HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER:AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

Nutrient pollution of air and water is a persistent problem in Europe.However,the pollution sources are often analyzed separately,preventingthe formulation of integrative solutions.This study aimed to quantify the contribution of agriculture to air,river and coastal water pollution by nutrients.A new MARINA-Nutrients model was developed for Europe to calculate inputs of nitrogen(N)and phosphorus(P)to land and rivers,N emissions to air,and nutrient export to seas by river basins.Under current practice,inputs of N and P to land were 34.4 and 1.8 Tg.yr^(-1),respectively.However,only 12%of N and 3%of P reached the rivers.Agriculture was responsible for 55%of N and sewage for 67%of P in rivers.Reactive N emissions to air from agriculture were calculated at 4.0 Tg.yr^(-1).Almost twofifths of N emissions to air were from animal housing and storage.Nearly a third of the basin area was considered as pollution hotspots and generated over half of N emissions to air and nutrient pollution in rivers.Over 25%of river export of N ended up in the Atlantic Ocean and of P in the Mediterranean Sea.These results could support environmental policies to reduce both air and water pollution simultaneously,and avoid pollution swapping.

WATER POLLUTION AND AGRICULTURE:MULTI-POLLUTANT PERSPECTIVES

Agriculture is an important cause of multiple pollutants in water.With population growth and increasing food demand,more nutrients,plastics,pesticides,pathogens and antibiotics are expected to enter water systems in the 21st century.As a result,water science has been shifting from singlepollutant to multi-pollutant perspectives for large-scale water quality assessments.This perspective paper summarizes and discusses four main highlights related to water pollution and agriculture from the multi-pollutant perspective.These highlights reveal the spatial and temporal distribution and main sources of multiple pollutants in waters.Based on the highlights,a scientific agenda is proposed to prioritize solutions for sustainable agriculture(UN Sustainable Development Goal 2)and clean water(UN Sustainable Development Goals 6 and 14).This agenda points out that when formulating solutions for water pollution,it is essential to take into account multiple pollutants and their interactions beyond biogeochemistry.

Multiple pollutants from crop and livestock production in the Yangtze River: status and challenges

The rapid increase in the proportion of cash crops and livestock production in the Yangtze River Basin has led to commensurate increases in fertilizer and pesticide inputs. Excessive application of chemical fertilizer, organophosphorus pesticides and inappropriate disposal of agricultural waste induced water pollution and potentially threaten Agriculture Green Development(AGD). To ensure food security and the food supply capacity of the Yangtze River Basin, it is important to balance green and development, while ensuring the quality of water bodies. Multiple pollutants affect the transfer, adsorption, photolysis and degradation of each other throughout the soil-plant-water system. This paper considers the impact of multi-pollutants on the nitrogen and phosphorus cycles especially for crops, which are related to achieving food security and AGD. It presents prospective on theory, modeling and multi-pollutant control in the Yangtze River Basin for AGD that are of potential value for other developing regions.

GREEN AGRICULTURE AND BLUE WATER IN CHINA:REINTEGRATING CROP AND LIVESTOCK PRODUCTION FOR CLEAN WATER

Crop and livestock production are essential to maintain food security.In China,crop and livestock production were integrated in the past.Today,small backyard systems are still integrated but the larger livestock farms are landless and largely geographically separated from crop production systems.As a result,there is less recycling of animal manures and there are lower nutrient use efficiencies in the Chinese food production systems.This,in turn,results in considerable losses of nutrients,causing water pollution and harmful algal blooms in Chinese lakes,rivers and seas.To turn the tide,there is a need for agricultural“green”development for food production through reintegrating crop and livestock production.An additional wish is to turn the Chinese water systems“blue”to secure clean water for current and future generations.In this paper,current knowledge is summarized to identify promising interventions for reintegrating crop and livestock production toward clean water.Technical,social,economic,policy and environmental interventions are addressed and examples are given.The paper highlights recommended next steps to achieve“green”agriculture and“blue”water in China.

Optimizing nitrogen management in the food system for sustainable development: a case study of Quzhou County

Nitrogen(N) is an essential nutrient for food production. The rapid increase in population requires high inputs of N to meet the growing food demand. If not managed well, the substantial loss of N from the food system has multiple impacts on grain yield, air and water pollution, and the economic benefits of agricultural. Multi-objective(food security, environmental sustainability and economic sustainability) synergistic consideration of N management in the food system is still lacking. This study employed strategies for optimizing N management in the food system, using Quzhou County as a typical example on the North China Plain. Firstly, a food chain approach was adopted to understand drivers and reasons behind N losses from the food system.Secondly, a top-down approach was used to define multi-objective N management, taking into consideration food security, environmental sustainability and economic sustainability. Multi-objective N management aims to reduce N losses to the environment and increase N use efficiencies,while simultaneously increasing yields and economic benefits. Thirdly, 3R(reduce-retain-recycle) N management strategies were identified for specific crops and animals through a bottom-up approach and then analyzed the potential of these strategies to achieve the multi-objectives. Finally, there is a discussion of how to engage different stakeholders to promote the technologies implementation. This study provides new insights into the synergistic achievement of multi-objective N management in the food system and the development of environmentally-friendly agriculture.

Comments on the article of “Agriculture Green Development:a model for China and the world”

The coming century will be one of grand global challenges.We will be facing global warming,a growing world population and growing economies.To meet the needs of all world citizens in a sustainable way will not be easy.One of the challenges will be to feed the growing world population,while limiting global warming.Food and water security are at risk,and we will need to invest in innovative and clean technologies to ensure that also in the future there will be enough food to feed the word.This all is reflected in the UN Sustainable Development Goals.