Effects of salinity on growth of plant species from terrestrializing fens
Stofberg, S.F. ; Klimkovska, A. ; Paulissen, M.P.C.P. ; Witte, J.Ph.M. ; Zee, S.E.A.T.M. van der - \ 2015
Aquatic Botany 121 (2015). - ISSN 0304-3770 - p. 83 - 90.
climate-change - water - tolerance - salt - nutrient - netherlands - macrophytes - competition - vegetation - diversity
Terrestrializing lowland fens may be temporarily exposed to elevated surface water salinity, which may have serious consequences for nature conservation. We investigated the response of five fresh water fen plant species to elevated salinity. In a controlled greenhouse experiment, these species were exposed to salt concentrations up to 3000 mg Cl- l-1. Total biomass of the five species together was significantly reduced for salinity levels from 200 mg Cl- l-1. Four individual species showed leaf death and relative growth rate reduction, with effects at 1000 mg Cl- l-1 for Succisa pratensis, Thelypteris palustris and Viola palustris, and 3000 mg Cl- l-1 for Myosotis scorpioides. Comarum palustre showed no significant (.05 level) sensitivity. Biomass distribution was investigated as well. Root-shoot ratio of four species was affected by salinity, which in at least two cases seemed to be related to leaf death. Differences in specific leaf area as a result of salinity were only observed for C. palustre. Dry matter content increased in four species as a result of salinity. Salinity tolerance did not correspond to the environmental distributions of the species, nor could species traits be related to tolerance. Surface water salinity may affect vegetation development in terrestrializing fens at low concentrations. A reduction of plant growth would cause reduced fitness of some species and may lead to reduced root mat growth. Exposure to higher concentrations could eventually lead to a decrease of species richness.
Geoengineering in lakes: welcome attraction or fatal distraction?
Mackay, E. ; Maberly, S.C. ; Pan, G. ; Reitzel, K. ; Lurling, M.F.L.L.W. - \ 2014
Inland Waters : Journal of the International Society of Limnology 4 (2014). - ISSN 2044-2041 - p. 349 - 356.
modified bentonite clay - phosphate adsorption - phosphorus release - shallow lakes - water-quality - sediment - nutrient - aluminum - removal - phoslock(r)
The use of geoengineering techniques for phosphorus management offers the promise of greater and quicker chemical and ecological recovery. It can be attractive when used with other restoration measures but should not be considered a panacea. The range of materials being proposed for use as well as the in-lake processes targeted for manipulation continues to grow. With increasing political imperatives to meet regulatory goals for water quality, we recommend a coordinated approach to the scientific understanding, costs, and integration of geoengineering with other approaches to lake management.
Eutrophication of mangroves linked to depletion of foliar and soil base cations
Fauzi, A. ; Skidmore, A.K. ; Heitkonig, I.M.A. ; Gils, H. van; Schlerf, M. - \ 2014
Environmental Monitoring and Assessment 186 (2014)12. - ISSN 0167-6369 - p. 8487 - 8498.
northeastern united-states - avicennia-marina - ammonium-sulfate - shrimp farms - pond culture - forest trees - red spruce - nitrogen - nutrient - phosphorus
There is growing concern that increasing eutrophication causes degradation of coastal ecosystems. Studies in terrestrial ecosystems have shown that increasing the concentration of nitrogen in soils contributes to the acidification process, which leads to leaching of base cations. To test the effects of eutrophication on the availability of base cations in mangroves, we compared paired leaf and soil nutrient levels sampled in Nypa fruticans and Rhizophora spp. on a severely disturbed, i.e. nutrient loaded, site (Mahakam delta) with samples from an undisturbed, near-pristine site (Berau delta) in East Kalimantan, Indonesia. The findings indicate that under pristine conditions, the availability of base cations in mangrove soils is determined largely by salinity. Anthropogenic disturbances on the Mahakam site have resulted in eutrophication, which is related to lower levels of foliar and soil base cations. Path analysis suggests that increasing soil nitrogen reduces soil pH, which in turn reduces the levels of foliar and soil base cations in mangroves.
