CARACTERÍSTICAS DAS CHUVAS E INTERCEPTAÇÃO VEGETAL NO BIOMA CAATINGA

CARACTERÍSTICAS DAS CHUVAS E INTERCEPTAÇÃO VEGETAL NO BIOMA CAATINGA JOSÉ BANDEIRA BRASIL1; HELBA ARAÚJO DE QUEIROZ PALÁCIO2; JOSÉ RIBEIRO DE ARAÚJO NETO2; JACQUES CARVALHO RIBEIRO FILHO3 E EUNICE MAIA DE ANDRADE1 1 Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Campus do PICI, Bloco 804, Fortaleza-CE, Brasil. E-mail: [email protected]; [email protected] Instituto Federal de Educação, Ciência e Tecnologia do Ceará-IFCE, Campus Iguatu, rodovia Iguatu-Várzea Alegre, Km 05, s/n, Iguatu-CE, Brasil. E-mail: [email protected]; [email protected] Departamento de Ciências Ambientais e Tecnológicas, Universidade Federal Rural do Semi-Árido-UFERSA, Mossoró-RN, Brasil; [email protected]. 1 RESUMO A dinâmica da interceptação vegetal depende principalmente das características das chuvas e estrutura do dossel das árvores. Objetivou-se com este estudo analisar o efeito das características das chuvas (classes de precipitação (CP) - CP < 15 mm, 15 ≤ CP < 30 mm, 30 ≤ CP < 60 mm e CP ≥ 60 mm e classes de intensidade (CI) - 1,1 mm h-1 ≤ CI < 5 mm h-1, 5,1 mm h-1 ≤ CI < 25 mm h-1, 25,1 mm h-1 ≤ CI < 50 mm h-1 e CI ≥ 50,1 mm h-1) e as variações sazonais na interceptação em área de caatinga em regeneração. O experimento foi conduzido em uma microbacia experimental no município de Iguatu-Ceará, em seis anos consecutivos, de 2010 a 2015, totalizando 212 eventos. Foram monitorados a precipitação interna, escoamento pelos caules das árvores e perda por interceptação em uma área de 10 x 10 m. A precipitação total foi medida com o auxílio de um pluviômetro do tipo “Ville de Paris” instalado em área aberta. Constatou-se que não houve diferenças sazonais (período chuvoso - janeiro a junho e período seco - julho a dezembro) entre os percentuais médios de Precipitação interna (Pint), Escoamento pelo caule (Esc) e Perda por interceptação (I), em função das características das chuvas e da vegetação. Os resultados demonstram que as menores perdas relativas por interceptação foram observadas nas classes de precipitação > 60 mm e nos eventos mais intensos os percentuais médios de perda por interceptação são menores. Palavras-chave: Classes de chuva, intensidades pluviométricas, variabilidade sazonal. BRASIL, J. B.; PALÁCIO, H. A. de Q.; ARAÚJO NETO, J. R. de; RIBEIRO FILHO, J. C.; ANDRADE, E. M. deRAINFALL CHARACTERISTICS AND VEGETATION INTERCEPTION IN THE CAATINGA BIOME 2 ABSTRACT The mechanism of vegetation interception depends largely on the rainfall characteristics and canopy of the trees. The main objective of this study was to analyze the effects of the rainfall characteristics (precipitation classes (RC) - RC < 15 mm, 15 mm ≤ RC < 30 mm, 30 mm ≤ RC < 60 mm and RC ≥ 60 mm and intensity classes (IC) - 1,1 mm h-1 ≤ IC < 5 mm h-1, 5,1 mm h-1 ≤ IC < 25 mm h-1, 25,1 mm h-1 ≤ IC < 50 mm h-1 and IC ≥ 50,1 mm h-1) and the seasonal variations of the interception in an area with regenerating caatinga. The experiment was conducted on an experimental catchment in the municipality of Iguatu, Ceará, during six consecutive years, from 2010 to 2015, with a total of 212 events. Internal precipitation, tree trunk runoff and loss by interception in areas of 10 x 10 m were monitored. The total rainfall was measured with a “Ville de Paris” rain gage, installed in an open area. No seasonal changes were observed (wet season – January through June – and dry season – July through December) among the average percentages of internal precipitation (Pint), tree trunk runoff (Esc) and loss by interception (I), due to the rainfall and vegetation characteristics. The results show that the smallest relative losses by interception were observed in the precipitation classes over 60 mm and, among the most intense events, the average loss percentages by interception are smaller. Keywords: Rainfall classes, rainfall intensities, seasonal variability.

