140 years-long sedimentary records of PAHs and CN stable isotopes from Ninomiya River, Japan.

Anthropogenic activities' impacts over 140 years were studied at West Nanao Bay using a variety of geochemical techniques on sedimentary records. The bay is influenced by the Ninomiya River which is fed by a small watershed at which Tatzuruhama Town is located. Sedimentation rate was calculated using 210Pb-excess and 137Cs activities. C/N decreased after 1975, indicating a decrease in lignin-rich organic matter. From δ13C, δ15N and biogenic silica it was indicated that the population increased sewage-discharges until the construction of waste-water treatment plant in 1986. Several recorded changes in the landuse matched with the variation of the particle size. Total PAHs concentration was 1.17-62.78 µg g-1, being highest during Japan's fastest economic growth period (1946-1975). Using diagnostic ratios and PCA analysis, PAHs' sources were identified as pyrogenic for all depths, varying from coal combustion (90.7 %) before 1946 to a mixture of biomass and vehicle combustion after 1961.

Ecological and pharmacognostical characteristics in Ephedra saxatilis in the Yarlung Zangbo River Valley of southeastern Tibetan Plateau, China.

In the Yarlung Zangbo River Valley of the southeastern Tibetan Plateau, China (29°07'49.5"N, 92°41'11.0"E, 3256 m above sea level), we found an Ephedra saxatilis community in the xeric steppe with shrubland vegetation habitat of the broad alluvial plain of the river with soil having relatively higher water-soluble cation (Ca2+, 8.62; K+, 1.94; Mg2+, 2.38 mmol/100 g dry soil weight) and nitrogen (NO3-, 21.78; NH4+, 1.82 mmol/100 g dry soil weight) content. The ranges of ephedrine and pseudoephedrine in 13 E. saxatilis samples were as follows: ephedrine, not detected-3.03 of dry weight (%DW) and pseudoephedrine, not detected-1.36%DW. The 13 E. saxatilis plants collected in the study area showed intraspecific variability of ephedrine and pseudoephedrine with 6 samples containing ephedrine and pseudoephedrine, 6 samples containing only ephedrine, and 1 sample containing only pseudoephedrine.

Origin of surface water in the Southern Ocean: Implications of soluble radionuclide distributions.

Concentration data of soluble radionuclides in the southern South Indian Ocean and Southern Ocean transition zone are rare or insufficient for the study of its current system. We examined the lateral surface variations in soluble natural (226Ra and 228Ra) and anthropogenic (134Cs and 137Cs) radionuclide activity concentrations in the surface waters in this area from November 2021 to March 2022. The surface distributions of 226Ra and 137Cs concentrations were classified into Subantarctic Mode Water-, Antarctic Intermediate Water-, and Upper Circumpolar Deep Water (UCDW)-dominated areas along latitudinal band (40°S-65°S, 110°E-120°E). Notably, the highest 226Ra concentrations occurred along the longitudinal band (60°S-65°S, 40°E-120°E). Significantly lower 137Cs concentrations in the Southern Ocean than those in surface waters in other global oceans were observed along with depletion of 228Ra. Additionally, 226Ra and 137Cs concentrations appeared to show small variations between eastern and western areas (2.5-3.0 mBq/L and 0.06-0.03 mBq/L, respectively). Lateral profiles in the Southern Ocean are governed by a large contribution from deep/old waters (e.g., UCDW), with a small effect from southward transport of Subantarctic Mode Water.

Environmental processes and fate of PAHs at a shallow and enclosed bay: West Nanao Bay, Noto Peninsula, Japan.

From August 2019 to August 2020, particulate and dissolved polycyclic aromatic hydrocarbons concentrations (PAHs) were analyzed in the water body of West Nanao Bay, Japan, to determinate their levels, environmental pathways, and ecological risks at this remote but shallow and semi-enclosed bay. The 14 targeted PAHs were analyzed by high performance liquid chromatography-fluorescence detector. Even when water column stratifies, the summatory of 14 targeted dissolved PAHs did not follow significantly change with depth. Results agreed with our previous findings in the surface distribution at the bay and can be attributed to long retention time of the water mass of the semi-enclosed bay. Suspended solids start precipitating according to their size; with biggest particles rapidly settling in the proximities of river mouths. Partition coefficients (Kp) varied from 103 to 107, according to molecular weights. In general, highest Kp were found in the nepheloid layer. The risk quotients, RQ∑14 PAHs (NCs) (1.04-174.08), indicated that PAHs represented a very low to low environmental risks.

