Lead (Pb) is extensively used in industries and often inadvertently discharged into the environment. Despite some studies examining the effects of Pb pollution on raptors and waterfowl, its effects on other avian species have not been investigated. This study investigated the feeding selectivity of a black-headed gull (Chroicocephalus ridibundus) population using stable isotope ratios to determine the source of Pb pollution. Gulls in Tokyo and Mikawa Bay were captured from December 2016 to February 2017 and from December 2020 to March 2021, respectively. These gulls were measured 13C/12C carbon ratio (δ13C), and 15N/14N nitrogen ratio (δ15N). Blood Pb level (BLL) was measured gulls in Mikawa Bay. Based on the measurement values of δ15N, gulls were classified into two groups: primary and higher predator groups. No differences in stable isotope ratios were found between the two groups. The secondary consumers showed significantly high BLLs (P=0.002). BLLs during the wintering period were significantly higher in the primary consumer group. Our findings suggest that reducing Pb emissions, along with biological and chemical remediation of water sediment is required to prevent further Pb pollution and bioaccumulation in wild animals.

The cumulative ecological risks from multiple herbicides in Japanese rivers were evaluated using species sensitivity distribution and were compared with natural periphytic diatom communities. Region-specific predicted environmental concentrations were estimated at 9 rivers considering the region-specific parameters of environmental conditions. Then the multi-substance potentially affected fraction (msPAF) was calculated as a risk index of multiple herbicides using the computation tool NIAES-CERAP. On the other hand, river ecological survey focusing on diatom community were conducted in these 9 rivers and several biological metrics for species composition were calculated such as genus number, Shannon’s diversity, DAIpo, and SPEAR_herbicides which is an indicator of the herbicide effect on the diatom community. DAIpo and SPEAR_herbicides (but the population number of each genus was not log-transformed) significantly correlated with msPAF, indicating the applicability of these metrics for assessing the effect of herbicide mixture. Moreover, the percentage of abundance for genus Planothidium and Nitzschia were significantly correlated with msPAF negatively and positively, respectively.

Styrene is a volatile chemical used as a raw material for production of synthetic resins and synthetic rubbers. A study of inhibition of algal growth was carried out according to OECD test guideline 201 in a completely closed system to clarify the inhibition of growth of the green alga Raphidocelis subcapitata by styrene. The median effective concentration for growth rate (E_rC₅₀) and no-observed-effect concentration for growth rate (NOEC_r) based on the measured concentrations of styrene were 5.99 mg/L and 0.985 mg/L, respectively. Based on these results, the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) classification of hazards to the aquatic environment of styrene was Category 2 for short-term (acute) exposure and Category 3 for long-term (chronic) exposure.

We compared the sensitivity based on the 50 percent effective concentrations (EC₅₀s) of five species of plant to six herbicides, using an efficient high-throughput microplate-based toxicity assay. For five herbicides, the most sensitive species differed: Welsh onion Allium fistulosum was most sensitive to cyclosulfamuron (the inhibitor of acetolactate synthase), pretilachlor (the inhibitor of very long-chain fatty acid (VLCFA) synthesis) and pyrazoxyfen (the inhibitor of 4-hydroxyphenylpyruvate dioxygenase): watercress Nasturtium officinale was most sensitive to pyraclonil (the inhibitor of protoporphyrinogen oxidase); and basil Ocimum basilicum was most sensitive to esprocarb (the inhibitor of VLCFA synthesis). Simetryn, the inhibitor of photosynthesis, was evenly less toxic, with no differences in species sensitivity. These results suggested that a single species cannot represent the sensitivity of the primary producer assemblage to a given herbicide. To assess the ecological effects of herbicides, multispecies plant toxicity data sets are essential.