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The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽

10.1186/s12864-021-07372-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Xue Zhu ◽

Jiyue Qin ◽

Chongyang Tan ◽

Kang Ning

Keyword(s):

Gut Microbiome ◽

Seasonal Changes ◽

Dry Season ◽

Urban Setting ◽

Snp Analysis ◽

Wet Season ◽

Human Gut ◽

Human Gut Microbiome ◽

Genome Level ◽

Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

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Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

Marine and Freshwater Research ◽

10.1071/mf12114 ◽

2012 ◽

Vol 63 (9) ◽

pp. 788 ◽

Cited By ~ 17

Author(s):

N. E. Pettit ◽

T. D. Jardine ◽

S. K. Hamilton ◽

V. Sinnamon ◽

D. Valdez ◽

...

Keyword(s):

Water Quality ◽

Seasonal Changes ◽

Aquatic Macrophyte ◽

Plant Cover ◽

Critical Role ◽

Dry Season ◽

Nutrient Concentrations ◽

Wet Season ◽

Dry Tropics ◽

The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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Accurate Quantification of Seasonal Rainfall and Associated Climate–Wildfire Relationships

Journal of Applied Meteorology and Climatology ◽

10.1175/2010jamc2532.1 ◽

2010 ◽

Vol 49 (12) ◽

pp. 2559-2573 ◽

Cited By ~ 33

Author(s):

Matthew G. Slocum ◽

William J. Platt ◽

Brian Beckage ◽

Steve L. Orzell ◽

Wayne Taylor

Keyword(s):

Daily Rainfall ◽

Seasonal Rainfall ◽

Wet Season ◽

Rainfall Characteristics ◽

Central Florida ◽

South Central ◽

Multiple Regression Technique ◽

Precise Quantification ◽

Rainfall Anomalies ◽

Force Range

Abstract Wildfires are often governed by rapid changes in seasonal rainfall. Therefore, measuring seasonal rainfall on a temporally finescale should facilitate the prediction of wildfire regimes. To explore this hypothesis, daily rainfall data over a 58-yr period (1950–2007) in south-central Florida were transformed into cumulative rainfall anomalies (CRAs). This transformation allowed precise estimation of onset dates and durations of the dry and wet seasons, as well as a number of other variables characterizing seasonal rainfall. These variables were compared with parameters that describe ENSO and a wildfire regime in the region (at the Avon Park Air Force Range). Onset dates and durations were found to be highly variable among years, with standard deviations ranging from 27 to 41 days. Rainfall during the two seasons was distinctive, with the dry season having half as much as the wet season despite being nearly 2 times as long. The precise quantification of seasonal rainfall led to strong statistical models describing linkages between climate and wildfires: a multiple-regression technique relating the area burned with the seasonal rainfall characteristics had an of 0.61, and a similar analysis examining the number of wildfires had an of 0.56. Moreover, the CRA approach was effective in outlining how seasonal rainfall was associated with ENSO, particularly during the strongest and most unusual events (e.g., El Niño of 1997/98). Overall, the results presented here show that using CRAs helped to define the linkages among seasonality, ENSO, and wildfires in south-central Florida, and they suggest that this approach can be used in other fire-prone ecosystems.

