Dry January Research Articles

Staying dry in January

In support of Alcohol Concern's Dry January campaign, Roger Matthews, Chief Dental Officer at Denplan, looks at the wider implications of alcohol abuse and the role dental teams can play in reducing it

The impact of water transfers from the lower Yangtze River on water security in Shanghai

Shanghai is a megacity that increasingly relies on water drawn from the Yangtze River estuary. During periods of low flow, water in the estuary can become too saline for use in city water supplies. River flow is measured at the Datong gauging station 680 km upstream from the river mouth. Several existing and planned river water extractions are located below Datong, including the Eastern Route of the South-North Water Diversion Project (ERP). The effect of these extractions on discharge into the estuary and the associated salinity levels may be significant, even though the extractions are not reflected in the discharge at Datong. We estimate the effects of these downstream extractions on water discharge into the estuary (rather than at Datong), particularly the critical discharge level below which salinity compromises water security in Shanghai. Our results show that the ERP will cause the discharge into the estuary to fall below critical levels between December and February in dry years and January to February in normal years. Future water transfer projects along the lower Yangtze River will further compound the problem. Maintaining Shanghai's water security is therefore a significant challenge for China's water resource management institutions.

Spatial Considerations in Wet and Dry Periods for Phosphorus in Streams of the Fort Cobb Watershed, United States

AbstractThe Fort Cobb Watershed in Oklahoma has diverse biogeophysical settings and provides an opportunity to explore the association of water quality with a diverse set of landscapes during both wet (April 2007‐December 2009) and dry (January 2005‐March 2007) periods. The objective of this work was to identify spatial patterns in phosphorus (P) (soluble reactive P [SRP] and bioavailable P [BAP]) associated with landscape metrics for two distinct streamflow regimes. Spatial autocorrelation of P was evaluated using contiguous (side‐by‐side) and upstream (upstream:downstream) connectivity matrices. Biogeophysical metrics were compiled for each contributing area, and were partitioned based on association to P concentrations. Results for both SRP and BAP indicated that spatial autocorrelation was present (p < 0.05). There was more spatial autocorrelation and stream P concentrations were three to five times higher in the Wet phase than in the Dry phase (p < 0.05). Analysis with recursive partitioning resulted in higher R2 with spatial autocorrelation than without spatial autocorrelation and indicated that lateral metrics (topography, soil, geology, management) were better predictors for SRP than instream metrics. During Wet phase, lateral metrics indicative of rapid surface and subsurface water movement were associated with higher P stream concentrations. This research demonstrated that we can detect landscapes more vulnerable to P losses and/or contaminations in either drought or very wet periods.

Some Observations in North Castlemaine during a hot, dry January

Some Observations in North Castlemaine during a hot, dry January

Exact Goodness‐of‐Fit Tests for Markov Chains

Goodness-of-fit tests are useful in assessing whether a statistical model is consistent with available data. However, the usual χ² asymptotics often fail, either because of the paucity of the data or because a nonstandard test statistic is of interest. In this article, we describe exact goodness-of-fit tests for first- and higher order Markov chains, with particular attention given to time-reversible ones. The tests are obtained by conditioning on the sufficient statistics for the transition probabilities and are implemented by simple Monte Carlo sampling or by Markov chain Monte Carlo. They apply both to single and to multiple sequences and allow a free choice of test statistic. Three examples are given. The first concerns multiple sequences of dry and wet January days for the years 1948-1983 at Snoqualmie Falls, Washington State, and suggests that standard analysis may be misleading. The second one is for a four-state DNA sequence and lends support to the original conclusion that a second-order Markov chain provides an adequate fit to the data. The last one is six-state atomistic data arising in molecular conformational dynamics simulation of solvated alanine dipeptide and points to strong evidence against a first-order reversible Markov chain at 6 picosecond time steps.

