Assessment Of Nutrient Loads Research Articles

Hydrology and Nutrient Dynamics in Managed Restored Wetlands of California’s Central Valley, USA

Extensive wetland losses in California’s Central Valley have led to significant reductions in their natural functions, such as nutrient removal. Past studies suggest that individual wetland restoration efforts in the region yield mixed results mainly due to differences in management practices and degree of access to limited water resources, yet few studies have examined their hydrology or nutrient dynamics with any detail. Our objective was to explore nutrient reduction across a range of hydrological regimes. We recorded hydroperiods and nutrient concentrations of the received and discharged applied water at 21 managed wetlands on national wildlife refuges and private lands over 6 years from 2015 to 2020. Water depths at 18 of these wetlands were monitored continuously for over 400 days. Climatic variation over the observation period included exceptional drought, above-average flooding and relatively stable water conditions. Privately managed wetlands retained water for longer durations of time, but at shallower depths than seasonal wetlands in wildlife refuges. An assessment of nutrient concentrations at inflows relative to outflows was inconclusive and varied among years. However, assessment of nutrient loads indicated consistent retention of ammonium and nitrates across all management types, locations and time periods. Multivariate analysis indicated that climate and location played a role in influencing nutrient concentrations among wetlands. In conclusion, restored wetlands in the central valley provide ecosystem service functions such as removing nutrients from ambient water and provide unique habitats for waterfowls with the presence of seasonal flood and drain management practices.

Assessment of Nutrient Loads into the Ryck River and Options for Their Reduction

A massive shift in agricultural practices over the past decades, to support exceptionally high yields and productivities involving intensive agriculture, have led to unsustainable agriculture practices across the globe. Sustenance of such high yields and productivities demand high use of organic and industrial fertilizers. This acts as a negative pressure on the environment. Excessive use of fertilizers leads to nutrient surplus in the fields, which, as a part of catchment runoff, flows into the water bodies as diffuse pollution. These nutrients through rivers are eventually passed into seas. High nutrients ending up into water bodies cause eutrophication. The situation is worsened when such unsustainable agricultural activities are carried out on drained peatlands. As a result, the nutrients that were not part of the nutrient cycle in the landscape for years begin to leach out due to mineralization of peatlands, thereby putting an additional load of nutrients on the environment, that was already under the negative impact of nutrient surplus. In view of the above, a small lowland catchment of the Ryck river in northeast Germany was assessed for its nitrogen losses from agricultural lands through empirical modelling. Initial empirical modelling resulted in an average annual total nitrogen loss of 14.7 kg ha−1 year−1. After a comparative analysis of these results with procured data, the empirical equation was modified to suit the catchment, yielding more accurate results. The study showed that 75.6% of peatlands in the catchment are under agricultural use. Subsequently, a proposal was made for potential wetland buffer zones in the Ryck catchment. Altogether, 13 peatland sites across 8 sub-catchments were recommended for mitigation of high nutrient runoff. In the end, nutrient efficiency of proposed WBZs in one of the sub-catchments of Ryck has been discussed. The results show that (i) the modified empirical equation can act as a key tool in application-based future strategies for nitrogen reduction in the Ryck catchment, (ii) restoration of peatlands and introduction of WBZs can help in mitigating the nutrient runoff for improved water quality of Ryck, and subsequently (ii) contribute to efficient reduction of riverine loads of nutrients into the Baltic Sea.

Water Quality of Drainage Canals and Assessment of Nutrient Loads Using QUAL2Kw

The water quantity and quality in two of the four main drainage canals located in the plain of Chryssoupolis in Kavala, North Greece, are studied. The area is intensively used for agriculture. Irrigation water is supplied by Nestos River, using a network of irrigation canals. Drainage water and irrigation return flows are collected in the four main drainage canals, which outflow into the Thracian Sea, North Aegean. A monitoring program in the four canals was designed to monitor flow and main constituents of drainage water. Main pollutants included nitrate, phosphorus and suspended solids. Based on the collected data, the trophic state of the canals and its seasonal variation were assessed, and the limiting nutrient was identified. QUAL2Kw was also used to model flow and water quality in two of the four canals. The calibration and verification of QUAL2Kw was undertaken using the collected field data, in an effort to identify the pollution sources and propose future management actions for the improvement of drainage canal water quality. The results showed that QUAL2Kw is a useful tool to simulate water quality in rivers and canals, and to quantify the impacts of non-point source pollution from agricultural areas.

Recent Cattail Expansion and Possible Relationships to Water Management: Changes in Upper Taylor Slough (Everglades National Park, Florida, USA)

Recent appearance of cattail (Typha domingensis) within a southern Everglades slough-Upper Taylor Slough (Everglades National Park)-suggests ecosystem eutrophication. We analyze water quality, nutrient enrichment, and water management operations as potential drivers of eutrophication in Upper Taylor Slough. Further, we attempt to determine why surface water phosphorus, a parameter used commonly to monitor ecosystem health in the Everglades, did not serve as an early warning for eutrophication, which has broader implication for other restoration efforts. We found that surface water total phosphorus concentrations generally were below a 0.01 mg L(-1) threshold determined to cause imbalances in flora and fauna, suggesting no ecosystem eutrophication. However, assessment of nutrient loads and loading rates suggest Upper Taylor Slough has experienced eutrophication and that continued total phosphorus loading through a point-source discharge was a major driver. These nutrient loads, combined with increases in hydroperiods, led to the expansion of cattail in Upper Taylor Slough. We recommend other metrics, such as nutrient loads, periphyton and arthropod community shifts, and sediment core analyses, for assessing ecosystem health. Monitoring surface water alone is not enough to indicate ecosystem stress.