Lake Teganuma Research Articles

Plankton Metabolic Balance in the Central Part of Lake Teganuma

Plankton Metabolic Balance in the Central Part of Lake Teganuma

Historical analysis of domestic wastewater pollution and its measures in Lake Teganuma basin using surfactant concentrations recorded in sediment core samples

In order to learn whether it is possible to clarify the history of water pollution and its countermeasure from the fluctuation of chemicals accumulated in the sediment core of the lake, concentrations of linear alkylbenzenesulfonates (LAS) in sediment core samples collected from Lake Teganuma, which was severely polluted by domestic wastewater, were determined. The results were compared with concentrations of LAS in the lake water, waters of two large inflowing rivers, and in sewage from the Lake Teganuma basin. Sediment cores collected in 2003 and 2004 recorded the history of domestic wastewater pollution in the basin during the previous 25–35 years. LAS concentrations in the sediment core drastically decreased after the 1990s, and similar reductions of LAS were observed in the river and lake waters. Large amounts of LAS have still been used in the basin during 1980s to 2017, the drastic decrease of LAS concentrations in both the sediment and the river and lake waters is attributable the expansion of sewer system coverage in the basin since 1981. The effect of lake dredging was also estimated by the changes in surfactant concentrations. Thus, historical changes in not only pollution levels but also social factors can be assessed by determining sediment concentrations of chemicals in daily use such as LAS.

Lake Teganuma Water-Conveyance Pipeline Project Effects and Proposed Management

Lake Teganuma Water-Conveyance Pipeline Project Effects and Proposed Management

Size fractionation of nanoparticulate metal sulfides in oxic water of Lake Teganuma, Japan

Size fractionation of nanoparticulate metal sulfides in oxic water of Lake Teganuma, Japan

Sediment-Associated Radiocesium Originated from Fukushima Daiichi Nuclear Power Plant Flowing from Ohori River to Lake Teganuma

Sediment-Associated Radiocesium Originated from Fukushima Daiichi Nuclear Power Plant Flowing from Ohori River to Lake Teganuma

Floating-leaved and emergent vegetation as habitat for fishes in a eutrophic temperate lake without submerged vegetation

Although submerged vegetation is considered to be the most suitable refuge against predators and form of foraging habitat for small fishes, submerged plants are often scarce or lacking in turbid eutrophic lakes. To evaluate emergent (Zizania latifolia) and floating-leaved (Nelumbo nucifera) vegetation as refuge areas against predators and as foraging habitats for small fishes, we investigated the fauna, abundance, and size distribution of the fish community as well as the abundance of possible prey for small fishes in beds of each vegetation type in a eutrophic shallow lake: Lake Teganuma in Japan. The leaves and stems of N. nucifera occupied an area 4.2 times larger than that of Z. latifolia. The high coverage of the water surface with plants most likely induced the hypoxia found in the N. nucifera bed. The diversity of small fishes was greater in the Z. latifolia bed with piscivorous fish than in the N. nucifera bed without piscivorous fish. The diversity of fish species in the vegetation was enhanced when there was an increased diversity of possible food sources rather than an absence of predators. Some aquatic insects of the same species had a much lower δ13C signature at hypoxic locations than at less hypoxic locations in the N. nucifera bed. Such site differences within a bed were not observed in the organisms caught in the Z. latifolia bed. The insects in hypoxic zones with a δ13C signature lower than −30 ‰ were more depleted in 13C than the surface sediment or attached algae, suggesting that the larvae in the hypoxic zones incorporated the organic materials generated by methane-oxidizing bacteria. We can therefore conclude that floating-leaved vegetation, especially a N. nucifera bed, is not suitable as a replacement for submerged vegetation because of its potential to induce hypoxia, which can decrease the diversity of the fish fauna.

