, Zhuang D F. Study on the effect of petroleum dispersant BP-1100X to marine
enclosure ecosystem. Acta Ecologica Sinica, 1992, 12(4): 361–367.
[9]
Shi X, Wang X, Han X, et al. Relastionship between petroleum hydrocarbon and plankton in a mesocosm
experiment. Acta Oceanologica Sinica, 2001, 20(2): 231–240.
[10] Jiang Y, Wu Z H, Han X R, et al. Toxicity of polycyclic aromatic hydrocarbons (PAHs) to marine algae.
Marine Sciences, 2002, 26(1): 47–50.
[11] Li K Q, Wang X L, Zhu C J, et al. Ecological effects of No.0 diesel water accommodated fraction on marine
algae. Environmental Science, 2007, 28(2): 304–308.
[12] Xu H G, Yang B. Effects of crude and refined oil on the survival of plankton copepods Calanus sinicus.
Marine Environmental Science, 1983, 2(2): 55–59.
[13] Jensen M H, Nielsen T G, Dahllöf I. Effects of pyrene on grazing and reproduction of Calanus finmarchicus
and Calanus glacialis from Disko Bay, West Greenland. Aquat. Toxicol., 2008, 87(2): 99–107.
[14] Jia X P, Lin Q, Cai W G, et al. Toxicity of crude oil and fuel oils to important mariculture and multiplication
organisms of South China Sea. Journal of Fisheries of China, 2000, 24(1): 33–37.
[15] Perkinsa R A, Rhoton S, Behr-Andresc C. Comparative marine toxicity testing: a cold-water species and
standard warm-water test species exposed to crude oil and dispersant. Cold Reg. Sci. Technol., 2005, 42(3):
226–36.
[16] Sun P Y, Gao Z H, Cui W L, et al. Development and application of the oil finger identification. Beijing:
Ocean Press. 2007.
[17] Wang Z, Fingas M. Oil and petroleum product fingerprinting analyses. In: Nollet L M (Ed.),
Chromatographic Analysis of the Environment, Third Edition. 2006.
[18] Faksness L-G, Brandvik P J, Sydnes L K. Composition of the water accommodated fractions as a function of
exposure times and temperatures. Mar. Pollut. Bull., 2008, 56(10): 1746–1754.
[19] Connell D W, Miller G. J. Petroleum hydrocarbons in aquatic ecosystems—behavior and effects of sublethal
concentrations: part 2. CRC Critical Rev. Environ. Control, 1981, 11: 105–162.
[20] Sauer T C, Uhler A D. Pollutant source identification and allocation: advances in hydrocarbon fingerprinting.
Remediation Winter, 1994, 25–50.
[21] Barron M G, Podrabsky T, Ogle S, et al. Are aromatic hydrocarbons the primary determinant of petroleum
toxicity to aquatic organisms? Aquat. Toxicol., 1999, 46(3–4): 253–268.
[22] Wright D A, Welbourn P. Environmental Toxicology. Cambridge University Press, Cambridge, UK. 2002,
301–302.
[23] Holdway D A. The acute and chronic effects of wastes associated with offshore oil and gas production on
temperature and tropical marine ecological process. Mar. Pollut. Bull., 2002, 44(3): 185–203.
[24] Peterson C H, Rice S D, Short J W, et al. Long-term ecosystem response to the Exxon Valdez oil spill.
Science, 2003, 302: 2082–2086.
[25] Short J. Long-term effects of crude oil on developing fish: lessons from the Exxon Valdez oil spill. Energy
Sources, 2003, 25(6): 509 – 517.
[26] Wang L, Zheng B, Meng W. Photo-induced toxicity of four polycyclic aromatic hydrocarbons, singly and in
combination, to the marine diatom Phaeodactylum tricornutum. Ecotoxicol. Environ. Saf., 2008, 71(2): 465
– 472.
[27] Meng W, Wang L, Zheng B. Photoinduced toxicity single and binary mixtures of four polycyclic aromatic
hydrocarbons to the marine diatom Skeletonema costatum. Acta Oceanologica Sinica, 2007, 27(6): 41–50.
[28] Bopp S K, Lettieri T. Gene regulation in the marine diatom Thalassiosira pseudonana upon exposure to
polycyclic aromatic hydrocarbons (PAHs). Gene, 2007, 396(2): 293–302.
[29] Liu Y, Luan T, Lu N, et al. Toxicity of fluoranthene and its biodegradation by Cyclotella caspia alga. J. Integ.
Plant Biol., 2006, 48(2): 169–180.
[30] Liu N, Xiong D Q, Gao H, et al. Study on acute toxicity of three fuel oil to marine Chlorella. Marine
Environmental Science, 2006, 25(supp.1): 29 – 32.
