scholarly journals Assessment of Terrigenous Nutrient Loading to Coastal Ecosystems along a Human Land-Use Gradient, Tutuila, American Samoa

Hydrology ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 18 ◽  
Author(s):  
Christopher Shuler ◽  
Daniel Amato ◽  
Veronica Veronica Gibson ◽  
Lydia Baker ◽  
Ashley Olguin ◽  
...  
Keyword(s):  
Land Use ◽  
Nutrient Loading ◽  
Water Discharge ◽  
Nitrogen Isotope ◽  
Nutrient Flux ◽  
American Samoa ◽  
Nutrient Concentrations ◽  
Human Land Use ◽  
The Impact

Anthropogenic nutrient loading is well recognized as a stressor to coastal ecosystem health. However, resource managers are often focused on addressing point source or surface water discharge, whereas the impact of submarine groundwater discharge (SGD) as a nutrient vector is often unappreciated. This study examines connections between land use and nutrient loading through comparison of four watersheds and embayments spanning a gradient of human use impact on Tutuila, a high tropical oceanic island in American Samoa. In each study location, coastal radon-222 measurements, dissolved nutrient concentrations, and nitrogen isotope values (δ15N) in water and in situ macroalgal tissue were used to explore SGD and baseflow derived nutrient impacts, and to determine probable nutrient sources. In addition to sampling in situ macroalgae, pre-treated macroalgal specimens were deployed throughout each embayment to uptake ambient nutrients and provide a standardized assessment of differences between locations. Results show SGD-derived nutrient flux was more significant than baseflow nutrient flux in all watersheds, and δ15N values in water and algae suggested wastewater or manure are likely sources of elevated nutrient levels. While nutrient loading correlated well with expected anthropogenic impact, other factors such as differences in hydrogeology, distribution of development, and wastewater infrastructure also likely play a role in the visibility of impacts in each watershed.

scholarly journals Assessing the Eutrophic Susceptibility of New Zealand Estuaries

2020 ◽  
Vol 43 (8) ◽  
pp. 2015-2033 ◽  
Author(s):  
David R. Plew ◽  
John R. Zeldis ◽  
Bruce D. Dudley ◽  
Amy L. Whitehead ◽  
Leigh M. Stevens ◽  
...  
Keyword(s):  
Land Use ◽  
New Zealand ◽  
Physical Properties ◽  
Nutrient Loading ◽  
Management Strategies ◽  
Nutrient Concentrations ◽  
Intertidal Area ◽  
Land Use Patterns ◽  
Regional Patterns ◽  
Nitrogen Concentrations

Abstract We developed a method to predict the susceptibility of New Zealand estuaries to eutrophication. This method predicts macroalgae and phytoplankton responses to potential nutrient concentrations and flushing times, obtained nationally from simple dilution models, a GIS land-use model and physical estuary properties. Macroalgal response was based on an empirically derived relationship between potential nitrogen concentrations and an established macroalgal index (EQR) and phytoplankton response using an analytical growth model. Intertidal area was used to determine which primary producer was likely to lead to eutrophic conditions within estuaries. We calculated the eutrophication susceptibility of 399 New Zealand estuaries and assigned them to susceptibility bands A (lowest expected impact) to D (highest expected impact). Twenty-seven percent of New Zealand estuaries have high or very high eutrophication susceptibilities (band C or D), mostly (63% of band C and D) due to macroalgae. The physical properties of estuaries strongly influence susceptibility to macroalgae or phytoplankton blooms, and estuaries with similar physical properties cluster spatially around New Zealand’s coasts. As a result, regional patterns in susceptibility are apparent due to a combination of estuary types and land use patterns. The few areas in New Zealand with consistently low estuary eutrophication susceptibilities are either undeveloped or have estuaries with short flushing times, low intertidal area and/or minimal tidal influx. Estuaries with conditions favourable for macroalgae are most at risk. Our approach provides estuary-integrated susceptibility scores likely to be of use as a regional or national screening tool to prioritise more in-depth estuary assessments, to evaluate likely responses to altered nutrient loading regimes and assist in developing management strategies for estuaries.

scholarly journals Human land-use impacts viral diversity and abundance in a New Zealand river