手賀沼のマコモ帯とヒメガマ帯で採集された魚類とその安定同位体比

手賀沼のマコモ帯とヒメガマ帯で採集された魚類とその安定同位体比

Relationship between vegetation cover and aquatic plant diversity across six sub-watersheds surrounding Lake Teganuma, Japan

Relationship between vegetation cover and aquatic plant diversity across six sub-watersheds surrounding Lake Teganuma, Japan

PICK-UP RATE OF SUSPENDED SOLIDS AND PARTICULATE COMPONENTS OF NITROGEN AND PHOSPHORUS FROM BED IN RIVER AND LAKE

We measured in-situ pick-up rates of sediment and particulate components of nitrogen (P-N) and phosphorus (P-P) in an urban river and a lake with a new device we developed. Field sites for this study were Lake Teganuma and its influent river, Oohori River. The measured results show that the temporal variations of pick-up rates of P-N, P-P and sediment in Oohori River were appreciably found and mainly caused by hydrologic conditions and sedimentation environments. Pick-up rates of P-N, P-P and sediment in the river and lake increase with flow velocity. Note that the pick-up rates of P-N and P-P are appropriately modeled with power functions of bottom shear stress similar to that of sediment.

Daily change in wind-induced sediment resuspension and phosphorus forms in a shallow eutrophic lake

We recorded the daily changes in wind and forms of phosphorus (P), including total P (TP), dissolved inorganic P (DIP), and particulate inorganic P (PIP), in Lake Teganuma, Japan. On the Kanto Plain, where Lake Teganuma is located, wind speed increases in the daytime and decreases in the night-time. In the daytime, TP increased, which was related to suspended solids (SS) and wind velocity, indicating that TP and SS were supplied by sediment resuspension. An increase in PIP during the daytime was also observed. However, a decrease in the PIP: SS ratio coincided with increasing DIP, indicating that release from PIP may increase DIP during the daytime. The DIP supply in the daytime was due to increased pH, which is related to phytoplankton growth. The night-time decrease in DIP with an increase in the PIP: SS ratio and high PIP concentration indicate DIP sorption by suspended inorganic matter. The night-time pH decrease influenced the PIP increase, resulting in depleted DIP (0.004 mg l ―1 ). Therefore, the complicated P cycle, combining resuspension with P kinetics, suggests that daytime resuspension increases PIP, releasing DIP from SS-sorbed P, thus increasing available DIP and increasing phytoplankton and pH. The increased pH further releases DIP into the surface water. The release of P from PIP greatly influences the increase in DIP. Thus, the timing of resuspension creates a very suitable environment for phytoplankton in the lake. In contrast, during the night-time, PIP is a sink of inorganic P.

Simultaneous Estimation of SS and Chlorophyll in Shallow Water through Remote Sensing

The simultaneous estimation of SS and Chlorophyll-a (Chl.a) in shallow water through remote sensing was tried in this study. Lake Teganuma located in Chiba Prefecture was selected as test site. Twelve spectral / Chl.a data sets were acquired using outboard boat in the lake on 28 May 2009 and 22 Oct. 2008. These data sets were related to SS or Chl.a using simple single band or two band ratio models. As result, statically significant correlation was observed between a of the simulated ALOS/AVNIR-2 Band (760-890nm) and SS, or reflectance ratio of the simulated AVNIR-2 band 3 (610-690nm) and band 4 and Chl.a. These models were validated though the ALOS/AVNIR-2 data and the buoy data set on 20 May 2008 and 28 Oct. 2009.

ダイオキシン類水質環境基準値を超過した水深の浅い湖沼の水質特性

The concentration of dioxins in the water of Lake Shimoteganuma, in which exceeded the environmental quality standard of dioxins (annual mean value: 1 pg-TEQ · l-1, TEQ: toxic equivalency quantity) was exceeded from 2003 to 2007, was investigated. The neighboring lakes, Lake Teganuma and Lake Inbanuma, are shallow lakes like Lake Shimoteganuma. The concentrations of dioxins in the water of these lakes have not exceeded the environmental quality standard. When the result of the sediments of three lakes were compared, the proportion of fine sediment (<75 μm) of Lake Shimoteganuma was the smallest. However, the concentration of dioxins in fine sediment, which tend to float in water, was the highest. A water quality survey at defferent depths was performed. Because TEQ and iron (Fe) concentrations increased toward the bottom, it was surmised that Fe and dioxins were originated from the sediment. Only the TEQ of water near the bottom exceeded 1 pg-TEQ · l-1 in August. However, the TEQs of all the layers exceeded 1 pg-TEQ · 1-1 in October. It seemed that admixture between deffernt depths was more common in October. Analyzing surface water quality from the inlet to the outlet of the lake, the concentration of dioxins increased with the concentration of chlorophyll-a, SS (suspended solids) and Fe in October. The rising widths of TEQ were 1.6 and 2.0 pg-TEQ · l-1, respectively. By analyzing surface water quality for two years, TEQ was found to be over 1 pg-TEQ · l-1 from summer to autumn on the whole. TEQ was below 1 pg-TEQ · l-1 from winter to spring. The concentration 1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin, which can be used as an estimate of TEQ, correlated with the concentrations of iron and chlorophyll-a in water of Lake Shimoteganuma.