[31] Paixão J F, Nascimento I A , Pereira S A, et al. Estimating the gasoline components and formulations toxicity
to microalgae (Tetraselmis chuii) and oyster (Crassostrea rhizophorae) embryos: an approach to minimize
environmental pollution risk. Environ. Res., 2007, 103(3): 365–374.
[32] Hjorth M, Vester J, Henriksen P, et al. Functional and structural responses of marine plankton food web to
pyrene contamination. Mar. Ecol. Prog. Ser., 2007, 338: 21–31.
[33] Sargian P, Mas S, Pelletier E, et al. Multiple stressors on an Antarctic microplankton assemblage: water
soluble crude oil and enhanced UVBR level at Ushuaia (Argentina). Polar Biol., 2007, 30(7): 829–841.
[34] Ohwada K, Nishimura M, Wada M, et al. Study of the effect of water-soluble fractions of heavy-oil on
coastal marine organisms using enclosed ecosystems, mesocosms. Mar. Pollut. Bull., 2003, 47(1–6): 78–84.
[35] Nayar S, Goh B P L, Chou L M. Environmental impacts of diesel fuel on bacteria and phytoplankton in a
tropical estuary assessed using in situ mesocosms. Ecotoxicology, 2005, 14(3): 397 – 412.
[36] Semple K T, Cain R B, Schmidt S. Biodegradation of aromatic compounds by microalgae. FEMS Microbiol.
Lett., 1999, 170(2): 291–300.
[37] Juhasz A L, Naidu R. Bioremediation of high molecular weight polycyclic aromatic hydrocarbons: a review
of the microbial degradation of benzo[a]pyrene. Int. Biodeter., Biodeg., 2000, 45(1–2): 57–88.
[38] Fiala M, Delille D. Annual changes of microalgae biomass in Antarctic sea ice contaminated by crude oil
and diesel fuel. Polar Biol., 1999, 21(6): 391–396.
[39] Hjorth M. Plankton stress responses from PAH exposure and nutrient enrichment. Mar. Ecol. Prog. Ser.,
2008, 363: 121–130.
[40] Wang X, Zhang J, Shi X, et al. Determination of toxicokinetic parameters for bioconcentration of
water-soluble fraction of petroleum hydrocarbon associated with No. 0 diesel in Changjiang estuary and
Jiaozhou Bay: model versus mesocosm experiments. Arch. Environ. Contam. Toxicol. 2002, 42(3): 272–279.
[41] Aksmann A, Tukaj Z. Intact anthracene inhibits photosynthesis in algal cells: a fluorescence induction study
on Chlamydomonas reinhardtii cw92 strain. Chemosphere, 2008, 74(1): 26–32.
[42] Koshikawa H, Xu K Q, Liu Z L, et al. Effects of the water-soluble fraction of diesel oil on bacterial and
primary production and the trophic transfer to mesozooplankton through a microbial food web in Yangtze
estuary, China. Estuar. Coast. Shelf Sci., 2007, 71(1 – 2): 68 – 80.
[43] Sikkema J, Bont J A M, Poolman B. Mechanisms of membrane toxicity of hydrocarbons. Microbiol. Rev.,
1995, 59(2): 201–222.
[44] Wang L, Zheng B. Toxic effects of fluoranthene and copper on marine diatom Phaeodactylum tricornutum. J.
Environ. Sci., 2008, 20(11): 1363–1372.
[45] Chen G, Xiao H, Tang X X. Responses of three species of marine red-tide microalgae to pyrene stress in
protein and nucleic acid synthesis. Marine Environmental Science, 2008, 27(4): 302–347.
[46] Wang L, Zheng B, Meng W. Photo-induced toxicity of four polycyclic aromatic hydrocarbons, singly and in
combination, to the marine diatom Phaeodactylum tricornutum. Ecotoxicol. Environ. Saf., 2008, 71(2):
465–472.
[47] Tang X X, Huang J, Wang Y L, et al. Interaction of UV-B Radiation and anthracene on DNA damage of
Phaeodactylum tricornutum. Acta Ecologica Sinica. 2002, 22(3): 375–378.
[48] Singh A K, Gaur J P. Effects of petroleum oils and their paraffinic, asphaltic, and aromatic fractions on
photosynthesis and respiration of microalgae. Ecotoxicol. Environ. Saf., 1990, 19(1): 8–16.
[49] Wang X L, Yang R J, Zhu C J. Studies on size effect on Chaetoceros curvisetus in different concentrations of
petroleum hydrocarbon. Periodical of Ocean University of China, 2004, 34(5): 849–853.
[50] Calbet A, Saiz E, Barata C. Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on the
marine copepod Paracartia grani. Mar. Biol., 2007, 151(1): 195–204.