2022 ◽  
Author(s):  
Rebecca French ◽  
Justine Charon ◽  
Callum Le Lay ◽  
Chris Muller ◽  
Edward C Holmes
Keyword(s):  
Land Use ◽  
Water Systems ◽  
Viral Diversity ◽  
Native Forest ◽  
Virus Species ◽  
Human Land Use ◽  
Forest Sites ◽  
Viral Communities ◽  
The Impact ◽  
Urban Sites

Although water borne viruses have important implications for the health of humans and other animals, little is known about the impact of human land use on viral diversity and evolution in water systems such as rivers. We used metagenomic next generation sequencing to compare the diversity and abundance of viruses at sampling sites along a single river in New Zealand that differed in human land use impact, ranging from pristine to urban. From this we identified 504 putative virus species, of which 97% were novel. Many of the novel viruses were highly divergent, and likely included a new subfamily within the Parvoviridae. We identified at least 63 virus species that may infect vertebrates, most likely fish and water birds, from the Astroviridae, Birnaviridae, Parvoviridae and Picornaviridae. No putative human viruses were detected. Importantly, we observed differences in the composition of viral communities at sites impacted by human land use (farming and urban) compared to native forest sites (pristine). At the viral species level, the urban sites had higher diversity (327 virus species) than the farming (n=150) and pristine sites (n=119), and more viruses were shared between the urban and farming sites (n=76) than between the pristine and farming or urban sites (n=24). The two farming sites had a lower viral abundance across all host types, while the pristine sites had a higher abundance of viruses associated with animals, plants and fungi. We also identified viruses linked to agriculture and human impact at the river sampling sites in farming and urban areas that were not present at the native forest sites. Overall, our study shows that human land use can impact viral communities in rivers, such that further work is needed to reduce the impact of intensive farming and urbanization on water systems.

scholarly journals Quantifying the nutrient flux within a lowland karstic catchment

2015 ◽  
Vol 12 (10) ◽  
pp. 10221-10260
Author(s):  
T. McCormack ◽  
O. Naughton ◽  
P. M. Johnston ◽  
L. W. Gill
Keyword(s):  
Nutrient Loading ◽  
Hydrological Model ◽  
Nutrient Flux ◽  
Agricultural Runoff ◽  
Nutrient Loss ◽  
Nutrient Concentrations ◽  
Main Process ◽  
Stable Conditions ◽  
Nitrogen Concentrations ◽  
Hydrological Functioning

Abstract. Nutrient contamination of surface and groundwaters is an issue of growing importance as the risks associated with agricultural runoff escalate due to increasing demands on global food production. In this study, the nutrient flux occurring within the surface and groundwaters of a lowland karst catchment in western Ireland was investigated with the aid of alkalinity sampling and a hydrological model. Water samples were tested from a variety of rivers, lakes (or turloughs), boreholes and springs at monthly intervals over three years. Alkalinity sampling was used to elucidate the contrasting hydrological functioning between different turloughs. Such disparate hydrological functioning was further investigated with the aid of a hydrological model which allowed for an estimate of allogenic and autogenic derived nutrient loading into the karst system. The model also allowed for an investigation of mixing within the turloughs, comparing observed behaviours with the hypothetical conservative behaviour allowed for by the model. Within the turloughs, nutrient concentrations were found to reduce over the flooded period, even though the turloughs hydrological functioning (and the hydrological model) suggested this should not occur. As such, it was determined that nutrient loss processes were occurring within the system. Denitrification during stable flooded periods (typically 3–4 months per year) was deemed to be the main process reducing nitrogen concentrations within the turloughs whereas phosphorus loss is thought to occur mostly via sedimentation and subsequent soil deposition. The results from this study suggest that, in stable conditions, ephemeral lakes can impart considerable nutrient losses on a karst groundwater system.

scholarly journals KAJIAN KERUSAKAN DAN KERUNTUHAN TUBUH BENDUNGAN AKIBAT PENGARUH BANJIR (STUDI KASUS : BENDUNGAN CIPAMINGKIS KAB. BOGOR)

2021 ◽  
Vol 14 (2) ◽  
pp. 113
Author(s):  
Heri Suherlan
Keyword(s):  
Land Use ◽  
Carrying Capacity ◽  
Rainy Season ◽  
Water Discharge ◽  
The Body ◽  
Rice Fields ◽  
The Impact ◽  
Damage Study