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Seasonal Distribution and Abundance of Dugongs in the Western-Gulf-of-Carpentaria

Wildlife Research ◽

10.1071/wr9890141 ◽

1989 ◽

Vol 16 (2) ◽

pp. 141 ◽

Cited By ~ 7

Author(s):

P Bayliss ◽

WJ Freeland

Keyword(s):

Relative Density ◽

Relative Abundance ◽

Coastal Waters ◽

Seasonal Changes ◽

Aboriginal People ◽

Dry Season ◽

Seasonal Distribution ◽

Wet Season ◽

Aerial Surveys ◽

The 1960S

Aerial surveys of coastal waters (27 216 km2) in the western Gulf of Carpentaria during the dry season of 1984 and wet season of 1985 indicated no major seasonal changes in distribution and relative abundance of dugongs. Minimum population size in the dry season was estimated as 16 816 � 2946 (standard error), with a relative density of 0.62 k 0.11 km-2, and that for the wet season 16 846 + 3257, with a relative density of 0.62 � 0.12 km-2. The estimates exclude 5% of observations which could have been either dugongs or Irrawaddy dolphins, and were corrected for submerged dugongs and those missed on the surface. Dugongs were unevenly distributed over the study area, and neither mean group size nor proportion of calves varied between seasons. Dugong abundance was correlated with area of available seagrass. The catch rate of dugongs by Aboriginal people off Numbulwar decreased six-fold between the 1960s and 1985 (60 to 10 p.a.), possibly due to excessive hunting.

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Flowering and fruiting phenologies of seasonal and aseasonal neotropical forests: the role of annual changes in irradiance

Journal of Tropical Ecology ◽

10.1017/s0266467406003890 ◽

2007 ◽

Vol 23 (2) ◽

pp. 231-251 ◽

Cited By ~ 115

Author(s):

Jess K. Zimmerman ◽

S. Joseph Wright ◽

O. Calderón ◽

M. Aponte Pagan ◽

S. Paton

Keyword(s):

Soil Moisture ◽

Seasonal Variation ◽

Solar Irradiance ◽

Seasonal Changes ◽

Light Availability ◽

Barro Colorado Island ◽

Wet Season ◽

Neotropical Forests ◽

Seasonally Dry ◽

Solar Declination

The seasonality of both rainfall and solar irradiance might influence the evolution of flowering and fruiting in tropical forests. In seasonally dry forests, to the degree that soil moisture limits plant productivity, community-wide peaks in reproduction are expected during the rainy season, with seedfall and germination timed to allow seedlings to become well established while soil moisture is available. Where soil moisture is never seasonally limiting, seasonal changes in light availability caused by periods of cloudiness or seasonally low zenithal sun angles should favour reproduction during seasons when irradiance levels are high. To evaluate these predictions, we documented the timing of flower and fruit fall for 10 and 15 y at El Verde, Puerto Rico, and Barro Colorado Island (BCI), Panama. At El Verde, rainfall is abundant year-round and solar declination largely determines seasonal variation in irradiance. At BCI, rainfall is abundant throughout the 8-mo wet season while drought develops and average solar irradiance increases by 40–50% over the 4-mo dry season. Seasonal variation in the number of species flowering and fruiting at both sites was generally consistent with the hypothesis that seasonal variation in irradiance limits the evolution of reproductive phenologies. Community-level metrics provided no evidence for a similar role for moisture availability at BCI. Seasonal variation in irradiance also strongly influenced seed development times at both sites. Thus, community-wide phenologies reveal a strong signature of seasonal changes in irradiance, even in those forests that exhibit some degree of seasonality in rainfall.

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EFICIÊNCIA DA COBERTURA VEGETAL NA REDUÇÃO DAS PERDAS DE ÁGUA E SOLO NO MUNICÍPIO DE IGUATU

Irriga ◽

10.15809/irriga.2018v23n1p133 ◽

2018 ◽

Vol 23 (1) ◽

pp. 133-142 ◽

Cited By ~ 1

Author(s):

Antonio Gebson Pinheiro ◽

Julio Cesar Neves Dos Santos ◽

Helba Araújo De Queiroz Palácio ◽

José Ribeiro De Araújo Neto ◽

Eunice Maia De Andrade

Keyword(s):