An inter-comparison of model-simulated east–west climate gradients over South Africa

This study examines how the east–west gradient of climate over South Africa is represented in terms of mean rainfall, tropospheric humidity and circulation, and surface latent heat flux in the satellite era 1980-2001. Inter-comparisons of NCEP2 reanalysis and GPCP satellite-gauge merged rainfall with coupled general circulation model (GCM) simulations from generic CMIP-3 are made, with a focus on the maize belt 25°-29°S, 25°-30°E. The summer climatology is analysed for the zonal gradient in vertical atmospheric structure and the annual cycle of rainfall. A wet bias is found in most simulations over the eastern mountains, but in two GCMs (CSM3, PCM) it extends over the western plateau. The east-west gradient in vegetation affects the vertical flux of surface moisture into the atmosphere. ECMWF reanalysis and SAFARI-2000 flux tower data reveal that this process is triggered during daytime heating, so model ability to handle the diurnal cycle is crucial. Inter-annual variability is briefly studied and two operational ensemble models (CFS and ECHAM4) simulate and forecast summer rainfall variations with positive correlation to observed values. The AIRS satellite night and day relative humidity structure is contrasted for dry and wet January months. All five generic CMIP-3 models: GFDL2, CSM3, PCM, HADen, ECHAM4 project a drying trend in the maize area over the period 2000–2050, using the SRES A1B scenario. Recommendations for observing the surface and mixed layer moisture fluxes are given.

Drought‐induced mortality of a Bornean tropical rain forest amplified by climate change

Drought‐related tree mortality at a regional scale causes drastic shifts in carbon and water cycling in Southeast Asian tropical rain forests, where severe droughts are projected to occur more frequently, especially under El Niño conditions. We examine how the mortality of a Bornean tropical rain forest is altered by projected shifts in rainfall, using field measurements, global climate model (GCM) simulation outputs, and an index developed for drought‐induced tree mortality (Tree Death Indexη) associated with a stochastic ecohydrological model. All model parameters have clear physical meanings and were obtained by field observations. Rainfall statistics as primary model forcing terms are constructed from long‐term rainfall records for the late 20th century, and 14 GCM rainfall projections for the late 21st century. These statistics indicate that there were sporadic severe droughts corresponding with El Niño events, generally occurring in January–March, and that seasonality in rainfall will become more pronounced, e.g., dry (January–March) seasons becoming drier and wet (October–December) seasons becoming wetter. The computedη well reflects high tree mortality under severe drought during the 1997–1998 El Niño event. For the present, model results demonstrate high and low probabilities of mortality in January–March and October–December, respectively, and they predict that the difference in such probabilities will increase in the future. Such high probability of mortality in the dry season is still significantly high, even considering the beneficial effect of increased soil water storage in the wet season (which is projected to increase in the late 21st century).

Seasonal Variation of Temporal Patterns of Water Flux in a Cashew Orchard Under Sub-humid Tropical Conditions

There is a growing interest in the understanding of the dynamics of sap flow and the transpiration process in plants. In this study, Xylem sap flux was monitored in a 4-year-old cashew (Anacardium occidentale) orchard for eight months (2–4 weeks per month), covering both wet and dry seasons of 2002 at Ejura in Ghana. Sap flux (Fd) was related diurnally with vapor pressure deficit (De), incoming solar radiation (Rs), and estimated evaporative demand (Eo) on a monthly and a seasonal basis. Cross-correlation analysis was used to estimate time lag (τ) between diurnal pattern of Fd and Rs, De or Eo. The maximum correlation coefficient (rmax) from cross-correlation of Fd with Rs (range = 0.85–0.93) was often slightly higher than rmax of Fd and De (range = 0.83–0.92), indicating that the diurnal Fd was more dependent on Rs than De for most part of the year. Generally, τ of Fd with Rs ranged from 0–60 min, 0–30 min with Eo, and led De from 0–180 min during the year. Student t-test showed that average diurnal Fd was not statistically different, from month to month, all year round, suggesting that trees were able to source for required water even during February and March, which are the peak dry months in West Africa. Regressions between Fd and De or Rs showed that De exerted more control on tree water use during the wet (June, July, October) than dry (January, February, March) or transition (November, December) periods. The good relation of Fd with the climatic parameter was exploited to calibrate an approximation function to predict seasonal water use to a very high degree of accuracy. A simple mono-climatic model, combining the parabolic response of Fd to Rs and the linear response to De, was highly successful (F = 9118.5, P < 0.0001, r2 = 0.82, n = 3984) in predicting sap flux in the orchard. This result suggested that sap flow data might be used to estimate stand transpiration conveniently at about hourly time steps to avoid the usual time-lag problem associated with the use of sap flow data for transpiration estimates.