[51] Bellas J, Thor P. Effects of selected PAHs on reproduction and survival of the calanoid copepod Acartia
tonsa. Ecotoxicology, 2007, 16(6): 465–474.
[52] Barata C, Baird D, Medina, et al. Determining the ecotoxicological mode of action of toxic chemicals in
meiobenthic marine organisms: stage-specific short tests with Tisbe battagliai. Mar. Ecol. Prog. Ser., 2002,
230: 183–194.
[53] Wang L P, Zheng B H, Meng W. Photo-induced toxicity of polycyclic aromatic hydrocarbons to the brine
shrimp Artemia Salina nauplii. Acta Scientiae Circumstantiae, 2008, 28(4): 748–754.
[54] Pelletier M C, Burgess R M, Hot K T, et al. Phototoxicity of individual polycyclic aromatic hydrocarbons
and petroleum to marine invertebrate larvae and juveniles. Environ. Toxicol. Cherm., 1997, 16(10):
2190–2199.
[55] Cleveland L, Little E E, Calfee RD, et al. Photoenhanced toxicity of weathered oil to Mysidopsis bahia.
Aquat. Toxicol., 2000, 49(1–2): 63–76.
[56] Spehar R L, Poucher S, Brooke L T, et al. Comparative toxicity of fluoranthene to freshwater and saltwater
species under fluorescent and ultraviolet light. Arch. Environ. Contam. Toxicol., 1999, 37(4): 496–502.
[57] Saiz E, Movilla J, Yebra L, et al. Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on
naupliar and adult stages of the marine cyclopoid copepod Oithona davisae. Environ. Pollut., 2009, 157(4):
1219–1226.
[58] van Wezel A P, Opperhuizen A. Narcosis due to environmental pollutants in aquatic organisms:
residue-based toxicity, mechanisms and membrane burdens. Crit. Rev. Toxicol., 1995, 25(3): 255–279.
[59] Di Toro D M, McGrath J A, Hansen D J. Technical basis for narcotic chemicals and polycyclic aromatic
hydrocarbon criteria. I. water and tissue. Environ. Toxicol. Chem., 2000, 19(8): 1951–1970.
[60] Barata C, Calbet A, Saiz E, et al. Predicting single and mixture toxicity of petrogenic polycyclic aromatic
hydrocarbons to the copepod Oithona davisae. Environ. Toxicol. Chem., 2005, 24(11): 2992–2999.
[61] Bejarano A C, Chandler G T, He L, et al. Individual to population level effects of South Louisiana crude oil
water accommodated hydrocarbon fraction (WAF) on a marine meiobenthic copepod. J. Exp. Mar. Biol.
Ecol., 2006, 332(1): 49–59.
[62] Bejarano A C, Chandler G T, He L, et al. Risk assessment of the NIST petroleum crude oil standard water
accommodated fractions (WAFs) on a meiobenthic copepod: further application of a copepod-based full
life-cycle bioassay. Environ. Toxicol. Chem., 2006, 25(7): 1953–1960.
[63] Yamada M, Takada H, Toyoda K, et al. Study on the fate of petroleum-derived polycyclic aromatic
hydrocarbons (PAHs) and the effect of chemical dispersant using an enclosed ecosystem, mesocosm. Mar.
Pollut. Bull., 2003, 47(1–6): 105–113.
[64] Lee R F, Hagen W, Kattner G. Lipid storage in marine zooplankton. Mar. Ecol. Prog. Ser., 2006, 307:
273–306.
[65] Carls M G, Short J W, Payne J. Accumulation of polycyclic aromatic hydrocarbons by Neocalanus copepods
in Port Valdez, Alsaka. Mar. Pollut. Bull., 2006, 52(11): 1480–1489.
[66] Wang X, Wang W X. Bioaccumulation and transfer of benzo[a]pyrene in a simplified marine food chain.
Mar. Ecol. Prog. Ser., 2006, 312: 101–111.
[67] Smith R L, Hargreaves B R. Oxygen consumption in Neomysis americana (Crustacea: Mysidacea), and the
effects of naphthalene exposure. Mar. Biol., 1984, 79(2): 109–116.
[68] Olsen G H, Sva E, Carroll J, et al. Alterations in the energy budget of Arctic benthic species exposed to
oil-related compounds. Aquat. Toxicol., 2007, 83(2): 85 – 92.
[69] Olmstead A W, LeBlanc G A. Joint action of polycyclic aromatic hydrocarbons: predictive modeling of
sublethal toxicity. Aquat. Toxicol., 2005, 75(3): 253–262.
[70] Carls M, Rice S, Hose J. Sensitivity of fish embryos to weathered crude oil: I. low-level exposure during
incubation causes malformations, genetic damage, and mortality in larval Paciffic herring (Clupea pallasi).