Vegetation Cover ◽

Soil Loss ◽

Hydrological Processes ◽

Total Rainfall ◽

Rainfall Volume ◽

The One ◽

The City ◽

E Mail ◽

Soil Losses ◽

Vegetal Cover

EFICIÊNCIA DA COBERTURA VEGETAL NA REDUÇÃO DAS PERDAS DE ÁGUA E SOLO NO MUNICÍPIO DE IGUATU ANTONIO GEBSON PINHEIRO1; JÚLIO CESAR NEVES DOS SANTOS2; HELBA ARAÚJO DE QUEIROZ3; JOSÉ RIBEIRO DE ARAÚJO NETO4 E EUNICE MAIA DE ANDRADE5 1Departamento de Engenharia Agrícola, Universidade Federal Rural de Pernambuco, Rua Manuel de Medeiro, s/n, CEP:52171-90, Recife-PE. E-mail: [email protected];2Instituto Federal do Triângulo Mineiro – Campus Uberlândia, Fazenda Sobradinho, s/n, CEP:38400-970, Uberlândia-MG. E-mail: [email protected];3Instituto Federal do Ceará – Campus Iguatu, Rodovia Iguatu / Várzea Alegre km 05, s/n, CEP:63500-000, Iguatu-CE. E-mail: [email protected];4Instituto Federal do Ceará – Campus Iguatu, Rodovia Iguatu / Várzea Alegre km 05, s/n, CEP:63500-000, Iguatu-CE. E-mail: [email protected];5Departamento de Engenharia Agrícola, Universidade Federal do Ceará, Avenida Minter Hull, s/n, CEP:60455-970, Fortaleza-CE. E-mail: [email protected]. 1 RESUMO O estudo sobre as mudanças da cobertura vegetal é de importância primária para o entendimento de possíveis alterações em processos hidrológicos. Objetivou-se avaliar a influência da retirada da cobertura vegetal nas perdas de água e solo para diferentes classes de chuvas: < 20 mm, 20 – 60 mm, 60 – 80 mm e > 80 mm. O Estudo foi desenvolvido no município de Iguatu, Ceará. Foram monitoradas duas parcelas de erosão com diferentes manejos: solo exposto e com pastagem. O estudo ocorreu durante os anos de 2011 a 2014. O ano de 2011 caracterizou-se como o de maior volume pluviométrico (1.372 mm). Do total precipitado neste ano, 610 e 724 mm foram perdidos por escoamento superficial nas parcelas de pastagem e solo exposto, respectivamente; com perda de solo de 3.746 e 52.114 kg ha-1. Em 2013 ocorreu o menor somatório pluviométrico (630,8 mm), sendo perdidos por escoamento 85,8 e 313,4 mm e ocasionadas perdas de solo equivalentes a 82 e 12.820 kg ha-1 para as parcelas de pastagem e solo exposto, respectivamente. Tais resultados evidenciam a importância da cobertura vegetal na redução das perdas de água e solo e a forte influência da concentração de chuvas da região nos processos hidrológicos. Palavras-chave: escoamento superficial, classes de chuvas, solo exposto PINHEIRO, A. G.; SANTOS, J. C. N.; PALÁCIO, H. A. Q.; ARAÚJO NETO, J. R.; ANDRADE, E. MEFFICIENCY OF VEGETABLE COVERAGE IN REDUCING WATER AND SOIL WASTE IN IGUATU MUNICIPALITY 2 ABSTRACT The study on the changes of vegetal cover is of primary importance for the understanding of possible alterations in hydrological processes. The objective of this study was to evaluate the influence of vegetation cover removal on water and soil losses for different rainfall classes: < 20 mm, 20 - 60 mm, 60 - 80 mm and > 80 mm. The study was developed in the city of Iguatu, Ceará. Two erosion plots with different management were monitored: exposed soil and pasture. The study took place during the years 2011 to 2014. The year 2011 was characterized as the one with the highest rainfall volume (1,372 mm). Of the total rainfall during this year, 610 and 724 mm were lost by surface runoff in pasture and exposed soil plots, respectively; with soil loss of 3,746 and 52,114 kg ha-1. In 2013 the lower rainfall total occurred (630.8 mm), with waste due to runoff being 85.8 and 313.4 mm causing soil losses corresponding to 82 and 12,820 ha -1 for pasture and exposed soil plots, respectively. These results highlight the importance of vegetation cover to reduce water and soil losses and the strong influence of rainfall concentration in the region on hydrological processes. Keywords: runoff, rainfall classes, exposed soil

