We took several sediment cores from Punderson Lake (Ohio) in 2013. Here we report some metals (Pb and Cu) and plant nutrient (TP) data from one core taken from southern part of the lake (see figure attached below). This sediment data show some historic changes in the anthropogenic inputs of toxic metals and plant nutrients into the lake: 1) the peak lead (Pb) emission in the 1970s due to the use of leaded-gasoline in the region, 2) a surface enrichment of total phosphorus (TP) in the sediments, and 3) a nearly concurrent increase in copper (Cu) concentrations in the sediments. It is believed that the increase in TP was attributed to sewage and animal waste discharged from adjacent communities. The increased Cu as seen in the sediment profile was largely introduced as part of an algaecide to control the algal bloom problems in the lake. This study indicates that the ecosystem health of this lake is troublesome.
The Distribution of Trace Metals in Sediments Reveals a Large Ecosystem Change in Lake Erie:
Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, to reconstruct the eutrophication history of the lake over the past 210 years. Following a slow eutrophication during European settlement, Lake Erie experienced a period of accelerated eutrophication, leading to an ecosystem regime transition into a eutrophic lake state in 1950. Our results suggested that the lake’s biological productivity has ever since maintained fairly high even though a significant input reduction was realized from rigorous nutrient abatements that began as early as in 1969. This work underscored the role of in-lake biogeochemical cycling in nutrient dynamics of this already eutrophic lake.
This talk targets the senior design students in the Engineering College at CSU who might be interested in real time monitoring of water in the environment. First, the talk will begin with a brief introduction of water in the atmosphere and watersheds. Second, water-related problems such as flooding, drought, and water quality degradation will be discussed. Third, examples of contemporary monitoring programs will be mentioned. Fourth, the presenter will discuss some of the challenges in real-time water quality monitoring. Fifth, an alternative approach will be presented to overcome some of the weakness. Lastly, the talk will be concluded by proposing some ideas for future directions.
It has been reported that the past month of July (2012) is the hottest month on record in the United States. We also noted that a widespread drought affected ecosystems and agricultural practices in midwest and eastern parts of the nation. Here is one picture showing a marked drawdown in lake level in NY Adirondack Mountains.
The Use of Stable Isotopic Tracers in Earth and Environmental Science Research
I will present the idea of a stable isotope as a tracer for scientific research and show several examples of its application to different areas, including reconstruction of climate change in the past, partition of stream water from different sources, and estimation of open-water evaporation from isotopic enrichment.
The Cuyahoga River originates in its headwaters area in Geauga County (Ohio) with two branches: East Branch and West Branch (Fig. 1). The two branches join together at the southern end of Eldon Russell Park, Troy Township, Ohio, in the upper Cuyahoga River. The Cuyahoga River flows southwestward in a narrow valley toward Akron for about 70 km. It turns abruptly northward near Cuyahoga Fall, traverses a wide, deep preglacial valley in the Cuyahoga Valley National Park, and merges with Tinkers Creek before reaching Cleveland and Lake Erie.
Fig. 1 Map showing locations of the Cuyahoga River.
Results from water isotopic measurements show a relatively large range of variations in d18O and dD of river water in the Cuyahoga and Tinkers Creek (Fig. 2). Water samples taken on March 15, 2008 have significantly lower values of d18O and dD than those taken in warmer seasons (Fig. 3). This indicates a dominance of snowmelt in river water. Moreover, there is a positive excursion in the middle sections of the Cuyahoga River, suggesting a significant amount of “old” water (i.e., surface/subsurface reservoir water) mixing with fresh snowmelt in the river.
Fig. 2 Relationship of d18O and dD.
Fig. 3 Downstream changes in d18O of river water.
The Tibetan Plateau, situated in central Asia, is the largest and highest plateau on Earth, with an area of over 2.5 million km2 and an average elevation of over 4000 m (Yao 2008). Geologically, it consists of four blocks or terranes accreted successively to Eurasia, namely the Songpan-Ganzi flysch complex, the Qiangtang Terrane, the Lhasa Terrane, and the Himalaya (Dewey et al. 1988). Except for one lake (Qarhan Salt Lake) in the northeastern corner of the plateau, all the lakes sampled are located in the Lhasa Terrane and southern Tibet (Fig. 1). The main rock units exposed in the Lhasa Terrane include Jurassic-Cretaceous sedimentary and igneous rocks (north), Carboniferous-Permian metasedimentary and lower Cretaceous volcano-sedimentary rocks (central), and Cretaceous-early Tertiary Gandese batholiths and volcanic rocks (south) (Leier et al. 2007; Zhu et al. 2009).
The climate on the plateau, though varying considerably from west to east and from north to south, is characteristically cold and dry with seasonal winds, strong solar radiation, and a large diurnal temperature cycle. Annual precipitation ranges from less than 20 cm at Delingha in the northern plateau to over 50 cm at Nyalam in the southern plateau (Zhang et al. 2001), from less than 10 cm at Shiquanhe in the western plateau (Yu et al. 2007; Yu et al. 2009) to 47 cm at Yushu in the eastern plateau (Yu et al. 2006a; Tian et al. 2008c). Most (over 80%) of the precipitation occurs during the summer (from June to September) (Yeh and Gao 1979). The precipitation regime in this region is regulated primarily by the westerlies and the Asian monsoon system, which are usually characterized by a distinctive d18O signature (Araguas-Araguas et al. 1998; Johnson and Ingram 2004). There are three atmospheric circulation zones over the plateau: 1) the monsoon-dominated precipitation zone in south of 30˚N with an average d18O value of -16.2‰, 2) the westerly-dominated precipitation zone in north of 35˚N with an average d18O value of -7.7‰, and 3) the transitional precipitation zone between 30˚N and 35˚N with an average d18O value of -11.8‰ (Yao et al. 2009). Although variable from lake to lake, the mean annual temperature is 1.5°C in central Tibet and the mean annual temperature at lake surface during the summer is 13.5°C (Liu et al. 2009). Most lakes on the plateau freezes during the winter (December-April). Evaporation is fairly strong over the entire plateau with an average rate of 170cm/yr, as indicated by pan evaporation data (Zhang et al. 2007). The evaporation rate of Lake Yamdruk-tso (southern Tibet) is around 130 cm/yr (Tian et al. 2008a), comparable to those found in the western margin of the Great Basin in the United States (Yuan et al. 2006a)