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Bogs located near agricultural areas often receive high atmospheric nitrogen (N) depositions, and this may result in an increased soil and water N pool and enhanced N supply for plants and microorganisms. The consequences are changes in plant species composition and diffuse emissions of N species from these bogs. However, research on the resilience of rewetted bogs to high atmospheric N inputs is still sparse. Our aim was to evaluate the influence of N depositions on a bog that was rewetted after peat extraction down to bare 'black' (highly decomposed) bog peat. We monitored dry (NH3) and wet (NH4+ and NO3-) deposition, and plant available N as NH4 + and NO3 - in soil and water, over the course of one year. The amount of N stored in vegetation was also quantified. We detected a total N deposition of 32 kg ha-1 y-1 which by far exceeded the critical load (5-10 kg ha-1 y-1) for bogs, but there were no signs of deposition induced N increase in soil and bog water. Our findings suggest, rather, that levels of plant available N were crucially affected by mineralisation in areas with lower water table. Depending on the sampling station, the amount of N stored in the vegetation was 23 or 30 kg ha-1. Although it was likely that uptake by vegetation played a decisive role in buffering the high N depositions, it did not completely explain the whereabouts of excess N. Accordingly, other processes like peat growth, N removal by mowing or denitrification must have contributed to buffering N levels in soil and water. [ABSTRACT FROM AUTHOR]

Water quality monitoring stations are crucial for detecting excess pollutants in river sections, but identifying the causes of these exceedances can be challenging, especially in heavily polluted rivers with multiple contamination sources. To address this issue, we used the SWAT model to simulate pollution loads from various sources in the Haihe River Basin, analyzing the spatiotemporal distribution of pollutants from seven nitrogen/phosphorus sources in sub-basins. Our results show that crop production is the primary contributor to nitrogen and phosphorus loads in the Haihe River Basin, with the highest loads occurring in summer, followed by fall, spring, and winter. However, industries, atmospheric deposition, and municipal sewage treatment plants have a greater downstream impact on nitrogen/phosphorus contributions due to land use changes. The study highlights the need for targeted prevention and control policies based on the primary sources of pollution loads in different regions. • Soil and Water Assessment Tool model has strong applicability in complex watersheds. • Sources of N and P pollution are influenced by land use in the Haihe River Basin. • The spatiotemporal patterns of TN and TP loads in the Haihe River Basin are similar. • TN/TP contributions from point sources and atmospheric deposition are evident. • Stakeholder engagement and prevention at source are key to improving water quality. [ABSTRACT FROM AUTHOR]

Global and climate changes influence the basic conditions for agriculture. Therefore there is not only a demand for a strict climate protection but also for an adaptation of agriculture to changing conditions. For a study region of 60x40 km within the moraine landscape of North-East Germany mainly used for agriculture, water balance, nitrogen and Sulphur loads and crop yields were calculated for the present and for a possible future. The comparison between the Scenario 2050 and the Initial Situation in 2000 revealed significant changes of the water balance (decrease in percolation water, increase in actual evapotranspiration) and the concentration of nitrogen and Sulphur in the percolation water. The crop yields decrease only slightly if the CO 2 fertilizing effect is taken into account. Measures adopted in response to the changing climate conditions to achieve an economically and sustainable agriculture are recommended. [ABSTRACT FROM AUTHOR]