Seasonal variations in marine polycyclic aromatic hydrocarbons off Oki Island, Sea of Japan, during 2015-2019.

Concentrations of 13 phase-partitioned polycyclic aromatic hydrocarbons (PAHs) in seawater were monitored monthly off Oki Island, Japan, during 2015-2019 to elucidate seasonal variations, main source, and transport pathways of PAHs in the southwestern Sea of Japan. Total PAH (dissolved plus particulate) concentrations in surface seawater at 36°09.0'N, 133°17.3'E (site OK) were in the range 0.49-9.36 ng L-1 (mean 2.77, SD 2.05 ng L-1) with higher levels in summer-autumn, an order of magnitude lower than those in the East China Sea during 2005 and 2009-2011 and about one-third of those recorded in the Sea of Japan in 2008 and 2010. The main sources of dissolved and particulate PAHs were combustion products. Increasing dissolved PAH levels during July-October indicate that the area around southern Oki Island is impacted by PAH-rich summer continental-shelf water transported by the Tsushima Warm Current flowing from the East China Sea.

Relationship between ephedrine alkaloid profile in Ephedra gerardiana and soil characteristics of glacial landforms in southeastern Tibetan Plateau, China.

In the Kaluxung River catchment of the southeastern Tibetan Plateau in China, we identified three Ephedra gerardiana communities on different soils and glacial landforms from 4842 to 4899 m above sea level: a moraine community located on constantly collapsing sandy gravel alpine steppe slopes with exposed bedrock on the outer slope of the terminal moraine of the Qiangyong Glacier on Mt. Kaluxung; an outwash plain community located on a gentle alpine steppe slope with exposed bedrock at the terminal end of the outwash plain in the glacial valley of the southeast side of Mt. Noijinkangsang; and a river terrace community located in an alpine meadow on a rock-scattered flat river terrace along a glacier-fed river in the outwash plain in the glacial valley of the southeast side of Mt. Noijinkangsang. Based on the finding of identical DNA sequences of the intergenic spacers of chloroplast trnT-trnF and trnS-trnfM regions for all Ephedra specimens examined in this study, the E. gerardiana in this study were considered to comprise a genetically homogeneous population. Analysis of the relationship between ephedrine alkaloid profiles of these three communities and soil characteristics showed that the river terrace community in wet alpine meadow had significantly lower ephedrine content than did the moraine and outwash plain communities in dry alpine steppe (moraine community, 1.52 ± 0.44; outwash plain community, 1.42 ± 0.68; river terrace community, 0.33 ± 0.65%DW), but pseudoephedrine content showed the reverse pattern (moraine community, 0.86 ± 0.30; outwash plain community, 0.73 ± 0.60; river terrace community, 1.50 ± 0.71%DW). In addition, total alkaloid (ephedrine and pseudoephedrine) content in the river terrace community (1.83 ± 0.24%DW) was significantly lower than that in the moraine community (2.38 ± 0.64%DW) and outwash plain community (2.15 ± 0.55%DW).

Geochemical Control of PAHs by Inflowing River Water to West Nanao Bay, Japan, and Its Influences on Ecological Risk: Small-Scale Changes Observed under Near-Background Conditions at an Enclosed Bay.

Polycyclic aromatic hydrocarbons (PAHs), even at low concentrations, have been shown to trigger changes in life cycles and provoke abnormal behaviors in numerous marine organisms. From May 2019 to September 2020, particulate and dissolved PAH concentrations were analyzed on the surface water of West Nanao Bay, Japan, to determinate their levels, emission sources, environmental pathways, and ecological risks at this remote but semi-enclosed bay. The 14 targeted PAHs were analyzed by HPLC-fluorescence detector. Mean total PAH concentrations were lower than 20.0 ng L-1 for most samples. Based on fluoranthene (Flu) to pyrene (Pyr) ([Flu]/[Flu + Pyr]) and benzo[a]anthracene (BaA) to chrysene (Chr) ([BaA]/[BaA + Chr]) isomeric ratios and a varimax rotated PCA, it was established that biomass combustion was the principal source in the particulate phase and that liquid fossil fuel combustion was the principal source in the dissolved phase. From salinity and turbidity distribution, riverine discharges were determined to be the major and continuous transportation pathway of particulate PAHs. It was observed that rain events had a role in the transport of dissolved PAHs. The risk quotients (RQ∑14 PAHs (NCs): 0-84.53) indicated that PAHs represented a very low to low acute environmental risk. The results of this study will contribute to filling the paradigm gap of ecotoxicological studies in remote areas, working as a booster for future in-lab studies of non-lethal implications of endocrine disruptors such as PAHs.