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Assessing the Seasonal Changes on Physicochemical Parameters and Major Nutrient Levels in Water and Sediments from Sulal River, Bureti Sub County, Kericho County, Kenya

Chemical Science International Journal ◽

10.9734/csji/2021/v30i130213 ◽

2021 ◽

pp. 46-58

Author(s):

S. Cherotich ◽

D. A. Abong’o ◽

J. O. Onyatta

Keyword(s):

Seasonal Changes ◽

Physicochemical Parameters ◽

Nitrate Nitrogen ◽

Total Dissolved Solids ◽

Small Scale ◽

Wet Season ◽

Major Nutrient ◽

Domestic Use ◽

Residue Levels ◽

Major Chemical

Sulal River is a victim of nutrient pollution as it crosses different small-scale tea farms in Bureti Sub County, Kericho County. A study was conducted to evaluate different physicochemical parameters and major chemical fertilizer’s nutrients levels in water and sediments from Sulal River. In order to understand the degree of pollution in the river due to inflow of agricultural chemical fertilizer residue levels from its catchment, the samples were collected in the dry (February 2019) and wet seasons (November 2019). The ten chosen sampling sites stretched a length of 12 Km. Samples were analyzed for pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), sediment and water content (WC), nitrate-nitrogen (NO3-N), phosphorous (PO3-P) and potassium (K) using standard methods. Results were analyzed using IBM SPSS 20. The average results during dry and wet seasons in water samples for pH were 6.72±0.05 and 6.38±0.21, DO 6.78±0.59 and 9.58±0.64 mg/L, EC 174±5.02 and 205±20.14 µS /cm, TDS 92±4.59 and 120.70±19.57 mg/L, NO3-N 0.58±0.21 and 1.19±0.22 mg/L, PO3-P 0.00±0.00 and 0.13±0.84 mg/L and K 0.26±0.08 and 0.84±0.19 mg/L respectively. The average results during dry and wet seasons in sediment samples for pH were 6.62±0.20 and 6.75±0.17, EC, 67±6.66 and 52±10.19 µS /cm, WC 16.96±3.95 and 129.84±5.00%, NO3-N 0.70±0.35 and 0.42±0.23 mg/kg, PO3-P 0.49±0.25 and 1.14±0.40 mg/kg and K 1.53±0.45 and 2.86±0.31 mg/kg respectively. The levels of P in water during wet season and in sediments samples in both seasons were however, above the WHO (0.025 mg/L) and KEBS (0.030 mg/L) recommended limit for drinking and domestic use and WASREB (0.005 mg/L) level for the likelihood of eutrophication. Availability of excess phosphorus can accelerate eutrophication. The diversity of cancers has also been associated with drinking water containing phosphorous levels. The water from Sulal River may be used for irrigation purposes but not for drinking and domestic purposes. Significant seasonal variations were observed in all parameters analyzed except NO3-N in sediments. This indicates that rainfall had a great effect on some soil physicochemical properties.

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Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

Biogeosciences Discussions ◽

10.5194/bgd-11-7901-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 7901-7929

Author(s):

S. A. Parsons ◽

V. Valdez-Ramirez ◽

R. A. Congdon ◽

S. E. Williams

Keyword(s):

Seasonal Changes ◽

Biogeochemical Cycles ◽

Dry Season ◽

Tropical Region ◽

Soil N ◽

Wet Season ◽

Evergreen Forests ◽

P Limitation ◽

Global Trend ◽

The Difference

Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.