Continuous milking of dairy cows disrupts timing of peak IgG concentration appearance in mammary secretions
Baumrucker, C.R. ; Zbinden, R.S. ; Dorland, H.A. van; Remmelink, G.J. ; Kemp, B. ; Knegsel, A.T.M. van; Bruckmaier, R.M. - \ 2014
Journal of Dairy Research 81 (2014)4. - ISSN 0022-0299 - p. 403 - 409.
dry period length - continuous lactation - bovine somatotropin - immunoglobulin g(1) - passive transfer - cell turnover - colostrogenesis - colostrum - calves - nutrient
The length of the dry period in commercial dairy production is under close scrutiny. While the main concern is the composition and volume of milk produced, the evaluation of colostrum quality under these new paradigms has suggested a decline in IgG concentrations, while some reports indicate no change. Colostrum quality has been defined as an adequate concentration (>50 mg/ml) of immunoglobulin in the secretions to provide the newborn with maximal disease resistance. We investigated the appearance of IgG in mammary pre- and post partum secretions in cows without a dry period (continuously milked, Dry0) and compared the secretions with cows that experienced a dry period of 60 d (Dry60). Blood was collected during the experimental period and plasma analysed for progesterone (P4) and prolactin (Prl). Approximately -6 d relative to parturition, the Dry0 animals exhibited increased concentration of IgG in their secretions to an average of ~35 mg/ml that remained rather constant through subsequent pregnancy and following parturition. Dry0 cows were producing an average IgG concentration in parturition colostrum of 44·2±17·6 mg/ml that was not different than that of controls (66·86±16·8 mg/ml). However, Dry0 cows exhibited high variation, different peak times (day) of IgG concentration including times that occurred both pre and post parturition. IgG mass of the Dry0 cows remained rather constant pre- and post partum and did not show the same declining mass following parturition that was shown for the Dry60 cows. The change in plasma P4 and Prl were shown to have no timing effect on colostrum IgG concentration.
Modelling and evaluation of productivity and economic feasibility of a combined production of tomato and algae in Dutch greenhouses
Slager, B. ; Sapounas, A. ; Henten, E.J. van; Hemming, S. - \ 2014
Biosystems Engineering 122 (2014). - ISSN 1537-5110 - p. 149 - 162.
tubular photobioreactors - porphyridium-cruentum - solar irradiance - light - culture - growth - temperature - management - scenario - nutrient
Combination of production of algae and tomato increases efficient use of available resources of greenhouse enterprises, such as controlled environment, water and nutrients, carbon dioxide, greenhouse space and infrastructure and knowledge. No information is available, however, about the potential productivity and related costs of a combined tomato and algae production in Dutch greenhouses. The objective was to determine the algae productivity in tubular photobioreactors (PBRs) and the economic feasibility of combined production of tomato and algae in Dutch greenhouses. A model was developed to predict greenhouse climate from outside climate, to predict tomato and algae biomass production and to analyse scenarios of different locations and dimensions of tubular PBR in the greenhouse with regard to algae productivity and cost price of algae production. The results show that algal productivity is low if PBRs are installed under a tomato crop due to limited light levels. Areal algal productivity was calculated to be 5–6.5 kg DM m-2 if PBRs are installed in a separate greenhouse compartment next to tomato. In this case the minimum cost prices of algae production was calculated to be €11 kg-1 DM algae, which give perspectives for the future. The proposed model is important because it gives insight into the feasibility of algae and tomato production in Dutch greenhouses. This novel model approach and the scenario results provide better knowledge about the potential productivity and related costs and returns of algae production in greenhouses.
