No detected toxic concentrations in in situ algal growth inhibition tests—A convenient approach to aquatic ecotoxicology

Science of The Total Environment

Zhang

et al. 2016

Self Cite

• We tested petroleum hydrocarbon ecotoxicological effects on a simplified community.• Concentration-response relationships at a community-level were constructed.• A deduced no-effect concentration representing ecological interaction was named TCPE.• TCPE of petroleum hydrocarbons was higher than PNEC calculated from SSD.• Ecological interactions reduce toxic effect of petroleum hydrocarbons on a community. In this study, we developed a method to quantify and link the toxic effects in community-level ecosystems with concentrations of petroleum hydrocarbons. The densities of Platymonas helgolandica var. tsingtaoensis, Isochrysis galbana, and Brachionus plicatilis in single-species tests and customized ecosystems were examined in response to a concentration gradient of petroleum hydrocarbons ranging from 0 to 8.0 mg L −1 . A three-population ecological model with interspecies competition-grazing relationships was used to characterize population sizes with concentrations of petroleum hydrocarbons. A threshold concentration of the simplified plankton ecosystem of 0.376 mg L −1 for petroleum hydrocarbons was calculated from the proposed model, which was higher than the no-effect concentration of 0.056 mg L −1 derived from the single-species toxicity tests and the predicted no-effect concentration of 0.076 mg L −1 calculated from the species sensitivity distribution. This finding indicates that interspecies competition and grazing reduced the toxic effect of petroleum hydrocarbons at the community level. The sensitivity analysis for model parameters demonstrates that plankton population biomasses are highly sensitive to filtration rates. Antagonism between interspecies interactions and petroleum hydrocarbon toxicity was attributed to the reduced filtration rate and zooplankton grazing pressure. The proposed method is a simple G R A P H I C

Section: Model Constructionmentioning

confidence: 99%

Section: The Parameters In the Plankton Ecosystem Modelmentioning

confidence: 99%

Section: The Parameters In the Plankton Ecosystem Modelmentioning

confidence: 99%

Section: The Parameters In the Plankton Ecosystem Modelmentioning

confidence: 99%

Section: The Toxic Effects Of Petroleum Hydrocarbons On Plankton and mentioning

confidence: 99%

See 3 more Smart Citations

A method linking the toxic effects at community-level with contaminant concentrations

Science of The Total Environment

Zhang

et al. 2016

Self Cite

The Effects of Petroleum Hydrocarbons on Algae Can Be Reversed in the Presence of a Primary Consumer

Bull Environ Contam Toxicol

Yong

Liu

et al. 2015

Self Cite

The ecotoxicological effects of a mixture of petroleum hydrocarbons were tested on densities of two algae, Platymonas helgolandica var. tsingtaoensis and Isochrysis galbana, and of a rotifer, Brachionus plicatilis, by single-species and customized community experiments. Test concentrations ranged from 0 to 100 mg L(-1), while five to seven treatments were assessed in triplicate within 1 month. A significant decrease in densities during single-species toxicity tests were found when concentrations of petroleum hydrocarbons were above 1.0 mg L(-1). However, equilibrium densities of algae in the customized community showed a different pattern, which increased with concentration and reached a peak at 20.0 mg L(-1). The community-based no observed effect concentration (NOEC; 1.0 mg L(-1)) was different from the NOEC derived by single-species toxic tests (0.25 mg L(-1)). This demonstrates that ecotoxicological effects on plankton as part of a community is significantly different from single-species toxicity tests owing to ecological interactions.

The spatial distribution of dissolved and particulate heavy metals and their response to land-based inputs and tides in a semi-enclosed industrial embayment: Jiaozhou Bay, China

Liang

et al. 2015

Environ Sci Pollut Res

In order to evaluate heavy metal contamination in surface waters in the Jiaozhou Bay (JZB), a typical semi-enclosed bay in the north of China, and to identify the response of heavy metal distribution to terrigenous sources and tides, the land-based discharge flux of dissolved Cu, Pb, Zn and Cd and their particulates, as well as their concentrations, were synchronously surveyed in JZB in flood season and normal season respectively. The survey results showed that the amount of dissolved Cu clearly increased from the estuaries to the offshore waters during the flood season, especially from the Dagu estuary to the mouth of JZB. The same trend was observed for Pb. The isopleths of dissolved Zn during the flood season presented a different pattern in which a clear decrease was observed from the Lianwan, Moshui and Dagu estuaries to the offshore waters. However, the particulate Cu isopleths during the flood season, which had the same pattern as those of particulate Pb, Zn and Cd, showed a clear decrease from the Dagu estuary to the mouth of JZB. The isopleths for dissolved and particulate Cu during the normal season showed a clear decrease from the northeast to the entrance of JZB, and the same trend was observed for Pb, Zn and Cd. Observations based on synchronous investigations of the fluvial fluxes of the selected metals and their average concentrations in JZB showed that these patterns were controlled by the strong external fluvial inputs, especially from the Dagu River. The diurnal change in the Cu, Pb, Zn and Cd concentrations showed a periodicity with a cycle length of approximately 12 h in JZB, which indicates the noticeable impact of the semi-diurnal tide. The weighed average concentration from freshwater inputs calculated for dissolved Cu, Pb, Zn and Cd were higher than their average concentrations in JZB. This indicated that JZB had been contaminated with these metals, whose concentrations were also higher than those found in uncontaminated waters.