Phytoplankton community: indicator of water quality in the Armando Ribeiro Gonçalves Reservoir and Pataxó Channel, Rio Grande do Norte, Brazil

The current study analysed spatial-temporal modifications of the phytoplankton community and water quality, during dry and wet seasons. The phytoplankton community was studied in three areas: Armando Ribeiro Gonçalves Reservoir (ARG), which is an important public use reservoir in RN, Pataxó Channel (PC-before water treatment), Itajá, RN, and after the water treatment (WTP). Water samples from the reservoir were collected during both dry (January, February and November, 2006) and wet seasons (March to June, 2006). Quali-quantitative analyses of phytoplankton were carried out. Results indicated a qualitative similarity of the phytoplankton community in the three areas. However, significant differences were registered in these areas in relation to species relative abundance, with dominance of potentially toxic cyanobacteria, such as Planktothrix agardhii Gomont (dry season) and Microcystis aeruginosa Kutz (wet season). Ecological indexes obtained higher values before water treatment. Nevertheless, densities of cyanobacteria (organisms/mL) gradually reduced in the waters of the reservoir and of the Pataxó Channel before and after water treatment. After the treatment, density values of cyanobacteria were adequate for human consumption, according to the values established by the Health Ministry.

Mesozooplâncton do sistema estuarino de Barra das Jangadas, Pernambuco, Brasil

Estudos sobre o mesozooplâncton foram realizados no sistema estuarino de Barra das Jangadas, Pernambuco, Brasil (8º14'36"S, 34º56'28"W) visando analisar a estrutura da comunidade. As amostras foram obtidas com rede de plâncton, com malha de 300 µm, durante os períodos, seco (janeiro/2001) e chuvoso (julho/2001), nas marés de sizígia e de quadratura, em intervalos de três horas. Foram identificados 37 taxa, destacando-se Copepoda com as espécies Pseudodiaptomus acutus (F. Dahl, 1894), Pseudodiaptomus richardi (F. Dahl, 1894), Acartia lilljeborgi (Giesbrecht, 1892), Parvocalanus crassirostris (Dahl, 1894), Oithona hebes (Santos, 1973) e Notodiaptomus cearensis Wright, 1936. A densidade total durante o período seco variou de 69,34 a 8.568,34 org.m-3. Para o período chuvoso variou de 261,98 a 10.224,83 org.m-3. Os Crustacea meroplanctônicos (Brachyura zoea) foram muito freqüentes e muito abundantes, destacando seu importante papel na cadeia trófica pelágica. A diversidade específica durante o período seco, variou de 0,44 a 3,13 bits.ind-1, e para o período chuvoso de 0,66 a 2,93 bits.ind-1. Os baixos valores de diversidade ocorreram devido à dominância de Brachyura (zoea). A análise de agrupamento revelou a formação de dois grupos. O primeiro formado por espécies marinhas e euri-halinas, e o segundo por espécies indicadoras de ambientes estuarinos.

Ecohydrology and water resources management: a pilot study in Trinidad

An area of rainforest in Trinidad (10°N, 61°W) is remarkably rich in biodiversity, and receives the highest amount of rainfall in the island due to its orography and the dominant northeast trade winds. However, a year-round transfer of water from its pristine rivers is likely in the future, with ecological consequences. The results of a pilot study are presented, based on a simple, and graphical, segment-scale multi-objective methodology for the estimation of the optimal instream flow of the 13 rivers in this area. This methodology is based on a dimensionless ecohydrological factor, Δ, which enables the required hydraulic mean depth at a river cross-section to be expressed in terms of the average species length at maturity for a target group of amphibians, birds, fish, mammals and reptiles. Moreover, the methodology considers the socio-economic cost of ecological degradation brought about by streamflow abstraction, as well as the economic benefit of the same. An example illustrates the estimation of optimal instream flow for a value of Δ and, thereby, the corresponding optimal river intake operating rule, based on the hydraulic characteristics of a 0.1 km segment of one of the rivers, for the 20-year average dry (January—May) and wet (June–December) seasons. The limitations of the pilot study, and areas for further research, are also highlighted with a hope that it will ultimately evolve into a decision-making tool for water resources management.