Land use in the vicinity of Cipamingkis Sub-watershed is currently very intensive, so that damage to land which is feared has an impact on the level of fertility and carrying capacity of the land, resulting in the danger of flooding, erosion and landslides in the rainy season, as well as a decrease in water discharge and lack of groundwater in the season dry. The impact of these conditions Cipamingkis Weir in Sukasirna Village, Jonggol District on April 20, 2017 there was a breakdown of the lighthouse and the body of the weir which was built since 1982, the dam irrigated 4579 Ha of rice fields, unable to irrigate and in the lower reaches of the dam a lot of damage, including: eroded riverbanks, damaged river cliffs, and part of the land cracked and landslides.Seeing the condition needs to be made a research on Cipamingkis Dam Damage Study. This handling is urgently needed to reduce and reduce the consequences caused in the process of activities that cause erosion and flooding.

The effects of N:P ratio and nitrogen form on four major freshwater bacterial taxa in biofilms

2010 ◽  
Vol 56 (1) ◽  
pp. 32-43 ◽  
Author(s):  
Melissa A. Barlett ◽  
Laura G. Leff
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
N:P Ratio ◽  
Nutrient Concentrations ◽  
Nitrogen Form ◽  
Nutrient Stoichiometry ◽  
Surrounding Water ◽  
Dramatic Effect ◽  
Molar Ratios ◽  
The Impact

Bacteria in freshwater systems play an important role in nutrient cycling through both assimilatory and dissimilatory processes. Biotic and abiotic components of the environment affect these transformations as does the stoichiometry of the nutrients. We examined responses of four major taxa of bacteria in biofilms subjected to various N:P molar ratios using either nitrate or ammonium as a nitrogen source. Fluorescent in situ hybridization was used to enumerate the Domain bacteria as well as the α-, β-, and γ-proteobacteria, and the Cytophaga–Flavobacteria cluster. Generally, bacterial responses to the treatments were limited. However, the Cytophaga–Flavobacteria and β-proteobacteria both responded more to the ammonium additions than nitrate, whereas, the α-proteobacteria responded more to nitrate additions. The β-proteobacteria also exhibited peak relative abundance at the highest N:P ratio. Nutrient concentrations were significantly different after the incubation period, and there were distinct changes in the stoichiometry of the microcosms with ammonium. We demonstrated that bacteria may play an important role in nutrient uptake, and transformation, and can have a dramatic effect on the nutrient stoichiometry of the surrounding water. However, although some taxa exhibited differences in response to ammonium and nitrate, the impact of nutrient stoichiometry on the abundance of the taxa examined was limited.

scholarly journals Stable Isotopic Evidence for Nutrient Rejuvenation and Long-Term Resilience on Tikopia Island (Southeast Solomon Islands)

2021 ◽  
Vol 13 (15) ◽  
pp. 8567
Author(s):  
Jillian A. Swift ◽  
Patrick V. Kirch ◽  
Jana Ilgner ◽  
Samantha Brown ◽  
Mary Lucas ◽  
...  
Keyword(s):  
Land Use ◽  
Nutrient Dynamics ◽  
Solomon Islands ◽  
Isotope Analysis ◽  
Nutrient Status ◽  
Nitrogen Isotope ◽  
External Support ◽  
Deep Time ◽  
Human Land Use

Tikopia Island, a small and relatively isolated Polynesian Outlier in the Southeast Solomon Islands, supports a remarkably dense human population with minimal external support. Examining long-term trends in human land use on Tikopia through archaeological datasets spanning nearly 3000 years presents an opportunity to investigate pathways to long-term sustainability in a tropical island setting. Here, we trace nutrient dynamics across Tikopia’s three pre-European contact phases (Kiki, Sinapupu, Tuakamali) via stable carbon and nitrogen isotope analysis of commensal Pacific rat (Rattus exulans) and domestic pig (Sus scrofa) bone and tooth dentine collagen. Our results show a decline in δ15N values from the Kiki (c. 800 BC-AD 100) to Sinapupu (c. AD 100–1200) phases, consistent with long-term commensal isotope trends observed on other Polynesian islands. However, increased δ15N coupled with lower δ13C values in the Tuakamali Phase (c. AD 1200–1800) point to a later nutrient rejuvenation, likely tied to dramatic transformations in agriculture and land use at the Sinapupu-Tuakamali transition. This study offers new, quantifiable evidence for deep-time land and resource management decisions on Tikopia and subsequent impacts on island nutrient status and long-term sustainability.