Nutrient Cycling in a Natural Stand of Typha angustifolia

ABSTRACT We studied nutrient cycling within a natural monospecific stand of Typha angustifolia along the shoreline of Lake Teganuma, a shallow eutrophic lake northeast of Tokyo. Seasonal patterns of biomass and nutrient concentrations in the above- and belowground plant parts were observed over a period of two years, and nutrients released from the dead plants into the water environment were estimated at the end of the first year of the study. T. angustifolia shoots accumulated 46.7 g/m2 N and 4.7 g/m2 P in 2003 and 56.9 g/m2 N and 5.9 g/m2 P in 2004 during the growing season from April to December. At the end of the growing season, as nutrient production and accumulation slowed down, translocation of the nutrients and photoassimilate from leaves to rhizomes started. About 45–48% of the nitrogen and 37–45% of the phosphorus that had accumulated in the shoots were translocated to the rhizomes during the winter. After they died, the shoots released about 4.6 g/m2 of nitrogen and 0.8 g/m2 of phosphorus into the water.

千葉県手賀沼の底質に記録された富栄養化と重金属汚染の時系列解析

Records of short-term environmental changes caused by urbanization and industrialization are expected to be preserved in lake sediments. Besides, a consistent, high-resolution baseline record is required to interpret extreme influences of human impact such as heavy metal pollution and eutrophication. In this study, the numerical dates of the core samples taken from Lake Teganuma are determined using the 210Pb and 137Cs dating method. Concentrations of heavy metals are obtained for centrifuged water samples with wet core samples, and for HCl and acetic ammonium extracts with oven-dried core samples, to clarify the existing state and the mobility of metals. Total carbon content, total nitrogen content, and C/N ratio are also obtained for ovendried core samples to analyze the influence of human impact on water deterioration of Lake Teganuma. According to the analytical results for total carbon, nitrogen, and C/N ratio, the eutrophication in Lake Teganuma started around 1946 and shifted further to a critical condition in the late 1960's. Zn and Cu pollution began around 1955, while serious Cr pollution occurred around 1963. These responsible factors for the water environmental changes in Lake Teganuma represent stresses of population increase and drainage closure due to reclamation.

STUDY ON PHOSPHORUS BUDGET OF LAKE TEGANUMA IN SUMMER WITH FIELD OBSERVATIONS AND NUMERICAL COMPUTATION

To grasp the phosphorus budget in Lake Teganuma, we have performed the field observations and numerical computation of water quality in summer in 2003 and 2004. The observed results indicated that the COD and T-P increased in the longitudinal direction in the lake, while the T-N decreased in the same direction. It is also found that the COD and T-P in 2004 were much larger than those in 2003. From the computational results, the higher value of the phosphorus in 2004 was mainly caused by the increase of the phosphorus release from the bottom in the lake. The phosphorus budget analysis illustrates that the phosphorus releases in 2003 and 2004 were comparable with those before the beginning of the environmental improvement project using the North-Chiba water conveyance channel.