WATER QUALITY AND PERIPHYTON COMMUNITY OF A STREAM SYSTEM RECEIVING MUNICIPAL WASTE DISCHARGES IN RIVERS STATE, NIGER DELTA, NIGERIA

The water quality and periphyton parameters were investigated at 5 designated stations along Ntawogba stream system that lies within the Port Harcourt metropolis located between latitude 4º5” N and 5º 00”N and longitude 6º55” E and 7º 00”E. Sampling was done for dry (January – March 2004) and wet (June – August 2004)seasons using standard procedures. Samples were collected at the designated stations along the water course for physicochemical (temperature, pH, conductivity, alkalinity DO, BOD5, NO3, NH3, PO4, SO4) and periphyton descriptors (species richness, species diversity, abundance, biomass, and productivity). The spatio-temporal differences for the parameters were evaluated and the physicochemical attributes demonstrated spatial and seasonal trends but were essentially not statistically significant while the periphyton descriptors demonstrated seasonal and spatial differences and are more reliably affected by the waste water discharges.

Reservoir Storage Curve Estimation Based on Remote Sensing Data

A reservoir is one of the most efficient measures for integrated water resources development and management. The reservoir storage curve is a vital parameter for multipurpose reservoir operation and its precision is a key issue for water balance and strategic risk management. Compared with the traditional approach, the method based on remote sensing RS data provides better information, which can be helpful in reservoir operation and management. Fengman Reservoir was chosen as a case study to obtain the new storage curve that is based on LandSat data. The inflows of the reservoir were calculated in dry seasons December, January, and February from 1958 to 1986 on the basis of the designed storage curve and the new estimated curve, respectively. Compared with the observation data, the average relative error of inflow using the new estimated curve is much less than one using the designed curve. The results showed that reservoir storage curve estimation based on RS data is reasonable and has relatively high precision.

The behavior of selenium and arsenic in the Zhujiang (Pearl River) Estuary, South China Sea

Two cruises were undertaken to study the selenium species and arsenic, and their relationship with marine production in the Zhujiang (Pearl River) Estuary, covering both wet (July, 1999) and dry (January, 2000) seasons. Concentrations of dissolved Se (IV), Se (VI) and arsenic in the Zhujiang River are generally within the range of Chinese rivers and other large systems, like the Rhone River and Panama River. In January 2000, the concentration of selenium was lower than that in the July 1999. Total dissolved inorganic selenium averaged 2.77 nmol L −1 in the winter and 4.15 nmol L −1 in the summer, with Se (VI) accounting for 55% and 58%, respectively. Total dissolved inorganic arsenic averaged 25.8 nmol L −1 in the winter and 22.3 nmol L −1 in the summer. The data indicated that dissolved arsenic and selenium did not behave conservatively in the estuary. An important mobilization of dissolved selenium and arsenic was observed from the river up to halfway in the estuary. Both input flux (from river to estuary) and output flux (from estuary to coastal zone) of dissolved selenium and arsenic were calculated from statistical interpretations of the salinity profiles.