Phosphorus in China's Intensive Vegetable Production Systems: Overfertilization, Soil Enrichment, and Environmental Implications
Yan, Z.J. ; Liu, P.P. ; Li, Y.H. ; Ma, L. ; Alva, A. ; Dou, Z.X. ; Chen, Q. ; Zhang, F.S. - \ 2013
Journal of Environmental Quality 42 (2013)4. - ISSN 0047-2425 - p. 982 - 989.
cattle feedlot manure - organic phosphorus - amended soils - plant - nutrient - risk - availability - requirement - management - efficiency
China's vegetable production has experienced a rapid growth in recent years. Total production amounted to 522.7 million Mg (1 Mg = 10(6) g) in 2009, which was more than nine times that in 1980 and represented >50% of the world production. Meanwhile, excessive use of animal manures and chemical fertilizers in vegetable fields has brought various production and environmental challenges, including excessive accumulation of nutrients in soils and accelerated water pollution problems. In this study, we have evaluated the current status of phosphorus (P) in China's intensive vegetable production systems based on data summarized from nearly 100 publications plus results from our recent experiments. Gross overfertilization occurred in greenhouse (571 kg P ha(-1)) and open-field (117 kg P ha(-1)) vegetable systems compared with P removal in harvested crops (44 and 25 kg P ha(-1)) per season. Excess P input led to soil enrichment of labile P, measured as Olsen-P, averaging 179 (greenhouses) and 100 mg P kg(-1) (open fields) in the 0- to 20-cm soil depth, and in some cases led to P leaching, as evidenced by increases in Olsen-P and CaCl2 - P at the 40- to 60-cm soil depth. The vast majority of vegetable soils had Olsen-P exceeding the critical level (46.0-58.0 mg P kg(-1)) for optimum vegetable yield. Innovative policies and strategies are urgently needed to implement science-based nutrient management practices to attain sustainable vegetable production while protecting natural and environmental resources.
Case study on the efficacy of a lanthanum-enriched clay (Phoslock) in controlling eutrophication in Lake Het Groene Eiland (The Netherlands)
Lurling, M. ; Oosterhout, J.F.X. - \ 2013
Hydrobiologia 710 (2013)1. - ISSN 0018-8158 - p. 253 - 263.
rare-earth-elements - harmful cyanobacterial blooms - phosphorus binding clay - shallow lakes - organic-matter - nutrient - water - restoration - sediment - impact
Lake Het Groene Eiland was created in the beginning of 2008 by construction of dikes for isolating it from the surrounding 220-ha water body. This so-called claustrum of 5 ha was treated using lanthanum-modified clay (Phoslock®) to control eutrophication and mitigate cyanobacterial nuisance. Cyanobacteria chlorophyll-a were significantly lower in the claustrum than those in the reference water body, where a massive bloom developed in summer, 2008. However, PO4-P and TP did not statistically differ in these two waters. TN and NO3-N were significantly lower in the claustrum, where dense submerged macrophytes beds developed. Lanthanum concentrations were elevated after the applications of the modified clay in the claustrum, but filterable lanthanum dropped rapidly below the Dutch standard of 10.1 µg l-1. During winter, dozens of Canada geese resided at the claustrum. Geese droppings contained an average of 2 mg PO4-P g-1 dry weight and 12 mg NH3-N g-1 dry weight and might present a growing source of nutrients to the water. Constructing the claustrum enabled unrestricted bathing in subsequent three summers, as no swimming bans had to be issued due to cyanobacteria blooms. However, the role of the modified clay in this positive outcome remains unclear, and longevity of the measures questionable.
