Novel weapons: invasive plant suppresses fungal mutualists in America but not in its native Europe

Why some invasive plant species transmogrify from weak competitors at home to strong competitors abroad remains one of the most elusive questions in ecology. Some evidence suggests that disproportionately high densities of some invaders are due to the release of biochemicals that are novel, and therefore harmful, to naive organisms in their new range. So far, such evidence has been restricted to the direct phytotoxic effects of plants on other plants. Here we found that one of North America's most aggressive invaders of undisturbed forest understories, Alliaria petiolata (garlic mustard) and a plant that inhibits mycorrhizal fungal mutualists of North American native plants, has far stronger inhibitory effects on mycorrhizas in invaded North American soils than on mycorrhizas in European soils where A. petiolata is native. This antifungal effect appears to be due to specific flavonoid fractions in A. petiolata extracts. Furthermore, we found that suppression of North American mycorrhizal fungi by A. petiolata corresponds with severe inhibition of North American plant species that rely on these fungi, whereas congeneric European plants are weakly affected. These results indicate that phytochemicals, benign to resistant mycorrhizal symbionts in the home range, may be lethal to na?ve native mutualists in the introduced range and indirectly suppress the plants that rely on them.     

A PROPOSED APPROACH TO COORDINATION OF WATER RESOURCE DEVELOPMENT AND ENVIRONMENTAL REGULATIONS1

ABSTRACT: The planning and developing of water resources to meet the country's needs for water supply, flood control, hydroelectric power, irrigation, and navigation now needs to take more account of environmental needs and regulations. Water resource development is often beneficial to the environment, but may also be harmful, as in cases involving salmon and various other endangered species. As a national objective, the environment must be preserved and in some cases restored; but how can this be done consistent with other national objectives, relating to life and welfare of human beings? This problem has aroused the concern of many engineers and water scientists. As a result, a national conference on this subject was held in Chicago in June 1998, as an integral part of ASCE's Annual Conference on Water Resources Planning and Management and the Annual Conference on Environmental Engineering. At the conclusion of that conference, a post-conference meeting was held by a group of prominent water resource practitioners. It was concluded at this meeting that action should be taken by our government to establish a new form of interagency approach, involving the states, as a means of coordination in cases of national importance.     

Designing and implementing an urban river remediation

In 2017, Consumers Energy completed a sediment response action in the Flint River to address manufactured gas plant‐related impacts in sediments and at the groundwater‐surface water interface. The project site is located in an urban, channelized, developed reach of the river. Multiple property owners and site constraints presented unique challenges for the remedial design, including the presence of Hamilton Dam at the downstream edge of the site which was considered a high‐hazard dam in “very poor condition.” An additional consideration was the City of Flint water crisis which was initially exposed in 2014. The sediment response action was not related to the water crisis because the site is located approximately two miles downstream of the City's water intake, but design, permitting, and construction began after 2014, so the timing added a heightened sense of awareness from the public stakeholders. The successful completion of the sediment response action was the result of deliberate planning, iterative engineering, and open communication with stakeholders that enabled a careful balancing of objectives with sometimes competing interests.     

Clinch River Freshwater Mussels Upstream of Norris Reservoir,Tennessee and Virginia: A Quantitative Assessment from 2004 to 2009

The Clinch River is located in northeastern Tennessee (TN) and southwestern Virginia (VA) of the United States, and contains a diverse mussel assemblage of 46 extant species, including 20 species listed as federally endangered. To facilitate quantitative monitoring of the fauna, quadrat data were collected from 2004 to 2009 at 18 sites in the river, including 12 sites in TN and 6 sites in VA. Thirty‐eight mussel species were collected alive in total from quadrat samples taken annually at sites in the TN section of the river. Over the five‐year study period, mussel density averaged 25.5 m^?2 at all sites sampled in TN. In contrast, mussel density averaged only 3.1 m^?2 at sites sampled in VA. The best historical site in VA was Pendleton Island in Scott County, where mussel density was estimated as high as 25 m^?2 in 1979, comparable to current densities recorded in TN. Mussel densities are now <1 m^?2, indicating a collapse of the fauna. A severe reduction in mussel abundance has occurred in a 68‐km section of the river from St. Paul, VA, downstream to approximately Clinchport, VA (river kilometers 411.5‐343.3). While the environmental factors responsible for the faunal decline are largely unknown, they must have been severe and sustained to reduce such large populations to their current low levels. Long‐term water and habitat quality monitoring is needed to determine whether environmental degradation is still occurring in the river.     

Occurrence of estrogenic chemicals in South Korean surface waters and municipal wastewaters

Broad scale monitoring of estrogenic compounds was performed at 19 sampling points throughout the Yeongsan and Seomjin river basins and 5 wastewater treatment plants (WWTPs) adjacent to the Gwangju area, Korea, from December 2005 to August 2007. The concentrations of estrogenic compounds, including estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol-A, nonylphenol (NP) and 4-octylphenol (OP), in the samples was measured with gas chromatography/mass spectrometry (GC-MS). In addition, the estrogenic activities throughout the river were investigated using the E-screen assay. Of the six estrogenic chemicals, NP (114.6-336.1 ng L(-1)) and EE2 (0.23-1.90 ng L(-1)) were detected at the highest and lowest levels, respectively in both the river waters and the WWTP effluents. Bisphenol-A showed the largest concentration range, from 7.5 to 335 ng L(-1). The concentrations of E1, E2 and octylphenol ranges were 3.6-69.1, 1.2-10.7, and 2.2-16.9 ng L(-1), respectively. According to the calculated estradiol equivalent concentration (EEQ); however, no estrogenic contribution was observed due to the phenolic compounds in the river waters and effluents. E1 and E2 dominated in both the river water and effluent samples, with contributions to the calculated EEQ of over 79 and 77%, respectively. Conversely, EE2 was rarely detected in the river waters (21%) and effluents (0%). The largest contribution of EE2 to the calculated EEQ was 21% in the river water at S-7. The levels of E1, E2, and EE2 were remarkably decreased in the effluents, indicating that the 5 WWTPs did not contribute to the estrogenic effect of the receiving streams. Overall, the WWTPs did not contributed to the estrogenic activity of the receiving waters, but the livestock industry or wildlife may play an important role in the estrogenic contribution to river water.     