The effect of calcium hydroxide treatment on the nutritive and feeding value of Albizia procera for growing goats

Albizia procera (Albizia) is widely planted in Bangladesh for timber and the leaves are also used as forage. In the dry season the leaves are less palatable than in the wet season and this may be a consequence of an excessive content of tannin. Albizia foliage was collected in the wet (June) and dry (January) seasons from six agro-ecological zones across Bangladesh and chemical composition, for tannins in particular, was determined. Variation in the tannin content across the six zones proved to be minimal. However, the concentration of tannins was almost two-fold higher in the dry compared to the wet season. To assess the potential for deactivating the tannins in Albizia so as to improve its nutritive value, leaves were treated with alkali (either calcium hydroxide or potassium carbonate) or polyethylene glycol (PEG). Alkali treatment reduced the concentrations of extractable tannin by as much as 92%. The ability of calcium hydroxide to deactivate tannin was then tested in vivo. Young goats, fed a basal diet of hay and wheat bran, were allocated to 4 equal groups ( n = 4 per group) and supplemented with fresh Albizia foliage (at 300 g/kg of the diet) that was either untreated, or treated with either PEG, calcium hydroxide or calcium hydroxide + PEG. The supplements were fed daily for 9 weeks to allow the effects of chemical treatment on intake and growth rate to be defined. In vivo digestibility, nitrogen (N) balance, and microbial N supply were measured over the 5th week. Intakes of feed dry matter (DM) and the digestibility of DM were similar across treatments (mean intake 32 g/(kg LW day), mean DM digestibility 0.63). However, both the PEG and the PEG + calcium hydroxide treatments, compared to the control and calcium hydroxide only treatments, increased N digestibility (0.72, 0.70 versus 0.60, 0.61), N retention (0.43, 0.48 mg N/mg versus 0.26, 0.27 mg N/mg N intake), and microbial N supply (23.7, 21.4 g/day versus 14.2, 12.4 g/day). These increases translated into a 35% improvement in growth rate (40, 36 g/day versus 26, 29 g/day). Calcium hydroxide alone did not improve the feeding value of Albizia. These data highlight the danger of assuming an assayable reduction in tannin, such as that observed in the calcium hydroxide treatment, will translate into an improvement in nutritive value and subsequent animal performance. Since the performance of the goats improved maximally when PEG was added to the calcium hydroxide-treated Albizia it was clear that the tannins were still as active as in the untreated Albizia. It was concluded that calcium hydroxide does not deactivate the tannins in Albizia.

UARS/MLS Cloud Ice Measurements: Implications for H2O Transport near the Tropopause

Abstract A technique for detecting large hydrometeors at high altitudes is described here and applied to the Upper Atmosphere Research Satellite/Microwave Limb Sounder (UARS/MLS) 203-GHz radiance measurements at tangent pressures between 200 and 46 hPa. At these tangent pressures the radiances remain optically thin and cloudy-sky radiances are brighter than normal clear-sky cases. Unlike infrared/visible cloud observations, the 203-GHz radiances can penetrate most ice clouds and are sensitive to ice crystals of convective origin. Rough ice water content (IWC) retrievals are made near the tropopause using estimated size distributions from in situ convective studies. The seasonal mean IWC observed at 100 hPa reaches vapor-equivalent 20 ppmv or more over convective centers, dominating the total water content. Convectively lofted ice, therefore, appears to be hydrologically significant at the tropical cold point. IWC is well correlated spatially with relative humidity with respect to ice (RHi) at 100 hPa during both the dry (January–March) and moist (July–September) periods.

The nutrient status of Nong Han, a shallow tropical lake in north‐eastern Thailand: Spatial and temporal variations

AbstractSpatial and temporal patterns of nutrient (nitrate‐N, ammonia‐N and phosphate) concentrations in the Nong Han water column were examined during the dry (January – May) and wet (August – October) seasons in 2001. Low nitrate‐N concentrations in the water were common. High ammonia‐N concentrations were found on all occasions, but particularly in the early wet season. Phosphate concentrations in the water column were very high. The very low nitrate‐N and low ammonia‐N concentrations (in early dry, late dry and late wet seasons), and low phosphate concentrations (in the early dry season) were attributed to assimilation by dense stands of macrophytes, in particular submerged types during the low water season. Additionally, higher nitrate‐N concentrations found in the late wet season might be related to increases in the water level and nitrification activity at the sediment–water interface. The very high ammonia‐N and phosphate concentrations in the water during the early wet season possibly reflect run‐off from agricultural areas in the Nong Han catchment and the regeneration of ammonia‐N and phosphate from recently degraded organic matter (particularly decaying macrophytes) in the surface sediment layer. Also, higher phosphate concentrations in the bottom water of most samples in the late dry and late wet seasons were attributed to temporary anaerobic conditions caused by submerged macrophyte decomposition and aerobic conditions, respectively. These hypotheses are consistent with dissolved oxygen and pH conditions found in both seasons.