Environ. Toxicol. Chem., 1999, 18(3): 481–493.
[71] Weinstein J, Garner T R. Piperonyl butoxide enhances the bioconcentration and photoinduced toxicity of
fluoranthene and benzo[a]pyrene to larvae of the grass shrimp (Palaemonetes pugio). Aquat. Toxicol., 2008,
87(1): 28–36.
[72] Wassenberg D M, Di Giulio R T. Synergistic embryotoxicity of polycyclic aromatic hydrocarbon aryl
hydrocarbon receptor agonists with cytochrome P4501A inhibitors in Fundulus heteroclitus. Environ. Health
Persp., 2004, 12(17): 1658–1664.
[73] Bellas J, Saco-Álvarez L, Nieto Ó, et al. Ecotoxicological evaluation of polycyclic aromatic hydrocarbons
using marine invertebrate embryo–larval bioassays. Mar. Pollut. Bull., 2008, 57(6–12): 493–502.
[74] Saco-Álvareza L, Bellasa J, Nieto Ó, et al. Toxicity and phototoxicity of water-accommodated fraction
obtained from Prestige fuel oil and Marine fuel oil evaluated by marine bioassays. Sci. Total Environ., 2008,
394(2–3): 275–282.
[75] Pollino C, Holdway D A. Toxicity testing of crude oil and related compounds using early life stages of the
crimson-spotted rainbowfish (Melanotaenia fluviatilis). Ecotoxicol. Environ. Saf., 2002, 52(3): 180–189.
[76] Little, E E, Cleveland L, Calfee R, et al. Assessment of the photoenhanced toxicity of a weathered petroleum
to the tidewater silverside. Environ. Toxicol. Chem., 2000, 19(4): 926–932.
[77] Chen M S, Fan G Q. Toxicity effect of Shengli crude oil on the embryo and larva of marine fish. Marine
Environmental Science, 1991, 10(2): 1–5.
[78] Lv F R, Xiong D Q, Ding S Q, et al. Acute toxic effects of petroleum hydrocarbon water –accommodated
fractions on larvae development of Hemicentrotus pulcherrimus. Journal of Dalian Maritime University,
2008, 34(2): 24–27, 32.
[79] Lu G H, Yuan X, Zhao Y H. QSAR study on the toxicity of substituted benzenes to the algae. Chemosphere,
2001, 44(3): 437–440.
[80] Zhou Q X, Kong F X, Zhu L, et al. Ecotoxicology. Beijing: Science Press. 2004.
[81] Hansen B H, Altin D, Vang S-H, et al. Effects of naphthalene on gene transcription in Calanus finmarchicus
(Crustacea: Copepoda). Aquat. Toxicol., 2008, 86(2): 157–165.
[82] Brinkworth L C, Hodson P V, Tabash S, et al. CYP1A induction and blue sac disease in early developmental
stages of rainbow trout (Oncorhynchus mykiss) exposed to retene. J Toxicol Environ Health A, 2003, 66(7):
627–646.
[83] Bauder M B, Palace V P, Hodson P V. Is oxidative stress the mechanism of blue sac disease in
retene-exposed trout larvae? Environ.Toxicol. Chem., 2005, 24(3): 694–702.
[84] Altenburger R, Walter H, Grote M. What contributes to the combined effect of a complex mixture? Environ.
Sci. Technol., 2004, 38(23): 6353–6362.
[85] Hylland K. Polycyclic Aromatic hydrocarbon (PAH) ecotoxicology in marine ecosystems. J Toxicol Environ
Health A, 2006, 69(1): 109–123.
[86] Mitchelmorea C L, Birmelinb C, Chipmana J K, et al. Evidence for cytochrome P-450 catalysis and free
radical involvement in the production of DNA strand breaks by benzo[a]pyrene and nitroaromatics in mussel
(Mytilus edulis L.) digestive gland cells. Aquatic Toxicology, 1998, 41(3): 193–212.
[87] Warshawsky D, Cody T, Radike M, et al. Biotransformation of benzo[a]pyrene and other polycyclic
aromatic hydrocarbons and heterocyclic analogs by several green algae and other algal species under gold
and white light. Chem.-Biol. Interactions, 1995, 97(2):131–148.
[88] Newman M C, Unger M A. Fundamentals of ecotoxicology (Second Edition). Boca Raton, FL: Lewis
Publishers. 2003.
[89] Zhang C S, Wang X L, Shi X Y, et al. Distributions of COD and petroleum hydrocarbons and their
relationships with occurrence of red tide in East China Sea. Chinese Journal of Applied Ecology, 2003, 14(7):
1093–1096.
[90] Cheng Z B. The formation mechanism and harm of red tide in Huanghua city coast. Marine Science Bulletin,
1992, 11(1): 100–102.