Handling the phosphorus paradox in agriculture and natural ecosystems: Scarcity,necessity, and burden of P

This special issue of Ambio compiles a series of contributions made at the 8th International Phosphorus Workshop (IPW8), held in September 2016 in Rostock, Germany. The introducing overview article summarizes major published scientific findings in the time period from IPW7 (2015) until recently, including presentations from IPW8. The P issue was subdivided into four themes along the logical sequence of P utilization in production, environmental, and societal systems: (1) Sufficiency and efficiency of P utilization, especially in animal husbandry and crop production; (2) P recycling: technologies and product applications; (3) P fluxes and cycling in the environment; and (4) P governance. The latter two themes had separate sessions for the first time in the International Phosphorus Workshops series; thus, this overview presents a scene-setting rather than an overview of the latest research for these themes. In summary, this paper details new findings in agricultural and environmental P research, which indicate reduced P inputs, improved management options, and provide translations into governance options for a more sustainable P use.     

Do DBPs swim in salt water pools? Comparison of 60 DBPs formed by electrochemically generated chlorine vs. conventional chlorine

Disinfectants are added to swimming pools to kill harmful pathogens. Although liquid chlorine(sodium hypochlorite) is the most commonly used disinfectant, alternative disinfection techniques like electrochemically generated mixed oxidants or electrochemically generated chlorine, often referred to as salt water pools, are growing in popularity. However, these disinfectants react with natural organic matter and anthropogenic contaminants introduced to the pool water by swimmers to form disinfectio...     

Bioconcentration and half-life of quinalphos pesticide in rice-fish integration system in the Mekong Delta,Vietnam

In order to determine the distribution and enable the elimination of quinalphos, a popular active pesticide compound used in the Mekong Delta, an experiment was set up in a rice-fish integration system in Can Tho City, Vietnam. Fish was stocked into the field when the rice was two-months old. Quinalphos was applied twice in doses of 42.5 g per 1000 m². Water, fish and sediment samples were collected at time intervals and analyzed by a Gas Chromatography Electron Capture Detector system. The results show that quinalphos residues in fish muscles were much higher than those of the water and the bioconcentration factor (logBCF) was above 2 for the fish. The half-life of first and second quinalphos applications were 12.2 and 11.1 days for sediment, 2.5 and 1.1 days for silver barb, 1.9 and 1.3 days for common carp, and 1.1 and 1.0 days for water, respectively.     

Airborne molds and mycotoxins associated with handling of corn silage and oilseed cakes in agricultural environment

In agricultural areas, the contamination of feedstuffs with molds and mycotoxins presents major environmental and health concerns. During cattle feeding, fungi and mycotoxins were monitored in corn silage, oilseed cakes and bioaerosols collected in Normandy. Most of the corn silages were found to be contaminated by deoxynivalenol (mean concentration: 1883 μg kg^?1) while a few of oilseed cakes were contaminated by alternariol, fumonisin B₁ or gliotoxin. In ambient bioaerosols, the values for fungi per cubic meter of air varied from 4.3 × 10² to 6.2 × 10⁵ cfu m^?3. Seasonal variations were observed with some species like Aspergillus fumigatus which significantly decreased between the 2 seasons (P = 0.0186) while the Penicillium roqueforti group significantly increased during the second season (P = 0.0156). In the personal bioaerosols, the values for fungi per cubic meter of air varied from 3.3 10³ to 1.7 10⁶ cfu m^?3 and the number of A. fumigatus spores significantly decreased between the 2 seasons (P = 0.0488). Gliotoxin, an immunosuppressive mycotoxin, was quantified in 3 personal filters at 3.73 μg m^?3, 1.09 μg m^?3 and 2.97 μg m^?3.     

Reply to Discussion1 - by George Ice,George Brown,John Gravelle,C. Rhett Jackson,Jeff Light,Timothy Link,Douglas Martin,Dale McGreer,and Arne Skaugset2 “Stream Temperature Relationships to Forest Harvest in Western Washington”3

Pollock, Michael M. and Timothy J. Beechie, 2010. Reply to Discussion –“Stream Temperature Relationships to Forest Harvest in Western Washington” by George Ice, George Brown, John Gravelle, C. Rhett Jackson, Jeff Light, Timothy Link, Douglas Martin, Dale McGreer, and Arne Skaugset. Journal of the American Water Resources Association (JAWRA) 46(4): 843-847. DOI: 10.1111/j.1752-1688.2010.00456.x     