To better understand performance recovery and its mechanism, after the deterioration of an anaerobic ammonia oxidation (anammox) process, experiments were conducted in a UASB reactor. A two-stage anammox reaction was conducted in the reactor, and long-term continuous operation was conducted for 202 d. The mechanism of performance recovery was studied by adjusting the total nitrogen (TN) concentration and hydraulic retention time (HRT) of the influent. The results showed that after the long-term continuous operation, the TN removal efficiency decreased from 88.22 % before deterioration to 11.68 %, and then recovered to 80.63 %. The nitrogen loading rate decreased from 2.25 kg-N/m3/d before deterioration to 0.26 kg-N/m3/d and then recovered to 2.79 kg-N/m3/d. Nitrogen removal load (NRR) decreased from 1.98 kg-N/m3/d to 0.26 kg-N/m3/d before deterioration and recovered to 2.25 kg-N/m3/d. Microbial diversity was analyzed by high-throughput sequencing. During the operation, the dominant anammox strains changed from Candidatus Kuenenia (24.19 %) before deterioration to Candidatus Brocadia (11.90 %) after recovery. The influent TN concentration and HRT were the key factors that affected performance recovery. Reducing the influent TN concentration and shortening the HRT can effectively avoid the inhibition of anammox by the substrate and enable the rapid recovery of nitrogen removal performance. As the microorganisms in the reactor recovered their activity through enrichment, the influent TN gradually increased, and produced NRR higher than the pre-deterioration level, so the reactor performance was fully restored. This study provides a scientific support for recovering the two-stage anammox process performance after deterioration. [Display omitted] • Anammox reactor performance was recovered after 148 d of regulation. • The performance was regulated by reducing HRT and adjusting TN concentration. • NRE recovered from 11.68 % to 80.6 % and NRR from 0.26 kg-N/m3/d to 2.25 kg-N/m3/d. • Candidatus Brocadia replaced Candidatus Kuenenia as dominant bacteria after recovery. • TN concentration had the greatest impact on the performance recovery. [ABSTRACT FROM AUTHOR]

The article discusses a research study on carbon flow differences revealed by δ15N and δ13C through estuarine benthic food webs when responding to relative macroalgae and eelgrass availability. Researchers examined the relationships of food webs in three Waquoit Bay system, Massachusetts sub-estuaries by collecting samples from the three estuaries, extraction of the benthic particulate organic matter (POM) from replicate samples and pooling fauna collected from three random sites in the estuary. Results showed the nitrogen (N) loading differences in the estuaries and the enriched producers and consumers in δ15 in response to high N load and the addition of isotopically heavy nitrogen.

Atmospheric nitrogen (N) deposition is believed to accelerate dissolved organic carbon (DOC) production and could lead to increased heavy metal mobility into water resources. We sampled intact soil cores from the Isle of Skye with low background N deposition history and having Serpentine rock known for its higher heavy metal concentrations including zinc (Zn), copper (Cu), nickel (Ni) and lead (Pb). The effects of 16 (16kgN) and 32 kg N ha−1 year−1 (32kgN), and liming with 32kgN (32kgN+Lime) on soil solution chemistry and heavy metal mobilization were investigated over the 15-month study. Nitrogen in deposition load was added at five ammonium (NH 4 +) to nitrate (NO 3 −) ratios of 9:1, 5:1, 1:1, 1:5 and 1:9 along NO 3 −dominance. We found significant effects of load on Cu and NH 4 +/NO 3 − ratio on pH, DOC and Zn in soil solution. However, under lime and ratio experimental factors, liming significantly influenced pH, DOC, Cu and Pb, and NH 4 +/NO 3 − ratio pH, DOC, Ni and Zn whereas interactions between lime and ratio was significant for Ni and Cu. pH and DOC increased with N load, liming and NO 3 − dominance, and both correlated significantly positively. Liming under NH 4 + dominance enhanced DOC production due to supply of base cations in lime. Mobilization of Cu, Ni and Pb was driven by DOC concentrations and, therefore, increased with load, liming and NO 3 − dominance in deposition. However, in contrast, low pH and high NH 4 + dominance was associated with Zn mobilization in soil solution. On the contrary, despite of some patterns, heavy metals in soil HNO 3 extracts were devoid of any load, lime and NH 4 +/NO 3 − ratio effects. Our study suggests that the effects of N load and forms in deposition on sites with high accumulated loads of metals need to be better quantified through soil solution partitioning models. Image 1 • 16 and 32 kg N ha−1 y−1, and 32 kg N ha−1 y−1 with lime applied to intact cores at five NH 4 +/NO 3 − ratios. • Changes in soil solution pH, DOC, NH 4 +, NO 3 −, Zn, Cu, Ni and Pb were analyzed over 15-month study. • pH and DOC increased with N load, liming and NO 3 − dominance in deposition. • Mobilization of Cu, Ni and Pb was driven by DOC concentrations. • Zn mobility was associated with low pH under NH 4 + dominance. Nitrogen load, liming and NH 4 +/NO 3 − ratios in deposition determined the changes in soil solution pH and DOC which governed Zn, Cu, Ni and Pb mobility. [ABSTRACT FROM AUTHOR]