Comparison of cyanobacterial and green algal growth rates at different temperatures
Lurling, M. ; Faassen, E.J. ; Kosten, S. ; Eshetu, Z. ; Huszar, V.M. - \ 2013
Freshwater Biology 58 (2013)3. - ISSN 0046-5070 - p. 552 - 559.
fresh-water zooplankton - climate-change - shallow lakes - community structure - microcystis-aeruginosa - phytoplankton - blooms - allelopathy - nutrient - daphnia
1.The hypothesis that cyanobacteria have higher optimum growth temperatures and higher growth rates at the optimum as compared to chlorophytes was tested by running a controlled experiment with eight cyanobacteria species and eight chlorophyte species at six different temperatures (20-35°C) and by performing a literature survey. 2.In the experiment, all organisms except the chlorophyte Monoraphidium minutum grew well up to 35°C. The chlorophyte Chlamydomonas reinhardtii was the fastest-growing organism over the entire temperature range (20-35°C). 3.Mean optimum growth temperatures were similar for cyanobacteria (29.2°C) and chlorophytes (29.2°C). These results are concordant with published data, yielding slightly higher mean optimum growth temperatures for cyanobacteria (27.2°C) than for chlorophytes (26.3°C). 4.Mean growth rates of cyanobacteria at 20°C (0.42day-1) were significantly lower than those of chlorophytes at 20°C (0.62day-1). However, at all other temperatures, there were no differences between mean growth rates of cyanobacteria and chlorophytes. 5.Mean growth rates at the optimum temperature were similar for cyanobacteria (0.92day-1) and chlorophytes (0.96day-1). However, analysis of published data revealed that growth rates of cyanobacteria (0.65day-1) were significantly lower than those of chlorophytes (0.93day-1) at their optimum temperatures. 6.Although climate warming will probably lead to an intensification of cyanobacterial blooms, our results indicate that this might not be as a result of higher growth rates of cyanobacteria compared with their chlorophyte competitors. The competitive advantage of cyanobacteria can more likely be attributed to their ability to migrate vertically and prevent sedimentation in warmer and more strongly stratified waters and to their resistance to grazing, especially when warming reduces zooplankton body size. © 2012 Blackwell Publishing Ltd.
‘Halophyte filters’: the potential of constructed wetlands for application in saline aquaculture
Lange, H.J. de; Paulissen, M.P.C.P. ; Slim, P.A. - \ 2013
International Journal of Phytoremediation 15 (2013)4. - ISSN 1522-6514 - p. 352 - 364.
waste-water treatment - shrimp aquaculture - removal - effluent - system - phytoremediation - mariculture - performance - nutrient - marshes
World consumption of seafood continues to rise, but the seas and oceans are already overexploited. Land-based (saline) aquaculture may offer a sustainable way to meet the growing demand for fish and shellfish. A major problem of aquaculture is nutrient waste, as most of the nutrients added through feed are released into the environment in dissolved form. Wetlands are nature's water purifiers. Constructed wetlands are commonly used to treat contaminated freshwater effluent. Experience with saline systems is more limited. This paper explores the potential of constructed saline wetlands for treating the nutrient-rich discharge from land-based saline aquaculture systems. The primary function of constructed wetlands is water purification, but other ancillary benefits can also be incorporated into treatment wetland designs. Marsh vegetation enhances landscape beauty and plant diversity, and wetlands may offer habitat for fauna and recreational areas. Various approaches can be taken in utilizing plants (halophytes, macro-algae, micro-algae) in the treatment of saline aquaculture effluent. Their strengths and weaknesses are reviewed here, and a conceptual framework is presented that takes into account economic and ecological benefits as well as spatial constraints. Use of the framework is demonstrated for assessing various saline aquaculture systems in the southwestern delta region of the Netherlands.
Assessing planetary and regional nitrogen boundaries related to food security and adverse environmental impacts
Vries, W. de; Kros, J. ; Kroeze, C. ; Seitzinger, S.P. - \ 2013
Current Opinion in Environmental Sustainability 5 (2013)3-4. - ISSN 1877-3435 - p. 392 - 402.