Assessing the Effect of Laboratory Environment on Sample Contamination for I-129 Accelerator Mass Spectrometry.

Environmental contaminations of 129I were continuously monitored in various sample preparation rooms for accelerator mass spectrometry at the University of Tsukuba. Monitoring of 129I was performed in the rooms used for the treatment of samples in the past, in order to compare with the results obtained in the sample preparation rooms. Ambient levels of atmospheric 129I in each room were estimated from the measured concentrations in the alkali trap solutions. This article reports the results of one year of monitoring the temporal changes of stable iodine (127I) and 129I contamination rates in the alkali trap solutions. It was found that 129I contamination rates were lower than approximately 104 atoms cm-2 day-1 in the rooms where ether no samples or only samples with environmental background levels of 129I were handled. Values from 104 to 105 atoms cm-2 day-1 were recorded in another room where environmental samples, such as the samples derived from nuclear power plant accidents, were treated. Higher levels of 129I, ranging from 106 to 107 atoms cm-2 day-1, were recorded in rooms used for treating neutron-activated iodine. The experimental results show that the 129I level depended on the 129I sample-preparation histories for the respective rooms. It is possible to estimate the 129I contamination risk from the atmosphere to the samples by knowing the 129I level in the preparation room.

Interannual Survey on Polycyclic Aromatic Hydrocarbons (PAHs) in Seawater of North Nanao Bay, Ishikawa, Japan, from 2015 to 2018: Sources, Pathways and Ecological Risk Assessment.

To improve the understanding of the emission sources and pathways of polycyclic aromatic hydrocarbons (PAHs) in the coastal environments of remote areas, their particulate and dissolved concentrations were analyzed on a monthly basis from 2015 to 2018 in surface waters of Nanao Bay, Japan. The concentration of the targeted 13 species of PAHs on the United States Environmental Protection Agency (USEPA) priority pollutant list in dissolved and particle phases were separately analyzed by high-performance liquid chromatography (HPLC) coupled to a fluorescence detector. Particulate and dissolved PAHs had average concentrations of 0.72 ng∙L-1 and 0.95 ng∙L-1, respectively. While most of the samples were lower than 1 ng∙L-1, abnormally high levels up to 10 ng∙L-1 were observed in the winter of 2017-2018 for particulate PAHs. Based on the isomer ratios of Flu to Flu plus Pyr, it was possible to determine that the pyrogenic loads were greater than the petrogenic loads in all but four out of 86 samples. The predominant environmental pathway for PAHs in winter was determined to be long-range atmospheric transportation fed by the East Asian winter monsoon, while for the summer, local sources were more relevant. By the risk quotients method, it was determined that PAHs in surface seawater presented a very low risk to marine life during the interannual survey.

Temporal Variations of Polycyclic Aromatic Hydrocarbons in the Seawater at Tsukumo Bay, Noto Peninsula, Japan, during 2014-2018.