Feed selection and dietary preferences of forage by small ruminants grazing natural pastures in the Sahelian zone of Cameroon

The grazing behaviour of two mixed flocks of sheep and goats on a Sahelian rangeland was observed in the Far North Province of Cameroon. The area was dominated by thorn shrubs and a herbaceous layer made up of annual grasses. The study ran for 9 months, covering the rainy (June–September), post-rainy (October–December) and cold dry (January–March) seasons. A simple method was adapted for estimating the dietary preference of goats and sheep, and variation in plant biomass. Observation on the vegetative cycles of some browse species was also done to see whether this influenced dietary preference. It was noticed that sheep and goats possess a certain degree of nutritional wisdom and that contrary to what most people might think, no amount of feed scarcity could force them to feed on some undesirable forage species. Browse species with high preference indices were Acacia seyal, A. senegal, Pterocarpus lucens and Ziziphus mauritiana. Goats spent 75% of their grazing time browsing, while the reverse was true for sheep. Maximum plant biomass was noticed in the month of September and high preference indices in the rainy season were seen to correspond to stages of maximum foliation of the browse species. The fruits, blossoms and pods produced by some of the browse species made a reasonable contribution to the diet of both goats and sheep, particularly in the dry season. Given the reputation of goats as highly-selective feeders, range management programmes should aim at preserving plant communities that are highly diversified in botanical structure as well as ensuring the survival of the tree species that are highly browsed by herbivores.

The Subtropical Zhujiang (Pearl River) Estuary: Nutrient, Trace Species and Their Relationship to Photosynthesis

Two cruises were undertaken to study the nutrients and trace species and their relation to marine production in the Zhujiang (Pearl River) Estuary, which cover both wet (August–September, 1996) and dry (January–February, 1997) seasons. Concentrations of nutrients (NO3−, NH4+, PO43−, and dissolved SiO2) and other major and trace species (alkalinity, DOC and Al) in the Zhujiang are generally within the range of Chinese rivers and comparable to other large systems, like the Huanghe (Yellow River) and Changjiang (Yangtze River). In the estuary, some species (e.g. SiO2) illustrate a fairly defined relationship with chlorinity, whereas others show considerable remobilization and/or changes in freshwater end-members, owing to the fact that fresh water enters the South China Sea from eight channels with various water flow and different compositions. The incubation experiments using in situ water samples reveal that while phosphate is the limiting element in riverine effluent plume, the photosynthesis turns to be nitrogen and/or silicon limited further offshore on the shelf region. Trace species (e.g. Cu2+and Fe2+) have important impact on the photosynthesis in the Zhujiang Estuary, with Fe2+to be a more limiting element than Cu2+. Atmospheric wet deposition may well stimulate photosynthesis and hence demonstrate a potential link with algal blooms in this area. Atmospheric impact on the photosynthesis increases from estuary toward the interior of South China Sea. The experimental data further suggest that in the turbid region of the Zhujiang Estuary, radiation reduction by suspended materials could be an important issue limiting photosynthesis, although the eutrophication is quite common in coastal environments of China.

Variation in fatty acid composition of palm oils from two varieties of the oil palm (Eelaeis guineensis)

AbstractA comparative study was carried out on the fatty acid content of palm oil samples from the red and yellow fruits of Dura and Tenera varieties of Elaeis guineensis in the dry (January) and wet (May) seasons. Significant differences in the fatty acid content of the oils from the two varieties were observed. The degree of total unsaturation of the oil samples varied, with oil from red fruits of Dura having the highest total unsaturated fatty acids.