critical loads - climate-change - forest ecosystems - reactive nitrogen - global assessment - european forests - deposition - nutrient - world - consequences
This paper first describes the concept of, governance interest in, and criticism on planetary boundaries, specifically with respect to the nitrogen (N) cycle. These criticisms are then systematically evaluated. We argue that planetary N boundaries should include both the benefits and adverse impacts of reactive N (Nr) and the spatial variability of Nr impacts. We revise the planetary N boundary by considering the need to: first, avoid adverse impacts of elevated Nr emissions to water, air and soils, and second, feed the world population in an adequate way. The derivation of a planetary N boundary, in terms of anthropogenic fixation of di-nitrogen (N2) is illustrated by first, identification of multiple threat N indicators and setting limits for them; second, back calculating N losses from critical limits for N indicators, while accounting for the spatial variability of these indicators and their exceedance; and third, back calculating N fixation rates from critical N losses. The derivation of the needed planetary N fixation is assessed from the global population, the recommended dietary N consumption per capita and the N use efficiency in the complete chain from N fixation to N consumption. The example applications show that the previously suggested planetary N boundary of 35 Tg N yr-1 is too low in view of needed N fixation and also unnecessary low in view of most environmental impacts.
Nitrogen and phosphorus inputs to the Black Sea in 1970–2050
Strokal, M. ; Kroeze, C. - \ 2013
Regional Environmental Change 13 (2013)1. - ISSN 1436-3798 - p. 179 - 192.
coastal zone - spatially explicit - danube river - global-model - nutrient - export - delivery - climate - waters - trends
Increased nitrogen (N) and phosphorus (P) inputs are major causes of eutrophication in the coastal waters of the Black Sea. The objective of this study is to analyze the past and future trends in river export of nitrogen and phosphorus to the coastal waters of the Black Sea and to assess the associated potential for coastal eutrophication. The Global NEWS-2 (Nutrient Export from WaterSheds) model was used for this purpose. Currently, most eutrophication occurs in the North Black Sea and the Azov Sea. In the future, however, this may change. We analyzed trends up to 2050 on the basis of the Millennium Ecosystem Assessment (MEA) scenarios. The results indicate that nutrient loads in rivers draining into the North Black Sea and the Azov Sea may decrease in the coming decades as a result of agricultural trends and environmental policy. However, in these scenarios, the targets of the Black Sea Convention are not met. In the South Black Sea, there is currently little eutrophication. But this may change because of increases in nutrient inputs from sewage in the future.
Covered storage reduces losses and improves crop utilisation of nitrogen from solid cattle manure
Shah, G.M. ; Groot, J.C.J. ; Oenema, O. ; Lantinga, E.A. - \ 2012
Nutrient Cycling in Agroecosystems 94 (2012)2-3. - ISSN 1385-1314 - p. 299 - 312.
ammonia emission - n mineralization - feedlot manure - organic-matter - soil - nutrient - availability - grassland - litter - carbon
A 2-year study was carried out to examine the effects of solid cattle manure storage method on (1) total carbon (C) and nitrogen (N) losses, (2) first-year and residual manure dry matter (DM) and N disappearance after litterbag placement on grassland, and (3) apparent herbage N recovery (ANR) after a single surface application to a sandy grassland field. About twelve tonnes of fresh (FRE) manure taken from a litter barn were stored per treatment as stockpiled (STO), composted (COM) and covered (COV) heaps for 130 days, and total C and N losses were estimated. Thereafter, patterns of DM and N disappearance from FRE, COM and COV manures were monitored using litterbags with three mesh sizes (45 µm, 1 mm and 4 mm). Herbage ANR from these manures was measured at application rates of 200, 400 and 600 kg N ha-1. During the storage period, only about 10 % of the initial Ntotal was lost from the COV heap, whereas these losses were 31 % from the STO heap and 46 % from the COM heap. The respective Ctotal losses were 17, 59 and 67 %. After field placement, overall manure DM and N disappearance rates from all mesh sizes of the litterbags were in the order: COV > FRE > COM (P <0.05). Independent of N application rate, total herbage ANR was the highest from COV and the lowest from COM manure over two growing seasons (23 vs. 14 %; P <0.05). Including the N losses during storage, an almost three times higher herbage ANR (20 vs. 7 %) of the manure N taken from the barn was observed by using COV versus COM manure. In case of FRE manure this ANR fraction was 17 %. It is concluded that COV storage reduced storage C and N losses to a minimum. After field application, manure stored under this method decomposed faster and more N was available for plant uptake, especially when compared to COM manure.