Concentrations of phase-partitioning 13 polycyclic aromatic hydrocarbons (PAHs) in seawater were investigated in the Tsukumo Bay, Noto Peninsula, Japan, during 2014-2018, to improve the understanding of the environmental behavior of PAHs in the coastal areas of the Japan Sea. Total PAH (particulate plus dissolved) concentrations in surface seawater were in the range 0.24-2.20 ng L-1 (mean 0.89 ng L-1), an order of magnitude lower than the mean values observed in the Japan Sea in 2008 and 2010. Although the PAH contamination levels during 2014-2018 were significantly lower than those in the East China Sea, the levels increased from 2014 to 2017 and were maintained at the higher level during 2017-2018. The main sources of particulate and dissolved PAHs during 2014-2018 were combustion products, of which the former were more influenced by liquid fossil-fuel combustion and the latter by biomass or coal combustion. The increase in particulate PAH concentrations in October-December during 2014-2018 was due to the impact of PAH-rich airmasses transported from the East Asian landmass in the northwesterly winter monsoon winds. The increase in dissolved PAH levels during July-September in 2014, 2016, 2017, and 2018 indicates that the Tsukumo Bay is possibly impacted by the PAH-rich summer continental shelf water transported by the Coastal Branch of the Tsushima Warm Current, which flows into the Japan Sea from the East China Sea.

Reconstruction of anthropogenic 129I temporal variation in the Japan Sea using a coral core sample.

The anthropogenic long-lived radionuclide 129I is receiving increased attraction as a new oceanic tracer in addition to usage as a fingerprint of radionuclide contamination of the marine environment. To demonstrate the robustness of 129I as an oceanic tracer in the Northwest Pacific area, specifically in the Japan Sea, the input history of 129I to surface seawater was reconstructed using a hermatypic coral core sample from Iki Island in the Tsushima strait. Iodine isotopes in each annual band were measured using AMS and ICP-MS after appropriate pre-treatments of small amounts of coral powder. The 129I/127I ratios in the 1940s were almost at background levels (<1 × 10-11) and increased abruptly in the early 1950s. Thereafter, the ratios continuously increased with some fluctuations; the maximum ratio, 7.13 ±â€¯0.72 × 10-11, being found in the late 1990s. After that period, the ratios remained nearly constant until the present time (2011). The 129I originated mainly from the nuclear weapons testings of the 1950s and the early 1960s, and from airborne releasing by nuclear reprocessing facilities. The dataset obtained here was used to construct a simple model to estimate the diffusion coefficient of 129I in the Japan Sea. The 129I/236U ratios over the observation period were also reconstructed to help constraining sources of 129I to the marine environment. Based on the results, the 129I/236U ratio obtained here could be an endmember of the water mass in the Kuroshio Current area of the Northwest Pacific Ocean.

Pre- and post-accident (129)I and (137)Cs levels, and (129)I/(137)Cs ratios in soil near the Fukushima Dai-ichi Nuclear Power Plant, Japan.

To evaluate the deposition density and extent of subsurface infiltration of (129)I and (137)Cs in the restricted area that was highly contaminated by the accident of Fukushima Dai-ichi Nuclear Power Plant, cumulative inventories of (129)I and (137)Cs, concentrations of (129)I and (137)Cs, and (129)I/(137)Cs ratio in 30-cm-long soil columns were compared with pre-accident levels from the same area. The cores were collected before and after the accident from locations of S-1 (4 km west of FDNPP) and S-2 (8 km west of FDNPP). Deposition densities of (129)I and (137)Cs in the soil following the accident were 0.90-2.33 Bq m(-2) and 0.80-4.04 MBq m(-2), respectively, which were 14-39 and 320-510 times larger than the pre-accident levels of (129)I (59.3-63.3 mBq m(-2)) and (137)Cs (2.51-7.88 kBq m(-2)), respectively. Approximately 90% of accident-derived (129)I and (137)Cs deposited in the 30-cm soil cores was concentrated in the surface layer from 0 to 44-95 kg m(-2) of mass depth (0-4.3-6.2 cm depth) and from 0 to 16-25 kg m(-2) of mass depth (0-1.0-3.1 cm depth), respectively. The relaxation mass depths (h0) of 10.8-11.2 kg m(-2) for (129)I estimated in the previous study were larger than those of 8.1-10.6 kg m(-2) for (137)Cs at both sites, owing to the larger infiltration depth of radioiodine mainly by the gravitational water penetration in the surface soil in our study sites. Approximately 7-9% of the accident-derived (129)I was present in the lower layer from 44 to 100 kg m(-2) (4.3-8.6 cm depth) at S-1, and from 95 to 160 kg m(-2) (6.2-10.2 cm depth) at S-2. Approximately 1% of (137)Cs seems to infiltrate deeper than (129)I in the lower layer at each site in contrast to the surface layer.