FIELD MEASUREMENTS OF NON-POINT SOURCES ON ROAD SURFACE USING A MODELED STORM-WATER SAMPLING (MOS) TECHNIQUE

To clarify environments of road deposits, one of main non-point sources in urban area, we have already presented a new technique, named as a modeled storm-water sampling (MOS) technique, in which one can easily obtain road deposits under simulated rainy conditions. By using the MOS technique, we performed the field measurements for road-deposit environments in the watershed of the Oohori River which inflows into Lake Teganuma. In addition, we used a direct sampling (DS) technique with a brush to compare the observed results obtained with the MOS technique. The observed results indicate that the SS and water quality measured with the DS technique are much larger than those with the MOS technique. This result corresponds to the experimental data conducted by the authors. The differences of the road-deposit environments between the residential and industrial area are also discussed.

HIGH-RESOLUTION ADCP MEASUREMENTS ON VERTICAL STRUCTURES OF CURRENT AND SUSPENDED SOLID IN AN URBAN RIVER

To realize more accurate measurements for pollutant loads in an urban river, in the present study, a high-resolution, acoustic Doppler current profiler (HR-ADCP) was used to measure the vertical distributions of current and SS in an urban river under rainy conditions. The field measurements with the bottom-mounted HR-ADCP were carried out at the downstream point of the Oohori River, one of main inflow rivers in Lake Teganuma. The observed results show that characteristic vertical structures of the current and SS appear in hydrologic events and then the vertical distribution of SS flux in the streamwise direction vary considerably in rising and falling stages. With the HR-ADCP measurements, we grasp the temporal variation for the dependence of the erosion rate of sediments on flow conditions.

EXTERNAL INFLOW AND INTERNAL PRODUCTION LOADINGS OF LAKE TEGANUMA IN SUMMER

To clarify the pollutant loads in Lake Teganuma, which is one of well-known eutrophied lakes in Japan, we performed field measurements on external inflow and internal production loadings from June to October in 2003. The external loadings of T-N, T-P and COD through main inflow rivers and the North-Chiba water conveyance channel were discussed quantitatively. The percentage of the internal production loading for COD in total loadings was from 45 to 65% under normal atmospheric conditions. The measured results suggested an adequate correlation between the internal production loading for COD and the solar radiation although the discharges from the channel and the inflow rivers were not correlative to the internal production loading for COD.

Distribution of estrogen, nonylphenol and its derivatives in the sediments of a shallow lake

To determine the distribution of endocrine disruptors (EDs) in lake water and sediments, field investigation was conducted in Lake Teganuma, which is a shallow eutrophic lake, highly affected by human activities. Concentration profiles with sediment depths were obtained for estrogens, nonylphenol (NP), nonylphenol ethoxylates (NPnEO), and nonylphenoxy acetic acids (NPnEC). 17beta-Estradiol (E2) was rarely detected, and 17alpha-ethynylestradiol (EE2) and estriol (E3) were undetected at all depths (0-98 cm) in any of the sediment core samples. The sediment concentrations of estrone (E1) ranging from <0.05 to 3.5 microg/kg-dry wt. and NP from 11.8 microg/kg-dry wt. to 21 mg/kg-dry wt. were obtained. The maximum concentrations of NPnEO and NPnEC in the core sediments were 2.5 mg/kg-dry wt. and 1.4 mg/kg-dry wt., respectively. The EDs concentrations are higher at the inlet than at the outlet (except for NP) in the sediments near the surface. The longitudinal distributions of E1, NPnEO and NPnEC in the benthic sediments show that the concentrations are highest at the inlet, and are fairly constant at lower levels towards the downstream. The obtained results also indicate that NP tends to be adsorbed to the organic particulates produced by algae, followed by sedimentation near the outlet of the lake.

GIS ANALYSIS ON POLLUTANT LOADS IN AN INFLUENT RIVER INTO LAKE TEGANUMA

To clarify the cause of pollutant loads in Oohori river, one of the main influent rivers into Lake Teganuma, we have attempted to perform a GIS analysis on pollutant loads in Oohori river. The comparison between the calculalted and observed pollutant loads for COD, T-N and T-P indicates that the calculated results give acceptable agreements with observed results. We also compare the calcuated pollutant loads in 1991 and 2002, showing that the contribution of the domestic waste water appreciably decreases with the increase of extension rate of sewerage and then the industrial waste water and non-point source are relatively dominat. The spatial distribution of the point and non-point sources in the watershed is examined with the GIS analysis.