Fruit and vegetable consumption and risk of aggressive and non-aggressive urothelial cell carcinomas in the European prospective investigation into cancer and nutrition
Ros, M. ; Bueno-de-Mesquita, H.B. ; Kampman, E. ; Büchner, F.L. ; Aben, K.K. ; Egevad, L. ; Overvad, K. ; Tjonneland, A. ; Roswall, N. ; Clavel-Chapelon, F. ; Boutron-Ruault, M.C. ; Moiros, S. ; Kaaks, R. ; Teucher, B. ; Weikert, S. ; Ruesten, A.V. ; Trichopoulou, A. ; Naska, A. ; Benetou, V. ; Saieva, C. ; Pala, V. ; Ricceri, F. ; Tumino, R. ; Mattiello, A. ; Peeters, P.H.M. ; Gils, C.H. van; Gram, I.T. ; Engeset, D. ; Chirlaque, M.D. ; Ardanazx, E. ; Rodriguez, L. - \ 2012
European Journal of Cancer 48 (2012)17. - ISSN 0959-8049 - p. 3267 - 3277.
bladder-cancer - vitamin-c - prospective cohort - carotenoids - smoking - diet - carcinogenesis - prevention - nutrient - folate
Background - Many epidemiological studies have examined fruit and vegetable consumption in relation to the risk of urothelial cell carcinoma (UCC) of the bladder, but results are inconsistent. The association between fruit and vegetable consumption and UCC risk may vary by bladder tumour aggressiveness. Therefore, we examined the relation between fruit and vegetable consumption and the risk of aggressive and non-aggressive UCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). Methods - After 8.9 years of follow-up, 947 UCC were diagnosed among 468,656 EPIC participants. Of these, 421 could be classified as aggressive UCC and 433 as non-aggressive UCC cases. At recruitment, fruit and vegetable consumption was assessed by validated dietary questionnaires. Multivariable hazard ratios were estimated using Cox regression stratified by age, sex and center and adjusted for smoking status, duration and intensity of smoking, and energy intake. Results - Total consumption of fruits and vegetables was not associated with aggressive UCC nor with non-aggressive UCC. A 25 g/day increase in leafy vegetables and grapes consumption was associated with a reduced risk of non-aggressive UCC (hazard ratio (HR) 0.88; 95% confidence interval (CI) 0.78–1.00 and HR 0.87; 95% CI 0.77–0.98, respectively), while the intake of root vegetables was inversely associated with risk of aggressive UCC (HR 0.87; 95% CI 0.77–0.98). Conclusion - Our study did not confirm a protective effect of total fruit and/or vegetable consumption on aggressive or non-aggressive UCC. High consumption of certain types of vegetables and of fruits may reduce the risk of aggressive or non-aggressive UCC; however chance findings cannot be excluded.
Warmer climates boost cyanobacterial dominance in shallow lakes
Kosten, S. ; Huszar, V.M. ; Bécares, E. ; Costa, S. ; Donk, E. van; Hansson, L. ; Lurling, M.F.L.L.W. - \ 2012
Global Change Biology 18 (2012)1. - ISSN 1354-1013 - p. 118 - 126.
fytoplankton - klimatologie - cyanobacteriën - temperatuur - meren - oppervlaktewaterkwaliteit - phytoplankton - climatology - cyanobacteria - temperature - lakes - surface water quality - fish community structure - trophic state - phytoplankton community - mesocosm experiments - blooms - nitrogen - nutrient - phosphorus - eutrophication
Dominance by cyanobacteria hampers human use of lakes and reservoirs worldwide. Previous studies indicate that excessive nutrient loading and warmer conditions promote dominance by cyanobacteria, but evidence from global scale field data has so far been scarce. Our analysis, based on a study of 143 lakes along a latitudinal transect ranging from subarctic Europe to southern South America, shows that although warmer climates do not result in higher overall phytoplankton biomass, the percentage of the total phytoplankton biovolume attributable to cyanobacteria increases steeply with temperature.
