China
Africa
Explore chapters and articles related to this topic
General introduction
Published in Abias Uwimana, Effects of Wetland Conversion to Farming on Water Quality and Sediment and Nutrient Retention in a Tropical Catchment, 2019
As water flows through landscapes with different land use (e.g. fishponds, rice fields and wetlands), nutrient cycling occurs through the interactions among nutrients and soil, sediments, microorganisms, litter, plants, atmosphere and the water. The extent to which water quality is affected, and sediment, nitrogen and phosphorus are retained or recycled depends on physical forces like the effects of hydrology, wind, vegetation, animals and humans, and in-situ biochemical processes like photosynthesis, biomass growth, death and decomposition. By these processes, sediments, nitrogen and phosphorus can accumulate in sediment, groundwater or biomass, be lost to the atmosphere (for nitrogen), exported through harvesting or lost to downstream areas through the effluent. Land use types with low flow velocities and dense vegetation cover favour sediment settling more than land uses with fast and turbulent flows and low vegetation density. Therefore, fishponds and natural wetlands are expected to contribute more to nutrient and sediment retention than rice fields. Increasing their use in valley bottoms can increase the overall retention function of valley bottoms.
Pollution: Nonpoint Source
Published in Yeqiao Wang, Wetlands and Habitats, 2020
Ravendra Naidu, Mallavarapu Megharaj, Peter Dillon, Rai Kookana, Ray Correll, W. W. Wenzel
Environmental contaminants can have a deleterious effect on non-target organisms and their beneficial activities. These effects could include a decline in primary production, decreased rate of organic matter break-down, and nutrient cycling as well as mineralization of harmful substances that in turn cause a loss of productivity of the ecosystems. Certain pollutants, even though present in very small concentrations in the soil and surrounding water, have potential to be taken up by various micro-organisms, plants, animals, and ultimately human beings. These pollutants may accumulate and concentrate in the food chain by several thousand times through a process referred to as biomagnification.
Ecosystems: Forest Nutrient Cycling
Published in Yeqiao Wang, Terrestrial Ecosystems and Biodiversity, 2020
Neil W. Foster, Jagtar S. Bhatti
Nutrient cycling in forest ecosystems is controlled primarily by three key factors: climate, site, abiotic properties (topography, parent material), and biotic communities. The role of each factor in ecosystem nutrient dynamics is discussed and illustrated with selected examples from boreal, temperate, and tropical zones. The importance of ecosystem disturbance to nutrient cycling is examined briefly, since some nutrients are added or lost from forest ecosystems through natural (e.g., fire, erosion, leaching) or human activity (harvesting, fertilization).
Ensuring planetary survival: the centrality of organic carbon in balancing the multifunctional nature of soils
Published in Critical Reviews in Environmental Science and Technology, 2022
Peter M. Kopittke, Asmeret Asefaw Berhe, Yolima Carrillo, Timothy R. Cavagnaro, Deli Chen, Qing-Lin Chen, Mercedes Román Dobarco, Feike A. Dijkstra, Damien J. Field, Michael J. Grundy, Ji-Zheng He, Frances C. Hoyle, Ingrid Kögel-Knabner, Shu Kee Lam, Petra Marschner, Cristina Martinez, Alex B. McBratney, Eve McDonald-Madden, Neal W. Menzies, Luke M. Mosley, Carsten W. Mueller, Daniel V. Murphy, Uffe N. Nielsen, Anthony G. O’Donnell, Elise Pendall, Jennifer Pett-Ridge, Cornelia Rumpel, Iain M. Young, Budiman Minasny
Through its effect on plant biomass, species diversity, and soil properties, land-use change alters both total stocks of soil nutrients as well as their cycling (Figure 6). This is particularly important for nutrients closely associated with SOC (especially N, P, and S) given the profound decrease in SOC stocks and concentrations with land-use change (see Section 2.2) as well as the critical role of SOC in soil fertility. For example, it has been reported in a global meta-analysis that upon conversion of forest to cropping land, the median decrease in soil N stocks was 42%, with corresponding decreases being 31% for P and 32% for S (Kopittke et al., 2017). Indeed, land use change from natural to agricultural ecosystems can disrupt nutrient cycling by decreasing organic matter and nutrient return to the soil, accelerating SOC decomposition rates through tillage, and also increasing nutrient losses through runoff, erosion, volatilization and leaching (Magdoff et al., 1997), as well as via product export. Further, conversion of naturally diverse ecosystems to agricultural use can have detrimental effects on nutrient cycling by reducing the diversity of organic materials entering the soil, which reduces food web diversity and thus nutrient cycling (Kostin et al., 2021; Tsiafouli et al. 2015).
Excretion from the benthic macrofauna covers little of spring nutrient uptake in a small Danish forest stream
Published in Inland Waters, 2021
Robert Lindenskov, Dean Jacobsen
Stream nutrient dynamics vary greatly in space and time, and measurements of parameters such as uptake length, velocity, and rate can be used to quantify biological activity, nutrient demand, and limitation (Ensign and Doyle 2006, Hoellein et al. 2007). Freshwater consumers play a role in ecosystem nutrient cycling and dynamics by contributing dissolved nutrients through leaching from food sources such as algae, detritus, or other animals while foraging, and by excreting soluble metabolic waste products containing nitrogen (N) and phosphorus (P). This process is potentially important because ammonium (NH4) and phosphate (PO4) are readily taken up by primary producers and heterotrophic microorganisms (Vanni 2002, Griffiths and Hill 2014). Excretion from freshwater consumers have been widely studied (Vanni 2002, Vanni et al. 2017), finding that excretion rates differ between species (Vanni et al. 2002, McManamay et al. 2011) and also vary temporally (Christian et al. 2008, Griffiths and Hill 2014), depending on, for example, food quantity and quality (Elser and Urabe 1999, James et al. 2007) and temperature (Gardner et al. 1981, Devine and Vanni 2002).
Low Impact Development practices in the context of United Nations Sustainable Development Goals: A new concept, lessons learned and challenges
Published in Critical Reviews in Environmental Science and Technology, 2022
Marina Batalini de Macedo, Marcus Nóbrega Gomes Júnior, Thalita Raquel Pereira de Oliveira, Marcio H. Giacomoni, Maryam Imani, Kefeng Zhang, César Ambrogi Ferreira do Lago, Eduardo Mario Mendiondo
An alternative for nutrient cycling is the reuse of plant biomass as a biofertilizer in another location (Ge et al., 2016), which allows the management with a proper dosage so that there is no toxicity by metals to the plants or consumers. Also, Chandrasena et al. (2016) investigated the pathogens concentration (E. coli and Campylobacter ssp.) in bioretention effluent and have obtained removal rates that were able to meet the Australian stormwater harvesting guidelines for irrigation.