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Temporal Variations of Submarine Groundwater Discharge into a Tide-Dominated Coastal Wetland (Gaomei Wetland, Western Taiwan) Indicated by Radon and Radium Isotopes

Water ◽

10.3390/w12061806 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1806 ◽

Cited By ~ 1

Author(s):

Feng-Hsin Hsu ◽

Chih-Chieh Su ◽

Pei-Ling Wang ◽

In-Tian Lin

Keyword(s):

Coastal Waters ◽

Seasonal Changes ◽

Submarine Groundwater Discharge ◽

Coastal Wetland ◽

Groundwater Discharge ◽

High Tide ◽

Dry Season ◽

Wet Season ◽

Submarine Groundwater ◽

Δd And Δ18o

Submarine groundwater discharge (SGD) is evidenced around Taiwan, but the seasonal/temporal changes of SGD have not been fully examined. Here, we report a time-series investigation of SGD into a tide-dominated coastal wetland, the Gaomei Wetland, located to the south of the Da-Chia River’s mouth, western Taiwan, by using environmental tracers (222Rn, 224Raex, 228Ra, δD, and δ18O). Our results showed that regardless of dry and wet seasons, the 222Rn activities in coastal waters were high at low tide but low at high tide. It represents the continuous input of 222Rn-enriched groundwater. However, the 224Raex and 228Ra activities showed seasonal changes with tide conditions. In the dry season, the 224Raex and 228Ra activities in coastal waters were low at low tide but high at high tide; whereas in the wet season, an opposite relation was observed with quite high 224Raex and 228Ra activities in the low-tide waters. Coupled with the lower δD and δ18O values of coastal and pore waters in the dry season, in comparison to those in the wet season, it is suggested that these phenomena probably reflected a seasonal difference in the main SGD component with fresh SGD in the dry season, but saline ones in the wet season. Based on a 222Rn mass balance model, the estimated SGD fluxes into the Gaomei Wetland varied with tidal fluctuations and ranged from 0.2 to 25 cm d−1 and from 0.1 to 47 cm d−1 for the dry and wet seasons, respectively. A slightly high SGD flux occurring during the wet season at spring tide, implied a stronger tidal pumping coupled with a larger hydraulic gradient between land and sea. In this study, we demonstrated that the variation of SGD into the Gaomei Wetland is not only controlled by the seasonal changes of groundwater recharge, but also by the tidal pumping process.

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Longevity of zinc phosphide on wheat bait in tropical Australia

Wildlife Research ◽

10.1071/wr00062 ◽

2001 ◽

Vol 28 (3) ◽

pp. 261

Author(s):

Laurie E. Twigg ◽

Gary R. Martin ◽

Noel Wilson ◽

Derek Goddard ◽

Richard Watkins ◽

...

Keyword(s):

Western Australia ◽

Zinc Phosphide ◽

Agricultural Crops ◽

Wet Season ◽

Total Rainfall ◽

Rainfall Events ◽

Tropical Environments ◽

Whole Wheat ◽

Tropical Australia ◽

Bait Stations

The longevity of zinc phosphide (ZP) on whole wheat bait (2.5% A.I.) was determined at the end of the ‘dry’ and ‘wet’ seasons at Kununurra, Western Australia, the time when rats can damage agricultural crops. While the total rainfall during the two trials was 74 mm and 155 mm, substantial loss of ZP was recorded only after significant rainfall events. Irrespective of season, the loss of ZP from bait applied in bait stations was minimal. The maximum recorded loss was 17%, and this occurred after 21 days’ exposure during the wet season where the bait stations were placed in-crop. Bait stations on the adjacent ‘hilled’ fallow recorded only an 8% loss of A.I. during the same period. However, the loss of ZP from exposed, simulated broadcast bait was much greater: 43% and 91% of ZP was lost from the wheat bait within 21 days during the ‘dry’ and ‘wet’ seasons, respectively. Nevertheless, regardless of the application method, sufficient ZP always remained on the wheat bait for it to be theoretically lethal to rats for at least 8–14 days. The potential of ZP bait for controlling rodent pests in tropical environments, and possible associated ‘problems’ of such an approach, are discussed.

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