The effects of multiple beneficial management practices on hydrology and nutrient losses in a small watershed in the Canadian prairies

Most beneficial management practices (BMPs) recommended for reducing nutrient losses from agricultural land have been established and tested in temperate and humid regions. Previous studies on the effects of these BMPs in cold-climate regions, especially at the small watershed scale, are rare. In this study, runoff and water quality were monitored from 1999 to 2008 at the outlets of two subwatersheds in the South Tobacco Creek watershed in Manitoba, Canada. Five BMPs-a holding pond below a beef cattle overwintering feedlot, riparian zone and grassed waterway management, grazing restriction, perennial forage conversion, and nutrient management-were implemented in one of these two subwatersheds beginning in 2005. We determined that >80% of the N and P in runoff at the outlets of the two subwatersheds were lost in dissolved forms, ≈ 50% during snowmelt events and ≈ 33% during rainfall events. When all snowmelt- and rainfall-induced runoff events were considered, the five BMPs collectively decreased total N (TN) and total P (TP) exports in runoff at the treatment subwatershed outlet by 41 and 38%, respectively. The corresponding reductions in flow-weighted mean concentrations (FWMCs) were 43% for TN and 32% for TP. In most cases, similar reductions in exports and FWMCs were measured for both dissolved and particulate forms of N and P, and during both rainfall and snowmelt-induced runoff events. Indirect assessment suggests that retention of nutrients in the holding pond could account for as much as 63 and 57%, respectively, of the BMP-induced reductions in TN and TP exports at the treatment subwatershed outlet. The nutrient management BMP was estimated to have reduced N and P inputs on land by 36 and 59%, respectively, in part due to the lower rates of nutrient application to fields converted from annual crop to perennial forage. Overall, even though the proportional contributions of individual BMPs were not directly measured in this study, the collective reduction of nutrient losses from the five BMPs was substantial.     

Thermochemical conversion of municipal solid waste into energy and hydrogen: a review

The rising global population is inducing a fast increase in the amount of municipal waste and, in turn, issues of rising cost and environmental pollution. Therefore, alternative treatments such as waste-to-energy should be developed in the context of the circular economy. Here, we review the conversion of municipal solid waste into energy using thermochemical methods such as gasification, combustion, pyrolysis and torrefaction. Energy yield depends on operating conditions and feedstock composition. For instance, torrefaction of municipal waste at 200 °C generates a heating value of 33.01 MJ/kg, while the co-pyrolysis of cereals and peanut waste yields a heating value of 31.44 MJ/kg at 540 °C. Gasification at 800 °C shows higher carbon conversion for plastics, of 94.48%, than for waste wood and grass pellets, of 70–75%. Integrating two or more thermochemical treatments is actually gaining high momentum due to higher energy yield. We also review reforming catalysts to enhance dihydrogen production, such as nickel on support materials such as CaTiO₃, SrTiO₃, BaTiO₃, Al₂O₃, TiO₃, MgO, ZrO₂. Techno-economic analysis, sensitivity analysis and life cycle assessment are discussed.

     

Continued decline of an Atlantic cod population: how important is gray seal predation?

The continental shelf ecosystem on the Eastern Scotian Shelf (ESS) has experienced drastic changes. Once common top predators are a small fraction of their historical abundance, and much of the current community structure is now dominated by pelagic fishes and invertebrates. Embedded within this food web, Atlantic cod and gray seal populations have recently exhibited nearly opposite trends. Since 1984, cod populations have decreased exponentially at a rate averaging 17% per year, whereas gray seals have continued to increase exponentially at a rate of 12%. We reexamined the impact of gray seals on Atlantic cod dynamics using more than 30 years of data on the population trends of cod and gray seals while incorporating new information on seal diet and seasonal distribution. The closure of the cod fishery over 10 years ago allowed for a better estimation of natural mortality rates. We quantified the impact of seals on ESS cod by (1) estimating trends in seal and cod abundance, (2) estimating the total energy needed for seal growth and maintenance from an energetics model, (3) using estimates of the percentage of cod in the total diet derived from quantitative fatty acid signature analysis (QFASA) and of the size-specific selectivity of cod consumed (derived from otoliths collected from fecal samples), and (4) assuming a gray seal functional response. Uncertainties of the model estimates were calculated using the Hessian approximation of the variance-covariance matrix. Between 1993 and 2000, cod comprised, on average, < 5% of a gray seal's diet. Our model shows that, since the closure of the fishery, gray seals have imposed a significant level of instantaneous mortality (0.21), and along with other unknown sources of natural mortality (0.62), are contributing to the failure of this cod stock to recover.