scholarly journals Discharge and sediment loads of two streams in the mid-hills of central Nepal

1970 ◽  
Vol 2 (3) ◽  
pp. 51-54 ◽  
Author(s):  
Roshan M Bajracharya ◽  
Subodh Sharma ◽  
Roberto Clemente
Keyword(s):  
Land Use ◽  
Stream Flow ◽  
Management Practices ◽  
Nutrient Loading ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Sediment Yields ◽  
Growing Seasons ◽  
Sediment Loads ◽  
Land Use And Management

Stream flow, nutrient loading, and sediment yield closely reflect land use and management practices in relation to growing seasons in mid-hill watersheds of the central Himalaya. A preliminary study was conducted to determine approximate total water discharge and sediment yields from the Galaundi and Pokhare catchments. Mean discharge and sediment loads during the 2002 rainy season were 2.1 m3?s-1 and 0.9 kg?s-1 for Galaundi Khola and 0.45 m3 s-1 and 0.28 kg?s-1 for Pokhare Khola. Estimates of total annual discharge of water and sediment were, respectively, 27.8 million m3 and 11,400 t (Galaundi) and 6.4 million m3 and 3,500 t (Pokhare). These corresponded to about 71.6% and 60.4% of total rain volumes and soil loss rates of 5.18 t?ha-1 and 5.83 t?ha-1 for Galaundi and Pokhare sub-watersheds, respectively. Good correlations were observed for stream discharge vs. sediment concentration (R2 = 0.83 and 0.94 respectively) and rainfall amount vs. discharge (R2 = 0.94 and 0.96 respectively) for both streams. Key words: stream flow, sediment concentration, land use, pre-monsoon, sub-watershed Himalayan Journal of Sciences 2(3): 51-54, 2004

scholarly journals Anthropogenic impact on biogenic Si pools in temperate soils

2011 ◽  
Vol 8 (3) ◽  
pp. 4391-4419 ◽  
Author(s):  
W. Clymans ◽  
E. Struyf ◽  
G. Govers ◽  
F. Vandevenne ◽  
D. J. Conley
Keyword(s):  
Land Use ◽  
Agricultural Development ◽  
Land Use Changes ◽  
Arable Land ◽  
Terrestrial Ecosystems ◽  
Human Land Use ◽  
Long Term Effect ◽  
Disturbed Land ◽  
The Impact

Abstract. Human land use changes directly affect silica (Si) mobilisation and Si storage in terrestrial ecosystems and influence Si export from the continents, although the magnitudes of the impact are unknown. Yet biogenic silica (BSi) in soils is an understudied aspect. We have quantified and compared total biogenic (PSia) and easily soluble (PSie) Si pools at four sites along a gradient of disturbance in southern Sweden. An estimate of the magnitude of change in temperate continental BSi pools due to human disturbance is provided. Land use clearly affects BSi pools and their distribution. Total PSia and PSie for a continuous forested site at Siggaboda Nature Reserve (66 900 ± 22 800 kg SiO2 ha−1 and 952 ± 16 kg SiO2 ha−1) are significantly higher than disturbed land use types from the Råshult Culture Reserve including arable land (28 800 ± 7200 kg SiO2 ha−1 and 239 ± 91 kg SiO2 ha−1), pasture sites (27 300 ± 5980 kg SiO2 ha−1 and 370 ± 129 kg SiO2 ha−1) and grazed forest (23 600 ± 6370 kg SiO2 ha−1 and 346 ± 123 kg SiO2 ha−1). Vertical PSia and PSie profiles show significant (p<0.05) variation among the sites. These differences in size and distribution are interpreted as the long-term effect of reduced BSi replenishment and increased mobilisation of the PSia in disturbed soils. In temperate regions, total PSia showed a 10 % decline since agricultural development (3000BCE). Recent agricultural expansion (after 1700CE) has resulted in an average export of 1.1 ± 0.8 Tmol Si yr−1, leading to an annual contribution of ca. 20 % to the global land-ocean Si flux carried by rivers. Human activities clearly exert a long-term influence on Si cycling in soils and contribute significantly to the land-ocean Si flux.

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