Spatiotemporal distribution,environmental risk and carbon emission reduction potential of livestock manure in Shaanxi Province,China

Shaanxi is a leading province in animal husbandry(AH)in China.However,the lack of provincial information on the characteristics and utilization potential of livestock manure(LM)hinders crucial management decisions.Therefore,we investigated the spatiotemporal distribution,availability and biogas potential of LM in Shaanxi,and examine the carbon emission reduction potential of AH.There has been a 1.26-fold increase in LM quantities in Shaanxi over the past 35 years,reaching 4635.6×10^(4)t by 2021.LM was mainly concentrated in northern Shaanxi and the eastern part of Hanzhong.Cattle and pig manure were the primary sources of LM,with the average LM land-load of 14.57 t·ha^(−1)in 2021.While the overall AH in Shaanxi has not exceeded the environmental capacity,the actual scales of AH in Ankang and Hanzhong have already surpassed the respective environmental capacities,posing a higher risk of N and P pollutions.In 2021,the estimated biogas energy potential of LM was 1.2×10^(11)MJ.From 2012 to 2021,the average carbon emission reduction potential in Shaanxi was 22%,with an average potential scale of 10%.The results of this research provide valuable data and policy recommendations for promoting the intensive use of LM and reducing carbon emissions in Shaanxi.

Novel sediment source fingerprinting quantifying erosion-induced total nitrogen and total phosphorus outputs from an intensive agricultural catchment,North China

Intensive farming is a primary cause of increased sediment and associated nitrogen(N)and phosphorus(P)loads in surface water systems.Determining their contributing sources,pathways and loads present major challenges in the high-intensity agricultural catchments.Herein,we quantify the sediment sources and magnitude of sediment total N and total P from different sources using a novel application of compound-specific stable isotope(CSSI)and fallout radionuclides(FRNs)of^(137)cs and^(210)pbex in an intensive agricultural catchment in North China.Sediment sources from surface and sub-surface soils were estimated from FRNs fingerprint and accounted for 62±7%and 38±7%respectively,while surface soil from land uses that originated from hillslope were identified by CssI fingerprint.Using a novel application of FRNs and CSSI sediment fingerprinting techniques,the dominant sediment source was derived from maize farmland(44±0.1%),followed by channel bank(38±7%).The sedimentation rate(13.55±0.30 t ha^(-1)yr^(-1))was quantifed by the^(137)cs cores(0-60 cm)at the outlet of this catchment.The total N and total P in sediment were both mostly derived from maize farmland and least from channel banks.The channel banks are significant sediment sources but contribute little to the input of sediment N and P for eutrophication.It implies that chemically-applied farmlands are the main hotspots for catchment erosion control and pollution prevention.The novel application of FRNs and CSSI techniques cost-effectively quantified sediment N and P loads from different sources with a single visit to the catchment,enabling rapid assessment for optimizing soil conservation strategies and land management practices.