The Life and Death and Consequences of Canals and Spoil Banks in Salt Marshes

We describe the consequence and demise of levees (spoil banks) built from dredging canals in Louisiana salt marshes using morphometric measurements made over 30 years, soil collections on the spoil bank and in the salt marshes behind, and complementary observations from other areas. These measurements were used to determine the temporal bounds of how long spoil banks last and if salt marsh soils remaining in salt marshes are affected. If the rates of changes in spoil bank morphology continue, then the estimated life time of the shrub-tree vegetation at a representative spoil bank is 81 years, the spoil bank width is 89 years, and the dredged channel will erode to the center of the spoil bank after 118 years. The soils in marshes behind the spoil bank have a higher bulk density than in reference marshes, accumulate more mineral matter per year, have lower root mass and are weaker. These observations are compatible with measurements of spoil bank width, vegetative cover and soil compaction, and the conversion from wetland to open water on a coastwide scale.

Microbiomes of the initial soils of mining areas of Yakutsk City (Eastern Siberia, Russia)

The microbiome of initial soils formed at the heaps and bottoms of surface sediment quarries in the surroundings of Yakutsk City(Eastern Siberia,Russia) has been characterized for the first time. In the initial Entisols, we detected Alphaproteobacteria (represented mainly by the family Rizobiales), Gammaproteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes (mostly Chitinophagales), Deltaproteobacteria, and Chloroflexi. The lower soil horizons had a more homogenous species diversity taxonomy that was dominated by Gammaproteobacteria. The morphologically different horizons did not differ microbiologically. This is caused by the limited soil development and relatively slow rate of revegetation of the spoil banks and heaps of the quarries under the severe climatic conditions of the Eastern part of Russian Arctic zone. Based on our findings, we propose that the soil microbiomes in such recently abandoned quarries are characterized by low diversity, which is a characteristic feature of the polar soils surrounding Yakutsk. Data obtained can be used for elaboration of reclamation strategies with taking into account the information about key microbial drivers of soil processes.

Life Cycle of Oil and Gas Fields in the Mississippi River Delta: A Review

Oil and gas (O&G) activity has been pervasive in the Mississippi River Delta (MRD). Here we review the life cycle of O&G fields in the MRD focusing on the production history and resulting environmental impacts and show how cumulative impacts affect coastal ecosystems. Individual fields can last 40–60 years and most wells are in the final stages of production. Production increased rapidly reaching a peak around 1970 and then declined. Produced water lagged O&G and was generally higher during declining O&G production, making up about 70% of total liquids. Much of the wetland loss in the delta is associated with O&G activities. These have contributed in three major ways to wetland loss including alteration of surface hydrology, induced subsidence due to fluids removal and fault activation, and toxic stress due to spilled oil and produced water. Changes in surface hydrology are related to canal dredging and spoil placement. As canal density increases, the density of natural channels decreases. Interconnected canal networks often lead to saltwater intrusion. Spoil banks block natural overland flow affecting exchange of water, sediments, chemicals, and organisms. Lower wetland productivity and reduced sediment input leads to enhanced surficial subsidence. Spoil banks are not permanent but subside and compact over time and many spoil banks no longer have subaerial expression. Fluid withdrawal from O&G formations leads to induced subsidence and fault activation. Formation pore pressure decreases, which lowers the lateral confining stress acting in the formation due to poroelastic coupling between pore pressure and stress. This promotes normal faulting in an extensional geological environment like the MRD, which causes surface subsidence in the vicinity of the faults. Induced reservoir compaction results in a reduction of reservoir thickness. Induced subsidence occurs in two phases especially when production rate is high. The first phase is compaction of the reservoir itself while the second phase is caused by a slow drainage of pore pressure in bounding shales that induces time-delayed subsidence associated with shale compaction. This second phase can continue for decades, even after most O&G has been produced, resulting in subsidence over much of an oil field that can be greater than surface subsidence due to altered hydrology. Produced water is water brought to the surface during O&G extraction and an estimated 2 million barrels per day were discharged into Louisiana coastal wetlands and waters from nearly 700 sites. This water is a mixture of either liquid or gaseous hydrocarbons, high salinity (up to 300 ppt) water, dissolved and suspended solids such as sand or silt, and injected fluids and additives associated with exploration and production activities and it is toxic to many estuarine organisms including vegetation and fauna. Spilled oil has lethal and sub-lethal effects on a wide range of estuarine organisms. The cumulative effect of alterations in surface hydrology, induced subsidence, and toxins interact such that overall impacts are enhanced. Restoration of coastal wetlands degraded by O&G activities should be informed by these impacts.

Selection of the Investor’s Type for the Project Utilization of a Man-Made Deposit Using Hierarchy Process Method

Factors influencing the volumes of investments in spoil banks reclamation are considered. Using goal hierarchy, all possible types of investors are analyzed, as well as their goals when obtaining licenses for the development of man-made deposits. On the example of Lvov basin spoil banks, four types of investors are systematized and different priorities of goals are assessed, the environmental criterion always being the first priority. It is made to prevent environmental catastrophe while developing man-made deposits in the region. Using the matrix of pair comparison, it is proved that the state or community is the optimal investor in developing man-made deposits. Both foreign investor and the spoil-bank owner can be on the second place after the state depending on the priority of profitability or social problems of the area.

Effects of varying doses of Frisol on European ash (Fraxinus excelsior L.) planted on spoil banks

Frisol forte (FR F) and Frisol active (FR A) are slow-acting organic fertilisers recommended for reclamation and revitalisation of undeveloped soils and degraded areas. Tentative results of experiments carried out with these products on spoil banks in the CR showed controversial reactions of plants - on the one hand a high mortality of seedlings and a very good growth on the other. Reasons for these disproportions projecting themselves into the welfare of woody plants probably lie in an incorrect dosage of products. Thus, a special long-term experiment was established with the objective to find an optimal dosing to be used in practice for the reclamation process on spoil banks. By the method of measuring and statistical evaluation of height and stem diameter growths it was discovered that the best results were achieved by the combined use of both products with a dosage in the range of 30-60 g FR F + 250 ml FR A/5 l of water/10 seedlings. The discovered dosage is lower than that indicated by the manufacturer and literature. The application of granulated FR F alone was not so effective. The best dosage in this case was also 60 g/seedling. A disadvantage of using the combination of both types of Frisol is that the water required for dissolving the FR A liquid concentrate is not always available in the location being reforested.