Phosphorus flows and use efficiencies in production and consumption of wheat, rice and maize in China
Ma, W. ; Ma, L. ; Li, J. ; Wang, F. ; Sisák, I. ; Zhang, F. - \ 2011
Chemosphere 84 (2011)6. - ISSN 0045-6535 - p. 814 - 821.
environmental impacts - food-production - nitrogen - perspective - nutrient
Increasing fertilizer phosphorus (P) application in agriculture has greatly contributed to the increase of crop yields during the last decades in China but it has also increased P flows in food production and consumption. The relationship between P use efficiency and P flow is not well quantified at national level. In present paper we report on P flows and P use efficiencies in rice, wheat, and maize production in China using the NUFER model. Conservation strategies for P utilization and the impact of these strategies on P use efficiency have been evaluated. Total amounts of P input to wheat, rice, and maize fields were 1095, 1240, and 1128 Gg, respectively, in China, approximately 80% of which was in chemical fertilizers. The accumulation of P annually in the fields of wheat, rice, and maize was 29.4, 13.6, and 21.3 kg ha-1, respectively. Phosphorus recovered in the food products of wheat, rice, and maize accounted for only 12.5%, 13.5%, and 3.8% of the total P input, or 3.2%, 2.6%, and 0.9% of the applied fertilizer P, respectively. The present study shows that optimizing phosphorus flows and decreasing phosphorus losses in crop production and utilization through improved nutrient management must be considered as an important issue in the development of agriculture in China.
Assessment of nitrogen fluxes to air and water from site scale to continental scale: an overview
Vries, W. de; Cellier, P. ; Erisman, J.W. ; Sutton, M.A. - \ 2011
Environmental Pollution 159 (2011)11. - ISSN 0269-7491 - p. 3143 - 3148.
biosphere-atmosphere exchange - greenhouse gases - field-scale - model - ammonia - emissions - nutrient - soils - n2o - grasslands
Phytoplankton community composition can be predicted best in terms of morphological groups
Kruk, C. ; Peeters, E.T.H.M. ; Nes, E.H. van; Huszar, V.M. ; Costa, L.S. ; Scheffer, M. - \ 2011
Limnology and Oceanography 56 (2011)1. - ISSN 0024-3590 - p. 110 - 118.
functional types - body-size - plankton - ecology - lake - diversity - classification - nutrient - evolution - patterns
We explored how well the aggregated biovolume of groups of species can be predicted from environmental variables using three different classification approaches: morphology-based functional groups, phylogenetic groups, and functional groups proposed by Reynolds. We assessed the relationships between biovolume of each group and environmental conditions using canonical correlation analyses as well as multiple linear regressions, using data from 211 lakes worldwide ranging from subpolar to tropical regions. We compared the results of these analyses with those obtained for single species following the same protocol. While some species appear relatively predictable, a vast majority of the species showed no clear relationship to the environmental conditions we had measured. However, both the multivariate and the regression analyses indicated that morphology-based groups can be predicted better from environmental conditions than groups based on the other classification methods. This suggests that morphology captures ecological function of phytoplankton well, and that functional groups based on morphology may be the most suitable focus for predicting the composition of communities
Phosphorus demand for the 1970-2100 period: A scenario analysis of resource depletion
Vuuren, D.P. van; Bouwman, A.F. ; Beusen, A.H.W. - \ 2010
Global environmental change : human and policy dimensions 20 (2010)3. - ISSN 0959-3780 - p. 428 - 439.