Hypoxia in the Baltic Sea: Biogeochemical Cycles, Benthic Fauna, and Management

Hypoxia has occurred intermittently over the Holocene in the Baltic Sea, but the recent expansion from less than 10 000 km² before 1950 to >60 000 km² since 2000 is mainly caused by enhanced nutrient inputs from land and atmosphere. With worsening hypoxia, the role of sediments changes from nitrogen removal to nitrogen release as ammonium. At present, denitrification in the water column and sediments is equally important. Phosphorus is currently buried in sediments mainly in organic form, with an additional contribution of reduced Fe-phosphate minerals in the deep anoxic basins. Upon the transition to oxic conditions, a significant proportion of the organic phosphorus will be remineralized, with the phosphorus then being bound to iron oxides. This iron-oxide bound phosphorus is readily released to the water column upon the onset of hypoxia again. Important ecosystems services carried out by the benthic fauna, including biogeochemical feedback-loops and biomass production, are also lost with hypoxia. The results provide quantitative knowledge of nutrient release and recycling processes under various environmental conditions in support of decision support tools underlying the Baltic Sea Action Plan.     

Estimating contaminant mass discharge: a field comparison of the multilevel point measurement and the integral pumping investigation approaches and their uncertainties

In this field study, two approaches to assess contaminant mass discharge were compared: the sampling of multilevel wells (MLS) and the integral groundwater investigation (or integral pumping test, IPT) that makes use of the concentration-time series obtained from pumping wells. The MLS approached used concentrations, hydraulic conductivity and gradient rather than direct chemical flux measurements, while the IPT made use of a simplified analytical inversion. The two approaches were applied at a control plane located approximately 40m downgradient of a gasoline source at Canadian Forces Base Borden, Ontario, Canada. The methods yielded similar estimates of the mass discharging across the control plane. The sources of uncertainties in the mass discharge in each approach were evaluated, including the uncertainties inherent in the underlying assumptions and procedures. The maximum uncertainty of the MLS method was about 67%, and about 28% for the IPT method in this specific field situation. For the MLS method, the largest relative uncertainty (62%) was attributed to the limited sampling density (0.63 points/m(2)), through a novel comparison with a denser sampling grid nearby. A five-fold increase of the sampling grid density would have been required to reduce the overall relative uncertainty for the MLS method to about the same level as that for the IPT method. Uncertainty in the complete coverage of the control plane provided the largest relative uncertainty (37%) in the IPT method. While MLS or IPT methods to assess contaminant mass discharge are attractive assessment tools, the large relative uncertainty in either method found for this reasonable well monitored and simple aquifer suggests that results in more complex plumes in more heterogeneous aquifers should be viewed with caution.     

Scaring as a tool to alleviate crop damage by geese: Revealing differences between farmers’ perceptions and the scale of the problem

Expanding populations of farmland foraging geese are causing escalating conflict with agriculture. We used questionnaires to investigate farmers´ perceptions in mid-Norway of spring staging geese and the extent to which they attempt to reduce pasture damage by goose scaring. We predicted farmers’ scaring effort (a measure of dissatisfaction) to increase on fields closer to goose roosting sites where goose grazing intensity was highest (measured by dropping counts). Results showed no such relationship, suggesting that farmers’ perception of goose use was not linked to actual goose use, but influenced by sociological factors and individual opinion. These results confirm the need to distribute subsidies/compensation to affected farmers based upon quantifiable measures of goose use rather than complaint levels. To avoid further conflict escalation, it is equally important that managers are aware of farmers´ perceptions and their causes, to effectively target communication about policies and measures to mitigate goose–agriculture problems.     

Genotoxicity in adult residents in mineral coal region—a cross-sectional study

The present study assessed the DNA damage in environmentally exposed volunteers living in seven municipalities in an industrial coal region, through the use of the comet assay with blood cells and the micronucleus test with buccal cells. Blood and buccal smears were collected from 320 male volunteers living in seven cities inserted in a coal region. They were ages of 18 and 50 years and also completed a questionnaire intended to identify factors associated with DNA damage through a Poisson regression analysis. The comet assay detected significant differences in DNA damage in volunteers from different municipalities, and neighboring cities (Pedras Altas, Aceguá, and Hulha Negra) had a higher level of DNA damage in relation to control city. Some of the risk factors associated with identified DNA lesions included residence time and life habits. On the other hand, the micronucleus test did not identify differences between the cities studied, but the regression analysis identified risk factors such as age and life habits (consumption of mate tea and low carbohydrates diet). We conclude that there are differences in the DNA damage of volunteers from different cities of the carboniferous region, but the presence of micronuclei in the oral mucosa does not differ between the same cities. Furthermore, we alert that some related factors may increase the risk of genotoxicity, such as residence location and time, and living and food habits. Finally, we suggest the need for continuous biomonitoring of the population, as well as for investing in health promotion in these vulnerable populations.