world - flows - environment - perspective - nutrient
The phosphorus (P) cycle has been significantly altered by human activities. For this paper, we explored the sustainability of current P flows in terms of resource depletion and the ultimate fate of these flows. The analysis shows that rapid depletion of extractable phosphate rock is not very likely, in the near term. Under best estimates, depletion would be around 20-35%. In worst case scenarios, about 40-60% of the current resource base would be extracted by 2100. At the same time, production will concentrate in Asia, Africa and West Asia, and production costs will likely have increased. As there are no substitutes for phosphorus plant nutrients in agriculture, arguably even partial depletion of P resources may in the long run be relevant for the sustainability of agriculture. Consumption trends lead to large flows of phosphorus to surface water and a considerable build-up of phosphorus in agricultural soils in arable lands. This may allow a reduction in future P fertiliser application rates in crop production. Results also indicate a global depletion of P pools in soils under grassland, which may be a threat to ruminant production.
Contribution of complementary foods to the total daily water needs of urban Guatemalan infants
Enneman, A. ; Campos, R. ; Hernandez, L. ; Palma, A.V. ; Vossenaar, M. ; Solomons, N.W. - \ 2010
Journal of Human Nutrition and Dietetics 23 (2010)5. - ISSN 0952-3871 - p. 520 - 528.
milk intake - nutrient - inadequate - toddlers - quality - maize
Background: Estimates of adequate intake (AI) for water only became available in 2005. The daily water AI for 6-12-month-old infants of both sexes is 800 mL. The present study aimed to estimate the water intake of urban infants receiving both breast milk and complementary feeding (CF) and to compare them with the reference AI. Methods: Sixty-four infants, 42 boys and 22 girls, aged 6-12 months on enrolment, from a low-income district of Guatemala City, were recruited to the study. Quantitative 24-h recalls and breastfeeding histories were collected in three serial interviews. The quantity of water was estimated from recipes and food composition moisture values for the CF items reported. The amount of breast milk needed to complement foods and beverages in meeting the individual energy needs was calculated, and breast milk's water contribution was derived accordingly. The total quantity of water in beverages, including human milk, liquids in recipes and moisture of foods, was tabulated as the infants' daily intake. Results: Some 56.3% of the water needs for boys and 41.1% for girls were satisfied by just water obtained from plain water, other complementary beverages and moisture of foods within CF, exclusive of breast milk. Adding the estimated breast milk intake, the median water intake for the infant sample was essentially equal to the 800 mL of the AI. Conclusions: The infants in this low-income community are approximating the recommended AI for daily water through the currently selected pattern of lactation and CF.
Improving load estimates for NO3 and P in surface waters by characterizing the concentration response to rainfall events
Rozemeijer, J.C. ; Velde, Y. van der; Geer, F.C. van; Rooij, G.H. de; Torfs, P.J.J.F. ; Broers, H.P. - \ 2010
Environmental Science and Technology 44 (2010)16. - ISSN 0013-936X - p. 6305 - 6312.
field-scale - land-use - phosphorus - catchments - dynamics - management - separation - frequency - transport - nutrient
For the evaluation of action programs to reduce surface water pollution, water authorities invest heavily in water quality monitoring. However, sampling frequencies are generally insufficient to capture the dynamical behavior of solute concentrations. For this study, we used on-site equipment that performed semicontinuous (15 min interval) NO3 and P concentration measurements from June 2007 to July 2008. We recorded the concentration responses to rainfall events with a wide range in antecedent conditions and rainfall durations and intensities. Through sequential linear multiple regression analysis, we successfully related the NO3 and P event responses to high-frequency records of precipitation, discharge, and groundwater levels. We applied the regression models to reconstruct concentration patterns between low-frequency water quality measurements. This new approach significantly improved load estimates from a 20% to a 1% bias for NO3 and from a 63% to a 5% bias for P. These results demonstrate the value of commonly available precipitation, discharge, and groundwater level data for the interpretation of water quality measurements. Improving load estimates from low-frequency concentration data just requires a period of high-frequency concentration measurements and a conceptual, statistical, or physical model for relating the rainfall event response of solute concentrations to quantitative hydrological changes